U.S. patent application number 15/428088 was filed with the patent office on 2017-05-25 for pavement repair system.
The applicant listed for this patent is William B. Coe. Invention is credited to William B. Coe.
Application Number | 20170145640 15/428088 |
Document ID | / |
Family ID | 51581084 |
Filed Date | 2017-05-25 |
United States Patent
Application |
20170145640 |
Kind Code |
A1 |
Coe; William B. |
May 25, 2017 |
PAVEMENT REPAIR SYSTEM
Abstract
A pavement repair system is provided utilizing solid phase auto
regenerative cohesion and homogenization by liquid asphalt
oligopolymerization technologies. The system is suitable for use in
repairing asphalt pavement, including pavement exhibiting a high
degree of deterioration (as manifested in the presence of potholes,
cracks, ruts, or the like) as well as pavement that has been
subject to previous repair and may comprise a substantial amount of
dirt and other debris (e.g., chipped road paint or other damaged or
disturbed surfacing materials). A system utilizing homogenization
by liquid asphalt oligopolymerization is suitable for rejuvenating
or repairing aged asphalt, thereby improving properties of the
paving material.
Inventors: |
Coe; William B.;
(Wrightwood, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Coe; William B. |
Wrightwood |
CA |
US |
|
|
Family ID: |
51581084 |
Appl. No.: |
15/428088 |
Filed: |
February 8, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15363858 |
Nov 29, 2016 |
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15428088 |
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15148998 |
May 6, 2016 |
9551114 |
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15363858 |
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14702610 |
May 1, 2015 |
9347187 |
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15148998 |
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14373889 |
Jul 22, 2014 |
9057163 |
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PCT/US2014/026755 |
Mar 13, 2014 |
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14702610 |
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13842640 |
Mar 15, 2013 |
8992118 |
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14373889 |
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61799515 |
Mar 15, 2013 |
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61799576 |
Mar 15, 2013 |
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61798090 |
Mar 15, 2013 |
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61794751 |
Mar 15, 2013 |
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61798469 |
Mar 15, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 7/12 20130101; E01C
11/005 20130101; E01C 19/15 20130101; E01C 19/48 20130101; C08L
95/005 20130101; E04B 1/66 20130101; B29C 63/02 20130101; B32B
2419/00 20130101; E01C 23/03 20130101; E01C 23/14 20130101; B32B
37/12 20130101; B32B 2310/0806 20130101; B29L 2031/732 20130101;
C08L 2205/03 20130101; C08L 95/00 20130101; C09D 119/003 20130101;
E01D 19/08 20130101; C08L 21/00 20130101; C08L 2555/86 20130101;
B32B 2037/1253 20130101; B32B 5/02 20130101; E01C 19/4853 20130101;
C08L 2555/84 20130101; B32B 2255/26 20130101; C09D 195/00 20130101;
E01C 23/06 20130101; E01D 22/00 20130101; C09J 119/003 20130101;
E01C 7/187 20130101; E01C 7/358 20130101; B32B 2315/06 20130101;
B32B 37/16 20130101; B32B 2272/00 20130101; E01C 7/26 20130101;
E02D 31/06 20130101; C09J 195/005 20130101; B29K 2021/003 20130101;
B32B 18/00 20130101; E01C 2301/10 20130101 |
International
Class: |
E01C 11/00 20060101
E01C011/00; C08L 95/00 20060101 C08L095/00; E01C 19/48 20060101
E01C019/48; E01C 23/03 20060101 E01C023/03; E01C 7/35 20060101
E01C007/35; E01C 7/18 20060101 E01C007/18 |
Claims
1-20. (canceled)
21. A method for providing an asphalt pavement with a new wearing
surface, comprising: spraying a rubberized asphalt emulsion onto a
surface of an asphalt pavement; broadcasting stone into the
rubberized asphalt emulsion; and irradiating the rubberized asphalt
emulsion with stone and a surface layer of the asphalt pavement
with radiation having a preselected peak wavelength of from 1 nm to
5 mm such that the rubberized asphalt emulsion hardens and bonds to
the stone, whereby the asphalt pavement is provided with a new
wearing surface.
22. The method of claim 21, wherein the peak wavelength of the
radiation is selected such that the radiation penetrates through
and heats the rubberized asphalt emulsion with stone and the
surface layer of the asphalt pavement to a depth of at least two
inches from a topmost pavement surface, wherein a temperature
differential throughout a top two inches of the pavement is
100.degree. F. or less, wherein a highest temperature in the top
two inches of the pavement does not exceed 300.degree. F., and
wherein a minimum temperature in the top two inches of the pavement
is at least 200.degree. F.
23. The method of claim 21, wherein the peak wavelength of the
radiation is selected based on at least one criterion selected from
the group consisting of absorbed wavelength quanta data related to
a stone petrography, an asphaltene/maltene content of the asphalt
of the rubberized asphalt emulsion or the asphalt pavement, an
average crack width by depth topography of the asphalt pavement,
and exploratory testing conducted on representative portions of the
surface of the asphalt pavement.
24. The method of claim 21, wherein the stone is from 1/4 inch to
3/8 inch in diameter.
25. The method of claim 21, wherein the asphalt pavement is an old
road base in need of repair, wherein the old road base is not
disrupted.
26. The method of claim 21, wherein the preselected peak wavelength
is from 1,000 nm to 10,000 mm.
27. The method of claim 21, wherein the preselected peak wavelength
is from 1 nm to 10,000 nm.
28. The method of claim 27, further comprising irradiating the
rubberized asphalt emulsion with stone and the surface layer of the
asphalt pavement with a second radiation having a second
preselected peak wavelength of from 1 mm to 5 mm.
29. The method of claim 21, further comprising subjecting the new
wearing surface to compaction, whereby the irradiated rubberized
asphalt emulsion with stone is fused to the irradiated surface
layer of the asphalt pavement.
30. The method of claim 21, wherein the rubberized asphalt emulsion
comprises an elastomer selected from the group consisting of a
butyl rubber, a styrene-butadiene-styrene polymer, a
styrene/acrylate copolymer, a chlorinated natural rubber, a
thermoplastic, and a bioresin.
31. The method of claim 30, wherein the rubberized asphalt emulsion
comprises a 10,000 to 100,000 molecular weight grafted or ungrafted
polyisobutylene and a 10,000 to 100,000 molecular weight grafted or
ungrafted styrene-butadiene-styrene.
32. The method of claim 31, wherein the rubberized asphalt emulsion
comprises at least one binder crosslink component selected from the
group consisting of polyurethanes, isocyanates, bisphenol A-based
liquid epoxy resins, and aliphatic glycol epoxy resins.
33. The method of claim 32, wherein the rubberized asphalt emulsion
comprises 20% to 40% solids.
34. The method of claim 21, wherein the rubberized asphalt emulsion
comprises butyl rubber, diene modified asphalt, and a triglyceride
bioresin, wherein the rubberized asphalt emulsion contains no
perfluorocarbons and no polyaromatic hydrocarbons as volatile
components.
35. The method of claim 21, wherein the rubberized asphalt emulsion
is a waterborne emulsion of a polymer modified asphalt.
36. The method of claim 21, wherein the stone is granite rock, and
wherein the preselected peak wavelength is from 3,000 nm to 5,000
nm.
37. The method of claim 21, wherein the stone is limestone, and
wherein the preselected peak wavelength is from 3,000 nm to 4,000
nm.
38. The method of claim 21, wherein the stone is sand, and wherein
the preselected peak wavelength is from 5,000 nm to 8,000 nm.
39. The method of claim 21, wherein the radiation is generated by
at least one emitter, wherein each emitter comprises an emitter
panel comprising a birefringent material through which an
electromagnetic radiation generated by the emitter passes, wherein
the birefringent material exhibits biaxial birefringence.
40. The method of claim 21, wherein the broadcasting stone into the
rubberized asphalt emulsion comprises broadcasting a binder coated
stone into the rubberized asphalt emulsion.
41. The method of claim 21, wherein the rubberized asphalt emulsion
with stone forms a layer having a thickness of approximately 1/2
inch.
42. The method of claim 21, further comprising subjecting the
irradiated rubberized asphalt emulsion with stone to vibratory
compaction.
Description
INCORPORATION BY REFERENCE TO RELATED APPLICATIONS
[0001] Any and all priority claims identified in the Application
Data Sheet, or any correction thereto, are hereby incorporated by
reference under 37 CFR 1.57. This application is a continuation of
U.S. application Ser. No. 15/363,858, filed Nov. 29, 2016, which is
a continuation of U.S. application Ser. No. 15/148,998, filed May
6, 2016, now U.S. Pat. No. 9,551,114, which is a continuation of
U.S. application Ser. No. 14/702,610, filed May 1, 2015, now U.S.
Pat. No. 9,347,187, which is a continuation of U.S. application
Ser. No. 14/373,889, filed Jul. 22, 2014, now U.S. Pat. No.
9,057,163, which is the national phase under 35 U.S.C. .sctn.371 of
PCT International Application No. PCT/US2014/026755, filed Mar. 13,
2014, which is a continuation-in-part of U.S. application Ser. No.
13/842,640 filed Mar. 15, 2013, now U.S. Pat. No. 8,992,118, and
which claims the benefit of U.S. Provisional Application No.
61/799,515 filed Mar. 15, 2013, U.S. Provisional Application No.
61/799,576 filed Mar. 15, 2013, U.S. Provisional Application No.
61/798,090 filed Mar. 15, 2013, U.S. Provisional Application No.
61/794,751 filed Mar. 15, 2013, and U.S. Provisional Application
No. 61/798,469 filed Mar. 15, 2013. Each of the aforementioned
applications is incorporated by reference herein in its entirety,
and each is hereby expressly made a part of this specification.
FIELD OF THE INVENTION
[0002] A pavement repair system is provided utilizing solid phase
auto regenerative cohesion and homogenization by liquid asphalt
oligopolymerization technologies. The system is suitable for use in
repairing asphalt pavement, including pavement exhibiting a high
degree of deterioration (as manifested in the presence of potholes,
cracks, ruts, or the like) as well as pavement that has been
subject to previous repair and may comprise a substantial amount of
dirt and other debris (e.g., chipped road paint or other damaged or
disturbed surfacing materials). A system utilizing homogenization
by liquid asphalt oligopolymerization is suitable for rejuvenating
or repairing aged asphalt, thereby improving properties of the
paving material.
BACKGROUND OF THE INVENTION
[0003] Repair and maintenance of the civil infrastructure,
including roads and highways of the United States present great
technical and financial challenges. The American Association of
State Highway Transportation Officials (AASHTO) issued a bottom
line report in 2010 stating that $160 billion a year must be spent
to maintain infrastructure; however, only about $80 billion is
being spent. The result is a rapidly failing infrastructure. New
methods of maintaining existing roads and new methods of
constructing roads that would extend the useful life for the same
budget dollar are needed to meet the challenges of addressing our
failing infrastructure.
[0004] In the United States alone there are approximately 4.4
million center lane miles of asphalt concrete, with a center lane
comprising a 24 foot wide pavement surface having a lane in each
direction. Asphalt concrete paving surfaces are typically prepared
by heating aggregate to 400.degree. F., and applying liquid asphalt
(e.g., by spraying into a pug mill or drum coating) to yield a
mixture of 95% aggregate and 5% asphalt. If a temperature of
approximately 350.degree. F. is maintained for the mixture, it is
considered hot mix asphalt and does not stick to itself as long as
the temperature is maintained. The hot mix asphalt is typically
placed in a transfer truck, which hauls it to the job site, where
it is placed on either a gravel road base or onto an old road
surface that has been previously primed. A paving apparatus
receives the hot mix asphalt from the transfer truck and spreads it
out uniformly across the base surface, and as the material
progressively cools below 250.degree. F. degrees it is compacted
with a roller. The hot mix asphalt is rolled to a uniform density,
and after approximately one to three days of cooling and aging the
surface can be opened to traffic.
[0005] After such asphalt pavement has been in place for several
years, the pavement progressively ages. Water works its way into
the pavement. It begins to lose its integrity on the surface,
causing aggregate at the surface of the pavement to be lost. The
pavement surface roughens as aggregate is lost, and cracks begin to
form. Conventional pavement repair techniques at this stage in the
deterioration process include: pouring hot rubber asphalt into the
cracks, using cold patch (a cold mix asphalt that can be applied to
a damaged road surface, e.g., placed in a pothole, under ambient
temperature conditions using hand tools). Another technique for
repairing pavement exhibiting minimal damage involves application
of a liquid asphalt emulsion to the pavement surface so as to
provide a degree of waterproofing to slow the aging process, or,
for surfaces exhibiting more deterioration, application of a thin
layer of a slurry of aggregate and asphalt emulsion over the top of
the pavement.
[0006] Preparing and installing hot asphalt pavement involves
running aggregate through a heat tube (typically at around
400.degree. F.) where moisture is driven off to prevent boil over
when the rock contacts molten asphalt. The aggregate is added to
asphalt, optionally containing a rubber polymer. The aggregate is
sent through a mill having high velocity tines that rolls the
aggregate through a spray of asphalt. The resulting mixture of
aggregate with baked-on asphalt typically comprises 95% aggregate
and 5% asphalt (optionally with rubber polymer). The mixture exits
the mill at about 350.degree. F. and is transported into waiting
trucks (e.g., a belly dump truck) which are driven to the job site.
New pavement is laid down over an earthen base covered with gravel
that has been graded and compacted. Typically, the new road is not
laid in a single pass. Instead, a first 2-3 inch lift of loose hot
asphalt is laid down and partially compacted, and then a second
lift is laid over the first and compacted. The temperature of the
asphalt concrete pavement at this stage is typically about
140.degree. F. Additional lifts can be added as desired, e.g., to a
depth of approximately 12 inches, depending upon the expected usage
conditions for the road (heavy or light transportation, the
velocity of traffic, desired lifetime). Primer or additional
material is typically not put between layers of lift in new
construction, as the fresh pavement exhibits good adherence to
itself in new construction. New construction design typically never
requires any primer or additional material between the subsequent
lifts.
[0007] After approximately fifteen years of exposure to the
elements, it becomes cost prohibitive to attempt to maintain
asphalt pavement via conventional cold patching, waterproofing, and
slurry techniques. The conventional approach at this stage in the
deterioration of the pavement typically involves priming the
damages surface and applying a layer of hot mix asphalt. For
pavement too deteriorated for application priming and application
of a layer of hot mix asphalt, a cold-in-place recycling process
can be employed. In cold-in-place recycling, typically the topmost
2 to 5 inches of the damaged road surface is pulverized down to a
specific aggregate size and mixed with an asphalt emulsion, and
then re-installed to pave the same road from which the old paving
material has been removed.
[0008] Existing pavement (asphalt or concrete) is typically
repaired by use of an overlay, e.g., a mixture of aggregate and
asphalt such as described above for new road construction. In the
case of repaving over the top of rigid concrete, some type of
primer is typically applied, e.g., as a spray resulting in
application of approximately 10 gallons of primer per 1,000 square
feet of pavement. The primer can be an asphalt emulsion that
provides a tacky surface for the new overlay. A single layer of
overlay can be applied, or multiple layers, typically two or
more.
[0009] Cracks and stresses in a repaired underlying road bed will
quickly imprint themselves on new overlays of paving material, due
to the malleability of the new asphalt under rolling loads. As the
underlying road bed undergoes expansion and contraction under
ambient condition, cracks can be telegraphed up through as much as
three inches of overlying asphalt. A conventional method for
achieving some resistance to the telegraphing of old defects in the
underlying road bed is to put down a hot tack coat of asphalt, lay
a polypropylene mat (similar in appearance to spun-bond
polypropylene, typically 1/4-1/2 inches in thickness, available as
Petromat.RTM. from Nilex, Inc. of Centennial, Colo.) over the hot
tack coat of asphalt, followed by a layer of new hot asphalt
concrete which is then compacted over the existing surface. This
will inhibit the rate of telegraphing of cracks to a limited
extent, such that instead of taking place from 6 months to 2 years
after repair, the cracks do not telegraph for from to 1 year to 3
years after repair. This telegraphing phenomenon by the defects in
an existing aged roadbed manifest surface defects in a new pavement
overlay about three times sooner than is common to a fresh asphalt
concrete pavement placed on a compacted earthen and gravel base; as
is the practice in new construction.
[0010] Deterioration mechanisms of new highways have been
investigated over a 20 year life cycle. Overlays are typically
applied between the twelfth and fifteenth year. Typically, no
significant deterioration is observed over the first five years of
a well-built highway. Within the first five years, cracks or
potholes typically do not appear unless there is acute damage to
the pavement, or loose material underneath the pavement. After the
first five years, physical symptoms of deterioration are observed,
including lateral and longitudinal cracks due to shrinkage of the
pavement mass through the loss of binder and embrittlement of the
asphalt. Cracks ultimately result in creation of a pothole.
Raveling is a mechanism wherein the effects of exposure to water
and sun break down the adhesion between the rock on the top surface
of the pavement and the underlying aggregate, such that small and
then larger rock is released from the pavement. A stress fracture
is where the pavement, for one reason or another, may not have been
thick enough to withstand exposure to an extremely heavy load,
moisture, or poor compaction underneath. When combined with
shrinkage of the asphalt itself as it goes through heating and
cooling cycles, and application of oxidative stress, stress
fractures can also result. Stress fractures are characterized by
extending in different directions (unlike the lateral or
longitudinal cracking as described above).
[0011] The macro-texture of a pavement refers to the visible
roughness of the pavement surface as a whole. The primary function
of the macro-texture is to help maintain adequate skid resistance
to vehicles travelling at high speeds. It also provides paths for
water to escape which helps to prevent wheels of motor vehicles
from hydroplaning. This optionally may be accomplished through
cutting or forming grooves in existing or new pavements.
Micro-textures refer to the roughness of the surface of the
individual stones within the asphalt concrete pavement. It is the
fine texture that occurs on chippings and other exposed parts of
the surfacing. For concrete pavement this is usually the sand and
fine aggregates present at the surface layer and for asphalt it is
usually associated with the type of aggregates used. Micro-texture
creates frictional properties for vehicles travelling at low
speeds. The wet skid resistant nature of a road is dependent on the
interaction of the tire and the combined macro-texture and
micro-texture of the road surface.
[0012] Conventional repair of shallow surface fissures and raveling
uses various methods. Re-saturants are materials that soften old
asphalt. They are typically mixed with an emulsion and sprayed onto
the surface of the old pavement. The material penetrates into the
uppermost 20 or 30 mils of the pavement and softens the asphalt,
imparting flexibility. Thermally fluidized hot asphalt can also be
sprayed directly onto the surface, which hardens and provides
waterproofing. A fog seal is typically sprayed on the surface, and
can be provided with a sand blotter to improve the friction
coefficient. In a chip seal, a rubberized emulsion can also be
sprayed onto the aged pavement, and then stone is broadcast into
the rubberized emulsion which then hardens, bonding the stone.
Slurry seal employs a cold aggregate/asphalt mixture prepared in a
pug mill and placed on the aged pavement surface, but is applied in
a much thinner layer, e.g., 0.25-0.75 inches. Once the pavement
surface is repaired, any safety markings can be repainted.
[0013] The Federal Highway Administration, through the National
Academy of Sciences, has done research into pavement durability. A
20-year long-term paving program (LTPP) was initiated in 1984 in an
attempt to understand the failure mechanisms of paving. At the end
of the 20-year program and after five years of data analysis,
better ways have been developed for measuring pavement failure, the
most noteworthy being the Strategic Highway Research Program (SHRP)
grading system. The SHRP system can be used to determine the
physical qualities of an asphalt product and its potential for
long-term service. Subsequently, mechanical testing was developed
to determine when the ductility and flexibility of the pavement was
diminished, which correlates with end of its useful life as well as
the chemical changes in the asphalt itself over time were studied.
The presence of carbonyl groups and sulfoxides that are generated
over the life of the pavement cross-section was discovered to be
associated with asphalt embrittlement. This discovery now enables
prediction of useful life. Accelerated weathering chambers also can
be employed to determine the rate of formation of these telltale
carbonyl groups and sulfoxides in a new binder system,
binder/aggregate combination, or other paving material thereby
predicting an expected useful life. In terms of the chemistry of
deterioration, study data indicate that asphalt pavement fails
because it becomes brittle. Embrittlement leads to mass loss, which
leads to shrinkage, which produces cracks. Cracks become potholes,
the pavement stops flexing, and aggregate becomes dislodged.
[0014] Deterioration of asphalt binder is generally associated with
asphalt beyond the first 100 microns covering the rock surface. An
asphalt layer on aggregate at depths within 100 microns of the
asphalt/rock interface was found by the 20 year LTDP study to have
not experienced the presence of sulfoxides and carbonyl groups that
are associated with embrittlement. Therefore the properties of that
asphalt were similar to those of virgin asphalt initially placed on
the rock. While not wishing to be bound by theory, it is believed
that the tight bond of the asphalt within the first 100 microns of
the rock surface exhibited a high degree of intimacy. This intimacy
inhibits the movement of scavenging oxidizers into the asphalt
structure, thereby minimizing deterioration. Accordingly, it is
believed that in an aged paving material averaging 95% aggregate
and 5% asphalt, a 100 micron layer of good asphalt surrounds each
aggregate particle, with embrittled asphalt in between. It is this
"embrittlement zone" where ductility is lost and failure takes
place. Air gaps in the cross-section of the pavement can allow
water and air to gain access to the asphalt rock interface. Over a
period of time, the asphalt goes from being flexible to becoming
brittle. The chemistries associated with the embrittlement are
related to the formation of sulfoxide or hydroxyl groups, and
typically there is a loss of a hydrogen atom on the carbon
(oxidation) which causes the key molecular structures to become
shorter, thereby less flexible. Once that happens, the pavement
becomes inflexible, cracks open up, the pavement loses mass, and
rolling loads break up the pavement, causing cracking, potholes,
running, ravelling, and block cracking, each resulting in a loss of
the pavement integrity.
[0015] The conventional methods for repair of surface defects
inclusive of rejuvenators and fog seals typically do not exhibit a
desirable lifespan. The most durable conventional repair, a slurry
seal or a chip seal, may last only 7 or 8 years. An analysis of
pavement failure mechanisms provides an explanation for the poor
lifespan observed for new asphalt pavement and subsequent repairs.
The primary factor is that the repairs do not remedy the underlying
embrittlement of the asphalt binder deep within the pavement
cross-section. The embrittlement results from the scissioning of
the polymer chains present in the asphalt under the influence of
free radicals associated principally with water. Water penetrates
the pavement, and sunlight and traffic over the pavement surface
provides energy for reaction with oxygen and other pavement
components, yielding sulfoxide and carboxylate reaction products
and reduced polymer chain length through reaction with the
resulting free radicals. Loss of polymeric molecular weight impacts
the ability of the pavement to stretch and flex. A secondary
failure mechanism is loss of rock itself due to hydrolytic attack
of the asphalt-rock interface. Rocks typically comprise metal
oxides (e.g., calcium oxide, silicon dioxide, lithium oxide,
potassium oxide, sodium oxide). Hydroxide groups can form upon
exposure to water, resulting in oxidative reactions that impair the
adhesion of asphalt to the rock surface, a process referred to as
stripping.
[0016] Loss of waterproofing typically is a top down mechanism. The
asphalt breaks down from exposure to heavy load and the sun,
causing water to penetrate between the asphalt and rock. The
asphalt can lose its hydrophobicity, with paraffinic components
being broken down into more hydrophilic components, which in turn
accelerate the process of water adsorption. Raveling occurs,
resulting in a loss of macrotexture. Ultimately, the microtexture
of the surface is lost due to abrasion of tires across the surface
rubbing off the asphalt and polishing the rock surface, whereby the
coefficient of friction drops to unacceptable levels. Typically, a
brand new pavement will have a coefficient of friction of between
0.6 and 0.7. Over time, loss of microtexture and ultimately
macrotexture results in the coefficient of friction dropping to
below about 0.35, at which point the pavement becomes inherently
unsafe in terms of steer resistance in the presence of water. Even
if a pavement surface does not have raveling or cracking, it can
still be unsafe to drive on due to loss of adequate surface
texture. Microtexture and macrotexture mechanisms function at
different speeds. Typically, up to about 45 mph the microtexture
controls stopping distance. Between 45 and 50 the macrotexture
begins to have a greater effect on stopping distance, and above 50
mph the macrotexture is the principal determining factor in
stopping distance.
[0017] Accordingly, there are a variety of maintenance techniques
that can be employed on damaged asphalt pavement, some of them more
successful than others in preserving and extending the useful life
of the pavement. It is known that for pavement that is timely and
properly maintained, and repaired in the early stages of
deterioration, the typical useful life can be extended out to 19 or
20 years. However, in the current economic environment, the
conventional approach to road maintenance is to fix the most often
travelled pavement first, and then repair, as budgets allow,
progressively the better pavement, such that a useful life closer
to 12 or 13 years is typically observed.
SUMMARY OF THE INVENTION
[0018] A method for repairing asphalt pavement, such as alligatored
asphalt pavement, is desirable that is both inexpensive when
compared to conventional techniques, while yielding a paving
surface having an equally long or longer useful life when compared
to asphalt pavement repaired by conventional techniques. A method
is also provided for rejuvenating aged asphalt so as to bring its
paving properties closer to that of virgin pavement.
[0019] A composition and method for repairing pavement, that
exhibits an improved lifespan when compared to conventional methods
is desirable. Such a composition can result in improved binding
between the asphalt and rock. Such a composition can also impart
improved resistance to mechanical stress and shearing (e.g., from
rolling loads that operate at an angle of incidence). The
compositions are configured to modulate the failure mechanisms of
the pavement, so as to impart improved waterproofing, maintenance
of microtexture, maintenance of macrotexture, resistance to
embrittlement, resistance to delamination, and resistance to
mechanical stress. These improved properties greatly extend the
lifetime of the pavement beyond that which would be observed for a
conventional new pavement or a conventional repair method on
existing pavement.
[0020] In addition to pavement compositions, coatings and paints
comprising elastomers cured with terahertz radiation are also
provided that exhibit superior properties of useful lifetime,
durability, strength, and flexibility. Construction materials and
coatings for use in bridges and building foundations, and methods
of making same are provided. Materials configured to resist
ballistic forces and methods of making same are provided.
Lightweight concrete blocks and other construction materials, and
methods of making same are provided. Fire-resistant coatings and
construction materials, and methods of making same are provided.
Also provided are binders and elastomers substantially as described
herein, an emitter apparatus substantially as described herein, a
system for repairing pavement substantially as described herein,
and related methods.
[0021] In a generally applicable first aspect (i.e. independently
combinable with any of the aspects or embodiments identified
herein), a method for repairing asphalt, is provided comprising:
passing an emitter over the asphalt, wherein the emitter radiates
terahertz energy into the asphalt to a depth of at least 2 inches,
wherein a temperature differential throughout a top two inches of
asphalt is 100.degree. F. or less, wherein a highest temperature in
the top two inches of asphalt does not exceed 300.degree. F., and
wherein a minimum temperature in the top two inches of asphalt is
at least 200.degree. F., whereby voids and interstices in the
asphalt are disturbed without dehydrogenation of the asphalt, and
whereby oligomers present in the asphalt are linked together into
longer polymer chains, whereby ductility of the asphalt is
improved.
[0022] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the asphalt is in a form of
asphalt pavement.
[0023] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the asphalt pavement is damaged
asphalt pavement, and the method further comprises, before passing
an emitter over the asphalt: preparing a surface of the damaged
asphalt pavement comprising aged asphalt by filling in deviations
from a uniform surface plane with dry aggregate and compacting the
dry aggregate; and applying a reactive asphalt emulsion to the
prepared surface, whereby the reactive emulsion penetrates into
cracks and crevices in the damaged asphalt pavement and into areas
filled with the dry aggregate, wherein the reactive asphalt
emulsion comprises butyl rubber, a diene modified asphalt, and an
environmentally hardened bioresin, and wherein the reactive asphalt
emulsion contains less than 1% perflurocarbons as volatile
components.
[0024] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the method further comprises
removing road reflectors, thermoplastic imprinting, and safety
devices by mechanically removing prior to filling in
deviations.
[0025] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the reactive asphalt emulsion
further comprises a medium to high molecular weight
polyisobutylene.
[0026] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the dry aggregate is pre-coated
with an elastomeric composition, and wherein the reactive asphalt
emulsion is at least partially cured so as to yield dry,
free-flowing coated asphalt.
[0027] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), a temperature differential
throughout a top two inches of asphalt pavement is 50.degree. F. or
less.
[0028] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the terahertz energy comprises
wavelengths of from 1 nm to 5 mm.
[0029] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the terahertz energy comprises
wavelengths of from 1-5 mm.
[0030] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the terahertz energy comprises
wavelengths of from 2-5 mm.
[0031] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the asphalt pavement comprises
granite rock and is further exposed to electromagnetic radiation
that has a peak wavelength of from 3000 to 5000 nm.
[0032] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the asphalt pavement comprises
sand and is further exposed to electromagnetic radiation that has a
peak wavelength of 3000 nm or from 5000 to 8000 nm.
[0033] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the asphalt pavement comprises
limestone and is further exposed to electromagnetic radiation that
has a peak wavelength of from 3000 to 4000 nm.
[0034] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the asphalt pavement comprises
maltene asphalt and is further exposed to electromagnetic radiation
that has a peak wavelength of from 2000 to 8000 nm.
[0035] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the asphalt pavement comprises
asphaltene asphalt and is further exposed to electromagnetic
radiation that has a peak wavelength of from 2000 to 4000 nm.
[0036] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the emitter is a panel
comprising a serpentine wire and a micaceous material through which
energy generated by the emitter passes, and wherein the emitter
produces energy with a power density of from 3 to 15
W/in.sup.2.
[0037] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the oligomers possess 2-150
repeating units.
[0038] In an embodiment of the first aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the method further comprises,
after passing an emitter over the asphalt: allowing the pavement to
cool to below 190.degree. F.; and applying a compacting roller to
the asphalt pavement to minimize voids and surface irregularities,
wherein the asphalt is at a temperature no lower than 150.degree.
F., whereby a density of the compacted asphalt pavement is similar
to that of virgin asphalt pavement.
[0039] In a generally applicable second aspect (i.e. independently
combinable with any of the aspects or embodiments identified
herein), an emitter system is provided for repairing asphalt
pavement, comprising: a structural frame; and one or more emitter
panels situated within the structural frame and pointing downward,
wherein the metal frame is insulated with a layer of a high-density
ceramic, wherein each emitter panel comprises a serpentine wire
positioned between the high-density ceramic and a sheet of a
micaceous material exhibiting biaxial birefringence, wherein each
emitter panels is configured such that, in use, energy generated by
each emitter panel passes through the sheet of micaceous material
and impinges on an asphalt pavement, wherein each emitter panel is
configured to produce energy with a power density of from 3 to 15
W/in.sup.2.
[0040] In an embodiment of the second aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the structural frame is a metal
frame comprising one or more beams attached to one or more wheels,
and wherein the structural frame is configured to prevent bending,
sagging, or twisting even while traversing uneven terrain.
[0041] In an embodiment of the second aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the emitter system further
comprises a power source configured to supply electrical power to
the one or more emitter panels, wherein the power source is a
portable generator.
[0042] In an embodiment of the second aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the portable generator is a
diesel generator configured to deliver at least 250 kW.
[0043] In an embodiment of the second aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the emitter system further
comprises a power interrupting mechanism and a positioning
system.
[0044] In an embodiment of the second aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the emitter system further
comprises a power distribution device disposed on at least part of
the one or more emitter panels and on at least part of the frame,
wherein the power distribution device comprises one or more circuit
breakers or other power interrupting mechanisms.
[0045] In an embodiment of the second aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the system is sized so as to
irradiate a standard lane width of asphalt pavement in a single
pass.
[0046] In an embodiment of the second aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), each emitter panel is in a shape
of a square or a rectangle having dimensions of approximately 12
inches by approximately 24 inches, and wherein the emitter panels
are arranged in an array wherein each emitter panel abuts an
adjacent emitter panel, and wherein each emitter panel is connected
in parallel or in serial with other emitter panels.
[0047] In an embodiment of the second aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the array is approximately 12
feet wide, 8 feet long, and approximately 2 feet high.
[0048] In an embodiment of the second aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the emitter system further
comprises a vehicle configured to pull the array and the power
source over an asphalt pavement.
[0049] In a generally applicable third aspect (i.e. independently
combinable with any of the aspects or embodiments identified
herein), a method is provided for repairing an asphalt pavement,
comprising: passing the emitter system of the second aspect over an
asphalt pavement in need of repair, wherein the emitter system
radiates terahertz energy into the asphalt pavement to a depth of
at least 2 inches, wherein a temperature differential throughout a
top two inches of the asphalt pavement is 100.degree. F. or less,
wherein a highest temperature in the top two inches of the asphalt
pavement does not exceed 300.degree. F., and wherein a minimum
temperature in the top two inches of the asphalt pavement is at
least 200.degree. F., whereby voids and interstices in the asphalt
pavement are disturbed without dehydrogenation of the asphalt in
the asphalt pavement, and whereby oligomers present in the asphalt
of the asphalt pavement are linked together into longer polymer
chains, whereby ductility of the asphalt is improved.
[0050] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the asphalt pavement is damaged
asphalt pavement, the method further comprising, before passing an
emitter over the asphalt: preparing a surface of the damaged
asphalt pavement comprising aged asphalt by filling in deviations
from a uniform surface plane with dry aggregate and compacting the
dry aggregate; and applying a reactive asphalt emulsion to the
prepared surface, whereby the reactive emulsion penetrates into
cracks and crevices in the damaged asphalt pavement and into areas
filled with the dry aggregate, wherein the reactive asphalt
emulsion comprises butyl rubber, a diene modified asphalt, and an
environmentally hardened bioresin, and wherein the reactive asphalt
emulsion contains less than 1% perflurocarbons as volatile
components.
[0051] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the method further comprises
removing road reflectors, thermoplastic imprinting, and safety
devices by mechanically removing prior to filling in
deviations.
[0052] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the reactive asphalt emulsion
further comprises a 10,000 to 100,000 molecular weight grafted or
ungrafted polyisobutylene and a 10,000 to 100,000 molecular weight
grafted or ungrafted styrene-butadiene-styrene.
[0053] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the dry aggregate is pre-coated
with an elastomeric composition, and wherein the reactive asphalt
emulsion is at least partially cured so as to yield dry,
free-flowing coated asphalt.
[0054] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), a temperature differential
throughout a top two inches of asphalt pavement is 100.degree. F.
or less.
[0055] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the terahertz energy comprises
wavelengths of from 1 nm to 5 mm.
[0056] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the terahertz energy comprises
wavelengths of from 2 nm to 5 mm.
[0057] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the oligomers possess 2-150
repeating units.
[0058] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the method further comprises,
after passing the emitter system over the asphalt: allowing the
pavement to cool to below 240.degree. F.; and applying a compacting
roller to the asphalt pavement to minimize voids and surface
irregularities, wherein the asphalt is at a temperature no lower
than 150.degree. F., whereby a density of the compacted asphalt
pavement is similar to that of virgin asphalt pavement.
[0059] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the step of applying a reactive
asphalt emulsion further comprises heating the asphalt pavement;
wherein the asphalt pavement comprises granite rock and is exposed
to electromagnetic radiation that has a peak wavelength of from
3000 to 5000 nm in order to heat the asphalt pavement.
[0060] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the step of applying a reactive
asphalt emulsion further comprises heating the asphalt pavement;
wherein the asphalt pavement comprises sand is further exposed to
electromagnetic radiation that has a peak wavelength of 3000 nm or
from 5000 to 8000 nm in order to heat the asphalt pavement.
[0061] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the step of applying a reactive
asphalt emulsion further comprises heating the asphalt pavement;
wherein the asphalt pavement comprises limestone and is exposed to
electromagnetic radiation that has a peak wavelength of from 3000
to 4000 nm in order to heat the asphalt pavement.
[0062] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the step of applying a reactive
asphalt emulsion further comprises heating the asphalt pavement;
wherein the asphalt pavement comprises maltene asphalt and is
exposed to electromagnetic radiation that has a peak wavelength of
from 1000 to 10,000 nm in order to heat the asphalt pavement.
[0063] In an embodiment of the third aspect, which is generally
applicable (i.e., independently combinable with any of the aspects
or embodiments identified herein), the step of applying a reactive
asphalt emulsion further comprises heating the asphalt pavement;
wherein the asphalt pavement comprises asphaltene asphalt and is
exposed to electromagnetic radiation that has a peak wavelength of
from 1000 to 4000 nm in order to heat the asphalt pavement.
[0064] Any of the features of an embodiment of the first through
third aspects is applicable to all aspects and embodiments
identified herein. Moreover, any of the features of an embodiment
of the first through third aspects is independently combinable,
partly or wholly with other embodiments described herein in any
way, e.g., one, two, or three or more embodiments may be combinable
in whole or in part. Further, any of the features of an embodiment
of the first through third aspects may be made optional to other
aspects or embodiments. Any aspect or embodiment of a method can be
performed by a system or apparatus of another aspect or embodiment,
and any aspect or embodiment of a system can be configured to
perform a method of another aspect or embodiment.
DESCRIPTION OF THE DRAWINGS
[0065] FIG. 1A provides a top view of an apparatus for applying
aggregate and reactive emulsion to paving surface to be
repaired.
[0066] FIG. 1B provides a side and front view of the apparatus of
FIG. 1A. An air pot adhesive tank is not depicted. Electric power
and compressed air can be provided to the apparatus by a support
unit, not depicted. The hopper is loaded with a heated aggregate,
and the apparatus is configured to move at a speed of 20 feet per
minute, with a maximum speed of delivery of aggregate of 75 feet
per second.
[0067] FIG. 2 provides a schematic view of emitter of one
embodiment employed in a system to cure a polymer modified asphalt
emulsion and stone composite slurry over a damaged pavement.
[0068] FIG. 3A and FIG. 3B provide a schematic view of a portable
emitter device.
[0069] FIG. 4 illustrates various fatigue life considerations and
their impact on plausible useful life.
[0070] FIG. 5 depicts a Hamburg Wheel Test apparatus employed to
test selected asphalt pavement cores.
[0071] FIG. 6 provides a comparison of attributes of various cores
tested.
[0072] FIG. 7A provides results of a Hamburg Wheel Tracker test for
left dock (L3, L6, L9) asphalt pavement cores.
[0073] FIG. 7B provides results of a Hamburg Wheel Tracker test for
right dock (R3, R6, R9) asphalt pavement cores.
[0074] FIG. 8A provides results of a Hamburg Wheel Tracker test for
left dock (L3, L6, L9) asphalt pavement cores prepared so as to
achieve maximum cross-linking in all three aspects.
[0075] FIG. 8B provides results of a Hamburg Wheel Tracker test
conducted on the same L3, L6, and L9 asphalt pavement cores of FIG.
7A that had already been subjected to 25,000 cycles.
[0076] FIG. 9 provides a schematic depicting steps involved in
reconstruction of damaged or aged pavement using emitter technology
of an embodiment.
[0077] FIG. 10 provides a cost per lane miles per year comparison
of emitter technology of an embodiment versus conventional pavement
rejuvenation technologies.
[0078] FIG. 11 provides a comparison of attributes of emitter
technology versus conventional pavement rejuvenation
technologies.
[0079] FIG. 12 provides a comparison of ASTM D2486 scrub resistance
test results for conventional pavement coatings versus TractionSeal
Atomized Slurry (-150 stone).
[0080] FIG. 13A through FIG. 13D are photographs of the coatings
subjected to the ASTM D2486 scrub resistance test of FIG. 11. They
include a high performance coal tar at 500 cycles (FIG. 13A), a
premium seal coat at 650 cycles (FIG. 13B), an acrylic traffic
striping paint at 1250 cycles (FIG. 13C), and a TractionSeal
atomized slurry at 1650 cycles (FIG. 13D).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0081] The following description and examples illustrate a
preferred embodiment of the present invention in detail. Those of
skill in the art will recognize that there are numerous variations
and modifications of this invention that are encompassed by its
scope. Accordingly, the description of a preferred embodiment
should not be deemed to limit the scope of the present
invention.
[0082] Contrary to conventional methods, the systems of various
embodiments and associated paving repair methods not only repair
the pavement to a uniform surface with paving properties similar or
superior to conventional or conventionally repaired asphalt paving,
but also change the character of the underlying deteriorated road
bed to minimize or eliminate the telegraphing of cracks. This
character of the underlying pavement is a function of, e.g., the
starting composition of the road, how the road was initially
manufactured, exposure of the road to ambient conditions and
different loads over time, and prior repair processes.
[0083] Pavement that has undergone the long term stresses of sun,
rain and mechanical loads endures a continuous, oxidative chemical
attack which results in mass loss to the binder. As asphalt binder
mass loss occurs, the pavement shrinks, forming crack patterns:
laterally, longitudinally and into an alligatored mat. Visual,
physical evidence of this crack propagation usually begins within
the first seven years of the installation of a new asphalt concrete
(AC) pavement road.
[0084] A detailed reaction mechanism of asphalt oxidation,
resulting in this mass loss of chemicals, remains a developing
science. It is generally accepted that resinous sub-components such
as naphthene aromatic and polar aromatic fractions are consumed
during the oxidation process. These resins constitute the
continuous, solvating-suspension phase of asphalt; and, taken as a
whole, are referred to as maltenes. Suspended within the maltenes
are a high molecular weight substance known as asphaltenes. While a
final development of this reaction mechanism is being developed,
research scientists have identified the production rate(s) of
carbonyl groups such as ketones and carboxylic acid and sulfoxides,
identified by infrared spectroscopy, as the functional
`fingerprint` that the mechanism is progressing. A detailed
discussion of the relationship between asphalt compatibility, flow
properties, and oxidative aging is provided by Pauli et al., Int.
J. Pavement Res. Techol. 6(1):1-7, the entire contents of which is
hereby incorporated by reference herein. Pauli et al. provide
methodology for determining aging in asphalt pavement, which can be
employed to determine the degree of aging of asphalt pavement,
enabling a comparison of the quality of repair attained by various
methods (e.g., methods of the embodiments versus conventional Hot
In-Place Recycling, or conventional cold patch or hot patch
technology).
[0085] Asphalt concrete ductility and adhesion is primarily a
function of the maltene components. Aged asphalt binders,
containing a substantially high percentage of asphaltenes, exhibit
brittleness and sufficient loss of strength whereby rolling
mechanical loads accelerate the rate of damage to the stone-asphalt
composite structure. The uppermost one-half inch (0.50'')
cross-section of AC pavement has the highest concentration of
asphaltenes as the oxidative mechanism is accelerated by the
concentrated presence of moisture, air and sunlight at the pavement
surface. Such aged and alligatored pavement is repaired using the
pavement repair systems of various embodiments.
[0086] Solid phase auto-regenerative cohesion can be achieved
within an asphalt through the use of functional bio-resin modified,
conventional emulsions to achieve a robust fatigue life, including
self-healing properties, for infrastructure elements such as roads
and concrete structures. Homogenizing asphalt liquid oligomers
involves use of a highly efficient, heavy industrial, mobile
heating platform which is capable of emitting a broad bandwidth of
energy between near infrared to near microwave. The technology for
road construction and restoration has been developed to optimize
adhesive qualities and curing processes which substantially
attenuate well understood stress-strain relationships within the
aggregate binder system; thereby extending fatigue life.
Pavement Preparation Stage
[0087] The initial stage in the pavement repair methodology
preferably involves a preparatory stage. The rough surface and
cracks of aged, e.g., alligatored pavement are typically riddled
with dirt and organic matter, which are removed to allow new slurry
material to come in contact with the original stone-asphalt
composite structure. In this preparatory stage, the pavement
surface is cleared of such debris, as well as pavement markers
(road reflectors, raised pavement markers, temporary polyurethane
markers, tactile pavement structures, and the like).
[0088] It is generally preferred to remove pavement markers (road
reflectors, raised pavement markers, temporary polyurethane
markers, tactile pavement structures, thermoplastic imprinting,
crosswalk markings, or other marking or safety devices) by
mechanically removing, e.g., scraping off or combusting, prior to
conducting further steps. An advantage of the methodology of
various embodiments over conventional processes is that there is no
need to clean the pavement beyond broom clean, e.g., by removing
dirt and pavement markers, and there is also no need to remove any
paint or other such markings on the pavement surface.
[0089] Debris removal is advantageously accomplished by applying a
pressurized air-water mixture to the surface; however, other
methods can be performed instead of or in conjunction with
pressurized treatment. For example, the surface can be cleaned
using pressurized air only, pressurized water only, a pressurized
solvent, sweeping, vacuuming, or the like. In a preferred
embodiment, debris removal is preferably accomplished using a low
volume, high pressure water blasting system operating in the
100-500 psi range. A nozzle jet which delivers a conical pattern is
particularly preferred because it leaves no spray `shadow` as the
washing device moves parallel to the surface of the pavement. A
vacuum system positioned just ahead and just behind the high
pressure washing system can minimize the possible negative
environmental impact caused by dislodged material being transferred
into the atmosphere and adjacent ditch line. A conventional Hot
In-Place Recycle process virtually never follows this practice,
since when the uppermost pavement cross-section (approximately the
top 2'' of pavement) is planed or scarified, the dirt and organic
debris is simply rolled into the processed pavement, thereby
becoming small defects to the final, recycled pavement finish.
[0090] Large cracks (e.g., cracks wider than one inch), potholes
and divots are preferably filled with suitable cold or warm patch
asphalt concrete material and compacted to a dense structure
parallel to the elevation of the surrounding pavement surface. In
some embodiments, deviations from a uniform surface plane (e.g.,
potholes, divots, cracks, grooves, compressions, ruts, and the
like) in the pavement are filled and compacted with select
gradations of dry aggregate, e.g., prior to application of a cold
or warm patch asphalt, or an asphalt emulsion. Deviations from a
uniform surface plane can penetrate deep into the surface of a
rough pavement, typically to a depth of up to 3 or 4 inches. The
aggregate serves to infill lost volume to the structure and return
the pavement surface to a uniform plane, with no divots, ruts, or
other sizeable irregularities. The aggregate is also selected to
exhibit the proper combination of micro and macro texture to ensure
good traction for vehicles traveling over the road under ambient
conditions. Typical aggregate size ranges from 1/4 inches in
diameter to 3/8 inches in diameter; however, smaller or larger
aggregate can be employed. Suitable aggregate includes coarse
particulate material typically used in construction, such as sand,
gravel, crushed stone, slag, recycled concrete or asphalt
pavements, ground tire rubber, and geosynthetic aggregates. In
paving applications, the aggregate serves as reinforcement to add
strength to the overall composite material. Aggregates are also
used as base material under roads. In other words, aggregates are
used as a stable foundation or road/rail base with predictable,
uniform properties (e.g. to help prevent differential settling
under the road or building), or as a low-cost extender that binds
with more expensive cement or asphalt to form concrete. The
American Society for Testing and Materials publishes a listing of
specifications for various construction aggregate products, which,
by their individual design, are suitable for specific construction
purposes. These products include specific types of coarse and fine
aggregate designed for such uses as additives to asphalt and
concrete mixes, as well as other construction uses. State
transportation departments further refine aggregate material
specifications in order to tailor aggregate use to the needs and
available supply in their particular locations. Sources of
aggregates can be grouped into three main categories: those derived
from mining of mineral aggregate deposits, including sand, gravel,
and stone; those derived from of waste slag from the manufacture of
iron and steel; and those derived by recycling of concrete, which
is itself chiefly manufactured from mineral aggregates. The
largest-volume of recycled material used as construction aggregate
is blast furnace and steel furnace slag. Blast furnace slag is
either air-cooled (slow cooling in the open) or granulated (formed
by quenching molten slag in water to form sand-sized glass-like
particles). If the granulated blast furnace slag accesses free lime
during hydration, it develops strong hydraulic cementitious
properties and can partly substitute for Portland cement in
concrete. Steel furnace slag is also air-cooled. Glass aggregate, a
mix of colors crushed to a small size, is substituted for many
construction and utility projects in place of pea gravel or crushed
rock. Aggregates themselves can be recycled as aggregates. Many
polymer-based geosynthetic aggregates are also made from recycled
materials. Any solid material exhibiting properties similar to
those of the above-described aggregates may be employed as
aggregate in the processes of various embodiments. Once the dry
aggregate is placed in the damaged areas (potholes, large divots,
large cracks, or compressions), it is preferably compacted,
smoothed and leveled off.
Reactive Asphalt Emulsion Stage
[0091] After the surface of the aged pavement is cleaned, a
reactive asphalt emulsion or an aggregate composite slurry, e.g., a
hot slurry, is sprayed, poured, or otherwise applied onto cleaned
(and optionally hot patch asphalt concrete, cold patch asphalt
concrete, and/or the dry aggregate-filled) surface. The reactive
asphalt emulsion and/or aggregate composite slurry thus applied
quickly penetrates into small cracks and crevices in the aged
pavement as well as dry aggregate-filled areas, providing a
substantially fully saturated cross section to a surface of the
plane of the road. Because of the high penetrating ability of the
reactive asphalt emulsion in the emulsion and aggregate composite
slurry, only a small amount of binder is needed to form a strong
bond with the dry aggregate--typically approximately 10% binder to
90% dry aggregate is employed. The reactive emulsion is preferably
hot and typically applied in the form of a 20% to 40% solid
emulsion in water. The water in the reactive asphalt emulsion
either flashes off during subsequent activities, or is absorbed by
the aggregate or otherwise remains in the paving system. The binder
upon curing bonds not only the new aggregate together, but also new
aggregate to old pavement, and old pavement together.
[0092] The process methods utilize various combinations of
elastomers and other components so as to achieve a road surface
exhibiting an extremely good toughness, extremely good
stretchability, good environmental resistance, and good adhesion.
The compositions are waterborne, sprayable, and can be provided as
a single package. A plurality of crosslinkable binder elements is
employed. In addition to binding new aggregate and aged pavement,
the reactive emulsion compositions may be configured for use as a
primer/tack coat, a stress absorbing interlayer, or a texture
restoring and waterproofing top coat.
[0093] The compositions exhibit viscosities suitable for processing
using conventional paving techniques, and polymerize at a
temperature compatible with conventional asphalt paving
temperatures. Dissolving diluents and plasticizers are employed in
conjunction with the elastomers such that the rubberized mixture of
elastomer and asphalt is rendered into liquid form at room
temperature, which yields tremendous advantages in terms of
handleability and ease of installation in addition to long term
performance of the resulting paving material. The elastomer
compositions include butyl rubber, diene modified asphalt, and
chemically fortified bioresins (bioresins that have been taken
through a reactor cycle to enhance long term stability, sun
resistance, and long term hydrolytic resistance), and contain
negligible (<1%) to zero perflurocarbons (PFCs) and negligible
(<1%) polyaromatic hydrocarbons (PAHs) as the volatile
components.
[0094] Alternatively to and in conjunction with the placement of
dry aggregate in voids as previously described, the elastomer
compositions can be prepared as an ambient liquid that, at the job
site, may be sprayed into a mixer with aggregate. The composition
coats the stone using similar techniques as in a hot mix plant,
except that it is done at ambient temperature. The coated aggregate
is laid on the ground and spread with conventional drag boxes or
paving machines at a very thin coating. Depending upon the size of
the aggregate, a thickness of 1/10 inch can be obtained (e.g.,
using spray coating or other deposition techniques); however,
thicknesses of approximately 1/2 inch are typically employed with
aggregate having a diameter of up to approximately 3/8 inches.
[0095] The reactive emulsion is a waterborne emulsion of a polymer
modified asphalt. The asphalt itself can be provided in emulsion
form. Asphalt, also referred to as bitumen, is a sticky, black and
highly viscous liquid or semi-solid that is present in most crude
petroleums and in some natural deposits. Asphalt is used as a glue
or binder mixed with aggregate particles to create asphalt
pavement. The terms "asphalt" and "bitumen" are often used
interchangeably to mean both natural and manufactured forms of the
substance. Asphalt is the refined residue from the distillation
process of selected crude oils and boils at 525.degree. F.
Naturally occurring asphalt is sometimes referred to as "crude
bitumen." Asphalt is composed primarily of a mixture of highly
condensed polycyclic aromatic hydrocarbons; it is most commonly
modeled as a colloid.
[0096] A number of technologies allow asphalt to be mixed at
temperatures much lower than its boiling point. These involve
mixing the asphalt with petroleum solvents to form "cutbacks" with
reduced melting point or mixtures with water to turn the asphalt
into an emulsion. Asphalt emulsions contain up to 70% asphalt and
typically less than 1.5% chemical additives. There are two main
types of emulsions with different affinity for aggregates, cationic
and anionic.
[0097] Asphalt can also be made from non-petroleum based renewable
resources such as sugar, molasses, rice, corn, and potato starches,
or from waste material by fractional distillation of used motor
oils.
[0098] The asphalt can be modified by the addition of polymers,
e.g., natural rubber or synthetic thermoplastic rubbers. Styrene
butadiene styrene and styrene ethylenebutadiene styrene are
thermoplastic rubbers. Ethylene Vinyl Acetate (EVA) is a
thermoplastic polymer. The most common grade of EVA for asphalt
modification in pavement is the classification 150/19 (a melt flow
index of 150 and a vinyl acetate content of 19%). The polymer
softens at high temp, and then solidifies upon cooling. Typically,
approximately 5% by weight of the polymeric additive is added to
the asphalt. Rubberized asphalt is particularly suited for use in
certain embodiments.
[0099] Functionalized triglyceride bioresins can be employed as
thermoset components in certain emulsion formulations. Thermosets
harden at high temperature. When employed in combination with a
thermoplastic component, the composition maintains its shape better
on heating and under high temperature conditions. Suitable
bioresins are derived from triglycerides--fatty acid triesters of
the trihydroxy alcohol glycerol Triglycerides are an abundant
renewable resource primarily derived from natural plant or animal
oils that contain esterified mono- to poly-unsaturated fatty acid
side chains. They can be obtained from a variety of plant sources,
e.g., linseed oil, castor oil, soybean oil. Linseed oil comprises
an average of 53% linolenic acid, 18% oleic acid, 15% linoleic
acid, 6% palmitic acid, and 6% stearic acid. Cross-linking occurs
at points of unsaturation on the fatty acid side chains. The
triglycerides can be modified to contain epoxy and/or hydroxy
groups by methods known in the art to improve cross-linking and to
allow the triglyceride to be cross-linked using conventional
urethane crosslinking chemistries.
[0100] Suitable binder crosslink components include resins that are
multifunctional and react with active hydrogens, e.g., in
carboxylic or carbonyl, or hydroxyl. These resins can include
polyurethanes, isocyanates, bisphenol A-based liquid epoxy resins,
and aliphatic glycol epoxy resins as marketed by The Dow Chemical
Company. The binder crosslink component is water dispersible but
will stay buffered from going into a crosslink in the presence of
water. Upon evaporation of the water, it will self-cross within 24
hours just from UV initiation. As long as water is present in the
mix, the components can remain in proximity without cross-linking
(e.g., yielding a single component formulation).
[0101] Suitable suspension components include pre-crosslinked
bioresin suspension gels. They react with both the crosslink
component and catalyst to yield a tough, water resistant, shear
resistant plastic. The suspension component is preferably
relatively inexpensive, has tremendous robustness, and is not
hydrophobic.
[0102] Suitable catalysts include multi-functional pre-dispersed
initiators (MFXD. Multifunctional initiators are those that possess
more than one functional group capable of providing a site for
chain growth. The catalyst assists in improving growth of molecular
weight, and when compounded into the polymer imparts robustness.
The catalyst can be activated by either ultraviolet radiation
(e.g., sunlight) or heat. Suitable multifunctional catalysts can
include one or more sulfates and a reactive metal that is an
electron scavenger, which can cause crosslinking between a
hydrogen-seeking crosslinking agent and other functional groups in
the presence of water.
[0103] The components of the reactive emulsion composition can
undergo a thermotropic conversion, resulting in entanglement and/or
bridging at functional groups such that the resulting reaction
product comprises both thermoplastic and thermoset elements. The
resulting composition exhibits a superior suspension (the "yield")
against the settling of the much denser inorganic element (fine to
coarse aggregate) by the formation of a "clathrate" or "cage-like"
medium. This fully integrated, interlocking connectivity between
the three polymeric components maintains the aggregate in place and
better protected from the elements than in conventional
formulations.
[0104] The thermoplastic component and the thermoset/suspending
components possess chain-terminating functional groups that are
hindered mostly by water but will selectively react to form a
crosslink, upon water evaporation, to the thermoplastic
functionality rather than to the functionality of sister thermoset
molecules, thereby forming a true thermotrope rather than a less
precise molecularly entanglement which exhibits more amorphous (and
less useful) physical properties. The composition can be provided
as a single package, which is activated/cross-linked upon removal
of the water. The chain chemistry is such that thermoplastic
moieties are coupled to thermoset moieties. When heated, it will
act like a thermoplastic but it will have substantial resistance to
thermal distortion because of the thermoset components. The
relative amounts of thermoplastic and thermoset components will
determine the resistance. For example, a small amount of
thermoplastic moieties with a large amount of thermoset moieties
will exhibit little plasticity upon heating. The resulting
cross-linked material can be considered to be a thermotrope that
will behave like both a thermoset and a thermoplastic at different
temperatures.
[0105] The thermoplastic component in the water-borne compositions
of selected embodiments is a preferably a polymer modified asphalt
emulsion, with the polymer typically a styrene, ethylene, butadiene
styrene, or a styrene butadiene styrene polymer. The midblock,
e.g., butadiene and/or ethylene butadiene, can be linear or radial.
Polyethylene glycols, such as those available from Kraton and
Asahi, are water-soluble nonionic oxygen-containing high-molecular
ethylene oxide polymers having two terminal hydroxyl groups. They
are available in a broad range of molecular weight grades, and
include crystalline thermoplastic polymers (MW>2000) suitable
for use in certain compositions of the various embodiments. An
additional broad range of properties is available by integrating
polyisobutylene rubber (e.g., Oppanol.RTM. manufactured by BASF of
Ludwigshafen am Rhein, Germany). The Oppanol.RTM. polyisobutylenes
are of medium and high molecular weight, ranging from 10,000 MW up
to 5,000,000 MW. TABLE 1 lists properties of commercially available
Oppanol.RTM. polyisobutylenes that are suitable for use in
elastomer compositions of various embodiments.
TABLE-US-00001 TABLE 1 Viscosity in Average solution molecular
(isooctane, Staudinger weight, 20.degree. C.) Index viscosity
Concentration (J0) average (Mv) Stabilized Oppanol .RTM. [g/cm3]
[cm3/g] [g/mol] [with BHT] medium-molecular-weight Oppanol .RTM. B
10 SFN 0.01 27.5-31.2 40 000 No B 10 N 0.01 27.5-31.2 40 000 Yes B
11 SFN 0.01 32.5-36.0 49 000 No B 12 SFN 0.01 34.5-39.0 55 000 No B
12 N 0.01 34.5-39.0 55 000 Yes B 13 SFN 0.01 39.0-43.0 65 000 No B
14 SFN 0.01 42.5-46.4 73 000 No B 14 N 0.01 42.5-46.4 73 000 Yes B
15 SFN 0.01 45.9-51.6 85 000 No B 15 N 0.01 45.9-51.6 85 000 Yes
high-molecular-weight Oppanol .RTM. B 30 SF 0.005 76.5-93.5 200 000
No B 50 0.002 113-143 400 000 Yes B 50 SF 0.002 113-143 400 000 No
B 80 0.002 178-236 800 000 Yes B 100 0.002 241-294 1 110 000 Yes B
150 0.001 416-479 2 600 000 Yes B 200 0.001 551-661 4 000 000
Yes
[0106] The reactive emulsion and/or aggregate slurry can be sprayed
or poured on a prepared or unprepared pavement surface to be
repaired. Upon contact with hot rock or pavement, the water present
evaporates and the composition sets. Once set, the composition may
be treated with electromagnetic radiation and then compacted by a
vibrating roller while at or above 150.degree. F. (or above
175.degree. F., or above 200.degree. F.) but below the `blue smoke`
threshold (typically >300.degree. F.), preferably below
275.degree. F., most preferably about 250.degree. F. The resulting
surface has a very low void density, a high resistance to heating
and softening, and it has anchor points with a wearing core
essentially that is bound into it that will not move if new
pavement is placed on top. The compositions of various embodiments
enable the densification (or reduction in voids percentage) to be
dramatically improved, e.g., a pavement having 6-8% voids can be
densified to a pavement having 5% or less voids, or even 4% or less
voids, e.g., 2% to 2.5%, 3%, or 3.5% voids. A void percentage
reduction of 1%, 2%, 3%, 4%, or 5% or more (e.g., a void percentage
reduction of 1% would correspond to a densification of a pavement
having 6% voids to one having 5% voids) is desirable; however,
smaller reductions can also be advantageous. The life of the
pavement is increased substantially upon improvement in
densification.
[0107] Although dry, untreated aggregate can optionally be employed
in the preparatory stage, and later combined with the reactive
emulsion to yield a reactive emulsion and aggregate slurry, it can
be advantageous to combine the reactive emulsion and aggregate into
a slurry before applying to the aged (e.g., alligatored) pavement.
In certain embodiments it can be desirable to pretreat the
aggregate surface to form "anchor points" by coating with a water
dispersible thermoset resin that has, in addition to the functional
groups which selectively couple with the thermoplastic
functionality discussed above, an independent, mid-morphology,
pendulous functionality which bonds with a sufficiently improved
strength to the specific rock chemistry being used in the final
composition. Foremost, this dramatically improves binder adhesion
to the stone binder interface, thereby reducing moisture
susceptibility. It also assures that the film stays in place and
does not prematurely slip laterally. A benefit in an application
such as an interlayer primer is much higher compaction and thus a
lower void density, i.e., improved resistance to oxidative,
hydrocarbon embrittlement and ultimately a noticeably longer
useful.
[0108] The reactive emulsions exhibit superior properties when
compared to conventional formulations. The superior properties can
be in the areas of handling, storability, hazmat, curing
characteristics, environmental considerations, chemical resistance,
moisture susceptibility, sun resistance, tensile and flexural
quanta, and anti-strip quanta. The compositions can be handled,
stored and installed using conventional equipment. They can exhibit
reduced hot mix asphalt (HMA) concrete void density. They can
provide a novel way to restore microtexture to a pavement surface.
They can exhibit improved water resistance and/or sun resistance.
The compositions can provide the highest mechanical properties
versus unit of cost, and are sustainable. The compositions reform
and stabilize a broad range of weakness in asphalt and result in a
substantially lower life cycle cost of pavement maintenance.
[0109] FIG. 1A provides a top view of an apparatus for applying
aggregate and reactive emulsion to paving surface to be repaired.
FIG. 1B provides a side and front view of the apparatus of FIG. 1A.
An air pot adhesive tank is not depicted. Electric power and
compressed air can be provided to the apparatus by a support unit,
not depicted. The hopper is loaded with a heated aggregate, and the
apparatus is configured to move at a speed of 20 feet per minute,
with a maximum speed of delivery of aggregate of 75 feet per
second.
Elastomer Coated Aggregate Stage
[0110] In certain embodiments, after the aggregate has been placed
and the reactive emulsion has been applied, optionally a thin layer
(from about 1/8 inches or less to about 1 inches or more) of
elastomer coated aggregate can optionally be either sprayed or
spread across the surface of the pavement so as to provide a
uniform surface and to fill in any other depressions that were not
aggregate filled during the dry aggregate preparation stage.
Heating Stages
[0111] In certain embodiments, it can be desired to heat an asphalt
surface. Heating can be accomplished by conventional techniques, or
techniques as described herein. In certain embodiments wherein an
asphalt emulsion is applied to a pavement surface to be subjected
to exposure to terahertz electromagnetic radiation, it can be
desirable to heat the pavement surface prior to and/or after
application of the asphalt emulsion, but before any subsequent
application of terahertz electromagnetic radiation (e.g., to induce
crosslinking). In the heating stage, electromagnetic radiation of a
preselected peak wavelength is applied to the pavement surface
prior to and after application of the asphalt emulsion in order to
heat the asphalt. The heating radiation can be generated using
conventional techniques as described herein, or by modifying an
emitter as in various embodiments to emit a desired wavelength. The
wavelength of the electromagnetic radiation used for heating is
selected based upon the aggregate and/or asphalt present. Preferred
peak wavelengths for common materials are provided below. For
example, granite rock is advantageously heated by applying
electromagnetic radiation with a peak wavelength of from 3000-5000
nm. Sand, depending upon the composition, is advantageously heated
by applying electromagnetic radiation with a peak wavelength of
3000 nm or from 5000-8000 nm. Limestone is advantageously heated by
applying electromagnetic radiation with a peak wavelength of from
3000-4000 nm. Maltene asphalt is advantageously heated by applying
electromagnetic radiation with a peak wavelength of from 1000-8000
nm. Asphaltene asphalt is advantageously heated by applying
electromagnetic radiation with a peak wavelength of from 1000-3000
nm.
TABLE-US-00002 TABLE 2 Peak Wavelength Granite Maltene Asphaltene
(nm) Rock Sand Limestone Asphalt Asphalt 1000 X X 2000 X X 3000 X X
X X X 4000 X X X 5000 X X X 6000 X X 7000 X X 8000 X X 9000 X 10000
X
[0112] In operation, the preselected wavelength is achieved
primarily by the regulation of the surface temperature of the
emitter element (the wavelength produced by the heat source is
dependent upon the source temperature). This is achieved by
adjusting the source(s) by which the surface temperature is
achieved, and thus the peak wavelength, to match the spectral
absorption rate of the material to be heated. This principle
applies regardless of the construction of the heat source. By way
of example, an Incoloy tubular heater, the resistance wire of a
quartz heater, an FP Flat Panel heater or a Black Body Ceramic
Infrared heater operating at 850.degree. F. would all have the same
peak energy wavelength of 4,000 nm (4 microns).
[0113] Two common methods of temperature control in infrared
processes include varying the voltage input to the element and
adjusting the amount of on-time versus off-time of the elements. A
closed loop control system includes infrared sensors or
thermocouples attached or integral to the energy source. These
sensors or thermocouples monitor the temperature of the process and
signal a control which, in turn, signals an output device to
deliver current to (or turn of current from) the heat source.
[0114] With an established, preselected absorption rate strategy,
the watt density, process time cycle and distance to pavement
surface can be determined.
[0115] The heating electromagnetic radiation can be generated using
emitter systems as described herein. In a preferred embodiment, an
emitter system as depicted in FIG. 3A and FIG. 3B is modified to
emit a suitable wavelength for heating. In this system, a series of
easily removable emitter cartridges are mounted within a towable
stainless steel frame. Surface temperature modulation can be
achieved by one or more of: an AC power, waveform controller;
cartridge design; voltage regulation; and an on-off power schedule.
For example, IR heating cartridges can be swapped for terahertz
emitting cartridges as desired.
[0116] As employed herein, "optimal pre-thermalization" (OPT) is
defined as applying electromagnetic radiation of a preselected peak
wavelength to a particular pavement cross-section, wherein the
greatest temperature rise per unit of pavement mass is obtained for
the lowest expended unit of energy during any time sequence when
both parameters are being correlated. Pavement pounds/degree
Fahrenheit rise/kilowatt hours expended (Pp/delta F/kwh) is the
unit of measure of OPT.
[0117] Each cross-section of pavement has its own unique material
and topographic characteristics. Tailoring the system to take
advantage of these differences can be achieved by adjusting the
bandwidth and the power density of the electromagnetic radiation so
as to maximize radiation absorption for a given set of
conditions.
[0118] As a first step, this is done by reference to tables which
have been empirically developed by field experiments to classify
absorbed wavelength quanta as it relates to: 1) stone petrography,
2) asphaltene/maltene content of the binder and 3) categories of
average crack width.times.depth topography. This tool is referred
to as an OPT Chart. See, e.g., TABLE 2. Most asphalt concrete
pavement comprises about 95% stone and 5% binder by mass. Cracks in
pavement can include those referred to in the industry as `micro
fissures`, which are as narrow as approximately 0.004'', to larger
cracks up to approximately 3'' in width. Below the dimensional
range for micro fissures, the cracks are not easy to visibly detect
without magnification. Above the dimensional range for larger
cracks over 3'', such cracks are typically beaten into potholes by
wheel traffic. The systems of various embodiments are preferably
employed for repairing pavement with cracks of about 3'' in width,
or less, e.g., 0.004'' to 3'', or 0.004'' to 2'', or 0.004'' to
1'', or 0.004'' to 0.5'', or 0.004'' to 0.05'', or to any range
between.
[0119] The emitter emits electromagnetic waves with a combination
of horizontal, vertical and circular polarization. As a `rule of
thumb`, the width of a waveguide is of the same order of magnitude
as the wavelength of the guided wave. The cracks are potential
waveguide structures. Since the cracks may act as dielectric
waveguides, choosing a wavelength that is near the average maximum
absorption quanta of the stone and binder, but which may also
effectively carry the selected wavelength's zigzag progression deep
into a large portion of the cracks without energy loss, is an
effective strategy to achieve OPT.
[0120] Prior to beginning the repair of a specific section of
pavement, a small-scale, easily configurable emitter can be
deployed at the job site. This test assembly is pre-configured to
emit a specific IR wavelength at a given watt density pursuant to
the OPT Chart. Select locations within the field of repair, which
are representative of the average field conditions, are then heated
to determine the actual Pp/delta F/kwh. Once the effectiveness of
the pre-selected IR bandwidth and watt density have been measured
through the use of the small scale emitter, additional adjustments
may be made to the emitter frequency by cartridge construction,
voltage, power density and/or on-off power schedule to tune the
system, as necessary, to achieve OPT during project scale-up.
[0121] In operation, after the aged and alligatored pavement has
been cleaned of debris, the surface of the pavement is heated to
attain a temperature of about 240.degree. F., e.g., from about
150-350.degree. F., or from about 175-325.degree. F., or from about
200-300.degree. F., or from about 225-275.degree. F., or from about
230-250.degree. F., or any range between. The heating is
advantageously accomplished using an emitter array as described
herein (e.g., as depicted in 3); however, any alternative heating
system can also be employed, as discussed herein. The peak
wavelength is selected based on the pavement to be heated, e.g., by
use of an OPT table or by exploratory testing conducted on
representative portions of the surface using a small scale emitter.
After the cleaned aged and alligatored pavement has been heated,
the asphalt emulsion is applied as described herein.
Electromagnetic radiation is then applied to the emulsion to attain
a temperature sufficient to achieve curing, as described herein,
e.g., of about 250.degree. F. or a temperature of from about
150-350.degree. F., or from about 175-325.degree. F., or from about
200-300.degree. F., or from about 225-275.degree. F., or from about
230-250.degree. F., or any range between.
[0122] After the steps of pavement preparation and application of
the asphalt emulsion, the pavement can be considered a "wet" system
that, if left to slow cure, would eventually provide some degree of
quality as to the driving surface. However, the heating steps
subsequently employed in systems of certain embodiments result in a
dramatically superior driving surface.
[0123] The heating element applies electromagnetic radiation that
penetrates deep into the pavement and/or emulsion. When applied to
the emulsion, it softens and crosslinks the upper portions of new
material, yielding a material that after compression into a dense
structure will exhibit properties well exceeding those of
conventional asphalt pavement in terms of toughness, resilience,
flexibility, and/or resistance to cracks. In the lower, old
pavement portions beneath the new portions the heating and rolling
process compresses and pushes together the warmed old asphalt and
the preparation of the nearly volatile-free emulsion or the binder
emulsion, eliminating voids, to create a tougher and more durable
transition region between the old pavement substrate and the new
overlay. The transition region is a continuum, and at depths of
from 21/2 to 3 inches or more, past which the preparation of binder
emulsion and/or the electromagnetic energy do not penetrate. The
material is essentially old asphalt paving that has been remelted
and pushed together. Because it does not contain elastomer, the
properties will be similar to those of conventional asphalt;
however, cracks and fissures will have been eliminated by the
process and thus will not telegraph to the surface.
[0124] Accordingly, after application of the reactive emulsion (and
optionally the thin layer of elastomer coated aggregate) over the
aggregate filled pavement surface, a heat shuttle including a
heating element is passed over the pavement surface. The heat
shuttle can be of any suitable dimension, e.g., as large as or
larger than 32 feet wide by 32 feet long, or smaller, e.g., 8 feet
wide by 8 feet long, or 4 feet wide by 4 feet long. In a particular
preferred embodiment, the shuttle is sufficiently wide so as to
cover an entire width of a standard road or highway traffic lane
including associated shoulder, or a full width of a typical two
lane road. The heat shuttle is pulled across the top of the
prepared surface. As the heat shuttle passes over the surface, a
heating element delivers electromagnetic radiation of the
preselected peak wavelength, e.g., energy in the near microwave
(e.g., terahertz) to the mid-infrared range, that penetrates
through the layer of elastomer coated aggregate, and down into the
aggregate-filled new portions as well as the undisturbed old
portions of the pavement being repaired. The microwave-infrared
energy penetrates down to a depth of 3 or more inches, heating the
entire penetrated mass of repaired pavement to a temperature of at
least about 240.degree. F., but preferably not more than
275-300.degree. F., yielding a softened heated mass comprising the
topmost 1, 2, or even 3 inches of the pavement surface. An
advantage of the systems of certain embodiments is that the old
pavement is not disrupted as part of the repair process, such that
there is minimal oxidation of the old pavement upon application of
heat, such that minimal smoke is generated by the process.
[0125] Heat shuttles can be employed to heat pavement. Heat
shuttles can incorporate various different types of heating
elements. One conventional type of emitter comprises a stainless
steel tube wherein natural gas or liquid propane gas are mixed with
air and ignited, generating heat (infrared energy) that is released
through the stainless steel tube. Although other types of alloys
can also be employed for the tube, stainless steel is generally
preferred for its slow deterioration and for the bandwidth of
energy that radiates from the outside of that tube typically in the
medium to far infrared which exhibits good penetration into asphalt
pavement systems. Other types of emitters include those
incorporating a rigid ceramic element where the combustion takes
place in micropores in the ceramic element. Bandwidth for such
emitters is also in the medium to far infrared. Another type of
emitter incorporates a flexible cloth-like ceramic medium having
several layers, or layers of stainless steel cloth together with
ceramic cloth. The cloth traps the combustion gases so that no
flame is present on the surface of the element while generating
infrared emissions. Any suitable device capable of generating
infrared radiation that penetrates to a depth of 2, 3, 4 or more
inches into the pavement surface can be employed to heat
pavement.
[0126] A particularly preferred heat shuttle incorporates a ceramic
structure in a form of thin sheets of cloth-like material that can
operate at much higher temperatures (e.g., 2000.degree. C.) than
conventional ceramics (e.g., 1500.degree. C.). In this structure, a
higher combustion temperature can be obtained by catalyzing
combustion of an air/liquefied petroleum gas (LPG) mixture or
air/nitric gas mixture. The infrared energy generated is typically
of shorter wavelength than the previously described systems, and
can more quickly and efficiently heat the pavement than these
conventional systems. The system also avoids creation of an open
flame, with the resulting generation of smoke and other carbon
emissions from the heated pavement. Any combustible mixture that
adjusts the combustion reaction, if necessary, to generate
electromagnetic radiation of the desired peak wavelength, can be
employed to generate penetrating energy suitable for heating the
asphalt/aggregate mixture to be treated.
[0127] In certain embodiments, it can be desired to apply longer
wavelength radiation of the pavement. Combustible mixtures that
slow down the combustion reaction such that longer wavelengths are
produced, e.g., liquefied petroleum gas (LPG), can be employed to
generate such penetrating energy.
[0128] Conventional combustion systems typically generate energy
with a wavelength of from 1-5 nm. Instead, it is generally
preferred that energy of longer wavelengths, e.g., of from 2-5 mm
(terahertz range) be generated, e.g., to initiate crosslinking.
Heating (as opposed to crosslinking) the asphalt/aggregate mixture
to be treated can advantageously be accomplished, e.g., using
energy with a shorter wavelength of from 1000-10000 nm.
[0129] In certain embodiments, simplified electronics and software
can be employed in connection with a device that employs a simple
emitter, so as to avoid high capital expenditures. The emitter is
designed to produce radiation at a wavelength or range of
wavelengths that will penetrate the pavement while at the same time
minimizing excess heating in an upper region of the pavement, such
that substantially uniform heating throughout the asphalt medium
down to a depth of at least 1, 2 or 3 inches is obtained. In some
embodiments, substantially uniform heating includes a temperature
differential throughout a preselected depth, e.g., 2 inches, of no
more than 50.degree. F. In other words, the temperature of any
portion of the upper region is no more than 50.degree. F. higher
than any portion of the lowest region. However, in certain
embodiments, larger temperature differentials may be acceptable,
e.g., up to 100.degree. F. or more, provided that damage to the
cured surface is avoided.
[0130] To attain the desired temperature profile, radiation in the
infrared region is applied. The radiated energy applied to the
surface is selected so as to control a depth of penetration and a
rate of penetration to avoid heating or activating the asphalt too
quickly, which may damage the pavement. The devices of various
embodiments can be manufactured to minimize cost and are suitable
for use in the field. Field use can be achieved by powering the
device using a portable generator, e.g., a Tier 4 diesel engine,
which qualifies under current emission standards. In one
embodiment, the generator is electrically connected to a series of
emitter panels situated within a metal frame. The device can be
insulated with a high-density ceramic, and the panels can be nested
within the ceramic liner of a frame points to point downward
towards the pavement. One example of an emitter panel is provided
in FIG. 2.
[0131] An array of panels can be assembled together, as in an array
of 2.times.1 panels, or any other desired configuration, e.g.,
2.times.2, 2.times.3, 2.times.4, 2.times.5, 2.times.6, 2.times.7,
2.times.8, 2.times.9, 2.times.10, 2.times.11, 2.times.12,
2.times.13, 2.times.14, 2.times.15, 2.times.16, 2.times.17,
2.times.18, 2.times.19, 2.times.20, 2.times.(more than 20),
3.times.3, 3.times.4, 3.times.5, 3.times.6, 3.times.7, 3.times.8,
3.times.9, 3.times.10, 3.times.11, 3.times.12, 3.times.13,
3.times.14, 3.times.15, 3.times.16, 3.times.17, 3.times.18,
3.times.19, 3.times.20, 3.times.(more than 20), 4.times.4,
4.times.5, 4.times.6, 4.times.7, 4.times.8, 4.times.9, 4.times.10,
4.times.11, 4.times.12, 4.times.13, 4.times.14, 4.times.15,
4.times.16, 4.times.17, 4.times.18, 4.times.19, 4.times.20,
4.times.(more than 20), 5.times.5, 5.times.6, 5.times.7, 5.times.8,
5.times.9, 5.times.10, 5.times.11, 5.times.12, 5.times.13,
5.times.14, 5.times.15, 5.times.16, 5.times.17, 5.times.18,
5.times.19, 5.times.20, 5.times.(more than 20), 6.times.6,
6.times.7, 6.times.8, 6.times.9, 6.times.10, 6.times.11,
6.times.12, 6.times.13, 6.times.14, 6.times.15, 6.times.16,
6.times.17, 6.times.18, 6.times.19, 6.times.20, 6.times.(more than
20), 7.times.7, 7.times.8, 7.times.9, 7.times.10, 7.times.11,
7.times.12, 7.times.13, 7.times.14, 7.times.15, 7.times.16,
7.times.17, 7.times.18, 7.times.19, 7.times.20, 7.times.(more than
20), 8.times.8, 8.times.9, 8.times.10, 8.times.11, 8.times.12,
8.times.13, 8.times.14, 8.times.15, 8.times.16, 8.times.17,
8.times.18, 8.times.19, 8.times.20, 8.times.(more than 20),
9.times.9, 9.times.10, 9.times.11, 9.times.12, 9.times.13,
9.times.14, 9.times.15, 9.times.16, 9.times.17, 9.times.18,
9.times.19, 9.times.20, 9.times.(more than 20), 10.times.10,
10.times.11, 10.times.12, 10.times.13, 10.times.14, 10.times.15,
10.times.16, 10.times.17, 10.times.18, 10.times.19, 10.times.20,
10.times.(more than 20), 11.times.11, 11.times.12, 11.times.13,
11.times.14, 11.times.15, 11.times.16, 11.times.17, 11.times.18,
11.times.19, 11.times.20, 11.times.(more than 20), 12.times.12,
12.times.13, 12.times.14, 12.times.15, 12.times.16, 12.times.17,
12.times.18, 12.times.19, 12.times.20, 12.times.(more than 20),
13.times.13, 13.times.14, 13.times.15, 13.times.16, 13.times.17,
13.times.18, 13.times.19, 13.times.20, 13.times.(more than 20),
14.times.14, 14.times.15, 14.times.16, 14.times.17, 14.times.18,
14.times.19, 14.times.20, 14.times.(more than 20), 15.times.15,
15.times.16, 15.times.17, 15.times.18, 15.times.19, 15.times.20,
15.times.(more than 20), 16.times.16, 16.times.17, 16.times.18,
16.times.19, 16.times.20, 16.times.(more than 20), 17.times.17,
17.times.18, 17.times.19, 17.times.20, 17.times.(more than 20),
18.times.18, 18.times.19, 18.times.20, 18.times.(more than 20),
19.times.19, 19.times.20, 19.times.(more than 20), 20.times.20,
20.times.(more than 20), or (more than 20).times.(more than 20).
The panels can be of any suitable size, e.g., 1.times.1 inches or
smaller, 3.times.3 inches, 6.times.6 inches, 12.times.12 inches,
18.times.18 inches, or 24.times.24 inches or larger. The panels can
be one or more of square, rectangular, triangular, hexagonal, or
other shape. Preferably, each panel abuts an adjacent panel so as
to minimize non-emitting space; however, in certain embodiments
some degree of spacing between panels may be acceptable, such that,
e.g., circular emitters can be employed, or, e.g., square emitters
can be spaced apart. One example of a suitable array is a
2.times.12 array of one foot square panels.
[0132] While in certain embodiments an elongated (e.g., coiled,
straight, tubular, or other structures in a waveguide pattern)
semiconductor (e.g., silicon carbide, non-oriented carbon fiber,
doped boron nitride) or resistance conductors (e.g., iron-nickel)
can be employed in the emitter, in a particularly preferred
embodiment the panels include a serpentine wire as an emitter. An
advantage of the serpentine configuration is that it does not have
the high resistance exhibited by spaced apart coils. Accordingly,
more of the energy is emitted as radiation of the desired
wavelength. The coils are spaced apart to minimize the resistance,
and a radiant energy is emitted within a "sandwiched" space bounded
on the upper side of by the high-density ceramic that has a very
low permittivity and essentially redirects the reflected energy
from the serpentine wire downward.
[0133] On the lower side of the wires, which can advantageously be
embedded in a support or be self-supporting, is a thin micaceous
panel. The mica group of sheet silicate (phyllosilicate) minerals
includes several closely related materials having close to perfect
basal cleavage. All are monoclinic, with a tendency towards
pseudohexagonal crystals, and are similar in chemical composition.
The nearly perfect cleavage, which is the most prominent
characteristic of mica, is explained by the hexagonal sheet-like
arrangement of its atoms. Mica or other materials exhibiting
micaceous properties can include a large number of layers that
create birefringence or trirefringence (biaxial birefringence).
Birefringence is the optical property of a material having a
refractive index that depends on the polarization and propagation
direction of light. These optically anisotropic materials are said
to be birefringent. The birefringence is often quantified by the
maximum difference in refractive index within the material.
Birefringence is also often used as a synonym for double
refraction, the decomposition of a ray of light into two rays when
it passes through a birefringent material. Crystals with
anisotropic crystal structures are often birefringent, as well as
plastics under mechanical stress. Biaxial birefringence describes
an anisotropic material that has more than one axis of anisotropy.
For such a material, the refractive index tensor n, will in general
have three distinct eigenvalues that can be labeled n.sub..alpha.,
n.sub..beta. and n.sub..gamma.. Both radiant and conductive energy
from the serpentine wire is transmitted to the micaceous element.
The birefringent characteristics of the micaceous material can be
employed to transmit a subset of wavelengths generated by the
serpentine wire while filtering out other wavelengths. The emitter
of certain embodiment employs a sheath of stainless steel that
protects the micaceous material from being damaged. This conductive
sheath transfers energy with no significant wavelength translation.
By employing this combination of components (e.g., serpentine wire,
micaceous material, stainless steel sheath), energy generated by
the serpentine wire with a peak wavelength of about 2 micrometers
can have the peak wavelength be taken to about 20 micrometers. A
wavelength of 10 micrometers or less to 100 micrometers or more,
e.g., about 20 micrometers, can advantageously be used in
connection with asphalt applications to improve the characteristics
of the asphalt. The thickness or other characteristics of the
micaceous material can be adjusted to provide a targeted wavelength
or range of wavelengths to the surface.
[0134] In a particularly preferred embodiment, the device has a
2-foot wide by 12-foot long intercavity dimension, configured
similar to a hood, in which a ceramic insulation is mounted. The
emitter elements are advantageously 1 foot by 1 foot. E.g., a
2-foot wide device can be configured to be 2 elements wide by 12
elements long, for a total of 24 elements. Such elements can have a
Watt density of roughly 14 Watts per square inch, at full energy,
capable of being powered by, e.g., a generator that can deliver 250
kW. An example of a portable device suitable for use in repairing
asphalt pavement is depicted in FIG. 3A and FIG. 3B.
[0135] In some embodiments, an emitter assembly may comprise a
structural frame, a power source, a power interrupting mechanism,
an electromagnetic radiation emitter, and a positioning system. The
emitter assembly may be several feet wide, several feet long, and
several feet high. In some embodiments, the emitter assembly is
approximately 12 feet wide, 8 feet long, and approximately 2 feet
high. The emitter assembly may be other sizes as well and the scope
of the invention is not limited by the size of the emitter
assembly. The frame may support one or more of the other
components.
[0136] The frame may comprise structurally adequate members such as
metal supports, beams, rails, or other such structures. The frame
may be configured to prevent significant deformation when in use or
in transport. The frame may be designed to support at least part of
the weight of the various components. In some embodiments, the
frame comprises one or more beams. The beams may comprise a metal,
wood, or other material that can adequately support the weight of
the components. The beams may comprise aluminum or steel, and in
some embodiments it may be advantageous to use a material that is
both lightweight and strong. One or more beams may be disposed on
either side of the frame and on either end of the frame. The beams
on the side may be connected vertically through brackets, plates,
or other attachment mechanisms. The pieces may be welded together,
or bolts may be utilized to connect the pieces. One or more beams
may traverse the frame from one side to the other side, or from
front to back, and may be configured to provide support or an
attachment mechanism to other components. One or more beams that
traverse the frame may be disposed near the bottom of the frame,
such that one or more of the electromagnetic radiation emitters may
be attachable to the beams. The frame may attach to one or more
wheels, directly or indirectly, which may assist the frame in being
transported.
[0137] In some embodiments the frame may be configured to prevent
bending, sagging, or twisting even while traversing uneven terrain.
The frame may provide a robust structure that supports one or more
components of the assembly. Because the assembly may be used in a
variety of environments, it may be advantageous for the frame and
assembly to be resistant to deformation and deterioration when in
transport and in use. For instance, the assembly may be used on
roadways that are uneven. It may be advantageous for the frame to
withstand transport over an uneven surface. As another example, the
frame and assembly may be used in the outdoors in remote locations.
It may be advantageous for the frame and assembly to not only be
resistant to damage during the transport to the remote location,
but also for the frame and assembly to be resistant to the effects
of weather while at that location. Even during adverse conditions
and extensive travel and transport, it may be advantageous for the
bottom surface of the frame to remain a generally consistent
distance from a road or other surface over which the assembly may
be placed. Therefore, the frame may be sufficiently robust and
resistant to deformation or damage in a variety of conditions.
[0138] In order to transport the assembly, the frame may comprise
an attachment mechanism that may allow the assembly to be pulled.
In some embodiments, the frame comprises rings or hitches that are
connectable to a vehicle. The vehicle may be configured to pull the
assembly over short distances over the roadway, or longer distances
to transport the assembly to the work site.
[0139] A power source may be connected or connectable to at least
part of the emitter assembly. The power source may comprise a
generator and may comprise a diesel generator or other power
source. The power source may be disposed on the emitter assembly or
maybe connectable to the assembly. The power source may be part of
a second assembly positionable adjacent the emitter assembly. The
function of the power source may be to provide power or electricity
to a power distribution device that may be located on the emitter
assembly or on the frame. In some embodiments, a diesel powered
electric generator may be disposed on a platform or movable trailer
that may be connectable to the emitter assembly.
[0140] The power distribution device may be disposed on at least
part of the emitter assembly and may sit on at least part of the
frame. The power distribution device may comprise one or more
circuit breakers or other power interrupting mechanisms. The power
distribution device may be configured such that it receives power
from the power source and distributes it to one or more
electromagnetic radiation emitter panels. In some embodiments, the
power distribution device comprises a metal box and circuit
breakers, which may be similar to those found in commercial or
residential building units. The power distribution device may be
temporarily or permanently connected to the frame, and in some
embodiments, may be bolted to a surface of the frame.
[0141] The frame may support one or more electromagnetic radiation
emitters. The emitters may be approximately 12 inches by 24 inches,
and more than one emitter may be disposed on an emitter module. One
or more modules may be disposed on the emitter assembly. In some
embodiments, the assembly comprises six modules, with each module
measuring approximately 4 feet by 4 feet. In some embodiments, each
module comprises multiple emitter panels. The emitters may be
generally flat, and may be disposed adjacent one or more other
emitters. Each emitter panel may or may not abut a second emitter
panel. Each emitter panel may be directly or indirectly
electrically connected to the power interrupting mechanism, and may
be electrically connected in parallel or in series with other
emitter panels.
[0142] The emitter modules may comprise a top plate, and the top
plate may be disposed on the top and side surfaces. The modules may
further comprise a ceramic layer generally disposed underneath the
top plate. An emitter panel may be generally disposed beneath the
ceramic layer. An electrical connection from the emitter panel to
the power interrupting mechanism may travel through the ceramic
layer and through the metal shell. The module may be configured to
emit electromagnetic radiation in a generally downward direction,
and may be configured to prevent substantial electromagnetic
radiation from being emitted in an upward direction. The module may
also limit the amount of electromagnetic radiation emitted to the
side. It may be advantageous to at least partially limit the
emissions of electromagnetic radiation in some directions in order
to prevent injury to persons located nearby. Further, it may be
advantageous to generally direct the electromagnetic radiation in a
downward direction, so that the radiation is received by the
surface below the emitter assembly. During use the emitter assembly
may be positioned over a road or other surface, and the
electromagnetic radiation being emitted from the emitter panels may
be directed at the road or other surface.
[0143] In some embodiments, the panels and/or modules may be
independently separable from the emitter assembly. It may be
advantageous to be able to disconnect one or more emitter panels or
modules from the rest of the assembly in order to replace or repair
the panels or modules. There may be other advantages as well to
being able to separate portions of the assembly. The panels or
modules may attach to one or more beams of the frame using bolts or
other various attachment mechanisms. In some embodiments, the
panels are bolted to a beam that traverses the frame from front to
back. The beams define openings, through which one may access a
bolt or other attachment device. Other methods of attaching the
panels to the frame or assembly may be possible and the scope of
the invention is not limited by the method of attaching the
panels.
[0144] The emitter assembly may comprise a positioning system which
may comprise parts of the frame and wheels. The positioning system
may also comprise attachments from which the emitter assembly may
be connected to a supporting structure, such that the emitter
assembly may at least partially suspend from the structure. In some
embodiments, the emitter assembly comprises four wheels, with each
wheel generally disposed at the corners of the frame. More wheels,
such as six or eight or other number, may be advantageous depending
on the size of the emitter assembly. Each wheel may be connected to
a wheel support and each wheel support may be configured to allow
the height of the wheel, relative to the frame, to be independently
adjusted. Independently adjusting the height of the wheel may allow
the emitter assembly to be more accurately positioned above a road
or other surface. By being able to more accurately position the
emitter assembly above the surface, the distance between the
emitter assembly and the road or surface may be more uniform, and
in some embodiments the emitter assembly may be more effective and
consistent in transmitting the electromagnetic radiation from the
emitter panels to the road or surface.
[0145] The positioning system, including wheels, may allow the
assembly to be positioned in various locations, and may be
configured to allow the emitter assembly to be transported between
different locations. In some embodiments, the positioning system
may allow the emitter assembly to be translated above the surface,
before, during, or after use, either continuously or discreetly,
depending on user preference. For instance, the assembly may be
moved continuously along the surface while electromagnetic
radiation is being emitted from the emitting panels. Or, the
assembly may emit electromagnetic radiation at a first location,
then the assembly is moved to a second location, and then
additional electromagnetic radiation is emitted. The positioning
system may allow the emitter assembly to be translated in a forward
and back direction, in a side to side direction, or be rotated
about an axis. The frame or other part of the emitter assembly,
including the positioning system, may be configured to allow at
least part of the frame to be connected to a vehicle such that the
emitter assembly can be transported between locations. In some
embodiments, the assembly may be configured to be loaded onto a
transporting device, such as a trailer, that may be configured to
transport the assembly from a first location to a second
location.
[0146] A net frame is preferably attached to wheels on the outside
of the device, to permit adjustment of the emitter within the
cavity itself, or to permit adjustment of the height of the emitter
over the pavement. In a preferred embodiment, the emitter is
provided in a cavity approximately 6 inches deep, and a height of
the emitter surface over the pavement surface can be varied from as
low as a quarter of an inch or as high as an inch or more. The
emitter is preferably placed as close to the surface of the
pavement as is practical (e.g., <1 inch, or <0.5 inches, or
<0.25 inches) so as to minimize loss of energy via reflectance
and/or refraction by the pavement surface. However, if the spacing
is too close, imperfections in the pavement surface, or smoke or
dislodged gummy residue, may cause damage to the emitter.
[0147] In various embodiments for pavement repair applications, an
emitter design can be employed wherein multiple units (e.g., 1, 2,
3, 4, 5, 6, 7, 8, 9, or 10 or more) are grouped together. For
example, four units, each including a 3.times.3 emitter array, will
provide 36 square feet of emitter. Four units, each including a
4.times.6 emitter array, will provide 96 square feet of emitter. It
is generally preferred to employ a square footage of emitter that
can be supported by a desired generator. 250 kW generators are
generally preferred, as providing a good balance of power and cost,
but in certain embodiments larger generators can be employed, e.g.,
a 300 kW generator. Instead of a larger generator, two or more
smaller generators can be employed to provide adequate power for a
preferred array size. In a preferred embodiment, a 250 kw generator
can be employed to power a 100 square foot emitter array that puts
out 14 watts per square inch. Two such generators can be provided
on the same tug to power 250 square feet of emitter. In most paving
applications, the width of the road to be repaired is approximately
12 feet, so emitter arrays or groups of emitter arrays having a
width of 12 feet and a sufficient length to provide an appropriate
amount of energy to the surface are desirable.
[0148] In operation, circuits and sensors can be employed to
identify obstacles underneath the emitter unit, e.g., by sensing
reflected energy or heat buildup, and can adjust the power to the
emitter or the distance of the emitter from the pavement surface.
Other sensors can detect the presence of combusted organics, e.g.,
a laser that can detect a certain amount of smoke passing through
its beam. If high temperature is detected, the emitter can be
distanced from the pavement, power can be reduced, or the speed at
which the emitter passes over the surface can be decreased.
Similarly, if the temperature detected is too low, the power of the
emitter can be increased, it can be distanced from the surface, or
the speed at which the emitter passes over the surface can be
increased.
[0149] In certain embodiment, the heat shuttle passes over the
pavement, flashing off non-VOC components and bringing moisture in
the pavement to the surface, warming the mass of pavement. The
pavement is then allowed to cool down to a preferred temperature
for compression, at which time a vibrating roller is passed over
the surface. An advantage of the system is that virtually no smoke
is produced while operating the system. The resulting pavement has
a density similar to new pavement, but incorporates durable
elastomers imparting superior performance properties.
[0150] Another advantage of the system is that the elastomer
composition can be formulated to include a resealing adhesive that
does not lose its internal cohesion (stickiness) over time. A road
repaired using the system that begins to show signs of wear
(microfissures or cracks) can be readily repaired simply by passing
the heat shuttle across the surface (for, e.g., 30 seconds to 2 or
3 minutes), then passing a compaction roller over surface, which
repairs and reseals the cracks. Should a crack appear in the
pavement that is beginning to show signs of wear, one simply passes
the heat shuttle across the surface. A quick pass of the device of
30 seconds, followed by a roller pass, can result in a robust crack
repair. Preferably, such a heating/rolling treatment is employed
approximately every three to five years so as to maintain the
pavement in good condition for 20 years or more.
[0151] Upon exposure to a temperature of approximately 250.degree.
F., the elastomer of the reactive emulsion crosslinks, generating a
bond (between new aggregate, between new aggregate and old
pavement, or between portions of old pavement) of sufficient
strength such that a conventional road vibratory roller can be
applied over the top of the pavement surface to provide a new
driving surface. During rolling, the vibratory compaction
redensifies all the defects in the old road bed.
[0152] In some embodiments, additional elastomer can be applied
prior to vibratory compaction. The elastomer is preferably applied
as a spray that penetrates into the old road surface, filling
cracks and crevices such that when vibratory rolling takes place it
further bonds the old pavement together as well as regions between
the new material and the old material.
[0153] Rubber, e.g., ground tire filler, is a material commonly
employed in asphalt pavements. It is a high energy-absorbing
material. If it absorbs too much energy too quickly, it will become
a source of combustion and can damage the emitter unit or emit
fumes into the atmosphere. Accordingly, in some embodiments it is
desirable to include a feedback loop on each emitter panel (e.g., a
1 foot square panel) in an array, so as to continuously monitor the
power density at the emitter's particular setting and its effect on
the pavement. Each emitter panel can be independently operated so
as to provide an appropriate amount of energy to the surface
beneath. Because rubberized coating is commonly employed as crack
sealer on old roads, it can be desirable to have such control over
each emitter panel.
[0154] To provide satisfactory pavement repair, the presence of
irregularities and defects on the surface, such as cracks,
fissures, low areas, and the like, must be addressed. It is
typically preferred to sweep off any thick cross-sections of dirt,
to remove vegetation and to remove any reflectors that are on the
road. The presence of road paint, e.g., paint used for lane
markers, generally does not present any issues as to operation of
the emitter, provided it is thin and does not contain substances
that may prevent uniform heating. The paint employed in crosswalks
may contain substances that prevent uniform heating. In such
situations, the crosswalk markings can be removed, the emitter can
be operated so as not to move over the markings, or the emitter is
shut off when it goes over crosswalk markings (e.g., manually shut
off, or automatically shut off when markings are detected).
Crosswalks that comprise a thick thermal plastic strip placed on
the pavement can inhibit management of the delivery of energy into
the deep pavement, and are desirably removed and reinstalled prior
to pavement renovation, or such areas are avoided during
renovation.
[0155] Irregularities and defects on the surface of the pavement
can vary. The systems of various embodiments are particularly
suited to the repair of alligatored pavement. However, in some
instances, it may be suitable for repairing other damage. For
example, the aged asphalt the surface can have a boney, or rough
look and texture, where large rocks have essentially become islands
rising above the lower sections of the pavement due to fine rock
being dislodged. In some instances, fissures or potholes that are
in each up to two inches or more deep may be present. Severe
irregularities and defects can be advantageously repaired using a
combination of stone and a formulated elastomer that glues the
stone together once it's cured. The elastomer is applied to the
surface and then cured using the emitter device. In certain
embodiments, the coating can be as thin as one gallon or less per
hundred square feet of stone and elastomer spread over the surface,
e.g., a coating as thin as a few thousandths of an inch. In certain
embodiments, a mixture of elastomer and aggregate can be blended to
form a cold slurry that is spread over the surface to replace
volume on a damaged or deteriorated road and then cured using the
emitter device. In such embodiments, an initial application of heat
prior to the emitter can be applied, e.g., open flame or other
heating unit as described elsewhere herein, that causes an initial
flashing of volatile materials from the cold slurry. This initiates
some degree of curing, to prevent adhesion of the slurry to the
tires of the tow rig pulling the emitter. Alternatively, the tires,
the driving unit and the emitter device, are configured so as to
straddle the strip of pavement that is being repaired.
[0156] In the case of large and very long runs on highways, use of
the system can minimize closure time, even under conditions wherein
material is placed and compacted, due to the rapid curing observed.
In such embodiments, an uncured surface of various stone sizes and
elastomer recipes can be spread across the surface and then the
emitter device is pulled over it, simultaneously drying out and
heating the adhesive on the surface while also, at a different
wavelength, pushing energy deep into the pavement so that, based
upon the prescription for the repair, simultaneous curing of the
material on the top is achieved, along with and warming and
stirring to a homogenized state the interstitial asphalt of the
pavement from the surface down to a depth of 1, 2, or 3 inches or
more.
[0157] Following behind the emitter unit, a compactor can be
employed once the pavement cools. Typical temperatures after
emitter treatment are about 250.degree. F. Once heat dissipates
such that the temperature is 180-190.degree. F., a compacting
roller can be applied. A single or 2-drum roller with vibrating
capabilities can be run across the surface to compact the voids
that are in the old pavement, basically reducing it to a density
that is similar to that of virgin pavement, and further compacting
the new material down into voids and irregular surfaces of the
pavement where the binder emulsion, elastomer or other repair
material had been placed. Multiple passes of a roller can be
applied, e.g., two, three, four, or more passes. Three or four
passes will provide the density and the uniform fusion between the
particles that results in a long-lasting pavement
cross-section.
[0158] An elastomer (also referred to herein as binder, emulsion,
or the like) of certain embodiments typically comprises four
components, and is a very robust emulsion that can contain asphalts
of various softening points. The elastomer can also include butyl
rubber, a styrene-butadiene-styrene (SBS) polymer, and a bioresin.
The type of bioresins, the concentration of the SBS polymer, and
the molecular weight of the butyl rubber employed, along with other
components of the mixture, can be balanced to achieve a desired set
of properties of the adhesive system in its cured form. The
elastomer may, in certain embodiments, be employed as a mask to
protect the underlying pavement as it goes through this heating
cycle from oxidation at the surface, because the temperature is
higher at the surface than it is deep down when the emitter system
is applied to the pavement. In order to have a sufficient amount of
energy penetrating to depth so as to fluidize the asphalt, and to
minimize hot spots, the elastomer can act as a mask to avoid
oxidation of the asphalt where hot spots are present.
[0159] Depending upon the nature of the materials present in the
elastomer, a wavelength separating effect can occur in the
elastomer as in the micaceous material, such that certain
wavelengths are preferentially transmitted. The elastomer does not
have to be a pure organic material; it can have materials like
silicon dioxide or other materials that have a desired permittivity
to a particular wavelength, or birefringent or trirefringent
properties. In some embodiments, these components are present in a
volume as high as 50% in the elastomer composition; however, in
certain embodiments lower amounts can be desirably employed, e.g.,
from 1-10% by volume, or from 10-50% by volume.
[0160] The relative permittivity of a material under given
conditions reflects the extent to which it concentrates
electrostatic lines of flux. In technical terms, relative
permittivity is the ratio of the amount of electrical energy stored
in a material by an applied voltage relative to that stored in a
vacuum. For example, the power source can be the emitter, the
transmitting device can be the medium through which the emitter's
energy is passing, and the load is what actually happens when the
molecular structure of the various substances adsorbs the energy.
The movement of energy from the emitter device through the pavement
medium can be described in terms of the relative permittivity of
the pavement. For methodologies for creating a wavelength of
energy, typically resistance wires are used for heating, e.g.,
wires comprising iron, aluminum, titanium, platinum, etc., and a
variety of other materials that create design resistance. The
resistance of the flow of electric current creates radiant energy
that falls in the bandwidth from a millimeter long down a few
micrometers--the infrared (IR) microwave boundary. Materials are
heated depending upon the absorbent qualities of polar materials,
like water, that they contain. There are certain bandwidths in the
IR region that are highly condensed or captured within the
structure of, e.g., water, and quick energy absorption is observed
(e.g., a quick rise in terms of temperature as a result of that
absorbed energy). The IR microwave boundary can be considered that
region between far infrared and what can be considered extremely
short microwaves (e.g., 1 millimeter). In various embodiments, it
is desirable for the emitter to provide a substantial amount of
energy in this region, e.g., 1, 5, 10, 15, or 20 nm up to 1, 2 or
more millimeters, preferably from about 1000 nm to about 10000 nm,
depending upon the asphalt/aggregate to be heated, or from 2
microns to 1 millimeter. Many materials are substantially
transparent to microwaves having a bandwidth that is down in the
megahertz and kilohertz range, which are very long bandwidths
compared to IR heating. These microwaves penetrate materials
readily that do not have a high hydroelectric constant or a high
relative permittivity. The microwave transmissivity of common
materials such as are used in the paving industry or other
industries are well known or readily ascertained by one of skill in
the art. The refraction and reflection that takes place between the
emitter surface and the surface of the emulsion when it is placed
on the top of the pavement can likewise be ascertained, so as to
achieve a desired temperature profile in the pavement.
[0161] In an asphalt pavement surface contacted with energy having
a peak wavelength of from about 1000 nm to about 10000 nm, or up to
20 micrometers or more against the surface, the presence or absence
of the emulsion on the surface can have a profound affect in terms
of how much energy is refracted, reflected and, transmitted below
the surface to the interstices of the asphalt at, e.g., three
inches in depth. Refraction is the change in direction of a wave
due to a change in its medium. It is essentially a surface
phenomenon. Refraction is mainly in governance of the law of
conservation of energy. Momentum due to the change of medium
results in the phase of the wave being changed, but its frequency
remains constant. As energy moves from the emitter to the surface
of the pavement, the rate of movement remains the same, and the
wavelength remains the same; however, the incident wave is
partially refracted and partially reflected when it hits the
surface. Snell's Law, also referred to as the Law of Refraction, is
a formula that is used to describe the relationship between the
angles of incidence and refraction. Refraction that takes place at
interface, e.g., a boundary between air and a solid, can exhibit a
phenomenon referred to as an evanescent wave, wherein the
wavelengths on one side of the boundary are partially reflected and
partially refracted. At the boundary, reflected energy or
wavelengths can come back from the substance, creating a chaotic
collision of electromagnetic energy that is generally one-third of
the wavelength. For either a narrow energy source such as a laser
or a broad infrared radiant energy source coming to the surface of
a solid, one is able to measure this perturbance and predict with a
degree of accuracy how much energy is returned and how much is
transmitted, which impacts the amount of energy transmitted into
the pavement. An advantage of the emulsion on the pavement surface
is that it disrupts the organized formation of a wave bouncing back
out of the pavement, such that more energy can be transmitted into
the pavement. Knowing the wavelength that is presented to the
pavement, the evanescence wave that is created, and the
permittivity of the material enables one to predict and control the
heating characteristics of the pavement. The relative permittivity
is an absolute number for stone, for water, for the atmosphere of
the voids in the pavement, for the asphalt that is in the
interstices. When considered together, one can analyze what the
effect of a particular wavelength on its rate of movement through
the pavement, e.g., through the use of conventional probes for
determining energy levels and bandwidth changes. This permits the
emitter and the materials employed in the emulsion to be selected
such that the peak wavelength can be manipulated to maximize energy
absorption by the pavement or aggregate or asphalt emulsion/asphalt
emulsion while minimizing consumption of energy in generating the
electromagnetic radiation. For example, the wavelength can be
manipulated to about a millimeter, which is in the terawatt range.
In this range, the depth of penetration for the amount of energy
that is used from the generator is profoundly improved, such that
energy consumption is reduced.
[0162] For an emitter temperature that is at 750.degree. F., and
for an immediate surface temperature, e.g., 1/3 of the wavelength
below the emulsion layer that is 55.degree. F., within a few
seconds, because it is time-dependent, a temperature at just below
the surface, e.g., a millimeter below the surface, is 75.degree. F.
Moving down progressively in increments of 1/2 inch to one inch,
the emitter temperature versus the surface temperature versus the
temperature at various depths can be analyzed. This power depth
loss of the energy as it enters the pavement from the irradiated
surface can be compensated for by manipulating the surface energy,
the Watt density, the wavelength, the effects of evanescence wave
paths, and the wavelength of energy passing through the pavement so
as to increase the uniformity of heating from the surface to a
desired depth (e.g., 3 inches). As top temperature threshold, it is
desirable to avoid the formation of organic gases, which indicates
that the material has gone past the threshold of maintaining its
original molecular structure. If gas formation is not apparent, as
indicated by the absence of smoke, the power can be increased;
however, that is not the only factor that should be considered. The
other factor is a desire to minimize the amount of power that it
takes to get the energy as deep as it needs to be (e.g., as can be
determined by characterizing how deep the voids are that are part
of the flaws in the pavement so that it can be determined how long
the unit has to stay over a certain spot with a particular
configuration to reach that depth). One must also achieve a
temperature such that when a roller is applied to the heated
pavement, it is fluidized and will compress to eliminate voids,
whereby increased densification and homogenization of the repaired
pavement is achieved.
[0163] In terms of relative permittivity, that of water, for
instance, is 80 times higher than that of rock, which is 7.
Asphalt's relative permittivity is similar to that of water -60-70
times higher than that of rock. Rock can be considered
substantially microwave transparent. This means 95% of the pavement
cross-section is essentially transparent to millimeter wavelengths.
Referring back to Snell's Law, the more oblique the angle of the
radiation coming to the surface from its boundary zone (critical
angle incidence), the higher the refraction and the higher the
reflection. The angle of incidence of the radiation can therefore
be manipulated to adjust the amount of energy transmitted. The far
IR-near microwave wavelength is going to interface a solid surface
at a much more direct angle, such that for a microwave transparent
material like stone, some IR energy that is quickly absorbed by the
aggregate in the interstices can be desirable for heating (see,
e.g., TABLE 2).
[0164] In various embodiments, it is desired to move energy from
the emitter surface to 1, 2, or 3 inches deep in the pavement, in
the shortest amount of time without destroying or otherwise
significantly damaging the materials in the upper region. The
emitter system can enable this to be achieved. In contrast, heating
with gas-fired, open-flamed propane that generates primarily IR
radiation, e.g., with an uncontrolled peak wavelength, results in
excess surface heating--smoke coming off the pavement, indicating
destruction of organic pavement constituents such as rubber or
asphalt. The components' molecular weights can be negatively
impacted, causing the damaged portions to lose water resistance,
adhesiveness, and other desirable properties. The emitter system
also results in reduced fuel costs, compared to conventional
combustion systems, which are impractical to tune for peak
wavelength by adjusting, e.g., air/fuel mixtures, and are extremely
inefficient in terms of power consumption per unit of energy
transmitted to the pavement.
[0165] The composite structure of the pavement is 95% aggregate
that exhibits microwave transparency, whereas 75-78% of the
remaining 5% is in the form of polar molecules that are affected
dramatically by contact with far IR-near microwave radiation. In
use, the emitter is turned on and drawn across the pavement. The
entire continuum of the wavelengths and how energy is moving
through the pavement is in a state of flux, meaning that some water
molecules will be lost from the system. This changes the potential
for an evanescence wave, as the polar structures that are in the
emulsion are removed by evaporation, thus affecting the
transmission of energy. In addition, energy is stored within the
rock and the interstices of the asphalt, which also changes the way
that the energy moves through the substrate. It is therefore
desirable to have a system configured to monitor such conditions,
and that can also utilize feedback on how different Watt densities,
different emitters, and changes in the components that are employed
in the emulsion can maximize the use of the energy while minimizing
potential damage to the pavement during homogenization of the
interstices down to 1, 2, or 3 inches in depth and while minimizing
energy consumption.
[0166] By analyzing data from experiments with different paving
materials and different emulsion compositions, emitters can be
constructed that work well with conventional asphalt concrete
pavements, and that consume less than 20% of the power of heaters
in conventional use for heating pavement, or even less energy
(e.g., 5%). Such conventional methods include burning liquid
propane gas using a ceramic blanket, or the more sophisticated open
flame or catalyzed gas systems.
[0167] In one embodiment, the emulsion includes a birefringent or
trirefringent material, and is provided in the form of a
pre-manufactured film. The film is rolled over the surface of the
pavement, e.g., from a spool, and then the emitter system is run
over the top, yielding a sealed surface. It is desirable to avoid
driving too much energy into isolated spots in the pavement where
the energy is absorbed quickly, e.g., due to the higher
permittivity of asphalt, water or other organic material such as
rubberized asphalt. This can negatively impact the molecular
structure of the elastomer. The elastomer begins to melt and flow
over the surface of the asphalt, such that blowing off of water or
other volatiles is avoided. This results in a zero (defined by EPA
as less than 1%) volatile organic carbon (VOC) repair process.
[0168] The emitter systems typically generate about 0.1% VOC, which
is highly desirable from an environmental standpoint and superior
to many conventional processes which generate smoke and release
large amounts of VOC.
[0169] Rock or very fine aggregate can be coated with elastomer and
the elastomer can be pre-cured. The rock, which serves as a carrier
of the elastomer, can then be placed due to its dry, free-flowing
nature. By pre-firing the elastomer on a stone, e.g., in a plant,
one can minimize the amount of energy one has to use in the field.
Such a mixture would offer advantages over cold-mix asphalt in
terms of ease of handling in the field. The material is pre-dried,
taken to a jobsite, spread out, and then heated using the emitter
system to yield a quality asphalt concrete pavement surface.
Oligopolymerization
[0170] In some embodiments, the radiation emitted by the heat
shuttle can optionally be modulated to emit at least some radiation
in the far IR-near microwave region, in addition to the 1000-10000
nm peak wavelength radiation employed in heating the pavement or
aggregate or asphalt emulsion. This focuses heat on the asphalt
between aggregate instead of the aggregate itself, essentially
preheating the asphalt. This efficiently warms and disturbs the
polar molecules of asphalt in the voids and interstices in the
pavement without dehydrogenation of the asphalt. The approximately
100 .mu.m ductile asphalt coating on the rock surface becomes
turbulent and is thus mixed with the more brittle and short chain
molecules occupying a volume beyond 100 .mu.m from the stone
surface. The process can also be employed to polymerize oligomers
(approximately 2-150 repeating units) and other broken polymer
chains in the aged asphalt, causing them to link into longer chains
whereby ductility is improved. This process can be referred to as
oligopolymerization, and can be utilized in a process of
homogenization by liquid asphalt oligopolymerization. Core tests
indicate that pavement thus treated is as much as 95% equivalent
(or even more in certain circumstances) to the virgin asphalt
binder originally found in the pavement in terms of: compressive
strength, flexural compressive strength, and shear strength,
compared to mere heating without oligopolymerization. Infrared
radiation transitions to the microwave frequency at a wavelength of
about 1 millimeter. When the wavelength gets shorter than 1
millimeter, the radiation is considered far infrared. Terahertz
radiation, also called submillimeter radiation, terahertz waves, or
THz, is electromagnetic radiation with frequencies between the
high-frequency edge of the millimeter wave band, 300 gigahertz
(3.times.10.sup.11 Hz), and the low frequency edge of the
far-infrared light band, 3000 GHz (3.times.10.sup.12 Hz).
Corresponding wavelengths of radiation in this band range from 1 mm
to 0.1 mm (or 100 .mu.m). Because terahertz radiation begins at a
wavelength of one millimeter and proceeds into shorter wavelengths,
it is sometimes known as the submillimeter band, and its radiation
as submillimeter waves, especially in astronomy. Terahertz
radiation occupies a middle ground between microwaves and infrared
light waves. For inducing oligopolymerization it is preferred to
employ radiation wavelengths of from 10,000 nm, 15,000, 50,000,
100,000 nm, or 500,000 nm to 1,000 .mu.m or more, e.g., from 15,000
nm to 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8
mm, 1.9 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm or
more.
Comparison of Systems of the Embodiments to Conventional Hot In
Place Recycle (HIR)
[0171] The systems of the embodiments are noninvasive methods of
restoring the pavement to the highest possible physical
properties--properties superior to those of conventionally repaired
pavement, such that the asphalt exhibits characteristics similar
to, or better than, virgin asphalt ("rejuvenated asphalt").
[0172] Hot In-Place Recycle (HIR) is the conventional method for
repairing aged and alligatored asphalt pavement. HIR is described
in detail in Chapter 9 of "Pavement Recycling Guidelines for State
and Local Governments Participant's Reference Book", Publication
No. FHWA-SA-98-042 published December 1997 by the U.S. Department
of Transportation Federal Highway Administration, the entire
contents of which is hereby incorporated by reference herein.
Virtually all pavement heating employed in this
re-construction/maintenance method utilizes an LPG or NO energy
source. In LPG or NO energy source heating processes, the gas is
mixed with air and ignited within an outer shroud. The mixing and
ignition can be deployed as an open flame or controlled within a
tube or ceramic blanket emitter. Whether open flame or within a
controlled chamber, the surface temperature is generally above
1500.degree. F. and emits an electromagnetic bandwidth which is
less than 2000 nm (2.0 microns). Where the combustion is retarded
by a catalyst, the emitter temperature(s) can drop to as low as
600.degree. F. and exhibit a bandwidth as long as 100 microns.
While the use of a catalyzed flame with a longer wavelength would
be beneficial to more effectively warming aged asphalt, fumes from
the process will quickly contaminate the chemistry of the catalyst;
rendering it ineffective.
[0173] While gas fired technology (GFT) and the
diesel-generator-driven electric heat from emitter expend nearly
equivalent btu's in fuel consumption per unit of wattage output,
the tangible, emitter frequency control of the emitter system
maximizes energy absorption by the heated surface; thereby
resulting in up to a five-fold reduction in btu's consumed, as
compared to gas fired emitters, to achieve the same mass
unit/temperature rise.
[0174] Low-to-no smoke is associated with the emitter operation
during the pavement heating cycle, since the temperature of the
pavement surface can be carefully regulated to not exceed a `blue
smoke` temperature. In contrast, the GFT must overheat the surface
temperature (often >300.degree. F.--well in excess of a `blue
smoke` threshold) to drive energy sufficiently deep (1.5''-2.0'')
to achieve at least a 200.degree. F., sub-surface softening
temperature; thereby facilitating the HIR scarifying and/or planing
of the upper pavement surface. Turning the GST on and off as a
method of regulating temperature overrun for the pavement surface
is one commercial method of minimizing the occurrence of `blue
smoke` emissions, but the continual ramping back up from the `off`
mode substantially increases fuel consumption costs and CO.sub.2
generation from the heating unit.
[0175] This air emission advantage relating to generation of` `blue
smoke`, coupled with the extra fuel used to warm the pavement with
indiscreet, reduced radiant energy absorption, results in at least
an eight fold increase in CO.sub.2 emissions by GFT, as compared to
the emitter technology of the embodiments.
[0176] Burns to operators are less likely with the emitter
technology of the embodiments than with the gas fired technology.
Explosions are non-existent with emitter technology of the
embodiments, but are always a significant threat when operating
with flammable gas as in a GFT process. State-of-art, electrical
equipment employed in the emitter system prevents workers exposure
to electrical shock.
[0177] GHT/HIR processes and/or other short wavelength IR
electrical devices inevitably overheat and accelerate the oxidation
of surface asphalt during the process of repairing the old road
surface by disturbing it, mixing it with new material and covering
it. The emitter technology of the embodiments results in `gentle`,
regulated heating that prevents such accelerated oxidation from
occurring. A more thorough surface preparation eliminates the
adulterating effect of dirt and organic debris, thereby
substantially reducing the need for any scarifying of the old road
surface as the vibratory compaction of the new overlay material
adequately `mixes` these two substrates in a uniform, high
performance, fused monolith.
[0178] A newly applied lift of composite material comprising
AROS.TM. or other ground tire rubber, bio-resin enriched, high
carbon pitch and stone, installed as a cold process slurry or cold
mix asphalt, can be fully fused to the thermally activated existing
road surface without the damaging effects of excessive temperatures
to the binder chemistry. Materials added to the GFT are inevitably
exposed to higher, often difficult to regulate temperatures which
prematurely oxidize the chemistry. Therefore the final surface and
underlying road surface restoration can be expected to last
significantly longer.
Characteristics of Treated Pavement in the Field
[0179] Fatigue life and stress life are properties of asphalt
pavements. Stress is a unit of force per area. Strain is
deformation caused by stress. Fatigue life is the number of stress
cycles of specified character before a specimen or system sustains
failure of a specified nature. Stress life curve plots the
interrelationship between a system's specific stress quanta and
range, and the strain product thereupon imparted; resulting in a
predicted time to system failure. Accordingly, these measurements
are of interest in determining useful life or service life of
pavement.
[0180] The Federal Highway Administration (FHWA) has established
that good highway design practices shall utilize aggregate that
conforms to gradation bands and at percentages prescribed by the
"0.45 Power Curve", and that four specific categories of tests
shall be performed on those gradations. Those tests evaluate the
stone for: 1) toughness and abrasion resistance, 2) durability and
soundness, 3) angularity and 4) presence of minerals not otherwise
considered aggregate singularities aka "sand equivalencies".
Aggregate nomenclature divides rock which will not pass through a
#8 sieve as coarse and that which will pass as "fines". By mass,
for dense graded, hot mix pavement the 0.45 Power Curve shows that
about 50% of the aggregate are fines and 50% are coarse aggregate.
Coarse aggregate typically has made it through the crushing process
because it is much tougher than the fines. It is much tougher
because it doesn't have many micro-fissures or tiny cracks which
lead to fracturing under the high pressures associated with rock
pit crushing operations.
[0181] The requirement that aggregate be tested for durability and
soundness is targeting the detection of micro-fissures in the
aggregate as a weak point in road durability. Water which works its
way into such fissures during the service life of the road will
chemically weaken the stone or freeze and break it open. Typically
the coarse stone is not subjected to the test. The test for
durability and soundness consists of soaking the aggregate `fines`
in a dilute solution of either sodium sulfate or magnesium sulfate.
The sulfate salt, upon entering the micro-fissure, expands,
producing a similar effect to ice, thereby enlarging the
micro-fissure. After rinsing the soaked stone in fresh water a
percentage of the stone is flushed. If too much stone is lost in
this process then the stone is disqualified for use. The presence
of micro-fissures in the pavement mixture is a principal
contributing factor to moisture sensitivity and premature fatigue
degradation of the road. The homogenization process, to a great
extent, corrects the presence of this weak link.
[0182] Asphalt is composed of two phases. The continuous phase
comprises maltenes and the suspended phase comprises asphaltenes.
Maltenes are usually low in carbon by mass and linear in molecular
arrangement with molecular weights of less than 500. Maltenes have
large areas of free molecular space in proportion to their
hydrocarbon chain volume. Asphaltenes are much higher in carbon
content and most generally are of a molecular weight ranging
between 5,000 and 45,000. Asphaltenes are tightly wound with low
free molecular space relative to their molecular volume.
[0183] It has been discovered that asphaltenes have a propensity to
behave like a capacitor, surface storing electrons. Particularly
during the high temperature, short IR wavelength excursion that the
asphalt is subjected to in the preparation of hot mix asphalt in
the 350.degree. F. to 400.degree. F. region. This electron storage
creates repelling polarity between similar, highly charged
asphaltene particles. This polarity induces a partial, artificial
phase segregation of these high molecular weight particles. As the
partial, artificial phase segregated asphalt is coated on the
aggregate at the hot mix asphalt plant, this segregated condition
becomes fixed within the shoreline of the rough stone surface. This
imbalance within the two phases of the asphalt created in the
conventional hot mix plant becomes a permanent obstacle to optimal
compaction and long term durability of the thermoplastic binder.
Phase segregation is an obstacle to compaction. A homogeneous
asphalt behaves like a lubricant allowing the stone matrix to slide
into maximum compaction whereas a stratified asphalt behaves like a
contaminated (e.g., grit filled) lubricant and resists the slipping
action needed to allow the rigid surfaces to easily glide to full
embedment. Years of testing have verified that as little as a one
percent air void density reduction in dense graded asphalt concrete
can improve rutting resistance by over 100%.
[0184] Phase segregation is also an obstacle to long term
resistance to oxidation as atmospheric moisture and electromagnetic
energy perpetually work to strip and replace the most weakly bound
hydrogen atoms from the hydrocarbon chains of the maltene
structure. As hydrogen atoms are stripped both the ductility and
cohesive strength of the asphalt is diminished; leading to
embrittlement. A uniform dispersion of the very robust asphaltenes
acts to attenuate this stripping action as it will, by its
capacitive nature, attract and store much of the energy bias
delivered from the combined effect of rolling loads, sun loads and
water. The technology of various embodiments can be employed to
re-homogenize this hot-mix-plant-induced phase segregation to a
high level of uniformity. This restored phase uniformity halts
accelerated fatigue degradation due to excessive, void-induced
structural integrity and electro-chemical dehydrogenation.
[0185] Asphalt is typically strengthened by melting rubber and
other thermoplastic polymer modifiers into the bitumen at the hot
mix plant prior to coating the aggregate. This polymer modification
is usually accompanied by some form of crosslinking within the
polymer modifier to more fully develop, upon cooling, an
interconnected, crystalline grid within which the amorphous bitumen
may be stabilized.
[0186] The binder coating on the stone in a hot mix plant setting
is in the 3-5 mil range. Typically, once the coated stone is placed
and compacted, the crosslink exists only within the coating on each
singularity. Little to no post placement crosslinking between the
individual coated particles takes place. The inter-crosslinking
performs its task of stabilizing the bitumen but since the
potential for intra-crosslinking between the coated surface of the
compacted aggregate is disrupted by: 1) the loss of mobility as the
binder cools while 2) being simultaneously sheared into new,
relative positions, the probability that any stabilizing
crystallinity can be formed is low. This condition leaves the
interstitial load transference between coated moieties at a
diminished optimal quanta. Emitter heating and dielectric stirring
provides an environment to at least partially correct this
condition with a resultant improved resistance to fatigue
degradation.
[0187] Asphalt concrete fails as its flexibility gives way to
embrittlement. Embrittlement results when hydrocarbon chains in the
continuous maltene phase are de-hydrogenated through oxidative
cleavage. It is the combination of atmospheric moisture in the form
of rain, fog, and snow multiplied by the presence of surges of
electro-magnetic energy accompanying solar and mechanical loads
that drives this destruction. Embrittlement fatigue in the upper
one-half inch of pavement occurs more rapidly; often at two to ten
times the fatigue rate below that surface depth. Not only are the
oxidative forces more concentrated by the tearing action of tires,
snow removal equipment and surface debris but direct solar load in
the form of sunlight and wind places stress upon the surface which
result in rapidly developing cracks leading to the formation of
potholes, long fissures and block cracking, also referred to as
"alligatoring".
[0188] The emitter wavelength can be adjusted to effectively and
rapidly penetrate this upper crust region, disrupting the effects
of these surface stressors and thereby extending the accepted
stress life curve for surface deterioration. Cross-sections of
pavement below this upper half-inch crust undergo a slower but
often more persistent oxidative process. Moisture, which might
quickly evaporate at the surface thus terminating its oxidative
threat, becomes trapped in lower pavement voids for long periods.
This encapsulation allows it to slowly but persistently attack the
interstitial binder flexibility. However, of greater fatigue
consequence by moisture is the attack at the binder-stone interface
where direct contact between water and the plethora of reactive
hydroxyl sites resident in all aggregate results in a rapid binder
delamination.
[0189] Often "near new" pavement (pavement still in its first three
years from installation), will have a superior driving surface but
began to spall and break apart at between 1 to 3 inches deep. This
is caused by the delaminating effect of trapped moisture finding
its way to the binder-stone interface and reacting with the
hydroxyl groups on the aggregate surface. The emitter's adjustable,
deep pavement penetrating wavelength can, non-invasively, interrupt
this accelerated fatigue degradation process; significantly
extending the useful life of the pavement.
[0190] Thermal pumping is a term which describes the in-situ
movement of fluidized, hot asphalt (as it expands under an outside
heat source) from the confines of micro-fissures within the fine
aggregate in pavement. This cavity dwelling binder was first
absorbed during the hot mix plant blending but is coaxed out into
the interstitial air voids of the pavement matrix. This asphalt, as
well as the asphalt coating the first 100 microns thickness from
the stone surface, have been shown to be unchanged from the
original installed chemistry. Warming and stirring, plus
re-introducing, these virgin reservoirs of ductile, highly cohesive
binder, through the use of selective bandwidths of energy which
optimize a dipolar response, significantly improves the flexibility
of asphalt concrete.
[0191] Phase segregated binder throughout the aged asphalt concrete
matrix is bathed with an emitter supplied bandwidth of energy which
is between 1,000.times. to 100,000.times. longer than the near IR
emitted bandwidth of the open flame heating used in conventional
hot mix plants. This long wavelength, `gentle` heating causes a
dielectric relaxation of the asphaltenes allowing them to
re-integrate into a uniform homogeneity. Once this homogeneity is
restored the binder becomes: 1) more oxidation resistant and 2) a
much superior lubricant to the slippage of rock under a
re-compacting effort.
[0192] Vibratory compaction of a properly emitter treated road
cross-section can reliably reduce air void densities from a typical
7% to an improved 4.5-5% range. Between 1'' and 3'', the core
temperatures accompanying these homogenization changes is in the
240-300.degree. F. range. Without this lubricating effect, heavy
vibratory compaction attempts have proven to only break rock and
damage the pavement. Re-heating aged pavement to similar pavement
core temperatures with short wavelength, IR heaters do not result
in this significant beneficial response. Air void density reduction
not only improves the pavements resistance to mechanical rutting
but it also tightens the voids into which moisture can migrate. The
fluidization at the rock surface improves a re-wetting of the
binder upon the rock surface as a result of the dual action from
the increase of interstitial pressure upon compaction and the
dipole reaction of the electromagnetic field.
[0193] Hot mix asphalt (HMA) pavement preparation is a
HEAT+MIX+INSTALL dynamic. The methods of certain embodiments follow
a MIX+INSTALL+HEAT dynamic. This difference has a dramatic,
positive effect on fatigue life extension in addition to the
improvements above referenced through the use of the technology of
various embodiments on the underlying, aged asphalt. Use of
adhesive systems multiplies system effectiveness in delaying
fatigue degradation of new, virgin material and/or a mixture of old
milled pavement augmented by mixing with new, virgin material.
[0194] Adhesive can be provided in a waterborne emulsion form.
Numerous versions of the chemistry are commercially available from
Coe Polymer, Inc., of San Jose, Calif. Compounding the liquid onto
virgin aggregate is preferably achieved by belt or augur feeding a
metered flow of graded stone into a conventional dual shaft,
counter rotating pug mill, whereupon the liquid adhesive is sprayed
at a pre-determined rate. As the damp, coated stone exits the pug
mill it may be fed directly: 1) into a conventional paving machine
and thereby placed upon the receiving surface of the road, 2) into
a short term storage bin for transfer to a job site, 3) onto a
stockpile for storage or air drying or 4) through a drying device
which eliminates the moisture. The binder chemistry may be adjusted
to accommodate a successful processing under any of these four
methods of stone coating; however, method 4) is generally
preferred.
[0195] Superior asphalt adhesive performance can be achieved with a
binder chemistry that: 1) fully wets the irregularities of the
stone surface, 2) covalently bonds to all naturally occurring,
surface --OH groups, 3) upon water evaporation inter-crosslinks to
absolute insolubility, 4) remains a heat flowable thermoplastic but
only becomes plastic at temperatures higher than 200.degree. F., 5)
can be applied to stone then subjected to dehydration but
thereafter retain sufficient functionality for future
intra-crosslinking when tightly packed together with other
similarly processed stone, 6) after placement through a paving
device, to achieve a double crosslink by thermal or chemical
activation and 7) remains flexible to 0.degree. F. while still
retaining thermoplastic behavior within the temperature performance
range specified. To achieve these seven characteristics, a two coat
process has been devised. Adhesive Part 1, at approximately 60%
solids content, is applied onto the virgin stone surface at a wet
film thickness of about two mils as it passes through a pug mill;
then immediately flash dried and cross-linked onto the inorganic
surface of the aggregate. In a continuous operation the now dried,
thin coated moiety receives adhesive Part 2, also approximately 60%
solids, in a similar application and drying manner; whereupon it is
then transferred to storage. Part 1 adhesive maintains reactive
functionality, which immediately self-crosslinks upon contact with
Part 2 adhesive. Part 1 adhesive achieves performance
characteristics 1), 2), 3), and 4). Part 2 adhesive continues to
achieve performance characteristic 4), but is the principal
provider of performance characteristics 5), 6), 7), and 8).
[0196] After implementation of the above process, the coated stone
may be stored in bulk stockpiles indefinitely without self-adhering
at ambient temperature. Thereafter it may be shipped by any
conventional means to be placed and compacted onto the receiving
surface. Once partially compacted, the emitter device is rolled
over the surface whereupon the emitter wavelength is tuned to
activate the functionality of the reactive groups within Part 2
adhesive, thereby completing a double crosslink. The pavement
cross-section, when activated by the emitter during the second
crosslink typically achieves a temperature in the range of
325.degree. F. to 350.degree. F. As it cools to about 275.degree.
F. it is compacted to final density.
[0197] The deployment of the technology, beyond the prescriptive
preparation of the coated stone, is manifold. For example, old
pavement, after removal of surface debris and dirt embedded in open
cracks, may be homogenized, thereby warming the pavement to a
temperature of up to 300.degree. F. at a depth of up to 3''. Once
the pavement is warmed and the binder therein has been stirred, a
sprayable binder and stone slurry may be injected or calendered
into surface cracks of the pavement. While still warm above
250.degree. F., the pavement may be vibratory compacted to a
uniform, defect free, weather resistant surface. A rough, buckled
or rutted pavement profile may require surface milling to achieve a
desired ride quality. Once the emitter has rolled over the surface
and achieved a minimum pavement temperature of 250.degree. F. in
the region to be milled the removal may commence without damage to
the stone within the milled pavement matrix. Upon the removal of
this milled material it may be then immediately re-mixed at the job
site with a previously prepared binder coated stone and placed back
onto the pavement surface through a paving machine for compaction
and final crosslinking. This will save a lot of money by reducing
the demand for imported material. Conventional cold milling damages
stone but after grading out the recycled asphalt pavement (RAP) it
may be mix with a binder coated stone and reinstalled as outlined
herein.
[0198] Whenever the utilization of old road grindings is preferred,
after grading to the appropriate sieve spectrum, any combination of
site coating of these grindings and blending with binder coated
aggregate may be initiated with improved results over conventional
methods; but the final installed pavement mat must be heat
activated with the emitter prior to compacting to assure that the
adhesive is fully developed.
[0199] A pre-manufactured 1/8''-1/2'' thick road plating
composition of graded stone and binder may be manufactured in long
rolls or sheets at an offsite location. The sheets can be assembled
into an elastomer binding of approximately 1 mm thickness then
transferred to the point of application as, for example, 6'-0''
wide sections which are paved upon a pre-prepared dilapidated road
surface. Thereafter, the emitter rolls over the newly installed
wearing surface and irradiate both the old road base and the new
sheet such that a vibratory compaction can then fuse the structure
together. A binder primer or levelling course can first be
installed, in certain embodiments, to provide an improved
surface.
TractionSeal Micro
[0200] TractionSeal Micro is a friction enhancing fog seal-seal
coat. The technology is derived as a gel binder which is added to
water then a pre-packaged stone (fog seal -150/325 or seal coat
-50/200) is mixed therein. The gel may be mixed to create a
fivefold increase in coating volume. This means that for every
gallon of gel up to 5 gallons of ready to use sealer is made. The
liquid compound is quick drying and provides a scuff tolerant,
highly water and fuel resistant, permanently black, skid resistant
surface. The high softening point binder retains an engineered,
micro-stone composite, exhibiting aerospace derived, solid phase
auto-regenerative cohesion. This means that when an oxidative,
thermal or mechanical load damages the composite matrix it will,
upon one cooling-heating cycle, self-repair the remaining internal
binder. The binder technology wicks into the porous, brittle upper
asphalt region of pavement, replenishing lost aromatic resins. This
restores adhesive ductility and upon curing creates a
shrink-wrapped, stone matric wearing shield; protecting the old
pavement surface. The fog seal may be spray applied by distributor
truck. The seal coat may be spray or squeegee applied with
conventional equipment.
Hamburg Wheel Test
[0201] The Hamburg wheel test can be used as a screening tool for
hot mix asphalt. The Hamburg Wheel Tracking Test originated in
Germany in the mid-1970s. The test examines the susceptibility of
the HMA to rutting and moisture damage. The Hamburg Wheel Tracking
Test uses a steel wheel with weight that rolls over the sample in a
heated water bath. A designated number of passes are performed on
the sample, e.g., 20,000 passes or more. The rut depth is measured
by the machine periodically, usually every 20, 50, 100 or 200
passes. 20,000 passes typically take around 8-10 hours. Several
analytics are examined with the Hamburg Wheel Tracking Test
including post-compaction consolidation, creep slope, stripping
inflection point, and stripping slope. The Federal Highway
Administration has published a report providing details of the test
(see Publication Number: FHWA-RD-02-042 dated October 2000) and an
evaluation of the Hamburg test for Caltrans was published by UC
Davis (see Qing Lu and John T. Harvey, Research Report:
UCPRC-RR-2005-15 dated November 2005). In practical terms, the test
can be employed on any particular asphalt pavement, particularly a
pavement to which a fresh wearing surface has been applied, to
determine what, if any damage has occurred below the visible
surface of the pavement. The Hamburg test can be employed to
predict whether the resurfaced pavement will maintain a long
service life or whether it will rapidly degrade.
[0202] FIG. 5 depicts a Hamburg Wheel Test apparatus employed to
test selected asphalt pavement cores. The apparatus includes a left
dock and a right dock, each dock holding a front and a back asphalt
pavement core to be subject to testing. The core in the front left
dock was designated L3, the core in the rear left dock was
designated L9, the core in the front right dock was designated R3,
and the core in the rear right dock was designated R9, as also
referred to in FIGS. 5, 6, and 7. The L6 and R6 designations were
used to refer to the center point between the L3 and L9, and the R3
and R9 cores, respectively. The cores subject to testing were
laboratory prepared cores.
[0203] FIG. 6 provides a comparison of attributes of various cores
tested. Checkmarks indicate which design mix variables are
identical for the cores tested (including stone package, binder
grade, binder weight, final core temperature, and % air voids).
Application Sequence 1+2 indicated that the stone was coated with a
binder and then the coated stone was further coated with binder,
whereas Application Sequence 2 indicated that uncoated stone was
coated with binder in a single step. Stone XL indicated to what
degree crosslinking in the binder applied directly to the stone
(not bulk binder) occurred as induced by emitter technology, with
"NO" indicating that emitter technology was not applied to the
coated stone. Inter XL indicated to what degree crosslinking in the
bulk binder prior to application to the stone occurred as induced
by emitter technology, with "NO" indicating that emitter technology
was not applied to the bulk binder. Intra XL indicated to what
degree crosslinking between the binder on the coated stone and the
bulk binder occurred as induced by emitter technology, with "NO"
indicating that emitter technology was not applied. The amount of
crosslinking induced was selected by controlling the amount of
energy imparted to the core using emitter technology.
[0204] FIG. 7A provides results of a Hamburg Wheel Tracker test for
left dock (L3, L6, L9) asphalt pavement cores. The tests were
conducted in a 60.degree. C. water bath. The y-axis represented
axial deflection in millimeters, while the x-axis represented the
number of wheel passes the cores were subjected to. The L3 core
exhibited poor performance--essentially a steady slope down with
failure at almost a 45.degree. angle on the graph. While the binder
employed in preparing the tested cores was the same, the
crosslinking was different. The L3 core was not subjected to any
crosslinking. In contrast, the L9 core exhibited half as much
rutting as the L3 core. In the L9 core crosslinking between the
binder and stone, as well as crosslinking in the bulk binder, was
induced by application of emitter technology.
[0205] FIG. 7B provides results of a Hamburg Wheel Tracker test for
right dock (R3, R6, R9) asphalt pavement cores. The graph includes
a region identified as "Stripping Inflection". This region
illustrates that between about 9,000 and 11,000 cycles, the rate of
rutting begins to accelerate.
[0206] It has been discovered that if one can crosslink binder to
the stone using ambient cured crosslink technology, the moisture
sensitivity of the road is substantially improved. For example, the
R3 can be compared with the L3 core. The L3 core begins to fail at
5,000 to 6,000 cycles, with rutting down to 5 millimeters at 6,000
cycles. In contrast, the R3 core exhibits only half as much rutting
as L3 at the same number of cycles. The binder in the R3 core
exhibits more cohesive strength resulting in less moisture
sensitivity. In the Hamburg test, the asphalt-moisture relationship
dynamics typically do not manifest themselves in the early part of
the test. The core typically requires a period of exposure to water
under test conditions in order for water to work its way down into
the core, similar to the process of exposing pavement to the
elements under ambient conditions. Accordingly, a brand new road
may exhibit satisfactory performance for a couple of seasons, and
then suddenly begin to fall apart due to the moisture penetrating
the core and inserting itself between the binder and the rock.
Accordingly, the Hamburg test can be conveniently viewed in two
parts: resistance to rutting up to about 10,000 cycles, and rut
resistance after 10,000 cycles. Resistance to rutting up to about
10,000 cycles and beyond indicates that the stone and the binder
are well-adhered to each other, so as to resist water breakdown.
While intercrosslinking can improve rutting resistance in the first
10,000 cycles, it is stone crosslinking that improves the rut
resistance long term, pushing the stripping inflection point out
further. The R9 core exhibited the best performance of the cores
tested. The R9 core was subjected to 100% crosslinking on the stone
and 100% intercrosslinking. There was no significant loss of
moisture resistance, and the intercrosslinking of 100% kept the
material very stiff in terms of the overall rutting in the later
stages of testing. Intracrosslinking for R9 was at 20%.
[0207] FIG. 8A provides results of a Hamburg Wheel Tracker test for
right dock (L3, L6, L9) asphalt pavement cores prepared to maximize
stone crosslinking, intra-crosslinking, and inter-crosslinking. The
tests were performed in a 60.degree. C. water bath. The cores
exhibited a maximum rut of 3.6 mm in the middle of the core and an
average of 2.4 mm from readings in the middle of cores and a
reading at the joint. A second Hamburg Wheel Tracker test was
repeated on the same set of cores that had previously been
subjected to testing (first Hamburg Wheel Tracker test results
provided in FIG. 8A, and second, subsequent Hamburg Wheel Tracker
test results provided in FIG. 8B). For the second test, the cores
were set in high strength plaster so that the lower original
pavement would be fully contained. The second test resulted in a
maximum rut of 2.1 mm in the middle of the core and an average of
1.5 mm from the readings in the middle of the cores and a reading
at the joint. The cores so tested survived 50,000 cycles with less
than 4 mm of total rutting.
[0208] The cores were prepared as follows. A stone matrix was
provided that was 3/4'' graded along a Federal Highway
Administration (FHWA) 0.45 power curve. Coatings were provided that
comprised 60% polymer modified emulsions that were applied cold to
the dry stone of the stone matrix. A coating, referred to herein as
"Application Sequence 1 Coating" was prepared as follows. A mixture
of HCP Asphalt Emulsion from Delta Trading, LLC of Bakersfield,
Calif. and AFO 9837 Bioresin from Coe Polymer, Inc. of Sacramento,
Calif. was prepared. The ratio of HCP Asphalt Emulsion to AFO 0837
Bioresin was 96.00 to 4.00 (units of weight). To this mixture, MDI
PM200 Crosslink available from Tri-Iso Inc., Los Angeles, Calif.
was added. The ratio of mixture to MDI PM200 Crosslink was 100.00
to 5.00 (units of weight). The amount of solids in the Application
Sequence 1 Coating was 64.68 (units of weight, based on total units
of weight of 105.00). The specified amount of crosslinking agent
(MDI PM200 Crosslink) resulted in 100% crosslinking. Reduced levels
of crosslinking (e.g., Stone XL, Inter XL, or Intra XL as referred
to in FIG. 6) were achieved by reducing the amount of crosslinking
agent in the Application Sequence 1. A coating, referred to herein
as "Application Sequence 2 Coating" was prepared as follows. A
mixture of HCP Asphalt Emulsion from Delta Trading, LLC of
Bakersfield, Calif. and BER 2937 Bioresin Modified Isoprene-SBR
Terpolymer was prepared. The Isoprene-SBR was obtained from BASF
North America of Florham Park, N.J., and the BER 2937 Bioresin
employed to convert the Isoprene-SBR into a Terpolymer was obtained
from Coe Polymer, Inc. of Sacramento, Calif. The ratio of HCP
Asphalt Emulsion to BER 2937 Bioresin Modified Isoprene-SBR
Terpolymer was 85.00 to 15.00 (units of weight). The amount of
solids in the Application Sequence 2 Coating was 60.55 (units of
weight, based on total units of weight of 100.00). The combined
cured binders were evaluated according to guidelines set forth in
ASTM G154 QUV Accelerated Ageing Test--5,000 hrs. including cyclic
moisture at 300-400 nm. The results were no chalking, cracking or
hardening detected. The cured binder was also evaluated according
to the guidelines set forth in ASTM D6521-13 Accelerated aging of
Asphalt Binder--300 psi at 250.degree. F. for 30 days. The results
were no loss of ductility, no formation of carbonyl or sulfoxide
groups detected.
[0209] In Application Sequence 1, the coating was applied to the
stone in an amount of 4% neat resin (relative to stone weight), and
then air dried with ambient temperature crosslinking of the coating
to virgin stone surface. In Application Sequence 2, the coating was
applied to the pre-coated stone in an amount of 3.5% neat resin
(relative to stone weight). The second coating was applied over the
air cured first coating layer, and then air dried. No crosslinking
of the second coat occurred under ambient conditions (crosslinking
is only initiated when the stone-binder matrix is subjected to
temperatures of 250.degree. F. or greater within a compacted
cross-section). Loose, already coated stone was placed in gyratory
compactor cylinder already containing a core sample from an aged
pavement in the bottom. The cold compact stone-binder matrix was
compacted to 5-6% air void density. The resulting total compacted
core thickness was 60 mm with a lower one-half (30 mm) consisting
of the aged pavement cross-section and the upper one-half (30 mm)
consisting of new coated material. The compacted core was then
irradiated with 10,000 nm wavelength radiation to a core
temperature of 300.degree. F. The test section upon compaction and
irradiation curing simulated a one inch overlay repair system.
Hamburg Wheel Test results for the baseline aged pavement taken
from the same area as the aged pavement core samples referred to
above showed in excess of 20 mm rutting, thereby failing the
standard at approximately 5,000 cycles. Irradiating the entire core
to a temperature of 300.degree. F. for a minimum of ten minutes
completely crosslinked the Application Sequence 1 to the
Application Sequence 2 binder within its own matrix as well as
intercrosslinked the Application Sequence 1 and the Application
Sequence 2 into a monolithic polymer at the mechanical touchpoint
of each coated stone moiety.
[0210] A core subjected to 100% stone crosslinking, 100%
intercrosslinking and 100% intracrosslinking would exhibit
virtually no rutting, resulting in significantly longer service
life than any conventional asphalt. In certain embodiments a high
degree of intracrosslinking is desirable. A gap-created road has
voids between the stone that leaves room for water to percolate
through and move horizontally to keep the road from puddling. Such
a configuration helps avoid hydroplaning, and is referred to as an
open grade friction course. Such a configuration is employed in
portions of Interstate 10 that run along the Gulf Coast to avoid
standing water due to heavy rain. While in a dense graded structure
there is substantial rock contact, in a gap-graded road there is
substantially less rock contact, therefore the road cross section
experiences substantially greater mechanical loads at the contact
points. A high degree of intracrosslinking can compensate for the
greater loads. Intercrosslinking is a greater factor in such
gap-graded roads, because the stones touch in fewer spots as
opposed to being nested very tightly. Emitter technology can
advantageously be employed to engineer the binder to compensate for
what would be considered a substandard stone configuration, as in
gap-graded roads, resulting in longer pavement life than can be
achieved using conventional technologies.
[0211] FIG. 9 provides a schematic depicting steps involved in
reconstruction of damaged or aged pavement using emitter
technology. The first step typically involves surface preparation,
if necessary (e.g., removing debris and pavement markers, high
pressure washing and vacuum). Deep pavement repair is achieved by
the second and third steps. The second step involves ductility
restoration by applying emitter technology to the road surface,
followed by a third step of densification of the pavement, e.g.,
using high impact vibratory compaction or other conventional
compaction technologies, depending upon any overlay to be applied.
If desired, these steps can be followed by a final grade and
wearing surface process involving as step 4 the application of a
warm micromill and injection of high performance adhesive (a first
crosslinking), gravity feeding a pre-coated new stone matrix,
mixing new and warm milled aggregate and adhesive then paving,
followed by application of emitter technology to the upper
substrate (a second crosslinking). Step 5 involves a final
compaction and fusion of the wearing surface.
[0212] For conventional asphalt paving technologies, 30 years on
average is typically considered the plausible usable life, i.e.,
the life of the road without major maintenance. In contrast, the
actual useful life is typically considered only 18 years as an
average with the best pavement that is currently in use, namely
conventional hot mix pavement. One of skill in the art understands
that while a high toughness is desirable in asphalt paving, if too
much polymer is included in the asphalt coated on rock to improve
toughness, the material becomes so stiff that it cannot be laid
using conventional paver equipment and exhibits stripping problems.
The emitter technology of the embodiments enables a higher degree
of crosslinking in any polymer present to be achieved versus
conventional hot mix technology, so as to improve pavement
toughness in situ, thereby theoretically extending actual useful
life to 50 years or more for pavement using emitter technology.
FIG. 4 illustrates various fatigue life considerations and their
impact on plausible useful life. The considerations are divided
into process related and chemical related factors. In conventional
hot mix asphalt, a process related factor that reduces life is
oxidation of the binder prior to installation. The binder is
typically subjected to heating for hours prior to installation
(reduction of approx. 2 years of life). In contrast, the emitter
technology warms the pavement in place for only a few minutes (zero
net effect on plausible useful life). Gap graded segregation, where
smaller and larger rocks in the aggregate separate during handling
(transport, storage, transfer, etc.) can cause approx. 3 years
reduction in life. In contrast, in the emitter technology the
aggregate is mixed and laid on site, resulting in superior
homogeneity (a benefit of approx. 2 years in life).
[0213] Moisture sensitivity of the placed aggregate is a
significant factor in life reduction in conventional hot mix. Hot
mix is typically a very high viscosity material due to the presence
of rubberized asphalts. The high viscosity rubberized asphalt
material "smooths out" the surface of dry rock while exhibiting a
tendency to bridge the microstructure of the rock surface.
Accordingly, in conventional hot mix there is much surface area
that is left unwetted by the high viscosity rubberized asphalt
material. In contrast, a water-based material as is advantageously
employed in the technology of certain embodiments has a tendency to
wet out substantially more of the microstructure of the rock
surface, and typically will coat 10 times more of the rock surface
area than a conventional hot mix high viscosity rubberized asphalt
material. This results in a greater intimacy between the chemistry
of a water-based system than in a hot melt system, resulting in
reduced moisture sensitivity. Processes related to moisture
sensitivity result in approx. 4 years reduction in life for hot
mix, versus a gain of approx. 4 years for emitter technology.
[0214] Mat density is a factor relating to stiffness of the hot
mix. As discussed above, bituminous materials comprise two phases:
a continuous phase comprising maltenes and a suspended phase
comprising asphaltenes. Subjecting the material to short
wavelengths of energy as in conventional hot mix results in
dehydrogenation and grafting, causing islands to be formed that
takes away from the homogeneity of the asphalt. This reduction in
homogeneity can impact the compaction process, in that the asphalt
acts like a "dirty lubricant", causing the pavement to move
laterally instead of compacting vertically into a tighter mass at a
certain point. If the asphalt is cooled to the point where it will
not move sideways, then it becomes too stiff to compact vertically.
This results in a 6% void density content in conventional hot mix,
resulting in a loss of 3 years off the plausible useful life. In
contrast, a higher density down to 5% or even 4% or less void
density can be achieved with emitter technology, resulting in an
improvement of approx. 5 years. This is because a longer wavelength
of energy can be employed so lubricity between the binder on the
rock and the stone when the final compaction is performed is
improved, resulting in higher density. Applying emitter technology
and compaction to an aged roadbed that has stratification can
typically reduce void density content of the hot mix by a
percentage point (e.g., 6% void density content is reduced to 5%
void density content).
[0215] Chemistry-related fatigue life configuration can include
polymer selection. For example, the emitter technology can employ
polymer technologies not conventionally used in conventional hot
mix, e.g., certain glycol technologies. Aggregate binder
optimization includes processes related to achieving better wetting
of the rock surface by using crosslinking agents and stripping
agents (e.g., amine bases such as isocyanurates exhibit a weak acid
chemistry and bind to the hydroxyls on the stone surface) that add
significant resistance to moisture susceptibility. Buffered
isocyanurate can be particularly advantageous in conjunction with
emitter technology in that it will mix into the aqueous binder
system and improve wetting of the stone surface by a factor of 10
compared to conventional hot mix, and also create bonds that are
not susceptible to be broken down by polar materials like water.
The aggregate-binder selection can also be employed to enable poor
quality aggregate, e.g., rock that is porous or not as structurally
sound as is typically preferred, to be used in road building with
satisfactory useful life. The technology of the embodiments allows
one to compensate for such irregularities in the actual hardness or
the toughness of stone. The final chemistry related factors
identified in FIG. 5 include intercrosslinking, intracrosslinking,
and double crosslinking. Double crosslinking is used to describe a
process wherein there is a first crosslinking takes place at an
approximately 3 to 5,000 nanometer peak wavelength, and then a
second level of crosslinking that takes place as the road system
cools. The second phase of crosslinking that takes place creates a
resistance to the loads that the first crosslinking will endure
first. The combination of crosslinking that takes place at
different temperatures essentially creates tension between
crosslinks wherein the first phase crosslinks under compression
create tension in the second crosslinks, and vice versa. This
facilitates the pavement coming back to stasis after application of
compression by a rolling load by using a tension and compression
crystalline structure.
[0216] FIG. 10 provides a cost per lane miles per year comparison
of emitter technology versus conventional pavement rejuvenation
technologies. Notably, emitter technology can provide superior
results to conventional chip seal technology, type III microslurry,
and 1'' overlay with Petromat at significant cost savings. FIG. 11
provides a comparison of attributes of emitter technology versus
conventional pavement rejuvenation technologies.
[0217] FIG. 12 provides a comparison of ASTM D2486 scrub resistance
test results for conventional pavement coatings versus binder
enhanced TractionSeal Atomized Slurry (-150 stone). FIG. 13A
through FIG. 13D are photographs of the coatings subjected to the
ASTM D2486 scrub resistance test of FIG. 12. They include a high
performance coal tar at 500 cycles (FIG. 13A), a premium seal coat
at 650 cycles (FIG. 13B), an acrylic traffic striping paint at 1250
cycles (FIG. 13C), and a TractionSeal atomized slurry at 1650
cycles (FIG. 13D).
Coating Applications
[0218] Elastomer suitable for use in selected embodiments includes
a high viscosity material that is a thermoplastic, not a
thermotrope, such that it can be applied under ambient conditions.
It can exhibit superior adhesive qualities that are tuned to the
substrate onto which it is applied, whether it is wood, a pitted
rust, white metal, a rusty surface, self-priming, marine coatings,
agri-coatings, or the like (e.g., coating for pipes that are to be
placed underground). By manipulating the components of the
elastomer, a coating tailored to a particular application can be
obtained. Such coatings, once applied, can be cured using the
emitter system methodology to yield a coating with superior
qualities. An advantage of such a system is that it can be employed
to apply coatings under ambient conditions as are present in the
field.
[0219] The elastomers can be employed as house paints or other
similar structural coatings for use on, e.g., wood, stucco,
concrete, aluminum siding, or the like. For breathable substrates,
such as wood, moisture can penetrate from other locations, so the
wood must be permitted to breathe such that water does not
accumulate. Breathing can be engineered into a paint, and it can
also be engineered to have a much higher resistance to solar energy
so as to minimize chalking and some of the other problems exhibited
by house paint exposed to the elements. Whether it is in a marine
environment or just extremely cold temperatures and then high
intense heat, the elastomer can be engineered to provide a coating
that can be applied to a side wall or other surface, and can then
be cured using, e.g., a hand-held emitter. Spraying is a desirable
method of application; however, rolling or other methods of
application can also be employed. On, e.g., a wood surface, such a
cured coating exhibits a much longer useful life than does a
conventional house paint.
[0220] There are many different types of house paint, and most fall
into one of two categories: oil and water. Oil-based house paint is
referred to as alkyd, while the water-based type is commonly called
latex or acrylic. The main differences between the two are their
drying processes, their finishes, and the ease or difficulty of
clean up. Oil-based house paint takes longer to dry than the
water-based variety, but it contains additives to help speed up the
drying process. Oil paints also create a harder, glossier finish,
and require special chemicals for cleanup. Water based paints, on
the other hand, dry quickly as moisture evaporates. Their finish is
not as shiny or as durable, but the ease of clean up makes them a
popular choice. They can be cleaned up with warm water and a bit of
mild detergent. Within these categories are many different types,
starting with primer. While primer may not technically be
considered paint, it is a necessary step in most painting projects.
Primer is also available in oil-based and water-based formulas. It
is wise to select an oil-based primer when using alkyd house
paints, and a water-based primer when using latex. Specialty house
paints include anti-condensation or mold and mildew resistant
options. These are generally used in kitchens, baths, basements,
and any other area that may be damp. While this type cannot
completely prevent condensation, mold, or mildew, it can greatly
lessen their effects. Another specialty variety is heat resistant
or fire-retardant house paint. While these cannot completely
prevent fire, they do withstand much higher temperatures and slow
the spread of fire. They are often used for radiators and fireplace
surrounds. Coatings using elastomer technology as described herein
can be cured using terahertz radiation produced by an emitter as
described herein.
[0221] Fiber-reinforced polymer (FRP) linings have long been
accepted for the rehabilitation of pipelines that have deteriorated
through decades of service, but they can also be used to correct
design or construction deficiencies in new pipelines. As the water
distribution infrastructure continues to deteriorate across North
America, there is a continued need to develop pipeline
rehabilitation methods that are cost effective and minimally
disruptive, while also minimizing the time a pipe must be taken out
of service. Spray-on linings that satisfy the requirements of NSF
61 are one such emerging class of rehabilitation methods for pipes
and conduits subjected to internal pressure. Spray-on linings
currently used in waterline rehabilitation are either cement-based
or conventional polymer-based. Pipe liners prepared using elastomer
and emitter emitter technology for curing provide long lasting
coatings that are easy to apply and cure in place. The emitter
technology can be readily adapted to use in the interior of pipes
of various sizes, e.g., residential sewer lines of a few inches in
diameter or less, to large concrete or metal pipes of several feet
in diameter or more.
[0222] Mid IR to near microwave terahertz radiation can also be
employed to rapidly cure coatings using selected conventional
elastomeric or polymeric materials as well. Accordingly, in certain
embodiments, an emitter as in certain embodiments can be employed
to rapidly cure a conventional coating. However, cured coatings
employing elastomer technology are generally preferred, as they
exhibit superior properties in terms of durability, flexibility,
and resistance to the elements (water, temperature change, physical
contact, etc.).
[0223] Similarly, the elastomer as described herein for asphalt
pavement applications can be employed for use in marine coatings
(e.g., piers, sides of a ship, holding tanks, holds of a ship,
tankers, or other structures exposed to freshwater or seawater). A
layer of elastomer from 1-2 inches thick can be applied to such a
steel frame and then subject to curing. Such a cured elastomer
essentially forms a secondary container that has properties of
structural integrity that would far exceed those of a similar steel
frame. Such methodology can be employed to retrofit aging tankers,
e.g., petroleum tankers, so as to prevent leaks. A double hull
liner employing an elastomer can provide a high degree of
structural integrity in marine applications. Extrusion methodology
can be employed with elastomers of certain embodiments fabricated
as a thermoplastic, e.g., 20,000 centistokes, to permit fabrication
of thick sheets and layers exhibiting desirable properties.
Bridge and Building Foundation Applications
[0224] An elastomer coating can be placed on a foundation wall of a
new construction or can be used to repair an area where low grade
concrete has been employed, or the concrete has been exposed to
water, e.g., inside a parking garage, in a cistern or a power
transformer box, or the like. The system is desirable for use on
concrete that is configured to stay waterproof on the inside while
exposed to sources of water. For fixing leaks, silicon sealants are
conventionally used. However, for new construction such sealants
are not practical for use over large areas. The elastomer offers
the advantage that it can be sprayed onto, e.g., floors, walls,
ceilings, support beams, or the like, and when cured using the
emitter system has excellent flexibility through a broad range of
temperatures, tremendous adhesion to the surface, and self-heals,
such that a loss of structural integrity under normal conditions is
not observed.
[0225] In such applications in the construction industry, materials
such as recycled tires can be added to the elastomer composition to
provide good energy absorbance when cured using emitter technology.
An inexpensive energy adsorber such as rubber, included in the
elastomer at high concentrations, can greatly aid in obtaining a
more rapid finish.
[0226] In the case of foundation walls, a coating of elastomer can
be sprayed on that cures to a protective coating. The elastomer can
include water based bioresins or other materials in desired amounts
to create viscoelastic properties enabling a thick layer to be
sprayed onto vertical or overhead surfaces, which stays in place
without creeping before and during the curing process. In some
embodiments, a reinforcing membrane or fabric can be used in
conjunction with the elastomer, e.g., applied over the top of the
uncured elastomer layer, which acts as an adhesive for the membrane
and/or which penetrates into the membrane. For example, a elastomer
can be prepared that includes a bioresin suspending agent that
enables layers up to 1/8 inch or more in thickness to be sprayed in
place, then a reinforcing fabric can be applied, and the layer
cured. Multiple layers of elastomer and/or fabric can be built up,
with curing conducted as a final step or after one or more layers
of elastomer are applied.
[0227] The cure rate as well as the amount of energy required for
cure and at what density can be adjusted, so as to avoid blistering
of the cured layer. In conventional materials, fast exit of water
during the curing process can result in blistering. If conditions
are such that the water does not rapidly exit the material, the
water can act as a catalyst while it is in a highly energized
state, trapped in the material, without the water dissociating.
[0228] The amount of energy put in a water molecule trapped in an
elastomer can be calculated, and this information can be used to
manipulate the characteristics of the coating so as to avoid
blistering while placing a large amount of energy in the
coating.
[0229] The methods as described above for coating a concrete
structure, such as a vertical wall, can be adapted to concrete
structures present in bridges. Bridges, e.g., highway bridges, can
employ an asphalt cap, but are primarily constructed of concrete
and steel. These bridges can be paved, but are primarily
concrete-clad steel. In such embodiments, waterproofing properties
are highly desired, e.g., to prevent incursion of seawater. Cracks
and fissures from the shrinkage of the concrete can occur, so it is
desirable to compensate for this with a coating exhibiting stretch
and give. A bridge will have a wearing surface over the top, which
must float and give in different directions. In a high-rise
building, it is typical to have dirt being backfilled or gravel
with drain tiles or drainpipes that are put in to carry water away
from the footings of the building. In contrast, on a horizontal
bridge, you have the shearing action of the pavement that is put
over the top, e.g., concrete with asphalt paving atop, subjected to
stretching in two different directions. This pairing action doubles
or triples the amount of elastic recovery that the material needs.
When there is simultaneous motion in the X, Y, and Z plane, as in
bridges, special materials are conventionally employed for
waterproofing. These materials penetrate down to about a quarter of
an inch thick and are typically ureas or urethanes. Such materials
suffer from blistering due to moisture in the bridge deck, and will
eventually tear due to the motion they are subjected to. In
contrast, the elastomers described herein exhibit excellent
stiffness and tensile strength, and can heal itself even at subzero
temperatures. They can also be injected into the substrate to be
coated.
[0230] The elastomers are desirable for use, e.g., in concrete
structures where fractures have opened up and water drips onto the
structure (e.g., transported in by cars). Salts in such water
(e.g., road salt) can further attack any boundary between cement
and steel, causing the steel to corrode.
[0231] Conventionally, a membrane can be placed over the top of the
concrete; however, the membrane may still allow water to migrate
beneath its surface. Epoxies and urethanes can be used as sealants;
however, while they are tough enough to withstand traffic and are
taken up by the concrete well, they compromise the ability to flex,
and if they flex too much, they will break. Such materials are not
aerospace materials. In contrast, the elastomer of certain
embodiments can meet the physical properties of epoxy on a driving
surface for a parking garage, but will also self-heal and continue
to repair itself. It can also be used to inject down into cracks
and fissures and actually bring the water up beside the interface
between the elastomer and the cement, so as to become a completely
reactive material that has 1,000% elongation. This enables the
concrete to move, e.g., by heating and cooling of the structure
through the summer and winter) while the elastomer undergoes
self-heal. The elastomer and emitter curing method bridges a large
gap and meet a significant market need where exotic (and expensive)
materials have previously been employed, whether for remediation or
in new construction.
Light Blocks
[0232] The majority of regular concrete produced is in the density
range of 150 pounds per cubic foot (pcf). The last decade has seen
great strides in the realm of dense concrete and fantastic
compressive strengths (up to 20,000 psi) which mix designers have
achieved. Yet regular concrete has some drawbacks. It is heavy,
hard to work with, and after it sets, one cannot cut or nail into
it without some difficulty or use of special tools. Some complaints
about it include the perception that it is cold and damp. Still, it
is a remarkable building material--fluid, strong, relatively cheap,
and environmentally innocuous. And, it is available in almost every
part of the world.
[0233] Regular concrete with microscopic air bubbles added up to 7%
is called air entrained concrete. It is generally used for
increasing the workability of wet concrete and reducing the
freeze-thaw damage by making it less permeable to water absorption.
Conventional air entrainment admixtures, while providing relatively
stable air in small quantities, have a limited range of application
and aren't well suited for specialty lightweight mix designs.
[0234] Lightweight concrete begins in the density range of less
than 120 pcf. It has traditionally been made using such aggregates
as expanded shale, clay, vermiculite, pumice, and scoria among
others. Each have their peculiarities in handling, especially the
volcanic aggregates which need careful moisture monitoring and are
difficult to pump. Decreasing the weight and density produces
significant changes which improves many properties of concrete,
both in placement and application. Although this has been
accomplished primarily through the use of lightweight aggregates,
preformed foams have been added to mixes, further reducing weight.
The very lightest mixes (from 20 to 60 pcf) are often made using
only foam as the aggregate, and are referred to as cellular
concrete. The entrapped air takes the form of small, macroscopic,
spherically shaped bubbles uniformly dispersed in the concrete mix.
Today foams are available which have a high degree of compatibility
with many of the admixtures currently used in modern concrete mix
designs.
[0235] Foam used with either lightweight aggregates and/or
admixtures such as fly ash, silica fume, synthetic fiber
reinforcement, and high range water reducers (e.g.,
superplasticizers), has produced a new hybrid of concrete called
lightweight composite concrete.
[0236] Lightweight concrete blocks ("light blocks") can be prepared
using elastomer technology. The sand and aggregate employed in a
light block can be microcoated with elastomer, then subject it to
emitter curing as it comes out of an extruder. The resulting light
block exhibits a high degree of strength and shatter resistance,
making it desirable for use in areas subject to earthquakes. Such
technology can also be employed to prepare other strong, flexible
cement structures, e.g., extruded pipes, sheets, or even structures
conventionally prepared using cement (e.g., pavement, sidewalks,
steps, etc.) A road constructed using elastomer technology as
described herein would be extremely durable, with high resistance
to loss of fine particles off the surface, a high stiffness
modulus, and other desirable properties. Such elastomer technology
can be used in any application where it would be desirable to form
a solid structure by adhering small particles together (e.g., rock,
lightweight composite beads, any combination of fibrous materials
and stone), e.g., construction of building trusses, structural
members for building, and the like.
[0237] Aerated autoclaved concrete block is a lightweight building
material. An H-block, or double open-end unit, is open on both ends
which increases the space available for rebar and grout. A
mortarless masonry wall system is made from dry-stacked units that
can be subsequently grouted, partially grouted, or surface bonded.
Lightweight aerated concrete, also known as foamed concrete or
cellular concrete, is not an autoclaved aerated concrete (AAC)
product, it is conventional concrete with a wide range of
densities, choice of aggregates and mix designs. It is widely used
in the manufacture of single skin lightweight concrete wall panels,
employing tilt-up construction. This is an ideal situation for the
manufacture of light commercial structures and factories as well as
residential housing. Aerated lightweight concrete blocks and
lightweight tilt-up panels, foamed concrete floor screeds, sound
and thermal insulation, geotechnical and ornamental concrete
applications are all applications where the elastomer can be
employed. Aerated lightweight concrete lends itself to tilt-up
construction methods, and panels can be poured even on site, saving
transportation and handling costs. Casting of lightweight concrete
panels is very similar to producing regular panels and most
commercially available additives used with concrete can be used
with aerated lightweight concrete too. Amongst a range of
lightweight masonry blocks which can be produced from elastomer
include mortarless, interlocking lightweight blocks which save on
construction time, which can be produced in various densities. They
feature high insulation values, is fireproof and can be made in
several sizes. Architectural Ornamentation can be fabricated from
elastomer with foamed concrete. Fireplaces in natural stone are
often too heavy for some structures, especially if they are
retrofitted. Moreover, cellular concrete provides excellent
insulation, reducing the risk of fire. Lightweight aerated concrete
ornamentation products can be produced in a wide range of finishes,
such as marble, sandstone, slate of any color. The product range
includes columns, bench tops, ledges, arches, tiles, and the
like--anything which can be cast in molds. For sculpting, large
blocks of our aerated concrete can be cast and sculpted, using
woodworking tools. Low Cost Housing projects the world over are
generally very competitive, large in volume but low in margin for
the developer. On-site stack-casting of panels is employed, using
ready mix trucks which are charged with sand, cement and water
before the foam is added. The trucks discharge the lightweight
concrete directly into the molds. In certain parts of the world,
cast-in-place (in situ casting) is preferred, in particular in
seismic zones where a column-and-beam structure is required. This
can be incorporated in the structure. The elastomer light block
products are lightweight materials produced by blending a
cementitious slurry containing elastomer into a stable,
three-dimensional pre-form. The foam is produced by diluting a
liquid concentrate with water, then pressurizing it with air and
forcing it through a conditioning nozzle. The foam is then blended
with a base mix consisting of cement, fly ash, water and sometimes
aggregate. This causes the base mix to expand and become lighter.
The air bubbles hold their shape until the cement hydrates
permanently trapping the air in the material. The material is then
cured using terahertz radiation using emitter technology as
described herein. The materials are low density, light weight, can
be made permeable to air and water or nonpermeable, and have a high
bearing capacity.
[0238] Engineered, open-cell lightweight material can also be
fabricated that is capable of reducing loads without disturbing or
re-directing natural water flow, and can be used for applications
where drainage is needed in combination with a lightweight
material.
[0239] Shapes of light block that can be prepared include the
following: stretchers, solid block, half block, corner block, bond
beam, bull nose, chimney block, footer pads, post block, scored
block, open end pier, split face (e.g., 4'', 6'', or 8'' split
face), split ribbed, and any other suitable shape for the desired
construction, landscaping, or other application.
Fire-Resistant Materials
[0240] Elastomer as described herein for certain pavement
applications can also be desirable for use in fireproofing
applications. Fire retardant elastomers can be prepared by
incorporating fireproofing components as are known in the art,
e.g., phosphorous based or halogen based compounds, or other
materials, e.g., ceramic based materials, intumescent materials,
vapor-producing materials and the like. The elastomer can be
sprayed or otherwise applied to a surface to be rendered
fire-resistant, e.g., metal structural beams, ceiling panels,
interior spaces of walls, attic spaces, interior spaces in
vehicles, ships, aircraft, shipping containers, pallets, etc. The
elastomer can be cured in place using the emitter technology for
generating terahertz radiation as described herein.
[0241] Brominated compounds suitable for incorporation into the
fire-resistant elastomers include brominated azido compounds, e.g.,
brominated linoleyl azidoformate containing an average of four
bromines, tetrabromohexanesulfonylazide, tribromoneopentyl
azidoformate, brominated nonane-1,9-disulfonylazide containing an
average of four bromines, brominated poly(ethylene sulfonylazide)
containing approximately 40% by weight of bromine and an average of
20 sulfonylazide groups, 2,4,6-tribromocyclohexyl azidoformate,
brominated bicyclo[4.4.2]dodecane sulfonylazide containing an
average of four bromines, tribromocyclopentyl azidoformate,
2-(tribromocyclohexyl)acetylazide,
1,4-bis-azidoformyloxymethyl)tetrabromocyclohexane,
2,4,6-tribromophenyl azidoformate, 2,4,6-tribromophenyl
sulfonylazide, 2,4,6-tribromobenzoylazide,
2,3,4,5,6-pentabromophenyl azidoformate, brominated naphthyl
azidoformate containing an average of four bromines, brominated
biphenyl-bis-sulfonylazide containing an average of six bromines,
2,2-bis(4-azidoformyl-3,5-dibromophenyl)propane,
2,4,6-tribromobenzyl azidoformate,
1,4(bis-azidoformyloxymethyl)tetrabromobenzene, brominated
poly(sulfonylazidostyrene) containing approximately 38% bromine, an
average of four sulfonylazide groups and having a molecular weight
of approximately 500, beta,beta,beta-tribromoethoxyethyl
azidoformate, 4-(2,3-dibromopropyloxy)-2,3-dibromobutyl
sulfonylazide, copolymer of glycidol and epibromohydrin where the
hydroxyl groups have been converted to azidoformate groups and
having a molecular weight of approximately 700,
beta-(2,3,4,5,6-pentabromophenoxy)ethyl azidoformate,
3-(2,4,6-tribromophenoxy)-propionylazide,
3-(2,4,6-tribromocyclohexyloxy)propyl sulfonylazide, brominated
dicyclohexyl ether sulfonylazide containing an average of seven
bromines, brominated bis-azidoformate of the tetramer of
cyclohexanediol containing 16 bromines,
3-(2,3,4,5,6-pentabromocyclohexyloyx)-benzene sulfonylazide,
4,4'-diazidoformyl-2,2'-3,3'-, 5,5'-,6,6'-octabromodiphenylether,
brominated bis-azidoformate of polyphenyleneoxide tetramer
containing 16 bromines, the tribromoacetyl ester of pentaerythritol
azidoformate, the tribromobenzoyl ester of pentaerythritol
azidoformate, bis(2,3-dibromopropyl)-2-azidoformyloxymalonate,
bis(3,4,6-tribromopehnyl)-2-azidoformyloxymalonate,
2,4,6-tribromophenylazidosulfonylmethyl ketone, the sulfonylazide
of brominated dicyclohexyl ketone containing an average of six
bromines, brominated 4-azidoformyloxy-3-methyl-2-butanone
containing an average of three bromines,
4,4'-azidoformyloxy-2,2'-3,3'-5,5'-6,6'-octabromobenzophenone,
bis[beta-azidoformyloxyethyl]tetrabromophthalate,
4-azidoformyloxy-2,3-d ibromobutyltribromoacetate,
3-azidoformyloxy-2,2-dibromomethylpropyltribromoacetate,
beta,beta,beta-tribromoethyl-3-azidoformyloxypropionate, brominated
glyceryl tri(azidoformyloxystearate) containing an average of five
bromines and substituted with approximately one phosphate group per
molecule, the azidoformate of the ethylene oxide adduct of
2,4,6-tribromophenol containing on the average two ethylene oxide
groups, the azidoformate of the epibromohydrin adduct of
2,4,6-tribromophenol containing on the average three epibromohydrin
groups,
beta,beta,beta-tribromoethyl-4-azidosulfonylphenylcarbamate,
N-(azidoformyloxymethyl)-2,2,2-tribromoacetamide, and
N-(azidoformyloxyethyl)-2,2,2-tribromoacetamide.
[0242] Phosphorous-based materials suitable for incorporation into
the fire-resistant elastomers include diammonium phosphate,
monoammonium phosphate, or simple or complex mixtures of such
phosphates. Particularly suitable fire retardants of this variety
are prepared by reacting aqueous phosphoric acid with an alkylene
oxide, such as ethylene oxide, propylene oxide or butylene oxide.
See U.S. Pat. No. 3,900,327, which describes fire retardants formed
by reacting 0.5 to 1.5 parts of ethylene oxide by weight of
orthophosphoric acid. An improved fire retardant of this variety is
disclosed in U.S. Pat. No. 4,383,858 wherein an alkylene oxide of 2
to 4 carbon atoms is reacted with aqueous phosphoric acid, with the
weight ratio of oxide to acid being in the range of from about
0.01:1 to about 0.25:1.
[0243] Inorganic fire-retardants are well-known in the art and
include, without limitation, certain phosphate salts such as
ammonium polyphosphate, metal oxides, borates, and the like. In one
implementation of the invention, the inorganic fire-retardant is
one which undergoes an endothermic reaction in the presence of heat
or flame (an "endothermic inorganic fire-retardant"). Crystalline
materials having water of hydration are one example of endothermic
inorganic fire-retardants. Suitable inorganic materials comprising
water of hydration include, for example, crystalline oxides such as
alumina trihydrate, hydrated magnesium oxide, and hydrated zinc
borate, including but not limited to
2ZnO.3B.sub.2O.sub.3.31/2H.sub.2O, 4ZnO.B.sub.22O.sub.3.H.sub.2O,
4ZnO.6B.sub.2O.sub.37H.sub.2O, 2ZnO.2B.sub.2O.sub.33H.sub.2O, and
alumina trihydrate. It will be understood that the term "oxide," as
used herein, refers to inorganic substances comprising at least one
atom which forms at least one double bond to oxygen, and includes
substances having one atom double bonded to oxygen, for example
MgO, and substances having two or more atoms double bonded to
oxygen, for example zinc borate. The term "hydrated" refers to any
substance which includes water in the crystalline state, i.e.,
water of crystallization, and is used synonymously herein with the
term "water of hydration."
[0244] Intumescent materials suitable for incorporation into the
fire-resistant elastomers include are materials that react in the
presence of heat or flame to produce incombustible residues which
expand to cellular foam having good insulation properties.
Generally, intumescent materials include a polyhydric substance,
such as a latex, a sugar or polyol, and an intumescent catalyst
which can be a dehydrating agent, such as phosphoric acid, usually
introduced as a salt or ester. Upon heating, the acid catalyzes the
dehydration of the polyol to polyolefinic compounds which are
subsequently converted to carbon char. Blowing agents which release
nonflammable gases upon heating can be employed to facilitate
formation of the cellular foam. The most commonly used intumescent
coatings contain four basic components, sometimes called "reactive
pigments", dispersed in a binder matrix. The reactive pigments
include (1) an inorganic acid or a material which yields an acid at
temperatures between 100.degree. C. and 250.degree. C., such as for
example, ammonium polyphosphate which yields phosphoric acid; (2) a
carbon source such as a polyhydric material rich in carbon, also
referred to as a carbon hydrate, for example, pentaerythritol or
dipentaerythritol; (3) an organic amine or amide, such as for
example, a melamine; and optionally (4) a halogenated material
which releases hydrochloric acid gas on decomposition.
[0245] The basic intumescent mechanism is proposed to involve the
formation of a carbonaceous char by the dehydration reaction of the
generated acid with the polyhydric material. The amine may
participate in char formation, but is described primarily as a
blowing agent for insulating char foam formation. Because the
insulating char stops fire and remains on the substrate, it offers
better fire and thermal protection under severe fire conditions
than non-flammable type coatings.
[0246] Numerous patents and publications have disclosed intumescent
compositions containing one or more polymeric materials in
combination with phosphate containing materials and carbonific or
carbonic yielding materials. In European Patent 0 902 062, the
intumescent coating compositions can comprise vinyltoluene/acrylate
copolymers or styrene/acrylate polymers as a film-forming binder.
In U.S. Pat. No. 3,654,190, the intumescent coating contains a
solid vinyltoluene/butadiene copolymer associated to a chlorinated
natural rubber acting as a char former. In European Patent 0 342
001, a polymeric binder for intumescent coatings comprise
copolymers formed of a first monomer in a predominant amount and of
a second monomer in a minor amount, said second monomer being a
thermally labile co-monomer which is preferably a monomeric
aldehyde such as acroleine. In PCT Publication No. WO 01/05886, a
polymeric binder in an emulsion form is operative to form a film
when the composition is allowed to dry. The polymeric binder
described in PCT Publication No. WO 01/05886 is a styrene/acrylate
copolymer. The coatings industry seeks fire retardant coatings
which not only meet fire retardancy requirements, but which also
possess desirable coating properties.
[0247] Materials suitable for use in fire-retardant coatings of
various embodiments, such as various elastomers, are described, for
example, in U.S. Pat. No. 5,989,706; U.S. Pat. No. 5,925,457; U.S.
Pat. No. 5,645,926; U.S. Pat. No. 5,603,990; U.S. Pat. No.
5,064,710; U.S. Pat. No. 4,635,025; U.S. Pat. No. 4,345,002; U.S.
Pat. No. 4,339,357; U.S. Pat. No. 4,265,791; U.S. Pat. No.
4,241,145; U.S. Pat. No. 4,226,907; U.S. Pat. No. 4,221,837; U.S.
Pat. No. 4,210,452; U.S. Pat. No. 4,205,022; U.S. Pat. No.
4,201,677; U.S. Pat. No. 4,201,593; U.S. Pat. No. 4,137,849; U.S.
Pat. No. 4,028,333; U.S. Pat. No. 3,955,987, U.S. Pat. No.
3,934,066, U.S. Pat. No. 6,207,085; U.S. Pat. No. 5,997,758; U.S.
Pat. No. 5,882,541; U.S. Pat. No. 5,626,787; U.S. Pat. No.
5,165,904; U.S. Pat. No. 4,744,965; U.S. Pat. No. 4,632,813; U.S.
Pat. No. 4,595,414; U.S. Pat. No. 4,588,510; U.S. Pat. No.
4,216,261; U.S. Pat. No. 4,166,840; U.S. Pat. No. 3,969,291 and
U.S. Pat. No. 3,513,114.
[0248] While the disclosure has been illustrated and described in
detail in the drawings and foregoing description, such illustration
and description are to be considered illustrative or exemplary and
not restrictive. The disclosure is not limited to the disclosed
embodiments. Variations to the disclosed embodiments can be
understood and effected by those skilled in the art in practicing
the claimed disclosure, from a study of the drawings, the
disclosure and the appended claims.
[0249] All references cited herein are incorporated herein by
reference in their entirety. To the extent publications and patents
or patent applications incorporated by reference contradict the
disclosure contained in the specification, the specification is
intended to supersede and/or take precedence over any such
contradictory material.
[0250] Unless otherwise defined, all terms (including technical and
scientific terms) are to be given their ordinary and customary
meaning to a person of ordinary skill in the art, and are not to be
limited to a special or customized meaning unless expressly so
defined herein. It should be noted that the use of particular
terminology when describing certain features or aspects of the
disclosure should not be taken to imply that the terminology is
being re-defined herein to be restricted to include any specific
characteristics of the features or aspects of the disclosure with
which that terminology is associated. Terms and phrases used in
this application, and variations thereof, especially in the
appended claims, unless otherwise expressly stated, should be
construed as open ended as opposed to limiting. As examples of the
foregoing, the term `including` should be read to mean `including,
without limitation,` `including but not limited to,` or the like;
the term `comprising` as used herein is synonymous with
`including,` `containing,` or `characterized by,` and is inclusive
or open-ended and does not exclude additional, unrecited elements
or method steps; the term `having` should be interpreted as `having
at least;` the term `includes` should be interpreted as `includes
but is not limited to;` the term `example` is used to provide
exemplary instances of the item in discussion, not an exhaustive or
limiting list thereof; adjectives such as `known`, `normal`,
`standard`, and terms of similar meaning should not be construed as
limiting the item described to a given time period or to an item
available as of a given time, but instead should be read to
encompass known, normal, or standard technologies that may be
available or known now or at any time in the future; and use of
terms like `preferably,` `preferred,` `desired,` or `desirable,`
and words of similar meaning should not be understood as implying
that certain features are critical, essential, or even important to
the structure or function of the invention, but instead as merely
intended to highlight alternative or additional features that may
or may not be utilized in a particular embodiment of the invention.
Likewise, a group of items linked with the conjunction `and` should
not be read as requiring that each and every one of those items be
present in the grouping, but rather should be read as `and/or`
unless expressly stated otherwise. Similarly, a group of items
linked with the conjunction `or` should not be read as requiring
mutual exclusivity among that group, but rather should be read as
`and/or` unless expressly stated otherwise.
[0251] Where a range of values is provided, it is understood that
the upper and lower limit, and each intervening value between the
upper and lower limit of the range is encompassed within the
embodiments.
[0252] With respect to the use of substantially any plural and/or
singular terms herein, those having skill in the art can translate
from the plural to the singular and/or from the singular to the
plural as is appropriate to the context and/or application. The
various singular/plural permutations may be expressly set forth
herein for sake of clarity. The indefinite article "a" or "an" does
not exclude a plurality. A single processor or other unit may
fulfill the functions of several items recited in the claims. The
mere fact that certain measures are recited in mutually different
dependent claims does not indicate that a combination of these
measures cannot be used to advantage. Any reference signs in the
claims should not be construed as limiting the scope.
[0253] It will be further understood by those within the art that
if a specific number of an introduced claim recitation is intended,
such an intent will be explicitly recited in the claim, and in the
absence of such recitation no such intent is present. For example,
as an aid to understanding, the following appended claims may
contain usage of the introductory phrases "at least one" and "one
or more" to introduce claim recitations. However, the use of such
phrases should not be construed to imply that the introduction of a
claim recitation by the indefinite articles "a" or "an" limits any
particular claim containing such introduced claim recitation to
embodiments containing only one such recitation, even when the same
claim includes the introductory phrases "one or more" or "at least
one" and indefinite articles such as "a" or "an" (e.g., "a" and/or
"an" should typically be interpreted to mean "at least one" or "one
or more"); the same holds true for the use of definite articles
used to introduce claim recitations. In addition, even if a
specific number of an introduced claim recitation is explicitly
recited, those skilled in the art will recognize that such
recitation should typically be interpreted to mean at least the
recited number (e.g., the bare recitation of "two recitations,"
without other modifiers, typically means at least two recitations,
or two or more recitations). Furthermore, in those instances where
a convention analogous to "at least one of A, B, and C, etc." is
used, in general such a construction is intended in the sense one
having skill in the art would understand the convention (e.g., "a
system having at least one of A, B, and C" would include but not be
limited to systems that have A alone, B alone, C alone, A and B
together, A and C together, B and C together, and/or A, B, and C
together, etc.). In those instances where a convention analogous to
"at least one of A, B, or C, etc." is used, in general such a
construction is intended in the sense one having skill in the art
would understand the convention (e.g., "a system having at least
one of A, B, or C" would include but not be limited to systems that
have A alone, B alone, C alone, A and B together, A and C together,
B and C together, and/or A, B, and C together, etc.). It will be
further understood by those within the art that virtually any
disjunctive word and/or phrase presenting two or more alternative
terms, whether in the description, claims, or drawings, should be
understood to contemplate the possibilities of including one of the
terms, either of the terms, or both terms. For example, the phrase
"A or B" will be understood to include the possibilities of "A" or
"B" or "A and B."
[0254] All numbers expressing quantities of ingredients, reaction
conditions, and so forth used in the specification are to be
understood as being modified in all instances by the term `about.`
Accordingly, unless indicated to the contrary, the numerical
parameters set forth herein are approximations that may vary
depending upon the desired properties sought to be obtained. At the
very least, and not as an attempt to limit the application of the
doctrine of equivalents to the scope of any claims in any
application claiming priority to the present application, each
numerical parameter should be construed in light of the number of
significant digits and ordinary rounding approaches.
[0255] Furthermore, although the foregoing has been described in
some detail by way of illustrations and examples for purposes of
clarity and understanding, it is apparent to those skilled in the
art that certain changes and modifications may be practiced.
Therefore, the description and examples should not be construed as
limiting the scope of the invention to the specific embodiments and
examples described herein, but rather to also cover all
modification and alternatives coming with the true scope and spirit
of the invention.
* * * * *