U.S. patent application number 12/395472 was filed with the patent office on 2010-09-02 for crack resistant layer with good beam fatigue properties made from an emulsion of a polymer modified bituminous binder and method of selecting same.
This patent application is currently assigned to SEMMATERIALS, L.P.. Invention is credited to James J. Barnat, Vince Vopat.
Application Number | 20100222466 12/395472 |
Document ID | / |
Family ID | 42666249 |
Filed Date | 2010-09-02 |
United States Patent
Application |
20100222466 |
Kind Code |
A1 |
Barnat; James J. ; et
al. |
September 2, 2010 |
CRACK RESISTANT LAYER WITH GOOD BEAM FATIGUE PROPERTIES MADE FROM
AN EMULSION OF A POLYMER MODIFIED BITUMINOUS BINDER AND METHOD OF
SELECTING SAME
Abstract
A method of selecting a crack resistant layer to be applied to
an existing surface, the method comprising the steps of: selecting
at least one emulsified bituminous binder to examine, where the
emulsified bituminous binder comprises bitumen, one or more
emulsifier, and one or more polymers, where the one or more
polymers, the one or more emulsifier, or both include a sufficient
amount of conjugated diene such that at least 2.5% of the weight of
the emulsified bituminous binder residuum comprises conjugated
diene, preferably at least 3.0%, more preferably at least 3.5%, and
most preferably 4.0%; forming at least one bituminous mixture
comprising the emulsified bituminous binder and an aggregate;
testing each bituminous mixture for fatigue properties; and
selecting a bituminous binder for use in the crack resistant layer.
The method may further comprise the steps of testing the bituminous
mixture for fracture energy and selecting the emulsified bituminous
binder for use in the crack resistant layer based on fatigue
properties and fracture energy properties, and/or testing the
emulsified bituminous binder residuum for fracture energy and
selecting the emulsified bituminous binder for use in the crack
resistant layer based on fatigue properties and bituminous binder
residuum fracture energy properties.
Inventors: |
Barnat; James J.; (Tulsa,
OK) ; Vopat; Vince; (Tulsa,, OK) |
Correspondence
Address: |
HEAD, JOHNSON & KACHIGIAN
228 W 17TH PLACE
TULSA
OK
74119
US
|
Assignee: |
SEMMATERIALS, L.P.
Tulsa
OK
|
Family ID: |
42666249 |
Appl. No.: |
12/395472 |
Filed: |
February 27, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12395318 |
Feb 27, 2009 |
|
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12395472 |
|
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Current U.S.
Class: |
524/68 |
Current CPC
Class: |
C08L 21/00 20130101;
C08L 95/00 20130101; E01C 7/265 20130101; C08L 19/003 20130101;
E01C 7/187 20130101 |
Class at
Publication: |
524/68 |
International
Class: |
E01C 7/26 20060101
E01C007/26 |
Claims
1. A method of selecting a crack resistant layer to be applied to
an existing surface, the method comprising the steps of: selecting
at least one emulsified, bituminous binder to examine, where the
emulsified bituminous binder comprises bitumen, one or more
emulsifier, and one or more polymers, where the one or more
polymers, the one or more emulsifier, or both include a sufficient
amount of conjugated diene such that at least 2.5% of the weight of
emulsified bituminous binder residuum comprises conjugated diene;
forming at least one bituminous mixture comprising the emulsified
bituminous binder and an aggregate; testing each bituminous mixture
for fatigue properties; and selecting a bituminous binder for use
in the crack resistant layer.
2. The method of claim 1 where at least 3.0% of the weight of the
emulsified bituminous binder residuum comprises conjugated
diene.
3. The method of claim 1 where at least 3.5% of the weight of the
emulsified bituminous binder residuum comprises conjugated
diene.
4. The method of claim 1 where at least 4.0% of the weight of the
emulsified bituminous binder comprises residuum conjugated
diene.
5. The method of claim 1 where at least part of the conjugated
diene included in the emulsified bituminous binder comes from
latex.
6. The method of claim 5 where the emulsified bituminous binder is
formed by emulsifying a bituminous binder, and where the latex is
added to the bituminous binder before emulsification, during
emulsification, after emulsification, or combinations thereof.
7. The method of claim 1 where selecting the emulsified bituminous
binder for use in the crack resistant layer is based on mixture
fatigue properties.
8. The method of claim 7 where the testing of each bituminous
mixture for fatigue properties comprises subjecting each bituminous
mixture to a flexural beam fatigue test performed at 2,000
microstrains, 10 Hz, and 15.degree. C. per ASTM D 7460-08.
9. The method of claim 8 the flexural beam fatigue test results in
at least 5,000 cycles to failure.
10. The method of claim 8 the flexural beam fatigue test results in
at least 10,000 cycles to failure.
11. The method of claim 8 the flexural beam fatigue test results in
at least 15,000 cycles to failure.
12. The method of claim 1 further comprising the steps of testing
the emulsified bituminous mixture for fracture energy and selecting
the emulsified bituminous binder for use in the crack resistant
layer based on fatigue properties and fracture energy
properties.
13. The method of claim 12 where the testing of the emulsified
bituminous mixture for fracture energy comprises subjecting the
emulsified bituminous mixture to a Semi-Circular Bend Test or a
Disk-Shaped Compact Tension Test.
14. The method of claim 13 where the fracture energy test is the
Disk-Shaped Compact Tension Test and is performed at a temperature
of -10.degree. C. and a rate of loading of 1.0 mm/min, in
accordance with ASTM D 7313-07.
15. The method of claim 14 where the fracture energy test results
in a mixture fracture energy of greater than 600 J/m.sup.2.
16. The method of claim 14 where the fracture energy test results
in a mixture fracture energy of greater than 700 J/m.sup.2.
17. The method of claim 14 where the fracture energy test results
in a mixture fracture energy of greater than 800 J/m.sup.2.
18. The method of claim 1 further comprising the steps of testing
the emulsified bituminous binder residuum for fracture energy and
selecting the emulsified bituminous binder for use in the crack
resistant layer based on fatigue properties and bituminous binder
residuum fracture energy properties.
19. The method of claim 18 where the testing of the bituminous
binder residuum for fracture energy comprises testing a single edge
notch beam tested at 0.1 mm/sec at -30.degree. C., calculated by
ASTM D 5045-99 where the dimensions of the single edge notched beam
are B=6.0 mm, W=9.5 mm, A=4.9 mm, and L=44.0 mm where the samples
were conditioned at test temperature for 18 to 20 hours before
testing.
20. The method of claim 19 where the fracture energy test results
in a bituminous binder residuum fracture energy of greater than 40
J/m.sup.2 where the samples were conditioned at test temperature
for 18 to 20 hours before testing.
21. The method of claim 19 where die fracture energy test results
in a bituminous binder residuum fracture energy of greater than 50
J/m.sup.2 where the samples were conditioned at test temperature
for 18 to 20 hours before testing.
22. The method of claim 19 where the fracture energy test results
in a bituminous binder residuum fracture energy of greater than 60
J/m.sup.2 where the samples were conditioned at test temperature
for 18 to 20 hours before testing.
23. The method of claim 12 further comprising the steps of testing
the bituminous binder residuum for fracture energy and selecting
the emulsified bituminous binder for use in the crack resistant
layer based on fatigue properties, mixture fracture energy
properties, and bituminous binder fracture energy properties.
24. The method of claim 1 further comprising the steps of testing
the bituminous mixture for permeability and selecting the
emulsified bituminous binder for use in the crack resistant layer
based on fatigue properties and permeability.
25. The method of claim 24 where the bituminous mixture is tested
for permeability in accordance with ASTM D 3637.
26. The method of claim 25 where the permeability is greater than 8
cm.sup.2.
27. The method of claim 1 where the bituminous mixture has a Hveem
stability of greater than 21 per ASTM D 1560.
28. The method of claim 1 where the bituminous mixture has greater
than 1% air voids.
29. The method of claim 1 where the emulsified bituminous binder
further comprises additives.
30. The method of claim 29 where the additives comprise
cross-linking agents, accelerators, extenders, fluxing agents, or
combinations thereof.
31. The method of claim 1 where the aggregate comprises a hard and
inflexible mineral aggregate, a hard and inflexible man-made
aggregate, or a combination thereof.
32. The method of claim 1 where the bituminous mixture further
comprises recycled materials.
33. The method of claim 32 where the recycled materials are
reclaimed asphalt pavement, glass, ground rubber tires, ceramics,
metals, or mixtures thereof.
34. A crack resistant layer to be applied to an existing surface,
where the layer comprises: an aggregate; and an emulsified
bituminous binder, wherein the bituminous binder is comprised of
bitumen and one or more polymers, where the one or more polymers
include a sufficient amount of conjugated diene such that at least
2.5% of the weight of emulsified bituminous binder residuum
comprises conjugated diene, and where the bituminous binder is
emulsified to form an emulsified bituminous binder; where the
emulsified bituminous binder and the aggregate are mixed and form a
bituminous mixture wherein the mixture has a flexural beam fatigue
resistance of at least 5,000cycles at 2000 microstrains at 10 Hz
when tested 15.degree. C. per ASTM D 7460-08.
35. The crack resistant layer of claim 34 where at least 3.0% of
the weight of the emulsified bituminous binder residuum comprises
conjugated diene.
36. The crack resistant layer of claim 34 where at least 3.5% of
the weight of the emulsified bituminous binder residuum comprises
conjugated diene.
37. The crack resistant layer of claim 34 where at least 4.0% of
the weight of the emulsified bituminous binder residuum comprises
conjugated diene.
38. The crack resistant layer of claim 34 where at least part of
the conjugated diene comprising the bituminous binder residuum
comes from latex.
39. The method of claim 38 where the latex is added to the
bituminous binder before emulsification, during emulsification,
after emulsification, or combinations thereof.
40. The crack resistant layer of claim 34 where the layer exhibits
beam fatigue properties of at least 10,000 cycles to failure when
subjected to a flexural beam fatigue test at 2000 microstrains at
10 Hz when tested 15.degree. C. per ASTM D 7460-08.
41. The crack resistant layer of claim 34 where die layer exhibits
beam fatigue properties of at least 15,000 cycles to failure when
subjected to a flexural beam fatigue test at 2000 microstrain at 10
Hz when tested 15.degree. C. per ASTM D 7460-08.
42. The crack resistant layer of claim 34 where the bituminous
mixture exhibits desirable fracture energy properties when
subjected to testing for such fracture energy properties.
43. The crack resistant layer of claim 42 where the bituminous
mixture is tested for fracture energy properties with a
Semi-Circular Bend Test or a Disk-Shaped Compact Tension Test.
44. The crack resistant layer of claim 43 where the fracture energy
test is performed at a temperature of -10.degree. C. and a rate of
loading of 1.0 mm/min., in accordance with ASTM D 7313-07.
45. The crack resistant layer of claim 44 where the bituminous
mixture's fracture energy properties are desirable if the fracture
energy test results in a mixture fracture energy of greater than
600 J/m.sup.2.
46. The crack resistant layer of claim 44 where the bituminous
mixture's fracture energy properties are desirable if the fracture
energy test results in a mixture fracture energy of greater than
700 J/m.sup.2.
47. The crack resistant layer of claim 44 where the bituminous
mixture's fracture energy properties are desirable if the fracture
energy test results in a mixture fracture energy of greater than
800 J/m.sup.2.
48. The crack resistant layer of claim 34 where the emulsified
bituminous binder residuum has a fracture energy of greater than 40
J/m.sup.2 when a single edge notch beam is tested at 0.1 mm/sec. at
-30.degree. C., calculated by ASTM D 5045-99 where the dimensions
of the single edge notched beam are B=6.0 mm, W=9.5 mm, A=4.9 mm,
and L=44.0 mm where the samples were conditioned at test
temperature for 18 to 20 hours before testing.
49. The crack resistant layer of claim 34 where the emulsified
bituminous binder residuum has a fracture energy of greater than 50
J/m.sup.2 when a single edge notch beam is tested at 0.1 mm/sec. at
-30.degree. C., calculated by ASTM D 5045-99 where the preferred
dimensions of the single edge notched beam are B=6.0 mm, W=9.5 mm,
A=4.9 mm, and L=44.0 mm where the samples were conditioned at test
temperature for 18 to 20 hours before testing.
50. The crack resistant layer of claim 34 where the emulsified
bituminous binder residuum has a fracture energy of greater than 60
J/m.sup.2 when a single edge notch beam is tested at 0.1 mm/sec. at
-30.degree. C., calculated by ASTM D 5045-99 where the preferred
dimensions of the single edge notched beam are B=6.0 mm, W=9.5 mm,
A=4.9 mm, and L=44.0 mm where the samples were conditioned at test
temperature for 18 to 20 hours before testing.
51. The crack resistant layer of claim 34 where the bituminous
mixture's permeability is greater than 8 cm.sup.2 when tested in
accordance with ASTM D 3637.
52. The crack resistant layer of claim 34 where the bituminous
mixture has a Hveen stability of greater than 21 per ASTM D
1560.
53. The crack resistant layer of claim 34 where the bituminous
mixture has greater than 1% air voids.
54. The crack resistant layer of claim 34 further comprising
additives.
55. The crack resistant layer of claim 54 where the additives
comprise cross-linking agents, accelerators, extenders, fluxing
agents, or combinations thereof.
56. The crack resistant layer of claim 34 where the aggregate
comprises a hard and inflexible mineral aggregate, a hard and
inflexible man-made aggregate, or a combination thereof.
57. The crack resistant layer of claim 34 where the mixture further
comprises recycled materials.
58. The crack resistant layer of claim 57 where the recycled
materials are reclaimed asphalt pavement, glass, ground rubber
tires, ceramics, metals, or mixtures thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 12/395,318 titled A Crack Resistance Layer
With Good Beam Fatigue Properties and Method of Selecting Same
filed Feb. 27, 2009.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a crack resistant layer
with good beam fatigue properties and a method of selecting same.
More particularly, the present invention relates to a bituminous
binder with a critical amount of conjugated diene, which allows for
enhanced fatigue resistant properties in a crack resistant
layer.
[0004] 2. Description of the Related Art
[0005] When pavements deteriorate, they may be overlaid with hot
mix asphalt (HMA) to repair them. When designing an overlay, the
rate of crack propagation through the overlay, the rate of
deterioration of the reflective crack, and the amount of water that
can infiltrate through the cracks must be considered. One
disadvantage with such HMA overlays is that cracks in the old
pavement reflect through the new overlay. To relieve this
reflective cracking, thicker overlays may be placed. Another
disadvantage with these overlays is that they typically have a low
strain tolerance and a low resistance to reflective cracking.
[0006] To improve traditional HMA overlays, asphalt binders that
display the ability to undergo creep or stress relaxation at low
temperatures may be used. Such bituminous binders minimize the
potential for thermal and reflective cracking. However, the
disadvantage with such bituminous binders is that they are highly
ductile and have a low shear modulus at high temperatures, and thus
roads created with them tend to rut. Asphalts with high shear
modulus that resist rutting at high temperatures may also be used.
However, such binders tend to be brittle at low temperatures, and
thus roads created with them tend to crack. Typical asphalt
bituminous binders formulated for pavement applications usually
display either high shear modulus at high temperatures or high
ductilities at low temperatures but not both.
[0007] A typical highway HMA surface mixture has about 3% to 5% air
voids and a fatigue life of only about 500 cycles when tested at
15.degree. C. with a strain amplitude of 2,000 microstrains and
frequency of 10 Hz using a 4-point bending beam apparatus. The best
surface mixture with about 3% to 5% air voids has a fatigue life of
only about 2,000 to 5,000 cycles when tested at 15.degree. C. with
a strain amplitude of 2,000 microstrains and frequency of 10 Hz
using a 4-point bending beam apparatus. Other mixtures with air
voids greater than 5% to 7% may have a fatigue life of only about
500 to 1,500 cycles when tested at 15.degree. C. with a strain
amplitude of 2,000 microstrains and frequency of 10 Hz using a
4-point bending beam apparatus.
[0008] Blankenship et al., U.S. Pat. No. 6,830,408, which is
incorporated herein by reference, attempts to solve the foregoing
problems through the use of an interlayer that is placed on the
cracked road underneath the overlay. The interlayer includes a
mixture of aggregate and bituminous binder, preferably polymer
modified asphalt, and is used to delay or stop the occurrence of
cracking, control crack severity, reduce overlay thickness, and
enhance waterproofing capabilities. The interlayer is highly strain
tolerant and substantially impermeable.
[0009] The bituminous binder used in the interlayer of the '408
patent includes bitumen, one or more polymers, and, optionally, a
cross-linking agent to effect vulcanization of the polymer in the
bitumen. Limitations on the characteristics of the bituminous
binder and interlayer are set forth in the '408 patent. In
particular, the '408 patent specifies that the percentage of air
voids in the interlayer must be between 2.0% and 4.0%. This
produces a flexural beam fatigue performance of at least 100,000
cycles to failure.
[0010] The problem with such interlayers is that, in order to get
such a fatigue life and retard the progression of reflective cracks
in the pavement, these interlayers sacrifice a degree of their load
bearing capacity, as measured in the Hveem stabilometer, and
typically have Hveem stabilities of about 18-21. In order to
compensate for their low stability, these interlayers are placed
below the top layers of a pavement structure so that they are not
exposed to direct traffic loads. Thicker top layers help to improve
the total structural stability but are costly. Still further, the
top layers of the pavement structure cannot completely compensate
for the low load bearing capacity of the interlayer.
[0011] Blankenship et al., U.S. application Ser. No. 10/631,149,
which is incorporated herein by reference, attempts to solve this
problem through the use of a highly strain tolerant, substantially
moisture impermeable, hot mix reflective crack relief interlayer.
The interlayer includes a polymer modified bituminous binder mixed
with a dense fine aggregate mixture that is made primarily from
manufactured sand. This results in increased stability and improved
load bearing capacity. Limitations on the characteristics of the
bituminous binder and interlayer are set forth in the '149
application. In particular, the '149 application specifies that the
percentage of air voids in the interlayer must be between 1.0% and
5.0%, preferably 2.0% to 4.0%, and most preferably about 3.0%. This
produces a flexural beam fatigue performance of at least
50,000cycles to failure, preferably 80,000 and most preferably
100,000.
[0012] The problem with this interlayer is that it is impermeable.
When such an interlayer is placed on Portland Cement Concrete (PCC)
or another paved surface, the interlayer has the potential to trap
vapor underneath it. As changes occur in climatic and environmental
conditions, this causes the PCC to release moisture or vent. The
interlayer then rises, creating a blister. This causes overlays on
top of this interlayer also to rise and blister.
[0013] Blankenship et al., U.S. Pat. No. 7,479,185, which is
incorporated herein by reference, attempts to solve this problem
through the use of a layer that remains substantially moisture
impervious and retains its ability to retard the formation of
reflective cracks while having increased vapor permeability. This
layer may be an interlayer, but also may be a base layer or an
overlay.
[0014] Limitations on the characteristics of the bituminous binder
and layer are set forth in the '185 patent. In particular, the '185
patent specifies that the percentage of air voids in the layer must
be at least 3.0%, preferably at least 4.0%, more preferably at
least 4.5%, even more preferably at least 5.0%, and most preferably
at least 7.0%. This produces a flexural beam fatigue performance of
at least 5,000 cycles to failure, preferably at least 35,000 cycles
to failure, and most preferably at least 100,000 cycles to failure.
The '185 patent notes that there is typically an inverse
relationship between the air voids in a bituminous mixture and
fatigue resistance of that mixture. However, the bituminous mixture
of the '185 patent may be made by creating a very large amount of
air voids in an aggregate structure and then filling a large
portion of those voids with bitumen. The total amount of air voids
is critical. Too many air voids will limit fatigue resistance and
too few air voids will compromise permeability.
[0015] The problem with the '185 layer is the narrow operating
window. The perfect aggregate structure is required to produce the
skeletal structure that meets the requirements of fatigue
resistance, strength, and permeability. Local aggregates may not be
suitable requiring more costly aggregate sources to be used. Tight
tolerances at the hot mix plants creates off-specification product
that impacts costs. Additionally, a very high asphalt content is
required, which increases costs dramatically.
[0016] The current art uses mixture volumetric properties and film
thickness to achieve acceptable beam fatigue properties. The '408
patent to Blankenship requires air voids in a tight and low range,
extremely high binder film thicknesses, and extremely low DP's
(dust to effective binder ratio). The '149 application greatly
limits aggregate properties to effect acceptable beam fatigue
properties. The '185 patent allows for higher air void content but
also requires a higher binder film thickness. Hence, the current
art is void of any binder property that affects beam fatigue
properties.
[0017] In each of the foregoing, polymer is used in the bituminous
binder. Methods of preparing polymer modified bitumen is described
in Maldonado et al., U.S. Pat. No. 4,242,246, and Maldonado et al.,
U.S. Pat. No. 4,330,449, both of which are incorporated herein by
reference.
[0018] As is known in the art and used herein, emulsification of
asphalt refers to forming an emulsion of asphalt and water.
Emulsification basically requires that the asphalt and any desired
performance-enhancing additives be combined with an emulsifying
agent in an emulsification mill along with about 20 to 70 percent
by weight of water. Asphalt emulsions are desirable in many
applications because an emulsion may be applied at lower
temperatures than hot-mix asphalts because the water acts as a
carrier for the asphalt particles. For example, hot-mix asphalts,
which are mixes of asphalt, aggregate, and a single polymer, are
commonly applied at a temperature of 140.degree. C. to 232.degree.
C. to achieve the requisite plasticity for application. In
comparison, an asphalt emulsion typically may be applied at
54.degree. C. to 77.degree. C. to achieve the same working
characteristics. Once applied, the water evaporates, leaving the
asphalt. Also, emulsified asphalt products generally do not use or
release the environmentally-harmful volatile organic compounds
normally associated with asphalts diluted with light carrier
solvents such as diesel fuel, naphtha, and the like.
[0019] Notwithstanding the foregoing, there remains a need for a
crack resistant layer with low air voids and good beam fatigue
properties that does not suffer from the drawbacks of the layers of
the Blankenship patent and applications. Accordingly, it would be
desirable to provide an emulsion of a bituminous binder for a crack
resistant layer with greater than 1% air voids and greater than
5,000 cycles to failure, that is stable, that does not require
special aggregate structure or excessive asphalt content, and that
may be used as a base layer, interlayer, or overlay.
SUMMARY OF THE INVENTION
[0020] In general, in a first aspect, the present invention relates
to a method of selecting a crack resistant layer to be applied to
an existing surface, the method comprising the steps of: selecting
at least one emulsified bituminous binder to examine, where the
emulsified bituminous binder comprises bitumen, one or more
emulsifier, and one or more polymers, where the one or more
polymers, the one or more emulsifier, or both include a sufficient
amount of conjugated diene such that at least 2.5% of the
bituminous binder residuum weight comprises conjugated diene,
preferably at least 3.0%, more preferably at least 3.5%, and most
preferably 4.0%; forming at least one bituminous mixture comprising
the emulsified bituminous binder and an aggregate; testing each
bituminous mixture for fatigue properties; and selecting a
bituminous binder for use in the crack resistant layer. At least
part of the conjugated diene included in the emulsified bituminous
binder may come from latex, which may be added before
emulsification, during emulsification, after emulsification, or
combinations thereof. The testing of each bituminous mixture for
fatigue properties may comprise subjecting each bituminous mixture
to a flexural beam fatigue test performed at 2,000 microstrains, 10
Hz, and 15.degree. C. per ASTM D 7460-08. Such a flexural beam
fatigue test may result in at least 5,000 cycles to failure,
preferably at least 10,000 cycles to failure, and most preferably
at least 15,000 cycles to failure,
[0021] The method may further comprise the steps of testing the
bituminous mixture for fracture energy and selecting the emulsified
bituminous binder for use in the crack resistant layer based on
fatigue properties and fracture energy properties. The testing of
the bituminous mixture for fracture energy may comprise subjecting
the bituminous mixture to a Semi-Circular Bend Test or a
Disk-Shaped Compact Tension Test. The fracture energy test may be
the Disk-Shaped Compact Tension Test performed at a temperature of
-10.degree. C. and a rate of loading of 1.0 mm/min, in accordance
with ASTM D 7313-07, and may result in a mixture fracture energy of
greater than 600 J/m.sup.2, preferably greater than 700 J/m.sup.2,
and most preferably greater than 800 J/m.sup.2.
[0022] The method may further comprise the steps of testing the
emulsified bituminous binder residuum for fracture energy and
selecting the emulsified bituminous binder for use in the crack
resistant layer based on fatigue properties and bituminous binder
fracture energy properties. Testing of the emulsified bituminous
binder residuum for fracture energy may comprise testing a single
edge notch beam tested at 0.1 mm/sec at -30.degree. C., calculated
by ASTM D 5045-99 where the dimensions of the single edge notched
beam are B=6.0 mm, W=9.5 mm, A=4.9 mm, and L=44.0 mm (all
dimensions + or -1%), which may result in a bituminous binder
fracture energy of greater than 40 J/m.sup.2, preferably greater
than 50 J/m.sup.2, and most preferably greater than 60 J/m.sup.2.
The preferred testing device is an RSA III Dynamic Mechanical
Analyzer from TA Instruments, Inc of New Castle, Del.
[0023] The method may further comprise the steps of testing the
bituminous mixture for permeability and selecting the emulsified
bituminous binder for use in the crack resistant layer based on
fatigue properties and permeability. The bituminous mixture may be
tested for permeability in accordance with ASTM D 3637, which may
result in permeability greater than 8 cm.sup.2.
[0024] The bituminous mixture may have a Hveem stability of greater
than 21 per ASTM D 1560 and may have greater than 1% air voids. The
emulsified bituminous binder may further comprise additives, such
as cross-linking agents, accelerators, extenders, fluxing agents,
or combinations thereof. The aggregate may comprise a hard and
inflexible mineral aggregate, a hard and inflexible man-made
aggregate, or a combination thereof. The bituminous mixture may
further comprise recycled materials, such as reclaimed asphalt
pavement, glass, ground rubber tires, ceramics, metals, or mixtures
thereof.
[0025] In a second aspect, the invention relates to a crack
resistant layer having the properties set forth above.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] The present invention relates to an emulsion of a bituminous
binder for use in a crack resistant layer. The layer may be used to
resurface a distressed pavement surface, and may be used as a base
layer, an interlayer, or an overlay. Use of such a layer is
described in the Description of Related Art section above and in
the Blankenship patents and application. The bituminous binder is
such that the crack resistant layer has good beam fatigue
properties. A method of selecting such a bituminous binder is also
provided herein.
[0027] The layer is formed from a bituminous mixture, which is
comprised of an emulsion of a bituminous binder and an aggregate.
The bituminous binder includes bitumen, one or more polymers, and,
optionally, other additives, including but not limited to
cross-linking, accelerators, extenders, fluxing agents, and/or
other similarly appropriate additives suitable for use in
bituminous binders.
[0028] The polymer used in the bituminous binder may be any
elastomer, plastomer, or other polymer suitable for use in bitumen,
including but not limited to those described in the Maldonado and
Blankenship patents and application, and containing at least a
critical amount of conjugated diene. The critical amount of
conjugated diene is at least 2.5%, preferably at least 3.0%, more
preferably at least 3.5%, and most preferably 4.0%. Such high
amounts of conjugated diene have not previously been used in
similar layers because of the high cost of such a relatively large
polymer content, the difficulty to process, the difficulty to
handle the bituminous mixture, and the unknown favorable attributes
of high levels of conjugated diene. Surprisingly, it has been found
that increasing the amount of conjugated diene above the critical
amount produces a layer with improved fatigue resistance of any
asphalt-aggregate mixture. Thus, the life of the layer is
increased, making the layer cost effective despite the large
polymer content.
[0029] Emulsification materials used with the polymer modified
bituminous binder are those traditionally known by those skilled in
the art, such as cationic emulsifying agents, anionic emulsifying
agents, nonionic emulsifying agents, amphoteric emulsifying agents,
zwitterionic emulsifying agents, and combinations thereof. Typical
cationic emulsified polymer modified bituminous binders can be made
using known emulsifying agents such as primary amines, diamines,
ethoxylated amines, propoxylated amines, imidazolene amines, and
the like. Typical anionic emulsified polymer modified bituminous
binders can be made using emulsifying agents known by those skilled
in the art, such as salts produced from lignin-based, Vinsol-based,
or tall oil-based raw materials. Similarly, nonionic emulsified
polymer modified bituminous binders can be made using known
nonionic emulsifying agents such as oxylated nonolphenols. Typical
zwitterionic emulsifying agents include, but are not limited to,
families like Sulfobetanes and Sultanes of the general formula
RN.sup.+(CH3).sub.2(CH2).sub.xSO.sub.3. It should be understood and
appreciated that this is not an exhaustive list of emulsifying
agents that can be used. Rather, any emulsifying agent that is
known in the art capable of emulsifying the polymer modified
bituminous binder of the present invention can be used.
[0030] Satisfactory emulsified embodiments of the present invention
include from about 20 percent to about 80 percent by weight polymer
modified bituminous binder with about 80 percent to about 20
percent by weight water, emulsifying agent, and emulsion additives.
For special applications, such as thin film resurfacing, a greater
or lesser amount of water may be used. Generally, the amount of
water used is that amount which will give the emulsified mixture
the desired flow characteristics to allow proper placement and
curing of the emulsion. Quantity and type of emulsifying agent
typically is dictated by the ultimate use of the emulsion. Tests
indicate that the quantity and type of emulsifying agents suitable
for use with the present invention are consistent with existing
asphalt and asphalt-polymer emulsions known in the art.
[0031] The aggregate may be hard and inflexible mineral aggregates,
such as sand, stone, lime, Portland cement, kiln dust, or mixtures
thereof; man made hard and inflexible aggregates, such as wet
bottom boiler slag, blast furnace slag, or mixtures thereof; or any
other appropriate aggregate. The structure of the aggregate may be
any of those described in the Blankenship patent and applications,
or may be any other appropriate structure. The aggregate need not
include manufactured sand, as required by the '149 Blankenship
application.
[0032] Recycled materials, such as reclaimed asphalt pavement,
glass, ground rubber tires, ceramics, metals, or mixtures thereof,
or any other appropriate recycled material may be incorporated into
the mixture. Any conjugated diene from a recycled vulcanizate is
not considered as part of the bituminous binder and is not included
in the critical amount of conjugated diene as part of this
invention.
[0033] The bituminous mixture formed from the appropriate amount of
conjugated diene bituminous binder and the aggregate may meet any
local standards for traditional bituminous mixture properties such
as VMA, VFA, density, dust to binder ratio, and the like. However,
the Hveem stability per ASTM D 1560 should be greater than 21 and
the bituminous mixture should have greater than 1% air voids. The
bituminous mixture with suitable crack resistance will have a beam
fatigue of greater than 5,000 cycles to failure, more preferably at
least 10,000 cycles to failure, and most preferably at least 15,000
cycles to failure; a mixture fracture energy of greater than 600
J/m.sup.2, more preferably greater than about 700 J/m.sup.2, and
most preferably greater than about 800 J/m.sup.2; and a bituminous
binder fracture energy of greater than 40 J/m.sup.2, more
preferably greater than about 50 J/m.sup.2, and most preferably
greater than about 60 J/m.sup.2.
[0034] Generally, the method of selecting the bituminous binder for
use in the crack resistant layer involves mixing an emulsion of a
bituminous binder and an aggregate to form a bituminous mixture,
forming a specimen layer from the bituminous mixture, and testing
die specimen layer to determine beam fatigue. If the beam fatigue
is sufficient, the bituminous binder is appropriate for use in the
crack resistant layer. If not, another bituminous binder must be
used with higher conjugated diene content, and the process must
begin again. Additionally or alternately, the bituminous mixture
itself may be tested for fracture energy. Additionally or
alternately, the bituminous binder may be tested for fracture
energy. In both instances, if the fracture energy is sufficient,
the bituminous binder is appropriate for use in the crack resistant
layer. If not, another bituminous binder must be used and the
process must begin again. The bituminous mixture may also
additionally or alternately be tested for permeability, where the
bituminous binder is appropriate only if the permeability is
sufficient, and if not, another must be selected.
[0035] To produce the emulsified polymer modified bituminous
binder, the binder, polymer, and/or any additives are first mixed
to form a polymer modified bituminous binder, which is heated to a
predetermined temperature that will produce acceptable flow
characteristics. Once the polymer modified bituminous binder is
heated to the predetermined temperature, the polymer modified
bituminous binder is introduced into an emulsification mill with
the emulsifying agents, emulsion additives, and/or water.
Introducing the heated polymer modified bituminous binder into the
emulsification mill allows the final emulsion temperature to be
maintained within acceptable limits. Generally, acceptable limits
for the final combined temperature of the emulsified polymer
modified bituminous binder are less than about 100.degree. C. so as
to prevent Hash boiling of the water. It should be understood and
appreciated that emulsification temperatures can exceed the boiling
point of the aqueous phase with pressure and heat exchange
equipment. The mill operates to slice the polymer-binder mix finely
and mix it with the water, emulsifier, and emulsion additives to
form an emulsion. The emulsifying agent, acts to stabilize the
resulting emulsion so as to prevent agglomeration of the asphalt
prior to placement. The emulsion additives described herein for use
in emulsification can be any additive for providing the emulsified
polymer modified bituminous binder with predetermined properties.
Examples of additive include, but are not limited to, sulfur
containing compounds, thickeners, or other rheology modifiers,
tackifiers, flow improvers, pH adjusting chemicals, stabilizers and
the like.
[0036] Emulsified polymers, or more technically correct polymer
dispersions like latex products, are also suited to provide
sufficient amounts of conjugated diene to the bituminous binder.
These polymer dispersions may be premixed with the binder,
co-milled during the emulsification process, post added to the
bituminous emulsion, added directly to the mixture, and
combinations thereof. Latex products like natural rubber, SBR
(styrene-butadiene rubber), Neoprene (chloroisoprene), and the like
are suitable and within the scope of the invention.
[0037] Combinations of polymer sources like modified asphalt and
latex products, various points of addition like pre-emulsification,
co-emulsification, post emulsification, and combinations thereof
are also suitable so long as the sum total of the conjugated diene
content is sufficient to create a crack resistant layer.
[0038] The bituminous mixture produced from the emulsion of a
bituminous binder and aggregate should meet the criteria set forth
above, and should be mixed in sufficient quantities that the
bituminous mixture meets the criteria set forth above. In
particular, the emulsion of bituminous binder should include a
polymer comprising at least 2.5%, preferably at least 3.0%, more
preferably at least 3.5%, and most preferably at least 4.0%
conjugated diene based on the weight of the polymer modified
bitumen. Furthermore, the emulsion of bituminous binder should be
formed in such a way that the bituminous mixture is formed in such
a way that the specimen layer formed therefrom has at least 1% air
voids and a Hveem stability of at least 21.
[0039] The specimen layer may be tested for fatigue, preferably
using a beam fatigue test, most preferably using a flexural beam
fatigue test. A flexural beam fatigue test determines the number of
times a specimen may be flexed before it cracks. The test may be
performed using any appropriate parameters. For example, the test
may be performed at 2,000 microstrains, 10 Hz, and 15.degree. C.
per ASTM D7460-08. An appropriate bituminous binder should result
in a layer having at least 5,000 cycles to failure, preferably at
least 10,000 cycles to failure, and most preferably at least 15,000
cycles to failure when tested at 2,000 microstrains, 10 Hz, and
15.degree. C. per ASTM D 7460-08.
[0040] The bituminous mixture may be tested for mixture fracture
energy using any appropriate test, such as a Semi-Circular Bend
Test or a Disk-Shaped Compact Tension Test, and also using any
appropriate parameters. For example, when tested using a
Disk-Shaped Compact Tension Test performed at a temperature of
-10.degree. C., a rate of loading of 1.0 mm/min, and in accordance
with ASTM D 7313-07, an appropriate bituminous binder should result
in a bituminous mixture with a mixture fracture energy of greater
than about 600 J/m.sup.2, more preferably greater than about 700
J/m.sup.2, and most preferably greater than about 800
J/m.sup.2.
[0041] The bituminous binder may likewise be tested for fracture
energy using any appropriate test and any appropriate parameters.
For example, when testing a single edge notch beam at 0.1 mm/sec at
-30.degree. C. calculated by ASTM D 5045-9.9 where the preferred
dimensions of the single edge notched beam are B=6.0 mm, W=9.5 mm,
A=4.9 mm, and L=44.0 mm, an appropriate bituminous binder should
result in a bituminous binder fracture energy of greater than about
40 J/m.sup.2, more preferably greater than about 50 J/m.sup.2, and
most preferably greater than about 60 J/m.sup.2.
[0042] The bituminous mixture may be tested for permeability in
accordance with ASTM D 3637, in which case, an appropriate
bituminous binder should result in a permeability of greater than
about 8 cm.sup.2.
[0043] Mixture volumetric properties and/or binder film thicknesses
do not need to be strictly controlled to achieve desired
properties. The system can be optimized by choosing the lowest
conjugated diene content that achieved the desired mixture and/or
binder properties. The type of mixture, either coarse or fine,
large aggregate or small, high or low air voids content, can be
brought into acceptable levels of a crack resistant layer by
selecting a binder with the appropriate conjugated diene
content.
EXAMPLE 1
[0044] Eight polymer modified bituminous binders were created, four
by heating a Suncor PG64-22 bituminous binder, adding polymers,
mixing sufficiently to disperse the polymers within the bituminous
binder, and adding a sufficient amount of sulfur to cross-link. The
other four were created by the same process but with Suncor PG58-28
bituminous binder instead of PG64-22 bituminous binder. The
polymers used were Solprene 1205 with about 75% conjugated diene,
and Solprene 1110L with about 80% conjugated diene available from
Dynasol. Binders 1 through 8 are described in Tables 1 and 2.
TABLE-US-00001 TABLE 1 Suncor PG 58-28 Solprene Solprene Conjugated
Binder 1205 1110L Diene 1 0.00% 0.00% 0.00% 2 1.00% 1.00% 1.55% 3
2.00% 2.00% 3.10% 4 3.00% 3.00% 4.65%
TABLE-US-00002 TABLE 2 Suncor PG 64-22 Solprene Solprene Conjugated
Binder 1205 1110L Diene 5 0.00% 0.00% 0.00% 6 1.00% 1.00% 1.55% 7
2.00% 2.00% 3.10% 8 3.00% 3.00% 4.65%
[0045] The eight bituminous binders were used to form eight
bituminous mixtures, which in turn were used to form eight specimen
layers. Mixture gradation and general volumetric properties are set
forth in Table 3.
TABLE-US-00003 TABLE 3 9.5 mm Mixture Gradation Sieve (mm) %
Passing Mixture Properties Air Voids 4.0% 12.5 100 Pb 5.9% 9.5 100
VMA 15.0% 4.75 79.1 VFA 72.0% 2.36 46.6 DP 1.2 1.18 30.4 0.6 19.7
0.3 12.5 0.15 7.5 0.075 5.7
[0046] The layers were tested at 2,000 microstrains, 10 Hz, and
15.degree. C. per ASTM D 7460-08 for flexural beam fatigue. The
results are set forth in Table 4:
TABLE-US-00004 TABLE 4 Beam Conjugated Fatigue Diene Binder
(Cycles) Content Suncor PG 58-28 1 815 0.00% 2 2,165 1.55% 3 4,419
3.10% 4 26,247 4.65% Suncor PG-64-22 5 91 0.00% 6 592 1.55% 7 523
3.10% 8 1,994 4.65%
[0047] As can be seen from Table 4, a higher percentage of
conjugated diene resulted in a higher number of cycles to failure.
A logarithmic correlation coefficient (r.sup.2) between Beam
Fatigue and conjugated diene content was 0.961 and 0.862 for the
PG58-28 and PG64-22 binders respectively. The correlation
surprisingly demonstrates the positive effect of conjugated diene
on beam fatigue properties. If acceptable beam fatigue properties
are not achieved, another binder must be chosen with higher
conjugated diene content.
[0048] Each bituminous layer was tested for mixture fracture energy
and was tested at a temperature of -10.degree. C., a rate of
loading of 1.0 mm/min, and in accordance with ASTM D 7313-07. The
results are set forth in Table 5:
TABLE-US-00005 TABLE 5 Fracture Conjugated Energy Diene Binder
(J/m.sup.2) Content Suncor PG 58-28 1 699 0.00% 2 817 1.55% 3 1,150
3.10% 4 1,338 4.65% Suncor PG-64-22 5 434 0.00% 6 540 1.55% 7 671
3.10% 8 1,084 4.65%
[0049] A logarithmic correlation coefficient (r.sup.2) between
Mixture Fracture Energy and conjugated diene content was 0.973 and
0.955 for the PG 58-28 and PG64-22 binders respectively. Similarly,
the correlation surprisingly demonstrates the positive effect of
conjugated diene on mixture fracture energy properties. If
acceptable mixture fracture energy properties are not achieved,
another binder must be chosen with higher conjugated diene
content.
[0050] Each Binder was evaluated for Bituminous Binder Fracture
Energy and tested 0.1 mm/sec at -30.degree. C. per ASTM D 5045-99.
The results are set forth in Table 6:
TABLE-US-00006 TABLE 6 Binder Fracture Conjugated Energy Diene
Binder (J/m.sup.2) Content Suncor PG 58-28 1 9.31 0.00% 2 33.47
1.55% 3 46.45 3.10% 4 75.94 4.65% Suncor PG-64-22 5 10.70 0.00% 6
31.69 1.55% 7 46.15 3.10% 8 69.28 4.65%
[0051] As can be seen from Table 6, a higher percentage of
conjugated diene resulted in a higher binder fracture energy. A
linear correlation coefficient (r.sup.2) between conjugated diene
content and Binder Fracture Energy was 0.980 and 0.993 for the
PG58-28 and PG64-22 binders respectively. The correlation
surprisingly demonstrates the positive effect of conjugated diene
on binder fracture energy properties. If acceptable mixture binder
fracture energy properties are not achieved, another binder must be
chosen with higher conjugated diene content.
EXAMPLE 2
[0052] Four polymer modified bituminous binders were created, each
by heating a PG64-22 bituminous binder, adding polymers, mixing
sufficiently to disperse the polymers within the bituminous binder,
and adding a sufficient amount of sulfur to cross-link. The
polymers used were Solprene 1205 with about 75% conjugated diene
available from Dynasol and Solprene 411 with about 70% conjugated
diene available from Dynasol. The first bituminous binder was a
control and contained no conjugated diene. The second bituminous
binder contained 1.7% Solprene 1205 and 0.3% Solprene 411,
resulting in 1.49% total conjugated diene based on the weight of
the polymer modified bituminous binder. The third bituminous binder
contained 3.4% Solprene 1205 and 0.6% Solprene 411, resulting in
2.97% total conjugated diene based on the weight of the polymer
modified bituminous binder. Finally, the fourth bituminous binder
contained 5.1% Solprene 1205 and 0.9% Solprene 411, resulting in
4.46% total conjugated diene based on the weight of the polymer
modified bituminous binder. Binders 9 through 12 of are described
in Tables 7.
TABLE-US-00007 TABLE 7 PG 64-22 Bitumen Solprene Solprene
Conjugated Binder 1205 411 Diene Content 9 0.00% 0.00% 0.00% 10
1.70% 0.30% 1.49% 11 3.40% 0.60% 2.97% 12 5.10% 0.90% 4.46%
[0053] The four bituminous binders were used to form bituminous
mixtures, which in turn were used to form eight specimen layers.
Mixture gradation and general volumetric properties are set forth
in Table 8 and 9.
TABLE-US-00008 TABLE 8 9.5 mm Mixture Gradation Sieve (mm) %
Passing Mixture Properties Air Voids 4.0% 12.5 100 Pb 7.0% 9.5 99.6
VMA 15.9% 4.75 88.7 VFA 75.4% 2.36 62.5 DP 1.1 1.18 40.4 0.6 23.4
0.3 13.3 0.15 7.9 0.075 6.0
TABLE-US-00009 TABLE 9 4.75 mm Mixture Gradation Sieve (mm) %
Passing Mixture Properties Air Voids 4.0% 12.5 100 Pb 6.9% 9.5 100
VMA 15.8% 4.75 97.8 VFA 75.0% 2.36 77.4 DP 1.9 1.18 56.9 0.6 38.5
0.3 21.5 0.15 11.9 0.075 9.9
[0054] Each bituminous layer was tested for mixture fracture energy
and was tested at a temperature of -10.degree. C., a rate of
loading of 1.0 mm/min, and in accordance with ASTM D 7313-07. The
results are set forth in Table 10:
TABLE-US-00010 TABLE 10 Mixture Fracture Energy (J/m.sup.2)
Conjugated Diene Content 0.00% 1.49% 2.97% 4.46% 4.75 mm Mixture
345 438 615 1,371 9.5 mm Mixture 463 508 1,559 2,190
[0055] A logarithmic correlation coefficient (r.sup.2) between
Mixture Fracture Energy and conjugated diene content was 0.903 and
0.922 for the 9.5 mm and 4.75 mm mixtures respectively. The
correlation not only demonstrates the positive effect of conjugated
diene on mixture fracture energy properties, it also demonstrates
the ability of the binder alone to control mixture fracture energy
by increasing the conjugated diene content until acceptable
properties are achieved.
[0056] Each Binder was evaluated for Bituminous Binder Fracture
Energy and tested 0.1 mm/sec at -30.degree. C. per ASTM D 5045-99.
The results are set forth in Table 11:
TABLE-US-00011 TABLE 11 Binder Conjugated Fracture Diene Energy
Content (J/m.sup.2) 0.00% 23.7 1.49% 34.8 2.97% 41.8 4.46% 48.2
[0057] As can be seen from Table 11, a higher percentage of
conjugated diene resulted in a higher binder fracture energy. A
linear correlation coefficient (r.sup.2) between conjugated diene
content and Binder Fracture Energy was 0.981. The correlation
demonstrates the positive effect of conjugated diene on binder
fracture energy properties.
[0058] Alternate Mixtures:
[0059] A variety of alternate mixtures may be used to form the
crack resistant layer described herein, so long as the amount of
conjugated diene and the fatigue properties meet the requirements
set forth above, as well as the fracture energy properties if such
properties are considered. For example, every state and the Federal
Highway Administration have target levels for various types of
mixes. These target levels may be used, and the crack resistant
properties of the mixture may be optimized by varying the level of
conjugated diene content using the method set forth above. The
charts below set forth three alternate mixtures, as required by the
Texas Department of Transportation (Alternate Mixture #1), the
Oklahoma Department of Transportation (Alternate Mixture #2), and
the New Jersey Department of Transportation (Alternate Mixture
#3).
TABLE-US-00012 Alternate Mixture #1 TxDOT Special Specification
3111 Crack Attenuating Mixture Sieve Size % Passing 2'' -- Target
Laboratory- 98* Molded Density, % 11/2'' -- Binder Content 6.5%
minimum 1'' -- Design VMA, % Minimum 16.0 3/4'' -- Design VFA, %
73-76 1/2'' -- Dust/Binder Ratio 0.6-1.6 3/8'' 98.0-100.0 Number of
Gyrations 50 #4 70.0-90.0 #8 40.0-65.0 #16 20.0-45.0 #30 10.0-30.0
#50 10.0-20.0 #200 2.0-10.0 *% Air Voids = (100 - 98) = 2.0%
TABLE-US-00013 Alternate Mixture #2 Oklahoma DOT Special Provision
for Ultra Thin Bonded Wearing Course Sieve Size Type A Type B Type
C 3/4'' 100 1/2'' 100 75-100 3/8'' 100 75-100 50-80 #4 40-55 25-38
25-38 #8 22-32 19-27 19-27 #16 15-25 15-23 15-23 #30 10-18 10-18
10-18 #0 8-13 8-13 8-13 #100 6-10 6-10 6-10 #200 4-6 4-6 4-6
Asphalt Content 5.0-6.2 4.8-6.2 4.6-6.2 Typical Design Air Voids
9-14% 9-14% 9-14%
TABLE-US-00014 Alternate Mixture #3 NJ DOT 902.03 Open-Graded
Friction Course (OGFC) and Modified Open-Graded Friction Course
Mixture Designations (% Passing) Sieve Sizes OGFC-9.5 mm MOGFC-12.5
mm MOGFC-9.5 mm 3/4'' 100 1/2'' 100 85-100 100 3/8'' 80-100 35-60
85-100 No. 4 30-50 10-25 20-40 No. 8 5-15 10-15 10-15 No. 200
2.0-5.0 2.0-5.0 2.0-4.0 Minimum 5.5 5.7 6 asphalt binder, %.sup.1
Minimum % 15% 20% 18% Air Voids, design Minimum lift 3/4'' 11/4''
3/4'' thickness, design Fiber 0.4 0.4 0.4 Stabilizer, % Ndesign 50
50 50
http://www.state.nj.us/transportation/eng/specs/2007/spec900.shtm#t9020203-
1
[0060] From the above description, it is clear that the present
invention is well adapted to carry out the objects and to attain
the advantages mentioned herein as well as those inherent in the
invention. While presently preferred embodiments of the invention
have been described for purposes of this disclosure, it will be
understood that numerous changes may be made which will readily
suggest themselves to those skilled in the art and which are
accomplished within the spirit of the invention disclosed and
claimed.
* * * * *
References