Method for pre-treating reclaimed asphalt pavement

Abstract

The present application relates to a method to pretreat reclaimed asphalt pavement (RAP) with rejuvenator. As a result of this pretreatment, the quality of RAP binder can be improved to better meet the performance needs of new mix in which it may be included.

Description

Attorney Docket No.43172-0005WO1 METHOD FOR PRE-TREATING RECLAIMED ASPHALT PAVEMENT

[0001] Disclosed herein is a method to pretreat reclaimed asphalt pavement (RAP) withrejuvenator. As a result of this pretreatment, the quality of RAP binder can be improved to better meet the performance needs of new mix in which it may be included.

[0002] Reclaimed Asphalt Pavement (RAP) is the term given to removed and / or reprocessedpavement materials containing asphalt and aggregates. These materials are generated when asphalt pavements are removed, usually by milling the road surface, for reconstruction or resurfacing due to aging or other reason such as to obtain access to buried utilities. Pavement milling, also called asphalt milling, cold milling, or cold planning is a process of removing partof the paved surface, covering roads, driveways, bridges, or parking lots. Milling is carried outby milling machines or cold planers and removes anywhere from a small thickness sufficient tolevel out or smooth a pavement surface to a complete removal of the pavement. The machines use a rotating drum to grind the road surface and remove it. The milled material is deposited on aconveyor which delivers the milled asphalt into the bed of a truck. When properly crushed andscreened, RAP consists of high-quality, well-graded aggregates coated by asphalt cement. One reason for milling a pavement surface is recycling. The asphalt removed by the milling process may be recycled as aggregate for use in new pavement material. The asphalt that has been removed from the pavement is crushed and combined with new asphalt. Using recycled asphalt instead of entirely new asphalt for pavement reduces adverse environmental effects, waste, and the cost of new pavement.

[0003] The majority of the RAP that is collected from aging roadways is recycled and used,although not always in the same year that it is produced. The collected material is usually transported to an asphalt plant where it is stored until needed. Recycled RAP is almost always returned into the roadway structure in some form, usually incorporated into asphalt paving by means of hot or cold recycling. Before being introduced back into a “new” asphalt mix, RAP should undergo a process of rejuvenation in order to become homogeneous with the new asphalt. The rheology of the aged RAP should be brought back to a suitable level in order to form a homogeneous “new” batch of asphalt for paving. In many instances, the RAP is mixed with a rejuvenator compound and the admixture applied to the milled road surface. The treatment toAttorney Docket No.43172-0005WO1 rejuvenate RAP is carried out at the mixing facility to which it has been transported from the location where it was collected.

[0004] It has now been found that the RAP can be rejuvenated by applying the rejuvenatingagent or composition to the road surface at the location of the road being milled before the RAP is transported back to the location of the mixing plant for stockpiling. Provided herein is a method of treating deteriorated asphalt pavement which comprises treating a pavement in need of rejuvenation with a rejuvenating composition, thereafter milling the treated pavement to create reclaimed asphalt pavement and collecting the reclaimed asphalt pavement. In some embodiments, the treating step comprises spraying the rejuvenating composition onto the pavement surface. In one preferred embodiment, a rejuvenation composition is applied by spraying with a mobile application vehicle shortly before the roadway is milled with a milling machine. The timing between rejuvenator product application and milling can vary as a function of curing need, traffic control, mobilization(s), etc. but is usually about at least 15 minutes. Some embodiments comprise waiting at least one hour after milling the pavement before collecting the reclaimed asphalt pavement.

[0005] In an alternative embodiment, the RAP can be treated with a rejuvenation compositioninside the milling machine via injection system. In this embodiment, a rejuvenator solution storage tank must be integral or adjacent to the milling machine. A further embodiment for application of the rejuvenation composition is via spray nozzle(s) mounted somewhere along the discharge path as RAP makes its way from the milling machine into the bed of the truck that will haul the RAP back to the mixing facility. Some possible locations for the spray nozzle(s) are at the location where RAP is transferred to a conveyor belt, as it makes its way up a conveyor belt, as it is discharged off the conveyor belt, or as it enters the truck bed. In this embodiment, a rejuvenation agent storage tank must be integral with or adjacent to either the milling machine or the haul truck(s). In some embodiments, the treating step is carried out after the reclaimed asphalt has been milled and collected in a truck.

[0006] Some embodiments comprise storing the treated asphalt for future use. The rejuvenatedRAP can be stored for use later on in making asphalt compositions using Balanced Mix Design (BMD). This is defined as an asphalt mix design created using performance tests onAttorney Docket No.43172-0005WO1 appropriately conditioned specimens that address multiple modes of distress taking into consideration mix aging, traffic, climate and location within the pavement structure” per AASHTO PP 105-20. This definition was initially established by the former Federal Highway Administration (FHWA) Expert Task Group (ETG) Balanced Mix Design Task Force in 2015. In some embodiments, the reclaimed asphalt pavement is mixed with fresh asphalt. Some embodiments comprise combining the treated reclaimed asphalt with fresh asphalt to create a fresh paving material. In one embodiment of the method disclosed herein, a new pavement product is made from 70% fresh asphalt and 30% rejuvenated RAP.

[0007] Rejuvenating agents are products designed to restore original properties to aged(oxidized) asphalt binders by restoring the original ratio of asphaltenes to maltenes. Maltenes are the n-alkane (pentane or heptane)-soluble molecular components of asphalt, which is the residue remaining after petroleum refiners remove other useful derivatives such as gasoline and kerosene from crude oil. Asphaltene compounds are the other primary component of asphalt. As asphalt ages the balance between these two components in the binder needed to maintain the viscoelastic properties of the binder (and the pavement) is disturbed resulting in a brittle binder, leading to raveling (deterioration of the pavement by loss of asphalt and rocks), cracking and ultimately replacement.

[0008] Asphalt rejuvenation is the process of restoring chemical properties that have beendeteriorating since the moment new asphalt was laid down, either topically or in RAP. The rejuvenating compositions described herein penetrate into the surface pores of asphalt pavement and protect the underlying asphalt structure from further deterioration. The compositions also restore the viscosity profile and skid resistance of the pavement, act to seal small surface cracks and coat aggregate particles beneath the wearing surface.

[0009] Historically, asphalt rejuvenators are made from coal tar blended with aromatic oils andsolvents. Given the importance of environmental considerations, it is desirable to avoid use of restoration agents containing volatile organic compounds. A quick drying rejuvenating agent that can be applied by spraying onto the pavement surface is desirable.Attorney Docket No.43172-0005WO1

[0010] The rejuvenating compositions described herein penetrate into the surface pores ofasphalt pavement, restore the viscosity profile and of the pavement, and coat aggregate particles beneath the wearing surface.

[0011] In one preferred embodiment, the rejuvenating composition contains a rejuvenatingagent, a self-cross-linking polymer, water, and a surfactant.

[0012] In some embodiments, the rejuvenating agent is a tall oil-derived fatty ester; the self--cross-linking polymer is in an acrylic polymer emulsion comprising the self-cross-linking polymer, an emulsion surfactant, and water, wherein the self-cross-linking polymer comprises a combination of methylmethacrylate monomer and butyl acrylate monomer; the first surfactant is a non-ionic nonylphenol ethoxylate; the second surfactant is a tetramethyldecynediol in ethylene glycol; the de-foaming agent is a mixture of hydrophobic solids and foam destroying polysiloxanes in polyglycol.

[0013] In some embodiments, the rejuvenating agent is a tall oil-derived fatty ester. In someembodiments, the rejuvenating agent is a tall oil-derived fatty ester, wherein the tall oil-derived fatty ester has a cyclic content of at least 5 wt.%; the self-cross-linking polymer is in an acrylic polymer emulsion comprising the self-cross-linking polymer, an emulsion surfactant and water. In some embodiments, the rejuvenating agent is a tall oil-derived fatty ester, wherein the tall oil- derived fatty ester has a cyclic content of at least 5 wt.%; the self-cross-linking polymer is in an acrylic polymer emulsion comprising the self-cross-linking polymer, an emulsion surfactant and water, wherein the self-cross-linking polymer comprises a combination of about 35 wt.% to about 85 wt.% of methylmethacrylate monomer and about 30 wt.% to about 80 wt.% of butyl acrylate monomer, and wherein the emulsion surfactant comprises about 0.1 wt.% to about 5 wt.% of alkyl ethyloxylates; the first surfactant is a non-ionic nonylphenol ethoxylate; the second surfactant is a tetramethyldecynediol in ethylene glycol; the de-foaming agent is a mixture of hydrophobic solids and foam destroying polysiloxanes in polyglycol.

[0014] In one preferred embodiment, the rejuvenating agent is Sylvaroadtm RP-1000; the acrylicpolymer emulsion comprising the self-cross-linking polymer is Ottopol K-12T; the first surfactant is Brosurf NP-6; the second surfactant is Surfynol 104H; and the de-foaming agent isBYK 022. Sylvaroadtm RP-1000 is commercially available, e.g., from Arizona Chemical / Kraton.Attorney Docket No.43172-0005WO1Ottopol polymers, including K-12T, are commercially available, e.g., from Gellner IndustrialLLC. Brosurf NP-6 is commercially available, e.g., from FBC Chemical Corporation. Surfynol104H is commercially available, e.g., from PalmerHolland, North Olmsted Ohio. BYK 022 iscommercially available, e.g., from BYK Chemie GmBH-Wesel Germany.

[0015] In some embodiments, the tinting agent is carbon black. In some embodiments, thetinting agent is Novocolor IP. In some embodiments, the tinting agent is Novocolor IP 8594500.Novocolor IP tinting agents are commercially available, e.g., from Engineered PolymerSolutions and Color Corporation of America, Chicago, IL.

[0016] In some embodiments, the pavement rejuvenating compositions disclosed herein aremixed with RAP and the admixture re-applied to the road surface.

[0017] In one embodiment is a method of treating deteriorated asphalt pavement whichcomprises spraying a rejuvenating composition onto the deteriorated asphalt pavement to create treated asphalt, grinding the treated asphalt, collecting the ground up asphalt and combining the ground up asphalt with new asphalt to create new asphalt pavement material. In someembodiments, the rejuvenating composition comprises a tall oil-derived fatty ester. In someembodiments, the rejuvenating composition contains a rejuvenating agent, a self-cross-linkingpolymer, water, and a surfactant. In some embodiments, the self-cross-linking polymercomprises a combination of about 35 wt.% to about 85 wt.% of methylmethacrylate monomer and about 30 wt.% to about 80 wt.% of butyl acrylate monomer.

[0018] The pavement rejuvenation compositions disclosed herein are made by sequentialaddition of the constituents to a mixing vessel. Where applicable, each constituent should be agitated to ensure homogeneity and heated if necessary prior to the manufacturing process. The vessel used to make the rejuvenation compositions is thoroughly cleaned and should be free from any potential contaminants. The raw material order of addition is given below in Table 1 for an exemplary formulation (Composition 1).Attorney Docket No.43172-0005WO1 Table 1: Composition 1 Name Density (lbs. / gal.)Water 833

[0019] Table 2 below discloses the constituents in one exemplary formulation (Composition 1)and the weight percentage in which each constituent is present to provide an asphalt rejuvenation formulation as described herein. Table 2: Composition 1 Formula ND it (lb / l ) % b t

[0020] Table 3 below discloses the weight percent range of each constituent of an exemplarypavement rejuvenation formulation (Composition 1) described herein.Attorney Docket No.43172-0005WO1 Table 3: Composition 1 Formula RangeName Density % by wt. % by wt.

[0021] Table 4 below discloses the constituents in one exemplary formulation (Composition 2)and the weight percentage in which each constituent is present to provide an asphalt rejuvenation formulation as described herein. Table 4: Composition 2 Name Densitylbs. Gals.% by Actual %Attorney Docket No.43172-0005WO1 MIX ABOVE UNDER HIGH SHEER 40 minutes Ottopol K-12T (2200 #)c 883 22000 2492 2087% 897%emulsion. The “actual weight %” of water includes the water present in the acetic acid solution (72% water) and the Ottopol polymer emulsion (57% water). bThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of 28% acetic acid added to the composition. The “actual weight % for acetic acid is only the actual acetic acid (28%) and does not include the water present in the 28% acetic acid solution. cThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of Ottopol polymer emulsion added to the composition. The “actual weight % for Ottopol is for the weight solids portion of the polymer emulsion (43%) and does not include the water present in the polymer emulsion.

[0022] Table 5 below discloses the constituents in one exemplary formulation (Composition 3)and the weight percentage in which each constituent is present to provide an asphalt rejuvenation formulation as described herein. Table 5: Composition 3 Name Density% by Actual (lbs / al ) lbs. Gals.wt W i ht %Attorney Docket No.43172-0005WO1 aThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of water added to the composition, but not the water derived from the acetic acid solution or the Ottopol polymer emulsion. The “actual weight %” of water includes the water present in the acetic acid solution (72% water) and the Ottopol polymer emulsion (57% water). bThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of 28% acetic acid added to the composition. The “actual weight % for acetic acid is only the actual acetic acid (28%) and does not include the water present in the 28% acetic acid solution. cThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of Ottopol polymer emulsion added to the composition. The “actual weight % for Ottopol is for the weight solids portion of the polymer emulsion (43%) and does not include the water present in the polymer emulsion.

[0023] Table 6 below discloses the constituents in one exemplary formulation (Composition 4)and the weight percentage in which each constituent is present to provide an asphalt rejuvenation formulation as described herein. Table 6: Composition 4 Name Densitylbs. GActual (lbs. / gal.) als. % by wt.Weight %composition, but not the water derived from the acetic acid solution or the Ottopol polymer emulsion. The “actual weight %” of water includes the water present in the acetic acid solution (72% water) and the Ottopol polymer emulsion (57% water). bThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of 28% acetic acid added to the composition. The “actual weight % for acetic acid is only the actual acetic acid (28%) and does not include the water present in the 28% acetic acid solution.Attorney Docket No.43172-0005WO1 cThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of Ottopol polymer emulsion added to the composition. The “actual weight % for Ottopol is for the weight solids portion of the polymer emulsion (43%) and does not include the water present in the polymer emulsion.

[0024] Table 7 below discloses the constituents in one exemplary formulation (Composition 5)and the weight percentage in which each constituent is present to provide an asphalt rejuvenation formulation as described herein. Table 7: Composition 5 Name Density / gal.) lbActual (lbs. s. Gals. % by wt.Weight %composition, but not the water derived from the acetic acid solution or the Ottopol polymer emulsion. The “actual weight %” of water includes the water present in the acetic acid solution (72% water) and the Ottopol polymer emulsion (57% water). bThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of 28% acetic acid added to the composition. The “actual weight % for acetic acid is only the actual acetic acid (28%) and does not include the water present in the 28% acetic acid solution. cThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of Ottopol polymer emulsion added to the composition. The “actual weight % for Ottopol is for the weight solids portion of the polymer emulsion (43%) and does not include the water present in the polymer emulsion.Attorney Docket No.43172-0005WO1

[0025] Table 8 below discloses the constituents in one exemplary formulation (Composition 6)and the weight percentage in which each constituent is present to provide an asphalt rejuvenation formulation as described herein. Table 8: Composition 6 Name Densitys. / gal.) lb% by Actual (lb s. Gals.wt. Weight %composition, but not the water derived from the acetic acid solution or the Ottopol polymer emulsion. The “actual weight %” of water includes the water present in the acetic acid solution (72% water) and the Ottopol polymer emulsion (57% water). bThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of 28% acetic acid added to the composition. The “actual weight % for acetic acid is only the actual acetic acid (28%) and does not include the water present in the 28% acetic acid solution. cThe “lbs.”, “Gals.” and “% by wt.” indicates the amount of Ottopol polymer emulsion added to the composition. The “actual weight % for Ottopol is for the weight solids portion of the polymer emulsion (43%) and does not include the water present in the polymer emulsion.

[0026] Exemplary asphalt rejuvenation compositions are also provided in International PatentApplication No. PCT / US2023 / 063854, the teachings of which are incorporated herein by reference.

[0027] In one exemplary embodiment, a rejuvenation composition is prepared by combining therejuvenator (e.g., Sylvaroad RP-1000tm), with water, a self-cross-linking polymer in a polymerAttorney Docket No.43172-0005WO1 emulsion, a de-foaming agent and one or more surfactants as described herein. These constituents are mixed in a high shear mixer for about 40 minutes to form a pre-dispersion phase. The pH of the pre-dispersion phase is preferably adjusted to be between pH 4.5 and 5.5. The pre- dispersion is fully homogenous with no signs of phase separation.

[0028] Thereafter, the pre-dispersion phase is blended together with the self-cross-linkingpolymer in the polymer emulsion, a solvent and water to create the final rejuvenationcomposition. The final blended product is tested again for pH (preferably in the range between pH 4.0 and 6.0, and preferably between 4.5-5.0) and residual solids content, and treated to contain less than 1% particulate content when passed through a 250 micron sieve.

[0029] The preferred method for applying the rejuvenating compositions disclosed herein is byspraying the composition onto the pavement surface.

[0030] The distributor for spreading the asphalt rejuvenating composition can be a conventionalself-propelled spraying device that includes full circulation spray bars, a pump tachometer,volume measuring device, and a hand hose attachment suitable for application of thecomposition manually to cover areas inaccessible to the distributor. The distributor is designed and equipped to distribute the asphalt rejuvenating polymer sealer uniformly on variable widths of pavement surface at readily determined and controlled rates from 0.01 to 0.07 gallons per square yard of surface. The rate of application is controlled by an onboard computer control system designed to uniformly and consistently control the selected application rate in gallons per square yard.

[0031] In some embodiments, the asphalt rejuvenation composition is applied at a rate ofbetween about 0.01 and about 0.07 gallons per square yard. In some embodiments, the asphalt rejuvenation composition is applied at a rate of between about 0.015 and about 0.03 gallons per square yard. In some embodiments, the asphalt rejuvenation composition is applied at a rate of about 0.02 gallons per square yard. In some embodiments, the asphalt rejuvenation composition is applied at a rate of about 0.03 gallons per square yard. In some embodiments, the asphalt rejuvenation composition is applied at a rate of about 0.04 gallons per square yard. In some embodiments, the asphalt rejuvenation composition is applied at a rate of about 0.05 gallons per square yard. In some embodiments, the asphalt rejuvenation composition is applied at a rate ofAttorney Docket No.43172-0005WO1 about 0.06 gallons per square yard. In some embodiments, the method comprises spraying the asphalt composition onto the surface of the asphalt pavement, wherein the asphalt pavement is an asphalt road. In some embodiments, the asphalt pavement is dense-graded friction course pavement. In some embodiments, the asphalt pavement is open-graded friction course pavement. In some embodiments, the asphalt rejuvenation composition is applied with an asphalt sealer spray machine. In some embodiments, the asphalt rejuvenation composition is applied as a singlelayer to the asphalt pavement. In some embodiments, the asphalt rejuvenation composition driesin about one hour to about two hours on the asphalt pavement without the need for sanding. Insome embodiments, the complex modulus and the complex viscosity of the asphalt pavement are reduced by at least 40% at three months post-treatment with the asphalt rejuvenation composition.

[0032] The following process can be utilized to determine the pretreatment rate and / or cure timenecessary to improve the quality of RAP binder to better meet the performance needs of new mix in which it may be included: 1) Cut a sufficient quantity of 4-inch cores from the pavement surface to be milled; 2) Trim cut cores to the planned mill depth and carefully document sample geometry; 3) Completely fail control core(s) in indirect tension and capture load versus displacement; 4) Dose treatment core(s) over a range of practical rates (e.g., 3, 5, or 7 percent of binder content); 5) Completely fail treatment core(s) in indirect tension and capture load versus displacement; 6) Compute IDEAL-CTs with appropriate geometry corrections for all samples using captured data; and 7) Evaluate IDEAL-CT results and set dose rate to meet or exceed BMD requirements of agency / owner.

[0033] The following process can be utilized to verify the quality of binder in pretreatedstockpiled RAP meets the performance needs of new mix in which it may be included: 1) Mix RAP with 2% virgin neat asphalt binder; 2) Compact 6-inch SGC pills from RAP plus virgin neat asphalt binder mixture;Attorney Docket No.43172-0005WO1 3) Measure IDEAL-CT for RAP plus virgin neat asphalt binder mixture; 4) Burn RAP to produce uncoated rock, sand, and filler; 5) Mix uncoated rock, sand, and filler from RAP burn with measured residual binder plus 2% 6) Compact 6-inch SGC pills from uncoated rock, sand, and filler plus 2% virgin neat binder mixture; 7) Measure IDEAL-CTs for uncoated rock, sand, and filler plus 2% virgin neat binder mixture; and 8) Compare RAP to remix to ensure the results are favorable for pretreated RAP use in new mix.

[0034] There is no need for a new specification or qualified products list (QPL) becauseproduction balanced mix design (BMD) results will ensure new mix meets established quality requirements. As a result of pretreatment with rejuvenator, the quality of RAP binder can be improved to better meet the performance needs of new mix in which it may be included.

[0035] The following example illustrates a testing comparison of untreated reclaimed asphaltpavement (RAP) with RAP treated with an exemplary composition disclosed herein. EXAMPLE 1

[0036] Objective: Extraction and Recovery as per ASTM D8159 / ASTM D5404 and evaluaterecovered binder for full grade determination. In particular, this testing was performed to quantify the benefit of applying rejuvenating compositions, such as Composition 3 disclosed herein, to the surface of an aged roadway prior to milling. Description of test procedure R29

[0037] AASHTO R29 outlines the procedures for grading or verifying the performance grade(PG) of asphalt binders. This involves a series of tests to evaluate the material's behavior under different conditions, simulating its performance throughout its life cycle. Each test uses specialized equipment to assess specific binder properties essential for durability and performance.Attorney Docket No.43172-0005WO1

[0038] The first test in the process is the rotational viscometer (RV) test, which measures theviscosity of the binder at 135°C (275°F). This test ensures that the binder can be pumped and handled during construction. Using a rotational spindle immersed in the heated binder, the RV records the torque required to rotate the spindle. The viscosity must not exceed 3 Pa·s, ensuring the binder is workable and meets handling requirements.

[0039] The rolling thin film oven (RTFO) test simulates the short-term aging that occurs duringmixing and construction. Asphalt binder is placed in glass bottles, which are rotated continuously in a heated oven at 163°C (325°F) for 85 minutes. The test produces an aged binder sample for subsequent tests and evaluates mass loss due to volatile emissions, ensuring the binder remains stable under high temperatures.

[0040] Dynamic shear rheometer (DSR) testing evaluates the viscoelastic properties of thebinder. High-temperature tests are performed on unaged and RTFO-aged binder samples tomeasure the complex shear modulus (G*) and phase angle ( ), with a focus on rutting resistance.Intermediate-temperature tests on pressure aging vessel (PAV)-aged binder assess fatigueresistance. The results must meet specific criteria, such as G* / sin( ) values and G*sin( ) limits,depending on the test conditions.

[0041] The PAV test simulates long-term aging, representing the effects of years of oxidativeaging in service. RTFO-aged binder samples are placed in stainless steel pans and exposed to 2.1 MPa pressure and temperatures between 100°C and 110°C for 20 hours. The aged samples are used for low-temperature testing, providing insight into the binder's long-term durability.

[0042] At low temperatures, the bending beam rheometer (BBR) test measures the stiffness andrelaxation properties of the binder. A beam-shaped sample of PAV-aged binder is immersed in a cold bath and subjected to a constant load. The test records the stiffness (S) and m-value (creep rate) to determine the binder’s ability to resist thermal cracking. To meet performance criteria, the stiffness must be 300 MPa, and the m-value must be 0.300.

[0043] The direct tension test (DTT) is an optional low-temperature evaluation that measures thetensile strain and stress at failure. Conducted on PAV-aged samples, the DTT assesses theAttorney Docket No.43172-0005WO1 binder's ability to stretch without cracking at low temperatures. The failure strain must be at least 1%, indicating adequate resistance to brittle failure.

[0044] By following the steps in AASHTO R29, engineers can determine the PG of an asphaltbinder, ensuring its suitability for specific environmental and traffic conditions. Each test provides critical data that collectively define the binder’s performance characteristics, guiding its application in asphalt pavement construction. Description of test procedure M320

[0045] AASHTO M320, Standard Specification for Performance-Graded Asphalt Binder,defines the requirements and testing methods for performance-graded (PG) asphalt binders. The specification ensures that asphalt binders meet the necessary performance criteria under varying environmental and traffic conditions. It uses a series of tests performed at different stages of aging to evaluate high-temperature stability, intermediate-temperature fatigue resistance, and low-temperature cracking resistance. Each test employs specialized equipment to measure specific binder properties.

[0046] The first test involves the rotational viscometer (RV), which assesses the binder'sviscosity at 135°C (275°F). This test evaluates the binder's pumpability and workability during mixing and placement. The RV consists of a spindle immersed in the binder, and the torque required to rotate the spindle is measured. The viscosity must not exceed 3 Pa·s, ensuring that the binder can be handled and applied efficiently without issues during construction.

[0047] The rolling thin film oven (RTFO) test simulates the short-term aging of asphalt binderthat occurs during mixing and construction. The binder is placed in glass bottles and subjected to a rotating motion in a heated oven at 163°C (325°F) for 85 minutes. The test results provide an aged binder sample for subsequent testing and include an assessment of mass loss due to volatiles. This ensures that the binder maintains its composition under construction conditions.

[0048] The dynamic shear rheometer (DSR) is used to evaluate the binder's viscoelasticproperties and its ability to resist rutting and fatigue cracking. High-temperature DSR testing is conducted on unaged and RTFO-aged samples to measure the complex shear modulus (G*) andphase angle ( ). The results must satisfy minimum G* / sin( ) values, indicating sufficientAttorney Docket No.43172-0005WO1 stiffness and elasticity to resist deformation. Intermediate-temperature DSR testing on PAV-agedbinder evaluates the fatigue resistance, with results required to meet G*sin( ) limits.

[0049] The pressure aging vessel (PAV) simulates long-term oxidative aging that occurs overyears of service life. RTFO-aged binder samples are placed in the PAV and exposed to 2.1 MPa pressure at 100°C to 110°C for 20 hours. The aged binder from the PAV is used for low- temperature testing, providing insight into the binder’s durability and resistance to cracking over time.

[0050] Low-temperature properties are assessed using the bending beam rheometer (BBR). Abeam of PAV-aged binder is subjected to a constant load while submerged in a cold bath at the specified test temperature. The stiffness (S) and m-value (rate of stress relaxation) are measured. To meet the criteria, the stiffness must not exceed 300 MPa, and the m-value must be at least 0.300, ensuring resistance to thermal cracking in cold climates.

[0051] The optional direct tension test (DTT) measures the strain and stress at failure for PAV-aged binder samples at low temperatures. This test evaluates the binder's ability to stretch without cracking under thermal stresses. The failure strain must be at least 1%, demonstrating the binder's flexibility and resistance to brittle behavior.

[0052] The tests specified in AASHTO M320 collectively determine the binder’s performancegrade, defined by its ability to withstand high temperatures without rutting, intermediate temperatures without fatigue cracking, and low temperatures without thermal cracking. This specification ensures that the binder is suitable for the intended climatic and loading conditions, providing a basis for selecting materials in asphalt pavement design. Description of test procedure T315

[0053] AASHTO T315, Standard Method of Test for Determining the Rheological Properties ofAsphalt Binder Using a Dynamic Shear Rheometer (DSR), describes the procedure for evaluating the viscoelastic properties of asphalt binders. This test method measures the complexshear modulus (G*) and phase angle ( ), which indicate the binder's stiffness and elasticity undervarious conditions. These properties are critical for understanding the material’s ability to resist rutting and fatigue cracking. The DSR is the primary piece of equipment used for these tests.Attorney Docket No.43172-0005WO1

[0054] The dynamic shear rheometer (DSR) consists of parallel plates and a temperature-controlled chamber. The binder sample, prepared as a disk-shaped specimen, is placed between the plates. For testing unaged and RTFO-aged samples, 25-mm plates are used with a 1-mm gap, while for PAV-aged samples, 8-mm plates are used with a 2-mm gap. The DSR applies oscillatory shear stress or strain to the sample and measures the resulting deformation, providing data on G* and .

[0055] The first step involves testing the unaged binder at high temperatures to evaluate itsstiffness and elasticity. The DSR measures G* and under controlled oscillatory loading. Thetest ensures that the binder’s G* / sin( ) is at least 1.00 kPa, indicating adequate resistance torutting. This step establishes the baseline performance of the material.

[0056] Next, the RTFO-aged binder is tested to simulate the effects of short-term aging duringmixing and construction. The procedure mirrors the unaged binder test, with G* and measuredat the high PG temperature. The criterion for G* / sin( ) is increased to 2.20 kPa, reflecting theneed for greater stiffness to resist deformation after exposure to construction conditions.

[0057] Finally, the PAV-aged binder is tested at intermediate temperatures to assess its fatigueresistance. This test evaluates the ability of the binder to resist cracking under repeated loading.The DSR measures G*sin( ), which must not exceed 5000 kPa. Lower values indicate betterresistance to fatigue cracking, ensuring long-term performance under traffic loads.

[0058] By following the steps in AASHTO T315, engineers can obtain detailed rheologicalproperties of asphalt binders. These measurements play a critical role in performance grading and determining the suitability of the binder for specific climatic and traffic conditions. The DSR provides precise and reliable data, making it an essential tool in asphalt binder characterization. Description of test procedure T313

[0059] AASHTO T313, Standard Method of Test for Determining the Flexural Creep Stiffnessof Asphalt Binder Using the Bending Beam Rheometer (BBR), evaluates the low-temperature performance of asphalt binders. This test determines the creep stiffness (S) and m-value (rate of stress relaxation) of the binder to assess its ability to resist thermal cracking in cold climates. TheAttorney Docket No.43172-0005WO1 primary equipment used is the bending beam rheometer (BBR), which measures deflection in a binder beam subjected to a constant load.

[0060] The bending beam rheometer (BBR) is a precision instrument equipped with a loadingdevice, temperature-controlled bath, and sensors for measuring load and deflection. The binder is prepared into rectangular beams, typically 125 mm long, 6.25 mm wide, and 12.5 mm thick. The temperature-controlled bath maintains the test temperature, which is selected based on the binder’s intended climatic conditions.

[0061] The first step involves sample preparation, where the PAV-aged binder is poured intopreheated molds to create beams. The beams are allowed to cool and are trimmed to ensure uniform dimensions. Proper preparation is critical to obtain accurate and reproducible results.

[0062] The prepared beam is then conditioned in the BBR bath at the test temperature, usuallyfor 60 minutes. The bath temperature is controlled to simulate the pavement temperature at which low-temperature cracking might occur. Common test temperatures range from -10°C to - 40°C, depending on the performance grade of the binder.

[0063] During the test, a constant load of 100 grams is applied to the midpoint of the beam for240 seconds. The deflection of the beam under the load is measured over time. These measurements are used to calculate the creep stiffness (S) and m-value. Creep stiffness (S) represents the material's ability to resist deformation under load, while the m-value reflects its capacity to relax stress and reduce the risk of cracking.

[0064] To meet specification criteria, the creep stiffness (S) must not exceed 300 MPa, ensuringthat the binder is not too stiff and prone to cracking. The m-value must be at least 0.300, indicating that the binder can effectively relieve stress at low temperatures. Failure to meet these criteria suggests a higher risk of thermal cracking in service.

[0065] AASHTO T313 provides a reliable method for evaluating the low-temperatureperformance of asphalt binders. By determining stiffness and relaxation properties, this test helps engineers ensure that the binder selected for a project will perform adequately in cold climates, minimizing the potential for cracking and enhancing pavement durability.Attorney Docket No.43172-0005WO1 Asphalt Rejuvenating Composition

[0066] Composition 3 (Table 5) is an asphalt rejuvenator used in the methods of Example 1 totreat asphalt pavement (“treated millings’). Its primary active ingredient is Tall Oil Fatty Acid (TOFA), a bio-based substance derived from the liquid rosin of coniferous pine trees. TOFA is known for its effectiveness in reversing the aging process of asphalt by restoring essential properties lost over time. In addition to TOFA, Composition 3, and other compositions disclosed herein, contains carbon black, a common component in asphalt products that enhances durability and resistance to ultraviolet degradation. The product is formulated to be non-toxic, water-based, and solvent-free, aligning with environmental safety standards. Its rapid drying time minimizes tracking and disruption during application, making it a practical choice for asphalt maintenance. The combination of these components in Composition 3, and other compositions disclosed herein, offers a sustainable solution for extending the lifespan of asphalt pavements, providing both environmental benefits and improved performance.

[0067] When Composition 3, or another composition disclosed herein, is applied to the surfaceof an asphalt pavement in front of a milling machine, the proprietary polymer blend within promotes maintenance of safe friction for any vehicles that may travel the roadway between the application of the composition and the milling machine. In this case of these findings, Composition 3 was applied to the surface of the asphalt pavement in front of a milling machine.

[0068] Untreated (control) millings are simply milled asphalt upon which no rejuvenationcomposition was applied. Treated millings represent millings that were treated with Composition 3, or other compositions disclosed herein, prior to the milling process. In the case of these results, treatment with Composition 3 was applied 2 days prior to milling. Sampling of stockpiled milled material was completed after approximately 1 month. The timing of treatment and sampling was considered to be an appropriate simulation of typical practice, but significant variance is expected to yield similar results. For example, applying Composition 3 during milling either inside the equipment or at the point of truck discharge is expected to yield similar results.

[0069] Results from the comparative tests between untreated and treated millings are presentedin Table 9.Attorney Docket No.43172-0005WO1 Table 9: Recovered Residue Results Properties TestM th d SpecsUntreated Treated 2Attorney Docket No.43172-0005WO1 Table 9 Definitions

[0070] The “specs” column represents the specification requirement(s) in AASHTO M320.

[0071] Complex Shear Modulus (G*) represents the total stiffness of the binder, including bothelastic (recoverable) and viscous (non-recoverable) components. A higher G* indicates a stiffer binder.

[0072] Phase Angle ( ) is a measure of the lag between the applied shear stress and the resultingstrain, reflecting the balance between elastic and viscous behavior. The range of sin is from 0 to1. A smaller sin value (closer to 0) indicates more elastic (recoverable) behavior, while a largersin (closer to 1) indicates more viscous (non-recoverable) behavior.

[0073] In Bending Beam Rheometer (BBR) testing, stiffness (S(t)) and creep rate (m-value) arecalculated from the deflection of an asphalt binder beam under a constant load over time. These parameters evaluate the binder’s ability to resist thermal cracking and its stress relaxation behavior at low temperatures.

[0074] Creep stiffness measures the material’s resistance to deformation under a sustained load.It is calculated using the following formula:

[0075] The m-value measures the rate at which the binder relaxes stress over time, indicating itsability to relieve thermal stresses and avoid cracking. It is calculated as the slope of the stiffness curve on a log-log scale:Attorney Docket No.43172-0005WO1

[0076] Performance grading (PG) for asphalt binders is a specification system that classifiesbinders based on their ability to perform under specific climate and traffic conditions. The system, developed as part of the Superpave (Superior Performing Asphalt Pavement) mix design method, ensures that asphalt binders are selected to resist distresses such as rutting, fatigue cracking, and thermal cracking throughout the pavement’s service life.

[0077] The PG system is defined by two temperatures: the high-temperature and low-temperature extremes at which the binder must perform without failure. For example, a PG 64-22 binder is designed to perform at a maximum pavement temperature of 64°C and a minimum pavement temperature of -22°C. The high-temperature grade reflects the binder's ability to resist rutting under heavy traffic and hot conditions. The low-temperature grade indicates the binder's ability to resist thermal cracking in cold climates. The performance grading system incorporates tests on unaged binders, short-term aged binders (using the Rolling Thin Film Oven, RTFO), and long-term aged binders (using the Pressure Aging Vessel, PAV). This approach evaluates how the binder behaves during construction and over its service life. High and low temperature binder grades shift in increments of 6°C. For this reason, a 6°C shift in high and / or low temperature grade is a significant outcome. In the case of these findings, the high temperature performance grade is 77.4°C and -24.2°C represents the low temperature performance grade.

[0078] Rutting resistance is measured at high temperatures using the Dynamic Shear Rheometer(DSR) on unaged and RTFO-aged binder samples. A minimum stiffness requirement (G* / sin ) ensures the binder resists deformation under load. Fatigue resistance is measured at intermediate temperatures using the DSR on PAV-aged samples. A limit on G*sin ensures the binder resists cracking due to repeated loading. Thermal cracking resistance is assessed at low temperaturesAttorney Docket No.43172-0005WO1 using the Bending Beam Rheometer (BBR) and optionally the Direct Tension Test (DTT). Limits on creep stiffness and m-value ensure the binder can withstand cold-induced stresses.

[0079] There are several advantages of performance grading compared to previous “legacy”grading. For example, there is enhanced reliability. Binders are selected based on the specific conditions they will face, reducing the risk of premature pavement failure. Standardization is an additional advantage. The system provides a consistent framework for selecting and specifying binders globally. Versatility is a third advantage. The PG system can be adjusted for specific traffic conditions and regional climates, making it highly adaptable. By using the PG system, engineers can ensure that the asphalt binder used in a pavement mix will perform effectively in its intended environment, leading to longer-lasting and more reliable roadways. Results Summary

[0080] Treatment with Composition 3, or other compositions disclosed herein, is intended torestore properties to the age hardened binder in the milled asphalt surface. As shown in Table 9, the untreated millings generated a performance grade of 82-16, with a continuous grade of 84.3- 17.8, while the millings treated with Composition 3 lowered both the high end and lower end grading by one performance grade to 76-22 with a continuous grade of 77.4-24.2. These results indicate the high and low temperature performance binder grades were lowered (improved) by approximately 1 full grade (i.e., 6°C) for both high and low temperature performance. This is a significant outcome that essentially restored binder properties to those properties expected in virgin (unaged) asphalt. This was an ideal outcome and is the reason why an investment in the cost of pretreatment is a good investment with respect to the performance of new asphalt mix that contains recycled materials treated in this manner.

[0081] By comparing test results for treated and untreated reclaimed asphalt pavement (RAP),this testing proved that when a rejuvenating composition, such as Composition 3, is applied to the surface of an aged roadway prior to milling the performance grade of recovered liquid asphalt is improved by approximately one (6C) full binder grade for both high and low temperature performance. This essentially represents full property restoration of the aged binder.Attorney Docket No.43172-0005WO1

[0082] In this controlled experiment, the application of Composition 3 to an aged roadwaysurface prior to milling improved the performance grade of the age hardened liquid asphalt by one (6C) full performance grade for both hot and cold temperature performance. Agencies are struggling with utilizing recycling agents to produce new asphalt that contains higher percentages of reclaimed and recycled materials. Current practice is to either add recycling agents at the liquid asphalt terminals prior to shipping virgin tanker loads or at the plant during production using inline blending. In either case, there is limited opportunity for recycling agents to react with aged asphalt in the RAP. Additionally, products used in this manner must be selected from a qualified products list (QPL). Applying a composition such as Composition 3 prior to milling renders it unnecessary to go through a long and expensive QPL process and there is ample time for the reaction that results in property restoration.

[0083] These results solidify that pre-treatment of an aged asphalt roadway is advantageousbecause 1) the product can be applied prior to milling (wherein the polymer provides safe friction); 2) the product can be applied during the milling process (by adding the product to the milling water or RAP chamber); or 3) the product can be applied after milling (e.g., when RAP is discharged from the milling machine into the haul truck); and 4) contractors can satisfy mix quality standards with high percentages of RAP because pretreated material has a recovered binder grade that has now been proven to be improved by a full (6C) grade for both high and low temperature performance (essentially full property restoration of the aged binder). In other words, new mix will be healthier in terms of both high and low temperature performance with higher percentages of RAP that has been pretreated with Composition 3 or other compositions disclosed herein.

[0084] Various modifications of the invention, in addition to those described herein, will beapparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims. Each reference, including all patent, patent applications, and publications, cited in the present application is incorporated herein by reference in its entirety.

Claims

Attorney Docket No.43172-0005WO1 What is claimed:

1. A method of treating deteriorated asphalt pavement which comprises treating apavement in need of rejuvenation with a rejuvenating composition, thereafter milling the treated pavement to create reclaimed asphalt pavement and collecting the reclaimed asphalt pavement.

2. The method of claim 1, wherein the treating step comprises spraying therejuvenating composition onto the pavement surface.

3. The method of claim 1, which comprises storing the treated asphalt for future use.

4. The method of claim 1, wherein the reclaimed asphalt pavement is mixed withfresh asphalt.

5. The method of claim 1, wherein the rejuvenating composition contains arejuvenating agent, a self-cross-linking polymer, water, and a surfactant.

6. The method of claim 5, wherein the rejuvenating agent is a tall oil-derived fattyester.

7. The method of claim 5, wherein the rejuvenating agent is a tall oil-derived fattyester having a cyclic content of at least 5 wt.%; and the self-cross-linking polymer is in an acrylic polymer emulsion comprising the self-cross-linking polymer, an emulsion surfactant, and water.

8. The method of claim 5, which comprises applying the rejuvenating composition ata rate of between about 0.01 and about 0.07 gallons per square yard.

9. The method of claim 1, which comprises waiting at least one hour after millingthe pavement.

10. The method of claim 1, wherein the treating step is carried out after the reclaimedasphalt has been milled and collected in a truck.

11. The method of claim 1, which comprises combining the treated reclaimed asphaltwith fresh asphalt to create a fresh paving material.Attorney Docket No.43172-0005WO1 12. A method of treating deteriorated asphalt pavement which comprises spraying arejuvenating composition onto the deteriorated asphalt pavement to create treated asphalt, grinding the treated asphalt, collecting the ground up asphalt and combining the ground up asphalt with new asphalt to create new asphalt pavement material.

13. The method of claim 12, wherein the rejuvenating composition comprises a talloil-derived fatty ester.

14. The method of claim 12, wherein the rejuvenating composition contains arejuvenating agent, a self-cross-linking polymer, water, and a surfactant.

15. The method of claim 14, wherein the self-cross-linking polymer comprises acombination of about 35 wt.% to about 85 wt.% of methylmethacrylate monomer and about 30 wt.% to about 80 wt.% of butyl acrylate monomer.

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