Note: Descriptions are shown in the official language in which they were submitted.
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MODIFIED ASPHALT BINDERS AND COMPOSITIONS
CROSS-REFERENCE TO RELATED APPLICATIONS
[001] This application claims priority from U.S Provisional Application No.
62/273604,
with filing date of December 31, 2015.
FIELD
[002] The disclosure relates to additives for use with asphalt binders for
road paving
and other applications.
BACKGROUND
[003] Reclaimed asphalt includes reclaimed asphalt pavement (RAP), reclaimed
asphalt
shingles (RAS), asphalt reclaimed from plant waste, and asphalt recovered from
roofing felt,
among other sources. Recycled asphalt pavement is typically limited to use as
sub-surface
"black rock" or in limited amounts in asphalt base and surface layers because,
over time, asphalt
loses flexibility, becomes oxidized and brittle, and tends to crack,
particularly under stress or at
low temperatures. The effects are due to aging of the organic component of the
asphalt, e.g., the
bitumen-containing binder, particularly upon exposure to weather. The aged
binder is also
highly viscous. Consequently, reclaimed asphalt pavement has different
properties than virgin
asphalt and is difficult to process. Untreated RAP can be used only sparingly;
generally, an
asphalt mixture comprising up to 30 wt.% of RAP can be used as sub-surface
black rock.
Moreover, because of the higher demands of the pavement surface, untreated RAP
use there is
generally limited to 15-25%.
[004] RAS are generally recovered from two sources: production waste from
shingle
manufacture and waste streams of end-of-life shingles. These shingles contain
a bituminous
binder that can be recovered and reused. Binder reclaimed from production
waste is soft,
unoxidized, and still contains low-molecular-weight, volatile components.
However, the binder
recovered from used shingles¨by far the greater volume of recovered binder¨is
oxidized,
devoid of volatile components, and hardened by weathering and aging. Re-use of
this aged
binder requires rejuvenation.
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[005] It has been disclosed that RAP binders can be modified using ester-
functional
compositions derived from tall oil (see US2015/0240081 and W02013/090283). In
some cases,
the ester-functional compositions could be made from dimerized fatty acids or
by-products of the
dimerization process, including "Monomer" (or "Monomer acid") as disclosed in
US2015/0240081 and US7256162. Examples of suitable modifiers include ethylene
glycol
tallate, trimethylolpropane tallate, neopentyl glycol tallate, ethylene glycol
Monomerate, and
glycerol Monomerate. The ester-functional compositions are desirably made
using a thermally
stable alcohol such as trimethylolpropane or neopentyl glycol.
[006] US2014/0338565 discloses that certain ester-functional compositions
having at
least 5 wt. % of cyclic content (aromatic or cycloaliphatic rings) are
excellent for revitalizing
reclaimed asphalt. These esters or ester blends are derived from aromatic
acids, fatty acids, fatty
acid monomers, fatty acid dimers, fatty acid trimers, rosin acids, rosin acid
dimers, and mixtures
thereof. US4,549,834 discloses that reclaimed asphalt can be blended with
virgin asphalt, virgin
binder, or both. A variety of rejuvenators or rheology modifiers have been
developed to increase
the amount of reclaimed asphalt that can be incorporated in both the base and
surface layers.
Rejuvenating agents restore a portion of the asphalt paving properties and
binder bitumen
physical properties, such as viscoelastic behavior, so that the reclaimed
asphalt properties more
closely resemble those of virgin asphalt. Improving the properties of recycled
asphalt, and
particularly the properties of bitumen binder in RAP and RAS, allows increased
amounts of
reclaimed asphalt to be used in asphalt mixtures without compromising the
properties and
lifetime of the final pavement.
[007] Commonly used rejuvenating agents for reclaimed asphalt include low-
viscosity
products obtained by crude oil distillation or other hydrocarbon oil-based
materials (see, e.g.,
U.S. Pat. Nos. 5,766,333 or 6,117.227). Rejuvenators or rheology modifiers of
plant origin have
also been described. See, for example, U.S. Pat. No. 7,811,372 (rejuvenating
agents comprising
bitumen and palm oil); U.S. Pat. No. 7,008,670 (soybean oil, alkyl esters from
soybean oil, and
terpenes used for sealing or rejuvenating); U.S. Pat. Publ. No. 2010/0034586
(rejuvenating agent
based on soybean, sunflower, rapeseed, or other plant-derived oils); and U.S.
Pat. Appl. Publ.
No. 2008/0041276 (plasticizers for recycled asphalt that may be vegetable oils
or alkyl esters
made from vegetable oils). U.S. Pat. No. 8,076,399 describes a binder
composition comprising a
resin of vegetable origin, a vegetable oil, and a polymer having anhydride,
carboxylic acid, or
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epoxide functionality, but this binder is not specifically taught for
rejuvenation. Although
vegetable oils can provide desirable softening of aged binders, they are prone
to leaching from
the rejuvenated asphalt.
[008] Various fractions isolated from crude tall oil (CTO) distillation have
been used in
asphalt compositions, although they are not specifically taught for
rejuvenation or rheology
modification. See, for instance, U.S. Pat. Appl. Publ. No. 2010/0170417 (CTO
distillation
fractions as cutting solvents use in asphalt compositions); U.S. Pat. No.
8,034,172 (distilled or
oxidized tall oil components for use in asphalt compositions); and U.S. Pat.
Nos. 4,479,827 and
4,373,960 (patching compositions comprising asphalt, tall oil, and possibly an
organopolysiloxane).
[009] Improved rheology modifiers for bituminous binders are needed. In
particular,
the industry needs additives for reclaimed asphalt that can improve rutting
resistance while
maintaining good low-temperature cracking resistance and fatigue cracking
resistance. Better
rheology modifiers would reduce the cost of road construction by enabling
greater use of
reclaimed asphalt, especially RAS and RAP, in new pavements and reducing
reliance on virgin,
non-renewable binder and aggregate materials. A desirable rheology modifier
would reduce the
viscosity of aged binders to a level comparable to that of virgin binder and
would allow for
softer, more easily processed asphalt mixtures. Ideally, the rheology modifier
would derive from
renewable resources, would have good thermal stability at the elevated
temperatures normally
used to mix and lay asphalt, and could restore the original performance
grading to the binder.
SUMMARY
[010] In one aspect, the disclosure relates to a modified binder composition.
The binder
composition comprises a bituminous binder and a rheology modifier. In one
embodiment, the
rheology modifier is present in an amount of 0.05 to 20 wt.% of the binder
composition. The
rheology modifier is a blend comprising 5-50 wt.% of a polyol ester and C8-C24
free fatty acid
component. In one embodiment, the free fatty acid component may have an acid
value of at least
180 mg KOH/g. In another embodiment, the free fatty acid may include
unsaturated fatty acids
and their mixtures in an amount of at least 50% based upon the weight of the
free fatty acid.
[011] In another aspect, the disclosure relates to asphalt compositions
comprising
aggregate and the modified binder compositions.
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[012] In some aspects, the polyol ester is based on a polyol having high
thermal
stability. In other aspects, the free fatty acid component comprises tall oil
fatty acid.
[012a] In accordance with another aspect, there is provided a binder
composition
comprising: (a) a bituminous binder; and (b) 0.05 to 20 wt.%, based on the
amount of binder
composition, of a rheology modifier which comprises: (i) 5-50 wt.%, based on
the amount of
rheology modifier, of a polyol ester, and (ii) a C8-C24 free fatty acid
component having an
acid value of at least 180 mg KOII/g. In accordance with another aspect,
wherein the rheology
modifier comprises 10 to 50 wt.% based on the amount of rheology modifier, of
the polyol
ester and wherein the polyol ester derives from a thermally stable polyol and
at least one
molar equivalent of a C8-C24 fatty acid.
[0121)] In accordance with another aspect, there is provided an asphalt
emulsion
composition comprising: a) an aqueous phase comprising at least an emulsifying
agent, and
b) a dispersion phase comprising a bituminous binder and 0.05 to 20 wt.%,
based on the
amount of bituminous binder, of a rheology modifier which comprises: (i) 5-50
wt.%, based
on the amount of rheology modifier, of a polyol ester, and (ii) a C8-C24 free
fatty acid
component having an acid value of at least 180 mg KOH/g. In accordance with
another
aspect, wherein the rheology modifier is present in an amount of 0.1 to15 wt.
% of the total
weight of the asphalt emulsion. In accordance with another aspect, wherein the
bituminous
binder is present in an amount of 20 to 70 wt. % of the total weight of the
asphalt emulsion.
[012c] In accordance with another aspect, there is provided a method for
rejuvenating
asphalt pavement comprising: applying to the asphalt pavement a composition
comprising an
aqueous emulsion of at least an emulsifying agent, a bituminous binder; and
0.05 to 20 wt. %,
based on the amount of bituminous binder, of a rheology modifier which
comprises: (i) 5-50
wt. %, based on the amount of rheology modifier, of a polyol ester, and (ii) a
C8-C24 free fatty
acid component having an acid value of at least 180 mg KOH/g, and drying the
aqueous
emulsion.
DETAILED DESCRIPTION
[013] The following terms will be used throughout the specification and will
have the
following meanings unless otherwise indicated.
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[014] "Asphalt" refers to a composite material comprising a bituminous binder
and
aggregate, which is generally used for paving applications. Such asphalt is
also known as
"asphalt concrete." Examples of asphalt grades used in paving applications
include stone
mastic asphalt, soft asphalt, hot rolled asphalt, dense-graded asphalt, gap-
graded asphalt, porous
asphalt, mastic asphalt, and other asphalt types. Typically, the total amount
of bituminous
binder in asphalt is from 1 to 10 wt.% based on the total weight of the
asphalt, in some cases
from 2.5 to 8.5 wt.% and in some cases from 4 to 7.5 wt.%.
[015] "Aggregate" (or "construction aggregate") is particulate mineral
material
suitable for use in asphalt. It generally comprises sand, gravel, crushed
stone, and slag. Any
conventional type of aggregate suitable for use in asphalt can be used.
Examples of suitable
aggregates include granite, limestone, gravel, and mixtures thereof.
[016] "Bitumen" refers to a mixture of viscous organic liquids or semi-solids
from
crude oil that is black, sticky, soluble in carbon disulfide, and composed
primarily of
condensed aromatic hydrocarbons. Alternatively, bitumen refers to a mixture of
maltenes and
asphaltenes. Bitumen may be any conventional type of bitumen known to the
skilled person.
The bitumen may be naturally occurring. It may be crude bitumen, or it may be
refined
bitumen obtained as the bottom residue from vacuum distillation of crude oil,
thermal
cracking, or hydrocracking.
[017] Performance Grade" (PG) is defined as the temperature interval for which
a
specific asphalt product is designed. For example, an asphalt product designed
to
accommodate a high temperature of 64 C and a low temperature of -22 C has a PG
of 64-22.
Performance Grade standards are set by the National Committee of Highway and
Roadway
Professionals (NCHRP).
[018] The bitumen may be commercially available virgin bitumen such as paving
grade bitumen, e.g. bitumen suitable for paving applications. Examples of
commercially
available paving grade bitumen include, for instance, bitumen which in the
penetration grade
(PEN) classification system are referred to as PEN 35/50, 40/60 and 70/100 or
bitumen which
in the
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performance grade (PG) classification system arc referred to as PG 64-22, 58-
22, 70-22 and 64-
28. Such bitumen is available from, for instance, Shell, Total and British
Petroleum (BP). In the
PEN classification, the numeric designation refers to the penetration range of
the bitumen as
measured with the EN 1426 method, e.g., a 40/60 PEN bitumen corresponds to a
bitumen with a
penetration which ranges from 40 to 60 decimillimeters (dmm). In the PG
classification
(AASHTO MP 1 specification), the first value of the numeric designation refers
to the high-
temperature performance and the second value refers to the low-temperature
performance as
measured by a method which is known in the art as the Superpavesm system.
[019] The bitumen may also be contained in or obtained from reclaimed asphalt
shingles or reclaimed asphalt pavement, and is referred to as bitumen of RAS
or RAP origin,
respectively.
[020] "Binder" refers to a combination of bitumen and, optionally, other
components
such as elastomers, non-bituminous binders, adhesion promoters, softening
agents, or other
suitable additives. Useful elastomers include, for example, ethylene-vinyl
acetate copolymers,
polybutadienes, ethylene-propylene copolymers, ethylene-propylene-diene
terpolymers,
butadiene-styrene block copolymers, styrene-butadiene-styrene (SBS) block
terpolymers,
isoprene-styrene block copolymers and styrene-isoprene-styrenc (SIS) block
terpolymers, or the
like. Cured elastomer additives may include ground tire rubber materials. In
one embodiment,
the additional additives may be added to an asphalt binder in amounts ranging
from about 0.1 wt.
% to about 10 wt. %. The term bitumen is sometimes used interchangeably with
binder.
[021] "Recovered binder" or "reclaimed binder" refers to aged binder that is
present in
or is recovered from reclaimed asphalt. Normally, the recovered binder is not
isolated from the
reclaimed asphalt. Recovered binder has a high viscosity compared with that of
virgin bitumen
as a result of aging and exposure to outdoor weather.
[022] "Aged binder" includes recovered or reclaimed binder and laboratory-aged
binder. Aged binder can also refer to hard, poor-quality, or out-of-spec
virgin binders that could
benefit from combination with a rheology modifier as described herein,
particularly virgin
binders having a ring-and-ball softening point greater than 65 C by EN 1427
and a penetration
value at 25oC by EN 1426 less than or equal to 12 dmm.
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[023] "Laboratory-aged binder" refers to virgin binder that has been aged
using the
RTFO ("rolling thin film oven") and PAY ("pressure aging vessel") laboratory
aging test
methods that are known in the art.
[024] "Virgin binder" is binder that has not been used previously for road
paving or
roofing.
[025] "Virgin bitumen" (also known as "fresh bitumen") refers to bitumen that
has not
been used, e.g., bitumen that has not been recovered from road pavement or
reclaimed shingles.
Virgin bitumen is a component of virgin binder.
[026] "Virgin asphalt" refers to a combination of virgin aggregate with virgin
bitumen
or virgin binder. Virgin asphalt has not been used previously for paving.
[027] "Reclaimed asphalt" generally includes reclaimed asphalt shingles (RAS),
reclaimed asphalt pavement (RAP), reclaimed asphalt from plant waste,
reclaimed asphalt from
roofing felt, and asphalt from other applications.
[028] "Reclaimed asphalt shingles" (RAS) are asphalt compositions that have
been used
previously as roofing material or have been recovered as waste from shingle
manufacturing.
RAS recovered from these sources is processed by well-known methods, including
milling,
ripping, breaking, crushing, and/or pulverizing.
[029] "Reclaimed asphalt pavement" (RAP) is asphalt that has been used
previously as
pavement. RAP may be obtained from asphalt that has been removed from a road
or other
structure, and then has been processed by well-known methods. Prior to use,
the RAP may be
inspected, sized and selected, for instance, depending on the final paving
application.
[030] "Emulsion" generally refers as a multiphase material in which all phases
are
dispersed in a continuous aqueous phase. The aqueous phase may comprise
surfactants, acid,
base, thickeners, and other additives. The dispersed phase may comprise
thermoplastic natural
.. and synthetic polymers, waxes, asphalt, other additives including rheology
modifier(s),
optionally petroleum based oils or mixtures thereof, herein collectively
referred to as the "oil
phase." High shear and energy can be used to disperse the oil phase in the
aqueous phase using
apparatus such as colloidal mills.
[031] "Pavement preservation" refers to a proactive maintenance of roads to
prevent
them from getting to a condition where major rehabilitation or reconstruction
is necessary. A
pavement preservation application may be any of fog seal, slurry seal, micro-
surfacing, chip seal,
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scrub seal, cape seal, and combinations thereof wherein an asphalt emulsion
with optional
additives is applied onto an existing road or pavement as a "seal" to seal the
surface. In some
embodiments, polymer is added to the asphalt emulsion to provide better
mixture properties.
[032] "Fog seal" is a pavement preservation application of an asphalt emulsion
via a
spray application ("fogging").
[033] "Slurry seal" refers to a pavement preservation application wherein a
mixture of
water, asphalt emulsion, and aggregate is applied to an existing asphalt
pavement surface. A
slurry seal is similar to a fog seal except the slurry seal has aggregates as
part of the mixture for a
"slurry" and slurry seals are generally used on residential streets.
[034] "Microsurfacing" refers to a form of slurry seal, with the application
of a mixture
of water, asphalt emulsion with additives, aggregate (very small crushed
rock), and additives to
an existing asphalt concrete pavement surface. A difference between slurry
seal and
microsurfacing is in how they "break" or harden. Slurry relies on evaporation
of the water in the
asphalt emulsion. The asphalt emulsion used in microsurfacing contains
additives which allow it
to break without relying on the sun or heat for evaporation to occur, for the
surface to harden
quicker than with slurry seals.
[035] "Chip seal" refers a pavement preservation application wherein first
asphalt
emulsion is applied then then a layer of crushed rock is applied to an
existing asphalt pavement
surface. "Chip seal" gets its name from the "chips" or small crushed rock
placed on the surface.
[036] "Scrub seal" refers to a pavement preservation application that is very
close to a
chip seal treatment where asphalt emulsion and crushed rock are placed on an
asphalt pavement
surface. The only difference is that the asphalt emulsion is applied to the
road surface through a
series of brooms placed at different angles. These brooms guide the asphalt
emulsion into the
pavement distresses to ensure sealing the road. These series of brooms, known
as a "scrub
broom", give the treatment its title, "scrub seal."
[037] "Cape seal" is a combination of applications, i.e., an application of a
chip or scrub
seal followed by the application of slurry seal or microsurfacing at a later
date.
[038] "Rehabilitation" refers to applications carried out with pavements that
exhibit
distresses beyond the effectiveness of pavement preservation techniques, but
not too severe to
warrant the cost of complete reconstruction. As pavement ages, it will
deteriorate due to
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weathering and traffic loading, but not to the point of complete
reconstruction, so rehabilitation
techniques can be performed.
[039] "Cold in-place recycling" or CIR refers to applications involving a
milling
machine with a paver mixer, wherein the milling machine breaks and pulverizes
a thin amount of
the top layer of the old pavement. The material is crushed and screened to the
proper size and
asphalt emulsions and / or additives including rheology modifiers or
rejuvenators are mixed in to
rejuvenate the material to give more life. In some applications, virgin
aggregate can be added
and spread on the existing surface. The material is picked up by the paver and
spread, then
compacted using known methods, e.g., steel-wheel, pneumatic-tire, or vibratory
rollers.
[040] "Rubberized asphalt" refers to an asphalt mix, e.g., hot-mixed asphalt,
containing
crumb rubber. In some embodiments, the crumb rubber utilized is generated from
processing
crap tires, wherein the tires are shredded and the steel enforcement and
fibers are separated from
the rubber. In some embodiments, the crumb rubber serves as a modifier for the
asphalt and
gives the asphalt greater viscosity and may improve cracking properties.
[041] "Rheology modifier" generally refers to a composition or blend that can
be used
in asphalt compositions for road and pavement applications including but not
limited to new
construction, partial or complete re-construction, rehabilitation,
preservation, CIR, e.g., in
asphalt emulsion compositions, or in combination with aged binder or reclaimed
asphalt (or their
mixtures with virgin binder and / or virgin asphalt) to modify flow or other
properties of the aged
binder or reclaimed asphalt and, in some cases, restores some or most of the
original properties
of virgin binder or virgin asphalt.
[042] Good high-temperature performance is desirable to avoid of rutting,
which is a
common failure mode for asphalt road surfaces, particularly those that
experience high traffic
rates or high weight traffic. Combinations of polyol esters and fatty acids
such as tall oil fatty
acid (TOFA) have not been disclosed for use as rheology modifiers for
bituminous binders,
including reclaimed asphalt binders. It has been found that rheology modifiers
comprising a
blend of a polyol ester and a C8-C24 free fatty acid component help improve
the high-
temperature properties of bituminous binders without sacrificing low-
temperature performance,
e.g., modifying the binders. In one embodiment with the use of reclaimed (or
recycled) asphalt,
the modified binders in asphalt compositions expand the utility of reclaimed
asphalt thereby
helping the road construction industry reduce its reliance on virgin, non-
renewable materials.
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[043] Rheology Modifier. The rheology modifier is a blend comprising a polyol
ester
and a C8-C24 free fatty acid component.
[044] Polyol Ester. In one embodiment, the rheology modifiers are blends
comprising
70 wt.% or less, or 60 wt.% or less, or 2-50 wt.%, 4-50 wt.%, 6-50 wt.%, 8-50
wt.%, 10-50
wt.%, 15-50 wt.% or 20-50 wt.%, of a polyol ester, based upon the weight of
the rheology
modifier. In other aspects, the balance of the rheology modifier (e.g., 30
wt.% or more, 40 wt%
or more, or 50-98 wt.%, 50-96 wt.%, 50-94 wt.%, 50-92 wt.%, 50-90 wt.%, 50-85
wt.%, or 50-
80 wt.% based upon the weight of the rheology modifier) is a C8-C24 free fatty
acid component.
[045] Suitable "polyol esters" have an alcohol portion and an ester portion
derived from
a carboxylic acid, which is typically a fatty acid or a dimerized fatty acid.
[046] The alcohol portion of the polyol ester can be primary, secondary, or
tertiary; it
can be a monol, diol, or polyol. The alcohol can also derive from polyethers
such as triethylene
glycol or polyethylene glycols. Phenolate esters are also suitable. Suitable
alcohols include, for
example methanol, ethanol, 1-propanol, isobutyl alcohol, 2-ethylhexanol,
octanol, isodecyl
alcohol, benzyl alcohol, cyclohexanol, ethylene glycol monobutyl ether,
ethylene glycol,
propylene glycol, diethylene glycol, triethylene glycol. neopentyl glycol,
glycerol,
trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol,
sorbitol, sucrose, and
the like, and mixtures thereof. In another embodiment, alcohols may be used,
also identified
herein as "thermally stable" alcohols or polyols, which have a quaternary
carbon located beta to
the oxygen of any of its hydroxyl groups. Examples include trimethylolpropane,
neopentyl
glycol, trimethylolethane, pentaerythritol, dipentaerythritol, benzylic
alcohols, and the like, and
mixtures thereof
[047] The ester portion of the polyol ester derives from a carboxylic acid, a
saturated or
unsaturated fatty acid or dimerized fatty acid having 6 to 40 carbons, or 8 to
36 carbons. The
ester portion will often comprise a mixture of different fatty acids that are
present in natural
sources such as animal or vegetable oils.
[048] Suitable polyol esters can be made by reacting the alcohols described
above
directly with a fatty acid or with lower alkyl esters of the fatty acids and a
suitable
transesterification catalyst according to well-known methods.
[049] In some aspects, the fatty acid will comprise C8-C24 fatty acids with
some degree
(in some aspects, a high degree) of unsaturation. The fatty acid can be in a
polymerized form, as
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in dimerized fatty acid mixtures. The fatty acid may comprise one or more of
oleic acid, linoleic
acid, linolenic acid, and palmitic acid. Also suitable are Monomer acid
(defined below), dimer
acids, tall oil heads, and the like, and mixtures thereof.
[050] In some aspects, the polyol ester is a reaction product of an alcohol
and a tall oil
fatty acid (TOFA) or a TOFA derivative (e.g.. a TOFA dimer acid). Tall oil
fatty acid is isolated
from crude tall oil (CTO) by distillation. The CTO is a by-product of the
Kraft wood pulping
process. Distillation of CTO gives, in addition to tall oil fatty acid, a more
volatile, highly
saturated fraction of long-chain fatty acids (largely palmitic acid), known as
"tall oil heads."
Tall oil fatty acid is the next fraction, which contains mostly C18 and C20
fatty acids having
varying degrees of unsaturation (e.g., oleic acid, linoleic acid, linolenic
acid, and various isomers
of these). Another fraction, known as distilled tall oil or "DTO," is a
mixture of mostly tall oil
fatty acid and a smaller proportion of tall oil rosin. Tall oil rosin ("TOR"),
isolated next, consists
largely of a C19-C20 tricyclic monocarboxylic acid. The bottom fraction of the
distillation is
known as "tall oil pitch" or simply "pitch." Generally, any distillation
fraction that contains at
least some tall oil fatty acid can be used to produce a polyol ester useful
herein.
[051] Polymerized fatty acids can be used to make the polyol ester.
Unsaturated fatty
acids are commonly polymerized using acid clay catalysts. Fatty acids having
high levels of
mono- or polyunsaturation may also be used. In this process, the unsaturated
fatty acids undergo
intermolecular addition reactions by, e.g., the "ene reaction," to form
polymerized fatty acids.
The product comprises mostly dimerized fatty acid and a unique mixture of
monomeric fatty
acids. Distillation provides a fraction highly enriched in dimerized fatty
acid, commonly known
as "dimer acid." Such dimer acids are suitable for use in making the polyol
esters.
[052] The distillation of polymerized TOFA provides a fraction that is highly
enriched
in monomeric fatty acids and is known as "Monomer" (with a capital "M") or
"Monomer acid."
Monomer, a unique composition, may be used as a starting material for making
polyol esters
useful herein. Whereas natural source-derived TOFA largely consists of linear
C18 unsaturated
carboxylic acids, principally oleic and linoleic acids, Monomer contains
relatively small amounts
of oleic and linoleic acids, and instead contains significant amounts of
branched and cyclic C18
acids, saturated and unsaturated, as well as elaidic acid. The more diverse
and significantly
branched composition of Monomer results from the catalytic processing carried
out on TOFA
during polymerization. It is recognized that the reaction of Monomer with
alcohols to make
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"Monomerate" esters, yielding derivatives that differ from the corresponding
TOFA-based
esters. Monomer has been assigned CAS Registry Number 68955-98-6. Examples
include
CenturyTM M05 and M06 fatty acids from Arizona Chemical Company. U.S. Pat. No.
7,256,162, discloses Monomer composition and its conversion to various esters.
[053] Suitable polyol esters include, for example, ethylene glycol tallate
(e.g., the
ethylene glycol ester of tall oil fatty acid), propylene glycol tallate,
trimethylolpropane tallate,
neopentyl glycol tallate, methyl tallate, ethyl tallate, glycerol tallate,
()ley' tallate, octyl tallate,
benzyl tallate, 2-ethylhcxyl tallate, polyethylene glycol tallates, tall oil
pitch esters, ethylene
glycol Monomerate, glycerol Monomerate, trimethylolpropane Monomerate,
neopentyl glycol
Monomerate, 2-ethylhexyl Monomerate, ethylene glycol dimerate, 2-ethylhexyl
dimerate, 2-
ethylhexyl trimerate, and the like. In another embodiment, polyol esters may
include tallates
and Monomerates, especially trimethylolpropane tallate, ethylene glycol
Monomerate,
neopentyl glycol Monomerate, 2-ethylhexyl Monomerate, and glycerol Monomerate.
Suitable polyol esters are commercially available from Arizona Chemical.
[054] In one embodiment, the polyol ester is a reaction product of a thermally
stable
polyol and at least one molar equivalent of a C8-C24 fatty acid. In one
embodiment, the
thermally stable polyol is selected from triethylolpropane,
trimethylolpropane, neopentyl
glycol, pentaerythritol, and mixtures thereof. In yet another embodiment, the
polyol ester is
made from trimethylolpropane and a tall oil fatty acid.
[055] C8-C24 Free fatty acid component. In some embodiments, the C8-C24 free
fatty acid component is a major constituent. comprising 50-98 wt.%, 50-96
wt.%, 50-94 wt.%,
50-92 wt.%, 50-90 wt.%, 50-85 wt.%, 50-80 wt.%, or 60-80 wt.%, based upon the
weight of
the rheology modifier.
[056] Suitable C8-C24 fatty acids are well known and commercially available.
Suitable fatty acids can be saturated or unsaturated, and they can have linear
or branched
chains. In some aspects, the fatty acid is a C8-C20 fatty acid, a C10-C18
fatty acid, or a C14-
C18 fatty acid. Suitable fatty acids include, for example, caprylic acid,
capric acid, lauric
acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic
acid, myristoleic acid,
palmitoleic acid, oleic acid, elaidic acid, linoleic acid, conjugated linoleic
acid, linolenic acid,
erucic acid, and the like, and mixtures thereof. In another embodiment of the
present
disclosure, unsaturated fatty acids
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and their mixtures make up the majority of the free fatty acid component
(e.g., 50 wt.%, 60
wt.%, 70 wt.%, 80 wt.%, 90 wt.%, 95 wt.% or more, based upon the weight of the
free fatty acid
component), with the remainder being saturated fatty acids, optionally rosin
acids, and
unsaponifiables. For vegetable based free fatty acids, the saturated fatty
acid content is higher
than for tall oil than for pine derived fatty acids. For example, the
saturated fatty acid content of
tall oil fatty acid may be 10 wt.% or less (or 5 wt.% or less, or from 2 to 10
wt.%) based upon the
weight of the free fatty acid, and the saturated fatty acid content of
vegetable based fatty acids
may be 50 wt.% or less (or 40 wt.% or less, or 30 wt.% or less, or from 5 to
30 wt.%). The
unsaponifiables of the free fatty acid may be up to 5 wt.% (or up to 3 wt.%,
or from 0.1 to 5
wt.%), and for pine derived fatty acid, rosin acids may be 10 wt.% or less (or
5 wt.% or less, or 3
wt.% or less, or from 1 to 5 wt.%) based upon the total weight of the free
fatty acid.
[057] Fatty acid mixtures obtained from natural sources such as animal or
vegetable
oils, especially vegetable oils, are suitable for use. The fatty acid mixtures
are obtained by
hydrolysis of natural oils or by transesterification of the oils with a lower
alcohol (e.g., methanol,
ethanol), followed by saponification of the resulting lower alkyl esters. In
another embodiment,
the fatty acid is tall oil fatty acid (TOFA) or a mixture of compounds
obtained from tall oil
(derived from pine) that includes TOFA, e.g.. a mixture of TOFA and tall oil
fatty acid "heads."
Tall oil fatty acid has a high content of oleic acid and linoleic acid in
addition to lesser amounts
of saturated fatty acids (e.g., palmitic acid and stearic acid) and other
unsaturated fatty acids
.. (e.g., palmitoleic acid, conjugated linoleic acid, and linolenic acid).
Tall oil fatty acid is
commercially available from Arizona Chemical.
[058] The C8-C24 free fatty acid component has an acid value of at least 190
mg
KOH/g as measured by well-known titration methods. When the free fatty acid
component
includes fatty acids having 20 to 24 carbons, it will normally also have lower
fatty acids present
such that the acid value of the mixture will be at least 180 mg KOH/g or at
least 190 mg KOH/g,
or within the range of 180 to 300 mg KOH/g or 190 to 250 mg KOH/g.
[059] In one embodiment, the rheology modifier (e.g., the combination of the
polyol
ester and the C8-C24 free fatty acid component) has an acid value of 190 mg
KOH/g or less, 100
to 190 mg KOH/g, 110 to 180 mg KOH/g, 120 to 170 mg KOH/g, 130 to 160 mg KOH/g
or 130
to 145 mg KOH/g.
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[060] In some aspects, the rheology modifier has an iodine value within the
range of 80
to 200 mg I2/g, or 110 to 160 mg I2/g.
[061] Suitable blends of the polyol ester and the C8-C24 free fatty acid
component can
be prepared conveniently by reacting an excess of a C8-C24 fatty acid with a
polyol such that 50
to 90 wt.% of the resulting product is unreacted C8-C24 fatty acid. For
example, reaction of an
excess of TOFA with trimethylolpropane provides a mixture of polyol ester from
trimethylolpropane and unreacted TOFA, a blend that is well-suited for use as
a rheology
modifier when the unreacted TOFA is 50 to 90 wt.% of the resulting blend. It
is, of course, also
possible to prepare the rheology modifier blends by simply combining the
polyol ester with the
required amount of C8-C24 fatty acid.
[062] Applications. In one embodiment, the rheology modifier is for use in
asphalt
compositions comprising aggregate and a binder composition for any of new
construction, partial
or complete re-construction applications. The rheology modifier can be used
for any of paved
surfaces, road surfaces and sub-surfaces, runways, shoulders, bridges, bridge
abutments, gravel
substitutes for unpaved roads, and the like. In addition, the rheology
modifier can be used in a
variety of industrial applications, not limited to coatings, drilling
applications, and lubricants.
[063] In one embodiment, the asphalt compositions comprise any of virgin
asphalt,
reclaimed asphalt, or mixtures thereof. In yet another embodiment, the
rheology modifier is for
use in asphalt compositions comprising an asphalt emulsion for use in any of
rehabilitation,
preservation, or CIR applications.
[064] In one embodiment, the rheology modifier is for use in any of a warm-mix
composition, a hot-mix asphalt composition, e.g., mixed at a temperature
around 300 F ¨ 350 F,
which then can be applied to roadways using specialized machines, compacted,
and the asphalt
hardens as it cools. In another embodiment, the rheology modifier is used in a
cold-mix asphalt
formulation with aggregate, an emulsion and water.
[065] Rejunevation of Aged Binder / RA - Binder Compositions In one aspect,
the
rheology modifier is used in a modified binder composition with reclaimed
asphalt suitable for
use with asphalt, optionally with virgin binder and aggregate. The binder
composition comprises
a combination of a bituminous binder and the rheology modifier comprising a
blend of a polyol
ester and a C8-C24 fatty acid.
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[066] Suitable bituminous binders can come from a variety of sources,
including
reclaimed binders, optional virgin or performance-grade binders, or
combinations thereof. In
some aspects, the reclaimed binder is from any of reclaimed asphalt pavement
("RAP binder"),
reclaimed asphalt shingles ("RAS binder"), or combinations thereof The
bituminous binder can
include RAS binder, which is present in or recovered from RAS. Binders
reclaimed from
production waste during shingle manufacture can also be included. The
bituminous binder can
include RAP binder, which is present in or recovered from RAP. The bituminous
binder can also
include virgin binder or performance-grade binders in addition to any
reclaimed binder.
[067] The amount of bituminous binder in a reclaimed asphalt composition (RAS
or
RAP) is generally known from the supplier, but it may also be determined by
known methods,
e.g., solvent extraction. For instance, a known amount of RAS or RAP may be
treated with a
suitable solvent, e.g. dichloromethane, to extract the binder. The amount of
binder in the
extracted fraction can be measured, thereby providing the content of binder in
the RAS or RAP.
The amount of aged binder in the RAS or RAP depends on the source, age,
history, location, any
pre-treatment, and other factors. The amount of aged binder in RAS or RAP
typically ranges
from any of 1 to 35 wt. %, from 2.5 to 8.5 wt.%, and 4 to 20 wt.% based on the
total amount of
RAS or RAP. In one embodiment of RAP, the amount of aged binder can be up to
10 wt. %. In
one embodiment of a RAS, the amount of aged binder is typically in the range
of 20-25 wt. %.
[068] In some embodiments, the aged binder is isolated from the reclaimed
asphalt by
known methods. In other embodiments, the RAS or RAP is combined with a
desirable amount
of rheology modifier. In yet other embodiments, the rheology modifier is
combined and mixed
with the bituminous binder, and optionally virgin asphalt and / or RAP or RAS
to give a
modified asphalt product. In yet other embodiments, a desirable amount of
rheology modifier is
combined or first blended with virgin bitumen, then subsequently mixed with
RAP and / or RAS.
[069] The modified binder compositions comprise any of 0.05 to 20 wt.%, 0.5 to
15
wt.% or 1 to 10 wt.%, of the rheology modifier based on the combined amounts
of binder and
rheology modifier. The effective amount of rheology modifier needed to
rejuvenate the binder in
the RAS / RAP varies and depends on the source of the binder, age, its
history, and other factors.
[070] In some aspects, the binder composition comprises 50 to 70 wt.% of a
performance-grade or virgin binder. In some aspects, the binder composition
comprises any of
0.5 to 30 wt.%, 2 to 25 wt.%, or 4 to 15 wt.%, of the virgin binder. In other
aspects, the
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bituminous binder comprises a RAS binder, a RAP binder, or a mixture thereof
(100% recycled
asphalt and no virgin binder). In some further aspects, the binder comprises a
RAS binder.
[071] Evidence of the value of using the !theology modifier in modified binder
compositions can be demonstrated with dynamic shear rheometry (DSR) data.
Rheology, the
study of the deformation and flow of matter, provides a fingerprint of the
viscoelastic behavior of
a bitumen, whether virgin, aged, conditioned, or treated. This measured
behavior is correlated to
performance of the bitumen within the aggregate asphalt, and subsequently to
the performance of
the road. The tests performed function based on the principles of linear
viscoelasticity and the
superposition principle, where strain on a material is proportional to the
stress received. A stress
is applied to the sample and the response and delay of that response (phase
angle) are analyzed
and used to calculate moduli that represent different properties of the
sample.
[072] It is found that by combining bituminous binders with a rheology
modifier
comprising a blend of a polyol ester and a C8-C24 fatty acid, the high-
temperature properties of
the binders can be improved with minimal impact on low-temperature
performance. In one
example, by combining 10 wt. % of a 75:25 (w/w) blend of a tall oil fatty acid
and a polyol ester
made from trimethylolpropane and tall oil fatty acid with reclaimed RAS
binder, a desirable
impact on reducing the temperature at which the rheological high-temperature
criteria is satisfied
when compared with the results from either rheology modifier alone (see Table
1 results, below).
[073] In examples with RAS binder as shown in Tables 2 and 3, the intermediate-
temperature performance of the RAS binder can be altered from unacceptably
high to desirably
low by including, e.g., 10 wt.% of the rheology modifier blend. Moreover, the
rheological
intermediate-temperature criteria is satisfied with a 6 C improvement over the
results with 10
wt.% of either rheology modifier component used alone, demonstrating synergy
from the
modifier blend.
[074] Modified bituminous binder can also be used to improve the high-
temperature
performance of certain grades of asphalt binders without sacrificing low-
temperature
performance. As shown in Table 4, a performance-grade binder can be modified
by including up
to 20 wt. % RAP binder. In one example, an additional 20 wt.% of RAS binder
can be included
if a small proportion of the above-described rheology modifier blend
(combination of 75% tall
oil fatty acid and 25% TMP tallate) is also included. Divergence of G* values
in the range of
C to 70 C (Table 4) indicates an advantage in high-temperature performance
from the RAS-
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containing blend (note the 6 C increase in temperature at G* = 1.0 x 103 Pa).
Superimposable
values of G* at the low temperature end indicate that low-temperature
performance will likely be
retained despite the addition of 20 wt.% RAS binder to the blend. The
improvement at the high-
temperature end (Table 5) and the similar rheological profile at lower
temperatures (Table 4)
.. suggest an improvement in rutting resistance from the blend containing RAS
and rheology
modifier without a trade-off in fatigue or low-temperature performance.
[075] Methods for Forming Binder Compositions and Application: In some
embodiments, binder and asphalt compositions can be made by combining
components in any
desired order. In one convenient approach, an asphalt composition is made by
combining
rheology modifier with virgin binder, then blending the resulting mixture with
reclaimed asphalt,
e.g., RAS and/or RAP. In another approach, an asphalt composition is made by
combining
rheology modifier with RAS and/or RAP, optionally with virgin asphalt.
[076] In one aspect, the asphalt composition comprises aggregate, RAS and/or
RAP,
and the rheology modifier blend described above, wherein the asphalt
composition further
comprises virgin asphalt. The virgin asphalt comprises virgin binder and
virgin aggregate. The
asphalt composition comprises 1 to 99 wt. % of virgin aggregate based on the
combined
amounts of virgin asphalt, RAS, RAP, and rheology modifier blend.
[077] In another aspect, the asphalt composition comprises aggregate, RAS and
/ or
RAP, and the rheology modifier. Together, the RAS / RAP binder and the
rheology modifier
.. blend form a modified binder having a PG grade at least one grade lower
than that of the RAS
binder without the rheology modifier. For example, a shift in the PG grade
from PG 76-22 to PG
70-22 or from PG 64-22 to PG 58-22 represents a one-grade reduction.
[078] Polymer Compatiblization in Asphalt Compositions. Asphalt is often
modified
with elastomeric and plastomeric polymers such as Styrene-Butadiene Styrene
(SBS) as well as
ground tire rubber to increase high temperature modulus and elasticity, to
increase resistance to
heavy traffic loading and toughening the asphalt matrix against damage
accumulation through
repetitive loading. Such polymers are usually used at 3 to 7 wt% dosages in
the asphalt and can
be as high as 20% for ground tire rubber. The polymer is high shear blended
into asphalt at high
temperatures, e.g., > 180 C and allowed to "cure" at similar temperatures
during which the
polymer swells by adsorption in the asphalt until a continuous phase is
achieved. The volume
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phase of the fully cured polymer will be affected by degree of compatibility
of the polymer in
the asphalt and the fineness of the dispersed particles.
[079] In one embodiment, the rheology modifier is used to compatibilize
polymers and /
or ground tire rubber in the asphalt. In one embodiment, the rheology modifier
is added and
blended into the asphalt before the incorporation of the polymer, or the
curing stage.
[080] In one embodiment, the rheology modifier is added to a rubberized
asphalt
composition in any of a dry process or a wet process. In the dry process, the
crumb rubber is
combined with a heated aggregate, followed by the addition of the asphalt
binder and the
rheology modifier. In the wet process, the rheology modifier is mixed with
bitumen and rubber
particles, or blended separately with bitumen first then mixed together with
rubber particles.
The rubberized bitumen is then mixed with asphalt. The amount of rubber in the
rubberized
bitumen (or rubberized asphalt dispersion) is typically in the range of 1 to
25 wt.%. The
amount of rheology modifier is typically in the range of 1-10 wt. %. In one
embodiment, the
rubberized bitumen asphalt dispersion further contains 1 to 10 wt. % of a
polyamide stabilizer
having an amine number within the range of 50-500 mg KOH/g.
[081] Asphalt Emulsions: The rheology modifier can also be used in asphalt
emulsions for applications including pavement preservation, rehabilitation,
and CIR
applications. Examples of applications or treatments using asphalt emulsions
may include
rejuvenating, scrub seal, fog seal, sand seal, chip seal, tack coat, bond
coat, crack filler or as a
material for prevention of reflective cracking of pavements.
[082] Asphalt emulsions comprise globules of paving asphalt, water, an
emulsifying
agent or surfactant, and the rheology modifier. The emulsifying agent keeps
the paving
asphalt globules in suspension until it is applied to the pavement surface
when the water in the
asphalt emulsion starts to evaporate, In one embodiment, the emulsifying agent
provides a
cationic, anionic, non-ionic, or neutral character to the final emulsion
depending upon the
desired emulsion's electrochemical properties or the intended emulsion use,
for example, the
surface type on which the asphalt emulsion is to be applied. The rheology
modifier functions
to slightly soften the pavement to create a better bond when applied to an
existing pavement.
Asphalt emulsions can optionally include a latex dispersion, e.g., a SBR latex
dispersion as
disclosed in US Patent No. 7,357,594.
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[083] In one embodiment, the rheology modifier is used in a polymer-modified
asphalt
rejuvenating emulsion, which comprises an asphalt phase with an asphalt and
the rheology
modifier, and an aqueous phase comprising water, a polymer or copolymer (e.g.,
acrylics such
as polychloroprene, copolymers such as styrene-butyl acrylate copolymer) and
an emulsifying
agent. Examples of polymers or copolymers that can be used in the asphalt
emulsion are
disclosed in US Patent No. 8821064. The surfactant comprises from about 0.01%
to about
3.0% of the total weight of the emulsion. The polymer or copolymer is about 1%
to about
15% of the total weight of the emulsion. The asphalt phase comprises from
about 30% to about
70% of the total weight of the emulsion. The rheology modifier comprises about
0.1% to
about 15% of the total weight of the emulsion. The ratio of the rheology
modifier to the
polymer or copolymer may for example be from 1:10 to 5:1, from 1:3 to 3:1,
from 1:2 to 2:1, or
about 1:1. In one embodiment, the surfactant comprises about 5-30 wt. % of the
rheology
modifier.
[084] Depending on the type of emulsifying agent used, e.g., cationic.
anionic,
.. amphoteric and non ionic, an acid or a base may be needed to activate the
emulsifying agent. In
one embodiment with cationic emulsifying agents, acid may be added to adjust
the emulsion
pH to between 1.0 and 7Ø Suitable acids include inorganic acids, for example
hydrochloric
acid and phosphoric acid. In some embodiments with anionic emulsifying agents,
base may be
added to adjust the emulsion pH to between 7.0 and 12Ø In some embodiments
with
amphoteric emulsifying agents, both the cationic and anionic chemical
functionality are built
into the same molecule. Therefore, either functionality may be activated; the
cationic portion
may be activated by acid or the anionic portion may be activated by base. A
sufficient amount
of emulsifying agent is used maintain a stable emulsion, e.g., from 0.01 to
about 5% by weight
of the emulsion, from 0.1 A to about 3.0% by weight of the emulsion. Examples
of
emulsifying agents are disclosed in US Patent Publication No. 2014/0230693.
[085] Exemplary cationic emulsifying agents include polyamines, fatty amines,
fatty
amido-amines, ethoxylated amines, diamines, imidazolines, quaternary ammonium
salts, and
mixtures thereof Exemplary anionic emulsifying agents include alkali metal or
ammonium
salts of fatty acids, alkali metal polyalkoxycarboxylates, alkali metal N-
acylsarcosinates, alkali
metal hydrocarbylsulphonates, for example, sodium alkylsulphonates, sodium
arylsulphonates,
sodium
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alkylarylsulphonates, sodium alkylarenesulphonates, sodium lignosulphonates,
sodium
dialkylsulphosuccinates and sodium alkyl sulphates, long chain carboxylic and
sulphonic acids,
their salts and mixtures thereof Exemplary amphoteric emulsifying agents
include betaines and
amphoteric imidazolinium derivatives. Exemplary non-ionic emulsifying agents
include
ethoxylated compounds and esters, for example ethoxylated fatty alcohols,
ethoxylated fatty
acids, sorbitan esters, ethoxylated sorbitan esters, ethoxylated alkylphenols,
ethoxylated fatty
amides, glycerine fatty acid esters, alcohols, alkyl phenols, and mixtures
thereof. In one
embodiment, the emulsifying agent is an alkoxylated fatty amine surfactant.
[086] Method for Forming & Applications of Asphalt Emulsions: In one
embodiment
for making an asphalt emulsion (aqueous dispersion), a binder composition is
first heated so that
it melts, the rheology modifier is added, then an emulsifying solution
comprising water and
emulsifying agent is added to the molten binder composition. The emulsifying
solution and the
molten binder are mixed under high shear (e.g. in a colloid mill) to form an
emulsion.
[087] The final asphalt emulsion may be applied by hand spreading,
conventional
spreading, spraying, or other techniques, then letting the emulsion dry. A
recommended
application rate may be, for example, about 0.045 to about 2.7 liters/sq.
meter (about 0.01 to
about 0.60 gal/sq. yd.) or about 0.14 to about 2.0 liters/sq. meter (about
0.03 to about 0.45 gal/sq.
yd.). In one embodiment, the complex modulus of the dried composition is 2.3
kPa at 50 C.
after 3 days curing.
[088] EXAMPLES: The following examples merely illustrate the disclosure. The
skilled person will recognize many variations that are within the spirit of
the disclosure and
scope of the claims.
[089] Isolation of RAS Binder from Reclaimed Asphalt Shingles. Extraction of
the
RAS binder was performed per ASTM D2172, Standard Test Methods for
Quantitative
Extraction of Bitumen from Bituminous Paving Mixtures. The binder was
recovered from the
extracted residue as per ASTM D7906.
[090] Preparation of Polyol Tallate. A one liter four-necked reaction flask
equipped
with a thermocouple/nitrogen blanket combination, an overhead stirrer, a
sampling port, and a
takeoff to collet water of reaction was charged with 500.0g of TOFA, 85.5g of
polyol, and 0.27g
of esterification catalyst. Nitrogen blanketing was set to 0.1L/min and
agitation was set to 275
RPM. The temperature was set to 180 C and was achieved after approximately 50
minutes. The
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temperature was then set to increase to 250 C at a rate of 35 C/hour. The
reaction was
maintained at 250 C and sampled until the acid value specification of 15 mg
KOH/g maximum
was met and then cooled immediately.
[091] Blends of RAS Binder with Rheology Modifiers. Blends of RAS binder with
theology modifiers were done by placing 2.0g of RAS binder and a sufficient
amount of
rheology modifier in a 2oz. glass jar. Percent rheology modifier is determined
by percent mass
of binder (ex. 0.20g rheology modifier into 2.0g of binder equals 10% rheology
modifier). The
jar was then placed in an oven at 177 C along with a metal spatula to pre-heat
for approximately
20 minutes. The binder was stirred with the preheated spatula for 30 seconds
and returned to the
oven for another 20 minutes. The binder was stirred again for 30 seconds and
then poured out to
be tested via Dynamic Shear Rheometry ("DSR").
[092] Evaluation of Intermediate and High-Temperature Performance of RAS
Binders +
Rheology Modifiers by DSR. Samples of RAS binder containing 10 wt.% of
rheology modifiers
prepared as described above are evaluated for intermediate and high-
temperature properties
using DSR.
[093] Dynamic shear moduli are measured using 8-mm diameter parallel plate
geometries with a TA Instruments AR-G2 rotational dynamic shear rheometer.
Temperature
sweeps are performed at 2 C intervals over a temperature range of -15oC to 200
C at a rate of
6 C/minute and an angular frequency of 10 rad/sec. Initially the temperature
sweep maintains a
constant torque of 5000 1ANm up until the point at which the percent strain of
the sample reaches
15%, at which time the percent strain is then held constant at 15%.
[094] High- and intermediate-temperature performance parameters, e.g., G*/sin
6 and
G* sin 8, are calculated from the measured G*, the complex modulus, and 6,
delta degrees. The
control sample is an extracted RAS binder without added rheology modifier.
[095] Dynamic shear moduli are measured using 8-mm diameter parallel plate
geometry
with a Malvern Kinexus rotational dynamic shear rheometer. Temperature sweeps
are
performed at 2 C intervals over a temperature range of -15oC to 200 C and an
angular frequency
of 10 rad/sec.
[096] Intermediate-temperature properties. Fatigue cracking resistance of an
RTFO/PAV (rolling thin film oven/pressure aging vessel) aged asphalt binder
can be evaluated
using G* sin 6 (a fatigue factor). G* represents the binder complex shear
modulus and 6
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represents the phase angle. G* approximates stiffness and 6 approximates the
viscoelastic
response of the binder. Binder purchase specifications typically require the
factor to be less than
5000 kPa. The factor is considered a measure of energy dissipation which is
related to fatigue
damage. The critical temperature range for fatigue damage is near the midpoint
between the
highest and lowest service temperatures, calculated by the formula,
High PG +Low PG)
Intermediate Temp.= ( + 4
[097] High-temperature properties. High-temperature mechanical properties are
evaluated by the parameter G*/ sin 6. The factor is an indication of a
binder's resistance to
rutting. Binder purchase specifications typically require the factor to be
greater than 2.2 kPa for
RTFO aged asphalt and greater than 1 kPa before RTFO aging. In all of the
tested samples,
G*/sin 6 decreases significantly with addition of the rheology modifier.
[098] Dynamic shear rheometry (DSR) can be used to evaluate asphalt products
to
assess their likely performance at low, ambient, and elevated temperatures. At
low temperatures
(e.g., -10oC), road surfaces need cracking resistance. Under ambient
conditions, stiffness and
fatigue properties are important. At elevated temperature, roads need to
resist rutting when the
asphalt becomes too soft. Criteria have been established by the asphalt
industry to identify
rheological properties of a binder that correlate with likely paved road
surface performance over
the three common sets of temperature conditions. Thus, for low temperatures,
the complex
modulus (G*) of the modified binder measured at -10 C can be less than or
equal to the value for
virgin binder. For 30/50 grade virgin binder, G* at -10 C is ideally at or
below 2.8 x 108 Pa. At
ambient temperatures, the complex modulus of the modified binder can be less
than or equal to
the value for virgin binder. For 30/50 grade virgin binder, G* at 20 C is
ideally at or below 6.0 x
106 Pa.
[099] Fatigue criteria also relates to ambient temperature performance. The
product of
the complex modulus (G*) and the sine of the phase angle (6) measured at 10
rad/s is
determined. The temperature at which the value of G*sin 6 at 10 rad/s equals
5.0 x 106 Pa can
be less than or equal to 20 C for modified binders comparable to 35/50 grade
virgin binder.
[0100] At high temperatures, the quotient G*/sin 6 is of interest. The
temperature at
which the value of G*/sin 6 at 10 rad/s equals 1000 Pa can be reduced for
modified binders
compared with that of aged binder.
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Table 1. Summary of Dynamic Shear Rheomctry Results:
High-Temperature Performance'
Value of G*/sin 8 (kPa) at temperatures 60-180 C
Temperature at which
G*/sin 8 at 10 rad/s =
60 C 100 C 140 C 180 C 1.0 kPa ( C)
RAS* 9.35 x 103 2.52 x 102 1.62 x 101 5.85 x 10-1
174
RAS + 10% polyol 1.45 x 103 7.55 x 101 5.86 x 10 3.07 x 101
165
ester*
RAS + 10% 9.03 x 102 3.94 x 101 1.53 x 10 1.07 x 101
145
TOFA*
RAS + 10% blend
(75:25) of TOFA + 5.56x 102 2.84x 101 1.37x 10 1.04 x 10-1
144**
polyol ester
* Comparative examples
** Calculated value = 150 C
# Values reported on unaged samples
[0101] As shown, aged binder recovered from reclaimed asphalt shingles (RAS)
requires
heating to 174 C to achieve the targeted high-temperature criteria of G*/sin 6
at 10 rad/s = 1.0
kPa. Addition of 10 wt.% of a rheology modifier, e.g., polyol ester additive
or fatty acid, reduces
the temperature required for meeting the rheological high-temperature
criteria.
[0102] The example with 10 wt.% of a 75:25 (w/w) blend of fatty acid and
polyol ester
additive shows a greater impact on reducing the temperature at which the high-
temperature
criteria is satisfied when compared with either rheology modifier alone. Based
on gravimetric
considerations, the calculated value for meeting the criteria with the 75:25
blend is 150 C (e.g.,
0.75(145 C) + 0.25(165 C) = 150 C). However, the blend actually meets the high-
temperature
criteria at 144 C, or 6 C less than expected. The results indicate that using
the blend can be more
effective than using either rheology modifier alone.
[0103] Tables 2 and 3 summarize the intermediate-temperature performance
results. As
shown in Table 2, the recovered RAS binder meets the rheological requirement
(e.g., G*sin 6 at
10 rad/s = 5.0 x 106 Pa) only at 46.7 C, which is unacceptably high when the
goal is about 20 C.
Inclusion of 10 wt.% of either polyol ester additive or fatty acid gets close
to the goal, in each
case meeting the required value for G*sin 8 at 22.8 C. However, when a 75:25
blend of fatty
acid and polyol ester additive is used, the intermediate-temperature criteria
can be met at least
full six degrees lower (16.8 C), again demonstrating substantial synergy from
the blend.
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[0104] Table 3 shows the values of G* (complex viscosity, in pascals) as a
function of
temperature in the working range of 10oC to 60oC. As expected, the recovered
RAS binder has
the highest values of G* throughout the working temperature range. Inclusion
of 10% polyol
ester additive or 10% fatty acid provides a desirable reduction in G*. A
commercial product
(HydrogreenTM rejuvenator from Green Asphalt Technologies) provides a similar
reduction in
G* when used at 10 wt.%. However, a shift to even lower values of G* at any
given temperature
within the working range is achieved with the 75:25 blend of fatty acid and
polyol ester additive.
This shift is unexpected and demonstrates a desirable synergy between the
polyol ester and the
tall oil fatty acid. The results indicate that less of the blend will be
needed to push a recovered
RAS binder to useful stiffness compared with either the polyol ester or the
unsaturated fatty acid
alone.
[0105] Modified bituminous binder can be used to improve the high-temperature
performance of certain grades of asphalt binders. Table 4 compares G* values
measured from
two modified performance-grade binders. The PG 64-22 binder modified with 20
wt.% of RAP
binder is shown as it is common practice for asphalt manufacturers to utilize
up to 20% RAP
without the aid of a rejuvenator.
[0106] It was found that an additional 20 wt.% of RAS binder can be included
in this
blend if a small proportion (400 ppm) of a rheology modifier (combination of
75 wt.% fatty acid
and 25 wt.% polyol ester) is also included. As shown in Table 4, the higher
values of G* in the
range of 30oC to 70oC for the RAS containing mix indicate greater stiffness
than the 20% RAP
mix at these temperatures. However, the lower values of G* in the range of -10
C to 20 for the
RAS containing mix indicate less stiffness than the 20% RAP mix at lower
temperatures, despite
the addition of 20 wt.% RAS to the blend.
[0107] Table 5 shows that addition of RAS to the PG 64-22/RAP blend allows the
high-
temperature criteria to be met at a higher temperature (8oC increase in
temperature at G*/sin 6 =
1.0 x 103 Pa) while also allowing the intermediate-temperature criteria to be
met at a lower
temperature (2 C decrease in temperature at G*sin 6 = 5.0 x 106 Pa). The
results in Tables 4 and
5 suggest an improvement in rutting resistance from the blend containing RAS
with as good or
better fatigue and low-temperature performance.
Table 5. Summary of Dynamic Shear Rheometry Results
High-Temperature Criteria Fatigue Criteria
Temperature at which G*/sin 8 at Temperature at which G*sin at
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rad/s = 1000 Pa ( C) 10 rad/s = 5.0 x 106Pa ( C)
PG 64-22 binder + RAP binder
(80:20 w/w)* 72 19
PG 64-22 binder + RAP binder +
RAS binder (60:20:20 w/w) and
400 ppm added rheology 78 17
modifier
Observations: Can improve rutting resistance Rutting
resistance is improved
by +6 C by including RAS without sacrificing
fatigue
binder + rheology modifier. performance.
* Comparative example
[0108] The compositions and methods of the appended claims are not limited in
scope by
the specific compositions and methods described herein, which are intended as
illustrations of a
few aspects of the claims. Any compositions and methods that are functionally
equivalent are
intended to fall within the scope of the claims. Various modifications of the
compositions and
5 methods in addition to those shown and described herein are intended to
fall within the scope of
the appended claims. Further, while only certain representative compositions
and method steps
disclosed herein are specifically described, other combinations of the
compositions and method
steps also are intended to fall within the scope of the appended claims, even
if not specifically
recited. Thus, a combination of steps, elements, components, or constituents
may be explicitly
10 mentioned herein or less, however, other combinations of steps,
elements, components, and
constituents are included, even though not explicitly stated.
[0109] It may be evident to those of ordinary skill in the art upon review of
the
exemplary embodiments herein that further modifications, equivalents, and
variations are
possible. All parts and percentages in the examples, as well as in the
remainder of the
specification, are by weight unless otherwise specified. Further, any range of
numbers recited in
the specification or claims, such as that representing a particular set of
properties, units of
measure, conditions, physical states or percentages, is intended to literally
incorporate expressly
herein by reference or otherwise, any number falling within such range,
including any subset of
numbers within any range so recited. For example, whenever a numerical range
with a lower
limit, RL, and an upper limit RU, is disclosed, any number R falling within
the range is
specifically disclosed. In particular, the following numbers R within the
range are specifically
disclosed: R = RL + k(RU -RL), where k is a variable ranging from 1% to 100%
with a 1%
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increment, e.g., k is 1%, 2%, 3%, 4%, 5%. ... 50%, 51%, 52%. ... 95%, 96%,
97%, 98%,
99%, or 100%. Moreover, any numerical range represented by any two values of
R, as
calculated above is also specifically disclosed. Any modifications, in
addition to those shown
and described herein, will become apparent to those skilled in the art from
the foregoing
.. description and accompanying drawings. Such modifications are intended to
fall within the
scope of the appended claims.
[0110] The term "comprising" and variations thereof as used herein is used
synonymously with the term "including" and variations thereof and are open,
non-limiting
terms. Although the terms "comprising" and "including" have been used herein
to describe
various embodiments, the terms "consisting essentially or and "consisting of'
can be used in
place of "comprising" and "including" to provide for more specific embodiments
of the
disclosure and are also disclosed. Other than where noted, all numbers
expressing geometries,
dimensions, and so forth used in the specification and claims are to be
understood at the very
least, and not as an attempt to limit the application of the doctrine of
equivalents to the scope
of the claims, to be construed in light of the number of significant digits
and ordinary
rounding approaches.
[0111] Unless defined otherwise, all technical and scientific terms used
herein have
the same meanings as commonly understood by one of skill in the art.
CA 2953254 2018-04-05
Table 2. Summary of Dynamic Shear Rheometry Results: Intermediate-Temperature
Performance # .
Value of G*sin 8 (Pa) at temperatures 10-60 C
Temperature at which
C 20 C 30 C 40 C 50 C 60 C
G*sin 8 at 10 rack =
5.0 x 106 Pa (6C)
RAS* 2.62 x 107 1.70x 107 1.07x 107 6.50x 106
3.81x 106 2.11 x 106 46.7
_
RAS + 10% polyol
ester * 9.33 x 106 5.26 x 106 2.95 x 106 1.65 x 106
8.93 x 105 4.67 x 105 22.8
RAS + 10% 9.63 x 106 5.27 x 106 2.85 x 106 1.49 x 106
7.50 x 105 3.57 x 105 22.8
TOFA*
RAS + 10% blend
(75:25) of TOFA + 7.08 x 106 3.77 x 106 2.02 x 106 1.05
x 106 5.21 x 10' 2.38 x 105 16.8 (-)
polyol ester
o
n)
l0
* Comparative examples
in
f Values reported on unaged samples
n)
ui
.r,
n)
Table 3. Summary of Dynamic Shear Rheometry Results: Intermediate-Temperature
Performance+ o
1-,
c),
I
Value of G* (Pa) as a function of Temperature (10-60 C)
n)
LoI
0
10 C , 20 C 30 C 40 C 50
C 60 C
RAS* 9.38x 107 . 5.41 x 107 3.06x 107 1.67x 107
8.79x 106- 4.44x 106
RAS + 10% polyol ester* 2.51 x 107 . 1.31 x 107 6.89 x 106
3.50 x 106 1.74 x 106 -- 8.22 x 105
RAS + 10% TOFA* 2.43 x 10 . 1.22 x 107 6.00 x 106
2.88 x 106 1.32 x 106 -- 5.68 x 105
RAS + 10% Hydrogreen* 2.84x 107 _ 1.34 x 107 6.34x 106
2.94x 106 1.31 x 106 5.36x 105
RAS + 10% blend (75:25) of 1.79 x 107 8.63 x. 106 4.20 x 106
1.99 x 106 8.93 x 105 3.64 x 105
TOFA + polyol ester
* Comparative examples
# Values reported on unaged samples
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Table 4. Summary of Dynamic Shear Rheometry Results: Intermediate Temperature
Performance of PG 64-22
Blends with 20% RAP vs. blends with 20% RAP + 20% RAS + rheology modifier +
Value of G* (Pa) as a function of Temperature (-10 C to 70 C)
-10 C 0 C 10 C 20 C 30 C 40 C 50 C
60 C 70 C
PG 64-22 binder + RAP
binder (80:20 w/w)* 2.0x 108 8.0 x 107 2.8x 107 5.5x 106
6.0x 105 1.0x 105 2.0 x 104 5.0x 103 1.6 x 103
PG 64-22 binder + RAP
binder + RAS binder
(60:20:20 w/w) and 400 1.8 x 108 7.0 x 107 2.0 x 107 3.5 x 106
7.0 x 105 1.5 x 105 3.3 x 104 7.0 x 103 2.5 x 103
ppm added rheology
modifier
to
RAS = reclaimed asphalt shingle binder; rheology modifier = 75/25 (w/w) TOFA
to polyol ester.
* Comparative example
01
Values reported on imaged samples
LoI
0
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