U.S. patent application number 14/873870 was filed with the patent office on 2016-03-31 for process for cold-in-place recycling using foamed asphalt and lubrication additive.
The applicant listed for this patent is ALM HOLDING CO., Ergon Asphalt & Emulsions, Inc.. Invention is credited to Gaylon L. Baumgardner, Ervin Dukatz, David Lange, Gerald H. Reinke.
Application Number | 20160090701 14/873870 |
Document ID | / |
Family ID | 41462234 |
Filed Date | 2016-03-31 |
United States Patent
Application |
20160090701 |
Kind Code |
A1 |
Reinke; Gerald H. ; et
al. |
March 31, 2016 |
PROCESS FOR COLD-IN-PLACE RECYCLING USING FOAMED ASPHALT AND
LUBRICATION ADDITIVE
Abstract
Cold-in-place asphalt recycling is disclosed. A foamed asphalt
may be produced by injecting water and optionally compressed air
into a hot asphalt stream. A lubricating surfactant may be added to
the hot asphalt stream to improve performance. The foamed asphalt
may be mixed with reclaimed material to provide a uniformly coated
paving material that can compacted to a desired density.
Inventors: |
Reinke; Gerald H.; (La
Crosse, WI) ; Lange; David; (La Crosse, WI) ;
Baumgardner; Gaylon L.; (Jackson, MS) ; Dukatz;
Ervin; (La Crosse, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALM HOLDING CO.
Ergon Asphalt & Emulsions, Inc. |
Onalaska
Jackson |
WI
MS |
US
US |
|
|
Family ID: |
41462234 |
Appl. No.: |
14/873870 |
Filed: |
October 2, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14717628 |
May 20, 2015 |
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14873870 |
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14597465 |
Jan 15, 2015 |
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14717628 |
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12536065 |
Aug 5, 2009 |
8962071 |
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14597465 |
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61086331 |
Aug 5, 2008 |
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Current U.S.
Class: |
404/75 ;
427/138 |
Current CPC
Class: |
E01C 7/18 20130101; C08L
2555/22 20130101; Y10T 428/2991 20150115; Y02W 30/91 20150501; Y02A
30/30 20180101; E01C 2301/50 20130101; E01C 19/1004 20130101; Y02A
30/333 20180101; C04B 26/26 20130101; E01C 7/08 20130101; E01C
23/065 20130101; C09D 195/005 20130101; E01C 11/005 20130101; C08J
9/00 20130101; Y02W 30/95 20150501; C08L 95/00 20130101; E01C 19/16
20130101; E01C 19/08 20130101; C08J 2395/00 20130101; E01C 23/12
20130101; C04B 2111/0075 20130101; E01C 7/22 20130101; E01C 7/20
20130101; C08L 95/005 20130101; E01C 7/187 20130101; E01C 7/353
20130101; E01C 7/265 20130101; E01C 19/05 20130101; C04B 26/26
20130101; C04B 18/167 20130101; C04B 24/34 20130101; C04B 2103/40
20130101 |
International
Class: |
E01C 23/06 20060101
E01C023/06; E01C 7/18 20060101 E01C007/18; C08J 9/00 20060101
C08J009/00; E01C 7/26 20060101 E01C007/26; E01C 7/22 20060101
E01C007/22; C09D 195/00 20060101 C09D195/00; E01C 23/12 20060101
E01C023/12; E01C 7/20 20060101 E01C007/20 |
Claims
1. A method for forming a foamed asphalt binder, which method
comprises: injecting water and optionally a lubricating surfactant
or compressed air into a hot stream of an asphalt binder containing
a lubricating cationic surfactant, to form the foamed asphalt
binder.
2. The method of claim 1, further comprising: milling an existing
pavement surface to a desired depth to provide milled bituminous
material on-site; combining the milled bituminous material with the
foamed asphalt binder to produce a paving material; and compacting
the paving material on-site to provide a recycled pavement
surface.
3. The method of claim 2, wherein the recycled paving surface has a
density, measured two days after compacting, of at least about 88
percent of the theoretical maximum density.
4. The method of claim 2 comprising combining virgin aggregate and
the milled bituminous material with the foamed asphalt binder.
5. The method of claim 2, comprising laying the paving material
using a paver.
6. The method of claim 2, comprising laying the paving material
using a grader.
7. The method of claim 2, wherein the lubricating cationic
surfactant reduces the temperature needed for construction,
including laying and compacting the paving material, by as much as
60.degree. F.
8. The method of claim 1, comprising combining the milled
bituminous material with the foamed asphalt binder in an amount of
about 0.5 to 4 percent asphalt binder by weight of milled
bituminous material.
9. The method of claim 1, wherein compressed air is injected into
the hot stream of asphalt binder containing lubricating cationic
surfactant.
10. The method of claim 1, wherein lubricating surfactant is
injected into the hot stream of asphalt binder containing
lubricating cationic surfactant.
11. The method of claim 1, wherein the lubricating cationic
surfactant comprises an alkyl amine, alkyl quaternary ammonium
salt, heterocyclic quaternary ammonium salt, amido amine or
non-nitrogenous sulfur or phosphorous derivative.
12. The method of claim 1, wherein the lubricating cationic
surfactant comprises an ethoxylated di amine.
13. The method of claim 1, wherein the lubricating cationic
surfactant comprises an ethoxylated tallow amine.
14. The method of claim 1, wherein the lubricating cationic
surfactant comprises
tris(2-hydroxyethyl)-N-tallow-alkyl-1,3-diaminopropane.
15. The method of claim 1, wherein the lubricating cationic
surfactant is an ethoxylated diamine or an ethoxylated tallow amine
in an amount of about 0.05 to about 3 weight percent of the asphalt
binder.
16. The method of claim 1, wherein the foamed asphalt binder is
formed from about 0.5 to about 5 weight percent water and about
0.05 to about 3 weight percent ethoxylated diamine or ethoxylated
tallow amine.
17. The method of claim 1, wherein the hot stream of asphalt binder
containing lubricating cationic surfactant is at a temperature
greater than about 300.degree. F.
18. The method of claim 17, wherein the hot stream of asphalt
binder containing lubricating cationic surfactant is at a
temperature of about 300.degree. F. to about 380.degree. F.
19. The method of claim 17, wherein the hot stream of asphalt
binder containing lubricating cationic surfactant is at a
temperature of about 320.degree. F. to about 360.degree. F.
20. The method of claim 1, wherein the foamed asphalt binder
produces a uniformly coated paving material.
21. A cold-in-place asphalt recycling method to prepare a recycled
asphalt pavement surface, which method comprises: producing a
foamed asphalt binder by injecting water and optionally a
lubricating surfactant or compressed air into a hot stream of an
asphalt binder containing a lubricating cationic surfactant; in a
continuous mixing process, milling an existing pavement surface to
provide milled bituminous material and combining the foamed asphalt
binder with the milled bituminous material to produce a recycled
bituminous mix; conveying the recycled bituminous mix into a paver;
laying the recycled bituminous mix onto an existing grade; and
compacting the recycled bituminous mix to form a recycled asphalt
pavement surface.
22. The method of claim 21, wherein the foamed asphalt binder
comprises about 0.5 to about 5 weight percent water and about 0.05
to about 3 weight percent lubricating cationic surfactant.
23. The method of claim 21, wherein the hot stream of asphalt
binder containing lubricating cationic surfactant is at a
temperature greater than about 300.degree. F.
24. The method of claim 23, wherein the hot stream of asphalt
binder containing lubricating cationic surfactant is at a
temperature of about 300.degree. F. to about 380.degree. F.
25. The method of claim 23, wherein the hot stream of asphalt
binder containing lubricating cationic surfactant is at a
temperature of about 320.degree. F. to about 360.degree. F.
26. The method of claim 21, wherein the lubricating cationic
surfactant is an ethoxylated diamine or an ethoxylated tallow
amine.
27. The method of claim 21, wherein the lubricating cationic
surfactant comprises tris
hydroxyethyl)-N-tallow-alkyl-1,3-diaminopropane.
28. The method of claim 21, comprising combining virgin aggregate
and the milled bituminous material with the foamed asphalt
binder.
29. The method of claim 21, further comprising crushing the milled
bituminous material.
30. The method of claim 21, wherein the lubricating cationic
surfactant reduces the temperature needed for construction,
including laying and compacting the recycled bituminous mix, by as
much as 60.degree. F.
31. The method of claim 21, further comprising placing a hot mix
asphalt layer on the recycled asphalt pavement surface.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 14/597,465 filed on Jan. 15, 2015 which is a continuation of
U.S. application Ser. No. 121536,065 filed Aug. 5, 2009, which
claims the benefit of U.S. Provisional Patent Application
No.61/086,331 filed on Aug. 5, 2008, the entire contents of which
are incorporated herein by reference for all purposes.
TECHNICAL FIELD
[0002] The disclosure pertains to asphalt processing and more
particularly to cold-in-place asphalt recycling,
BACKGROUND
[0003] Cold-in-place recycling, commonly referred to as CIR, is a
process where an existing bituminous pavement or a combination of
bituminous pavement and untreated aggregate are milled or ground
from a pavement surface to a depth of up to 6 inches, combined with
a virgin bituminous material, mixed, and repaved without removal of
the materials from the existing grade.
SUMMARY
[0004] The invention is directed to improved processes for
cold-in-place recycling of asphalt. In one embodiment, the
invention is a cold-in-place recycling method in which an
ethoxylated diamine surfactant and water are mixed with an asphalt
binder to form a foamed composition of the surfactant and asphalt.
The foamed composition of the surfactant and asphalt is mixed with
milled recycled pavement to provide a uniformly coated paving
material that can be compacted to a desired density.
[0005] In another embodiment, the invention is a foamed
cold-in-place recycling method in which a foamed asphalt binder is
produced by injecting one or more of water and a compressed air
stream into a liquid asphalt stream that includes a lubricating
surfactant. The foamed asphalt binder is combined with bituminous
material in a continuous mixing process to produce a recycled
bituminous mix. The recycled bituminous mix is conveyed into a
paver and is then paved onto an existing grade.
[0006] In another embodiment, the invention is a foamed
cold-in-place recycling method in which a foamed asphalt binder is
produced by combining water and a lubricating surfactant into a
liquid asphalt stream. The foamed asphalt binder is combined with
bituminous material in a continuous mixing process to produce a
recycled bituminous mix. The recycled bituminous mix is conveyed
into a paver and is then paved onto an existing grade.
[0007] While multiple embodiments are disclosed, still other
embodiments of the present invention will become apparent to those
skilled in the art from the following detailed description, which
shows and describes illustrative embodiments of the invention.
Accordingly, the detailed description is to be regarded as
illustrative in nature and not restrictive.
DETAILED DESCRIPTION
[0008] The invention pertains to improved CIR processes in which a
lubricating additive is added to a foaming asphalt binder. This
provides better coating, easier construction, improved compaction,
and reduced processing temperatures. One indication of improved
coating is the richer color of the paving material, as the more
uniform the coating, the darker the color. The duller, browner
color of conventional CIR foamed mix is observed when all of the
particles are not coated. A firmer mat is also an indication that
the binder is coated or more uniformly spread over all the
particles rather than having small globules of asphalt interspersed
among the fine aggregate particles.
CIR Recycling
[0009] CIR recycling is a process in which an existing bituminous
pavement or a combination of bituminous pavement and untreated
aggregate are milled or ground from a pavement surface to a depth
of several inches, combined with a foamed asphalt material, mixed,
and repaved. In some embodiments, CIR recycling involves a train
method in which a number of pieces of equipment are arranged, in
order, to accomplish each of these tasks on site.
[0010] For example, in a train method, a milling machine may be
positioned at the front of the line to mill existing pavement down
a desired depth. A hammer mill crusher may be located behind the
milling machine, or "downstream" with respect to the flow of
materials, such that the hammer mill crusher (or another type of
mill or crusher) receives the milled bituminous material from the
milling machine. A pug mill may be located downstream of the hammer
mill crusher to mix the milled and crushed material with a foamed
asphalt binder in a continuous process. A tanker or other truck
holding hot asphalt may be disposed between the hammer mill crusher
and the pug mill.
[0011] Once the material has been mixed, it can be deposited on the
road and transferred to a paver using a pickup machine. In some
cases, the material can be dumped from the pug mill directly into
the paver. The paver lays the mix and the mix is then rolled or
compacted. In some cases, it has been determined that it is
beneficial to drop the mix from the pug mill onto the grade and let
the pickup machine transfer it to the paver as this can reduce or
eliminate frequent stopping and staffing of the paver.
[0012] In another process, a reclaimer is used to rip up or chew up
the pavement. The removed material is tilled or reclaimed
(sometimes virgin aggregate is added) and foamed asphalt is sprayed
onto the reclaimed mix, which is then deposited behind the
reclaimer. In some cases, a grader is used to shape the finished
mix for thickness and slope. In some instances, the material as
deposited is compacted without shaping. This process produces a
recycled mix that is suitable for correcting poor grades, adding
depth to the compacted layer (when using additional aggregate) and
generally obtaining a water shedding surface on which additional
layers of hot mix asphalt can be placed.
[0013] In another process, a stationary foaming mixing system can
be used in combination with milled material that is collected on
site and brought back to a central mixing location. This process
can be used to produce a cold mix that can be either grader or
paver laid to produced a hard, water shedding surface on which to
add a chip seal or an overlay. In each of these processes, a
lubricating surfactant can be used in the foaming process.
Foaming Process
[0014] In some embodiments, a foamed asphalt binder is beneficial
to the CIR process. A foamed asphalt binder can be produced using
several different techniques. In one technique, a foamed asphalt
binder is formed by injecting a small amount of water and
compressed air into a very hot stream of asphalt binder which
causes the asphalt binder to foam when the water/asphalt blend is
sprayed onto the milled bituminous material. In this process, about
1 to 5 weight percent water is injected into virgin asphalt binder
along with vigorous mixing of the components to create a foam. The
resultant mix that is placed develops strength very quickly because
of the relatively low level of water added to the asphalt binder to
make the foam and because of the relatively rapid loss of water
through evaporation caused by the heat of the asphalt.
[0015] In another technique, a foam is produced from an emulsion
that includes about 60 to 70 weight percent asphalt binder and
about 30-40 weight percent water combined at a temperature in a
range of about 30.degree. C. to 60.degree. C. Use of an emulsion
can result in effectively coating the milled material at or near
about 100 percent level.
[0016] In some cases, quicker setting emulsions impart a chemical
"break" to the emulsion which enables the emulsion to coat the
milled material and then chemically bond the asphalt particles to
the aggregate material and cause the water to break or separate
from the asphalt, There can be a noticeably faster cure imparted to
the emulsion system compared to conventional slow setting or medium
setting emulsion mixed blends.
[0017] In some embodiments, lubricating surfactants can be added to
the asphalt binder or to the water injected into the asphalt binder
to enhance foaming and to lubricate and enhance spreading of the
asphalt binder onto milled material particles. Consequently,
recycled bituminous materials can be produced that provide rapid
strength development while also providing about or up to 100
percent coating of particles and also provide the desired
appearance and density. In some cases, the lubricating effect
provided by the lubricating surfactants can prevent or
substantially reduce the tendency of some foamed CIR mixtures to
stick to the paver screed. Moreover, while foamed CIR may be
performed using binders at approximately 360.degree. F., the use of
lubricating, foam enhancing additives can result in the reduction
of the temperature needed for construction by as much as 60.degree.
F.
[0018] In some embodiments, a foamed asphalt binder can be produced
by injecting water and compressed air, along with one or more
lubricating surfactants, into a strewn of hot asphalt. The hot
asphalt stream may be a virgin asphalt such as PG 52-34 binder. In
some cases, the lubricating surfactant is added to the asphalt
prior to injecting the water and compressed air, In some instances,
the lubricating surfactant is added to the water prior to injection
of the water. In some embodiments, the hot asphalt is flowing
through a pipe or other structure, the water is injected into the
hot asphalt stream via a first nozzle and the compressed air is
injected into the hot asphalt stream via a second nozzle. In some
cases, foaming may occur with injection of water in the absence of
injection of compressed air.
Asphalt Binder
[0019] A variety of different asphalt binders are commercially
available. As an example, several different asphalt binders are
commercially available from a variety of sources. Non-limiting
examples of asphalt binders are PG 52-34, PG 58-34, PG 64-28, PG
70-28, PG 76-28, PG 70-22 and PG 76-22. A particular asphalt binder
is PG 52-34, which has an absolute viscosity (measured at
140.degree. F.) of 540 Poise, a penetration (at 77.degree. F.) of
236 dmm and a specific gravity (at 60.degree. F.) of 1.03.
Lubricating Surfactants
[0020] A variety of lubricating surfactants can be used in
producing foamed asphalt binders. Examples of suitable lubricating
surfactants include naturally occurring compounds and more commonly
synthesized chemical compounds from three categories of
surfactants: detergents, wetting agents and emulsifiers.
Surfactants can be specifically categorized as being anionic,
cationic, amphoteric and nonionic.
[0021] Suitable anionic surfactants include but are not limited to
fatty acids (saturated and unsaturated fatty acids), fatty acid
pitch (stearic acid pitch), fatty acid derivatives (fatty acid
esters and fatty acid sultanates), and organo phosphates (alkyl
phosphates).
[0022] Suitable cationic surfactants include, but are not limited
to, alkyl amines, alkyl quaternary ammonium salts, heterocyclic
quaternary ammonium salts, amido amines, and non-nitrogenous sulfur
or phosphorous derivatives.
[0023] Suitable amphoteric surfactants, which include an anionic
molecular portion and a cationic molecular portion, include but are
not limited to amino acids, amino acid derivatives, betain
derivatives (alkylbetains and alkylaminobetains), imidazolines, and
imidazoline derivatives.
[0024] Suitable nonionic surfactants include, but are not limited
to. fatty acid ester bonds (SPANS and TWEENS), with surfactant
ether bonds (alkylphenolpolyoxyethylenes and polyoxyethylenated
alcohols), surfactants with amid bonds (alcanolamides, mono and
diethanolamides and their derivatives), alkylenated oxide
copolymers and polyoxyethyleneated mercaptans.
[0025] Other surfactants and non-surfactant additives can be found
in U.S. patent application Ser. No. 11/871,782, filed Oct. 12, 2007
entitled WARM MIX ASPHALT BINDER COMPOSITIONS CONTAINING
LUBRICATING ADDITIVES, which application is hereby incorporated by
reference herein in its entirety.
[0026] In some embodiments, the lubricating surfactant is an
ethoxylated diamine. An illustrative but non-limiting example of a
suitable ethoxylated diamine is DT-3, or
tris(2-hydroxyethyl)-N-tallow-alkyl-1,3-diaminopropane. In some
embodiments, about 0.5 weight percent DT-3 can be used in the
asphalt binder.
Compositions
[0027] In some embodiments, a foamed asphalt may be produced by
injecting about 0.5 to 5 weight percent water and about 0.05 to
about 3 weight percent of an ethoxylated diamine surfactant into a
liquid asphalt stream. The liquid asphalt stream may be an asphalt
binder such as PG 52-34. In some embodiments, compressed air at a
pressure of about 20 to about 50 psi may also be injected into the
liquid asphalt stream to enhance foaming. In some embodiments,
during the foaming process, the liquid asphalt stream is at a
temperature in the range of about 300.degree. F. to about
380.degree. F. In some cases, the liquid asphalt stream is at a
temperature in the range of about 320.degree. F. to about
360.degree. F.
[0028] The resulting foamed asphalt may be combined with milled
bituminous material (either on site or at a central location) at a
rate of about 0.5 to 4 percent foamed asphalt binder by weight of
milled bituminous material. This material, once laid and compacted,
can achieve a density, measured two days after compaction, of at
least about 88 to about 95 percent of the theoretical maximum
density of the mix being placed.
EXAMPLE ONE
[0029] A trial run was conducted using the "train method" of
cold-in-place recycling. A PR1000T Caterpillar milling machine was
used to mill the existing pavement approximately 3.5 inches deep. A
portable 3033 Cedar Rapids hammer mill crusher with a double screen
deck was used to size the milled material to 1 inch and smaller
size. A portable Barber Green pugmill with a twin shaft
approximately 10 feet long was used to mix the milled material with
the foamed asphalt binder. The foaming process was conducted using
a Soter spray bar to inject water into the asphalt stream just
prior to introduction of the asphalt into the milled material.
After mixing the milled material with the foamed asphalt, the mix
was placed in a windrow behind the pugmill and a pickup machine was
used to transfer the mix to a paver which then laid the mix. A
screed on the paver provided initial compaction and final
compaction of the mix was accomplished with pneumatic and steel
wheeled rollers.
[0030] The asphalt binder used was a PG 52-34 at a nominal
temperature of 360.degree. F. The asphalt was delivered to the
project in a tanker and transferred to smaller tank designed to
straddle the windrow and so move down the paving project as the
entire milling and mixing train operates on the project. One to two
percent water is added at the milling head to cool the head and
keep down dust and another 1-2% water is added during the crushing
phase of the operation. This water is in addition to the water
injected at the spray head to produce the foamed asphalt. The
ambient temperature on this project was 70.degree. F. A total of
1.65% virgin 52-34 binder by weight was added to the milled
material. For this test 0.5% DT-3 ethoxylated diamine lubricating
additive was added by weight to the PG 52-34 binder.
[0031] At the spray bar in the mixing chamber the mixture color was
a darker richer looking color compared to comparable runs performed
without the lubricating additive. The mix was more workable in the
windrow and picked up easily for transfer to the paver. There was
good flow through the paver, flights and under the screed. The
coating was uniform and darker in color than the same mix produced
without the lubricating additive. The mat behind the paver was
firmer than the comparable untreated mix. The mix rolled well and
mat appeared firmer under the roller. There was an obvious color
difference between the conventional foamed CIR mix and the CR mix
produced with the lubricating additive. Cores were taken from both
the conventional and test sections 2 days after construction. These
cores were tested for density. The average density of 5 cores in
the conventional section was 127.3 lbs/ft3. The average density for
4 cores taken in the section produced with the lubricating additive
was 129.0 lbs/ft.sup.3.
EXAMPLE TWO
[0032] Another trial run was conducted using the "train method" of
cold-in-place recycling. A portion of the existing pavement was
milled, crushed and mixed with a foamed asphalt binder.
[0033] The foaming process was conducted by injecting water into
the asphalt stream just prior to introduction of the asphalt into
the milled material. After mixing the milled material with the
foamed asphalt the mix was transferred to a paver which then laid
the mix. A screed on the paver provided initial compaction and
final compaction of the mix was accomplished with pneumatic and
steel wheeled rollers.
[0034] The asphalt binder used was a PG 52-34 at a nominal
temperature of 360.degree. F. The asphalt was delivered to the
project in a tanker and transferred to smaller tank designed to
straddle the windrow and so move down the paving project as the
entire milling and mixing train operates on the project. One to two
percent water is added at the milling head to cool the head and
keep down dust and another 1-2% water is added during the crushing
phase of the operation. This water is in addition to the water
injected at the spray head to produce the foamed asphalt.
[0035] By mid-morning, as the pavement and air temperatures
increased, it was found that the asphalt mix developed a tendency
to stick to the screed as a result of the fines and binder
increasing in viscosity. An attempt was made to resolve the problem
by reducing the binder content from 1.2 or 1.3 gallons per foot to
0.8 gallons per foot. It was found that this reduced but did not
eliminate the problem. Moreover, this resulted in a
less-than-optimal binder content. It was found that by adding 0.3
weight percent of DT-3 to the binder, the binder content could be
kept at 1.2 gallons per foot while eliminating the mix sticking
problem.
[0036] Various modifications and additions can be made to the
exemplary embodiments discussed without departing from the scope of
the present invention. Although the embodiments described above
refer to particular features, the scope of this invention also
includes embodiments having different combinations of features and
embodiments that do not include all of the above described
features.
* * * * *