Asphalt emulsion containing sterol additive for asphalt pavement

Abstract

Pavement aging can be reduced by applying a surface layer or surface treatment containing an asphalt binder and sterol on an asphalt-containing pavement.

Description

[0001] Divisional application statement

[0002] This application is a divisional application of Chinese invention patent application No. 201880023192.4, filed on February 1, 2018, entitled "Asphalt Emulsion Containing Sterol Additives for Asphalt Road Surface". Background Technology

[0003] Asphalt pavement is a composite material, a mixture of mineral aggregates and liquefied asphalt (asphalt) binder, which hardens to form a robust surface. Asphalt is typically liquefied by heating. Asphalt pavement can also be produced using asphalt already mixed with a solvent (called lightweight asphalt) or asphalt already dispersed in water (called asphalt emulsion). Asphalt pavement can include recycled or reclaimed materials, containing recycled asphalt pavement (RAP), recycled asphalt shingles (RAS), waste tire rubber, and other post-consumer waste. Over time, asphalt pavement deteriorates due to oxidation of the asphalt binder, heavy loads, moisture damage, and varying climatic conditions, leading to fatigue cracking, which further accelerates the overall deterioration of the pavement.

[0004] Methods for restoring or repairing deteriorated asphalt pavements include removing and replacing the existing pavement with newly prepared or recycled pavement. The service life of existing pavements can also be extended by applying certain surface treatments. Summary of the Invention

[0005] This application discloses a method for using sterols in asphalt compositions, as well as methods for top-level construction of pavements and surface treatments for pavement maintenance and upkeep. The disclosed sterol-containing asphalt binders can delay, reduce, or otherwise overcome the aging effects in asphalt, thereby preserving or retaining some or all of the original properties of the original binder or original asphalt initially used during asphalt paving.

[0006] In one embodiment, a road paving method includes:

[0007] A sterol-containing bitumen binder is provided, wherein the sterol is added to the bitumen binder at 0.5 wt% to 15 wt% based on the bitumen binder;

[0008] Sterol-containing asphalt binders are combined with aggregates to form asphalt pavement materials;

[0009] Applying asphalt pavement material onto the asphalt pavement layer; and

[0010] The applied asphalt pavement material is compacted to form a road surface with a sterol-containing surface layer.

[0011] In another embodiment, a method for treating an asphalt-containing surface is disclosed, comprising:

[0012] Provides a surface treatment comprising a sterol-containing bitumen binder, wherein the sterol is added to the bitumen binder at 0.5 wt% to 15 wt% based on the bitumen binder; and

[0013] Surface treatment is applied to the surface of existing road surfaces. Attached Figure Description

[0014] Figure 1A A type of asphalt pavement structure is described.

[0015] Figure 1B Describes surface treatment Figure 1A Asphalt pavement structure.

[0016] Figure 1C It describes an asphalt pavement with interlayers.

[0017] Figure 2 The figure illustrates the m-criticality compared to the number of days of aging in an oven at 75°C.

[0018] Figure 3 The figure illustrates the S-criticality compared to the number of days of aging in an oven at 75°C.

[0019] Figure 4 The figure shows ΔTc compared to the number of days of aging in an oven at 75°C.

[0020] Figure 5 The figure shows the R value compared to the number of days of aging in an oven at 75°C.

[0021] Figure 6 The figure illustrates the high-temperature PG classification at 1.0 kPa compared to the number of days of aging at 75°C.

[0022] Figure 7 The illustration shows the S-critical and m-critical properties of the binder recovered from the top half inch and the second half inch of the compacted sample after 60 days of oven aging.

[0023] Figure 8 The figure illustrates the ΔTc and R-value properties of the binder recovered from the top half inch and the second half inch of the compacted sample after 60 days of oven aging.

[0024] Figure 9 The figure illustrates the S-critical and m-critical properties of the binder recovered from the top half inch and the second half inch of the compacted sample after 152 days of oven aging.

[0025] Figure 10 The figure illustrates the ΔTc and R-value properties of the binder recovered from the top half inch and the second half inch of the compacted sample after 152 days of oven aging. Detailed Implementation

[0026] This application discloses the use of sterols in compositions and methods applicable to pavement construction or pavement maintenance and upkeep. The applicant has previously demonstrated that sterols can delay, reduce, or otherwise overcome some of the effects of asphalt aging, thereby preserving or retaining some or all of the original properties of the original asphalt binder. See International Applications PCT / US16 / 037077, PCT / US16 / 64950, PCT / US16 / 064961, and PCT / US17 / 045887, each of which is incorporated herein by reference in its entirety. Sterols are particularly effective when the binder contains recycled or reclaimed materials such as RAP, RAS, or a combination of both; or when the binder contains paraffinic additives such as paraffinic base oils or refining oil bottoms (REOBs) typically used to soften binders.

[0027] The headings provided in this application are for ease of reading only and should not be construed as limiting.

[0028] Abbreviations, acronyms and definitions

[0029] “Aged” refers to hard, inferior or non-standard original bitumen or original binder, especially original binder with a ring and ball softening point greater than 65°C of EN 1427 and a penetration value at 25°C less than or equal to 12 dmm of EN 1426.

[0030] "Aggregates" and "construction aggregates" refer to granular mineral materials used in paving and road applications, such as limestone, granite, dark rock, gravel, crushed sand, crushed stone, crushed rock, and slag.

[0031] "Asphalt" refers to a binder and aggregate, and optionally other components suitable for mixing with the aggregate and binder. Depending on local usage, the terms "asphalt mixture" or "mixture" may be used interchangeably with the term "asphalt".

[0032] "Binder" refers to petroleum in a highly viscous liquid or semi-solid form. "Binder" can include, for example, asphalt. The term "asphalt binder" is used interchangeably with the term "binder".

[0033] "Asphalt" refers to a class of natural or manufactured black or dark-colored (solid, semi-solid or viscous) cementitious substances, mainly composed of high molecular weight hydrocarbons, among which asphalt, tar, pitch and asphaltenes are typical.

[0034] When used for materials containing sterols, "crude" refers to sterols that have not been fully refined and may contain components other than sterols.

[0035] The "m-critical" or "creep critical" rating refers to the low-temperature relaxation rating of the adhesive. The creep critical temperature is the temperature at which the absolute value of the slope of the flexural creep hardness relative to creep time is 0.300, as determined by ASTM (Bending Beam Rheometer (BBR) test). The creep critical temperature can also be determined by testing with a 4 mm Dynamic Shear Rheometer (DSR) at a value of -0.275.

[0036] "Clean" or "raw" adhesives are adhesives that have not been used on asphalt pavements or asphalt shingles or have been recycled from asphalt pavements or asphalt shingles, and may include performance grade adhesives.

[0037] When used for sterols or mixtures of sterols, "pure" means having at least industrial grade purity or at least reagent grade purity.

[0038] "Recycled bitumen" and "reclaimed bitumen" refer to recycled bitumen pavement, recycled bitumen shingles, recycled adhesives from old pavement, tile manufacturing waste, roofing felt and other bitumen-containing products or applications.

[0039] "Recycled asphalt pavement" and "RAP" refer to asphalt that has been removed or excavated from previously used roads or pavements or other similar structures and processed for reuse by a variety of well-known methods, including rolling, tearing, crushing, pulverizing or grinding.

[0040] "Recycled asphalt shingles" and "RAS" refer to shingles from sources including roof demolition, industrial waste asphalt shingles, and post-consumer waste.

[0041] "S-critical" or "hardness critical" rating refers to the low-temperature hardness rating of the adhesive. The hardness critical temperature is the temperature at which the adhesive achieves a flexural creep hardness of 300 MPa according to ASTM D6648 testing, or the temperature determined by a bending beam rheometer or a 4 mm DSR test, expressed as ΔTc.

[0042] "Softener" refers to a low-viscosity additive that assists (or promotes) the mixing and incorporation of recycled binder into the original binder during the asphalt production process.

[0043] "Sterol additives" refer to sterols or mixtures of sterols that can be combined with binders to slow down the aging rate of asphalt or binders, or to restore or renew aged asphalt or binders to provide some or all of the original properties of the original asphalt or binders.

[0044] "Sterol mixtures" refer to compositions, mixtures, or blends of pure sterols and crude sterols that can be combined with aged binders (such as recycled or regenerated bitumen) to slow down the aging rate of bitumen binders or to restore or renew aged binders to provide some or all of the original properties of the original bitumen or original binder.

[0045] “ΔTc” refers to the value obtained by subtracting the low-temperature creep or m-value critical temperature from the low-temperature hardness critical temperature. The 4mm dynamic shear rheometer (DSR) testing and analysis procedure is described in Sui, C., Farrar, M., Tuminello, W., Turner, T., A New Technique for Measuring low-temperature Properties of Asphalt Binders with Small Amounts of Material, Transportation Research Record: No 1681, TRB 2010. See also Sui, C., Farrar, MJ, Harnsberger, PM, Tuminello, WH, Turner, TF, New Low Temperature Performance Grading Method Using 4 mm Parallel Plates on a Dynamic Shear Rheometer. TRBPreprint CD, 2011 and Farrar, M., et al., (2012), Thin Film Oxidative Aging and Low Temperature Performance Grading Using Small Plate Dynamic ShearRheometry: An Alternative to Standard RTFO, PAV and BBr. Eurasphalt & Eurobitume5th E&E Congress-2012 Istanbul (pp. Paper O5ee-467). Istanbul: FoundationEuraspalt.

[0046] Unless otherwise stated, all weights, portions and percentages are based on weight.

[0047] Figure 1 is a cross-sectional view of a typical asphalt pavement section. Crushed aggregate is applied as a base course to the subgrade, which may be soil. The crushed aggregate base course can have an average thickness, for example, from about 152 mm (6 inches) to 305 mm (12 inches). One or more asphalt layers can be applied on top of the aggregate base course. Figure 1 shows two asphalt layers, referred to as the asphalt pavement base course and the asphalt pavement surface course. The asphalt pavement base course can have an average thickness, for example, from about 57 mm (2.25 inches) to about 305 mm (12 inches) when paved in several layers, or from 57 mm (2.25 inches) to about 127 mm (5 inches) when paved in several layers; and the asphalt pavement surface course can have an average thickness, for example, from about 38 mm (1.5 inches) to about 102 mm (4 inches) or from 38 mm (1.5 inches) to 63 mm (2.5 inches). It should be noted that the thickness is also determined by the maximum aggregate size.

[0048] The terms "base course" and "surface course" used to define asphalt layers should be understood as relative terms. The further an asphalt layer is from the base course, the more it is considered the "top" layer. The topmost asphalt layer—the surface course—is exposed to weather and elements such as sun, rain, snow, freezing, and thawing. Road surfaces also experience frictional wear, cracking, and other damage due to vehicle traffic. Over time, these environmental and service factors lead to the deterioration of asphalt pavements, particularly the surface course.

[0049] Ideally, sterol-containing asphalt pavement materials would be used to construct the entire road surface, from the base course to the top asphalt layer, because the asphalt layer will age over time. Aging is not limited to the top layer of the asphalt pavement (e.g., the top 38 mm to 65 mm of a compacted pavement). However, disregarding materials that may have been added to the binder or other components of the pavement material, the asphalt binder tends to age most severely on the surface, and the degree of aging and its subsequent detrimental effects on the binder generally decrease with pavement depth.

[0050] While sterols can be added to the entire asphalt pavement, they are relatively expensive. However, to control costs, one or more of the top asphalt layers can be paved with sterol-containing asphalt binder paving materials. This delays binder aging throughout the asphalt pavement by making the surface layer more resistant to aging, while protecting the underlying asphalt pavement from weather, elemental, and other damage caused by premature surface layer degradation over a longer period. For example, by delaying asphalt aging (especially in the top layer or layers), surface cracking associated with aging binders can be reduced, thus reducing airflow into the underlying pavement and associated oxidation. Similarly, by delaying asphalt aging in the top layer or layers, moisture absorption in the surface layer and moisture transport through cracks in that layer or layer can be reduced, thus limiting further damage to the pavement and limiting its aging rate. Overall pavement life is improved by extending the time it takes for the binder to reach the point where pavement damage begins.

[0051] When repaving a road surface, one might grind away, for example, the top 76 mm (3 inches) to 102 mm (4 inches) of the old pavement and replace part or all of the milled portion with a sterol-containing replacement portion. The replacement portion can be applied in many different configurations, thus making only the top 12 mm (0.5 inches) to 19 mm (0.75 inches) or the top 12 mm (0.5 inches) to 38 mm (1.5 inches) a thin overlay containing a sterol-containing binder. For example, two 38 mm paving layers can be applied, with only the top 38 mm including a sterol-containing binder. As another example, the milled 76 mm (3 inches) or 102 mm (4 inches) can be replaced with two 50 mm (2 inches) paving layers or a 50 mm (2 inches) paving layer with a 25 mm (1 inch) thin overlay (i.e., a thin layer), where only the top paving layer or overlay includes a sterol-containing binder.

[0052] Other compositions and methods for addressing pavement deterioration include the maintenance and upkeep of existing pavements using sterol-containing surface treatments disclosed in this application. In these treatments, sterols can be used as asphalt mixture components in surface treatments for pavement maintenance.

[0053] Asphalt surface treatment is a broad term encompassing several types of asphalt and asphalt-aggregate applications that can be used to extend the structural life of the underlying pavement. This treatment is typically less than 25 mm (1 inch) thick and can be applied to any type of pavement. Road surfaces can be, for example, primer granular substrates or existing asphalt or Portland cement concrete pavements. Surface treatments applied to existing pavements are often called seals. A surface treatment applied by spraying an asphalt emulsion and immediately rolling an aggregate overlay onto the applied emulsion is often called a chip seal. A sandwich seal is another surface treatment technique where large aggregates are first placed, then an asphalt emulsion (often polymer-modified) is sprayed onto the aggregates, followed immediately by a smaller aggregate overlay to lock in the seal. Cape seal is a single surface treatment followed by a slurry seal or micro-seal to fill voids. The above and other surface treatments can be applied multiple times as needed. In some embodiments, sterol-containing asphalt binders can be applied as a bonding layer and fog seal.

[0054] Considering factors such as region and climate, surface treatments involving sterol-containing bitumen binders can be applied in the form of emulsions, hot-applied asphalt, or lightweight bitumen. In all cases, the bitumen used in the surface treatment can contain polymer additives derived from categories such as styrene-butadiene rubber (SBR), styrene-butadiene-styrene (SBS) block copolymers, reactive ethylene terpolymers (RET), waste tire rubber, acrylic lattices, neoprene lattices, ethylene vinyl acetate (EVA), and polybutene. This list should not be considered restrictive, as any polymer that can be incorporated into bitumen in hot, lightweight, or emulsion form is a candidate. Some surface treatments are based solely on bitumen emulsions as binders (e.g., slurry seal or micro-surface seal). Chip seal can be constructed using emulsions, hot-applied bitumen binders, or lightweight bitumen. The choice of binder type for chip seal typically depends on the region or climate. The addition of sterols to any of these treatments can advantageously affect the aging of the binder in the surface treatment, thereby extending the service life of the surface treatment, which in turn provides extended anti-aging protection for the pavement under the surface treatment.

[0055] Regardless of the road construction process used, the main components include sterol additives added to the binder.

[0056] Sterol additives

[0057] The disclosed sterol additives preferably alter (e.g., reduce or delay) the aging rate of asphalt binders, or restore or renew aged or recycled binders to provide some or all of the properties of the original asphalt binder. The disclosed compositions and methods utilize a class of plant-derived chemicals, namely sterols. While phytosterols do not contain the same number of condensed or partially unsaturated rings as asphaltenes, they do possess the benefits of being non-linear or branched linear molecules. For example, sterols can alter or improve the physical and rheological properties of asphalt binders, such as hardness, effective temperature range, and low-temperature properties.

[0058] In some embodiments, the sterol additives belong to the triterpenoid class, particularly sterols or steranols. The disclosed sterols (e.g., triterpenoids) can be effectively used with asphaltenes. Asphaltenes comprise a large number of fused ring systems with a certain level of unsaturation. The asphaltenes content in typical binders can range from less than 10% to greater than 20%. Asphaltenes are generally described as materials insoluble in n-heptane. The exact structure is unknown, and based on the performance behavior of different binders, the asphaltenes structure in any two binders is unlikely to be the same, especially asphaltenes from different natural sources. Asphaltenes give binders their color and hardness, and their content increases as the binder ages. Therefore, the addition of RAP and / or RAS leads to an increase in asphaltenes content. Increased asphaltenes content, along with other oxidation products such as carbonyl compounds and sulfoxides, contributes to the hardening and eventual failure of asphalt mixtures. Chemically, asphaltenes are not readily soluble in aliphatic chemicals. Aromatic solvents readily dissolve asphaltenes, and aromatic processing oils have been used in recycled mixtures. However, these oils may contain polynuclear aromatic compounds, including the listed potential carcinogens, and are therefore not ideal additives. Most plant-based oils are straight-chain or branched hydrocarbons with a certain level of unsaturation, so they are less effective at delaying aging than at softening the overall binder in blends.

[0059] Triterpenoids are a major group of plant natural products, including sterols, triterpenoid saponins, and related structures. Triterpenoids can be natural or synthetic. They are typically obtained by extraction from plant material. Extraction processes for isolating triterpenoids are described, for example, in International Application Publications WO 2001 / 72315 A1 and WO 2004 / 016336 A1, the disclosures of which are incorporated herein by reference in their entirety.

[0060] Triterpenoids include phytosterols and phytosterols. The disclosed triterpenoids include any esterified and non-esterified forms of phytosterols mentioned in this application.

[0061] Exemplary pure phytosterols include campesterol, stigmasterol, β-sitosterol, Δ5-aminosterol, Δ7-stigmasterol, Δ7-aminosterol, brassosterol, or mixtures thereof. In some embodiments, the sterol mixture contains β-sitosterol as a pure sterol. In other embodiments, the sterol mixture contains a mixture of pure sterols. Commercially available pure sterols and mixtures of pure sterols include those called β-sitosterol (about 40-60% β-sitosterol; about 20-40% campesterol; about 5% stigmasterol) available from MP Biomedicals (catalog number 02102886). In some embodiments, pure sterols may include pure cholesterol. The cholesterol shown herein has similar effects to phytosterols.

[0062] In some embodiments, the pure sterol may contain at least 70 wt% sterol, and in some embodiments may contain at least 80 wt%, at least 85 wt%, or at least 95 wt% sterol.

[0063] Exemplary crude phytosterols include modified or unmodified natural products containing a significant amount of sterols, including a variety of plant sources such as corn oil, wheat germ oil, sage root, soybean pitch, and corn oil pitch. For example, tall oil pitch can be obtained indirectly from wood pulping, particularly pine pulping. For instance, tall oil is a product of wood pulping (e.g., by sulfate pulping), where tall oil pitch is a byproduct of tall oil distillation. Tall oil pitch is an extremely complex material that can contain rosin, fatty acids, oxidation products, and esterified substances, a significant portion of which are sterol esters. Plant sources of crude sterols are inexpensive because they are oil residues or tailings left over from various manufacturing processes.

[0064] In some embodiments, crude sterol sources include stigmasterol, β-sitosterol, campesterol, ergosterol, brassosterol, cholesterol, and lanosterol, or mixtures thereof. In some embodiments, crude sterol sources include soybean oil, corn oil, rice bran oil, peanut oil, sunflower seed oil, safflower oil, cottonseed oil, rapeseed oil, coffee seed oil, wheat germ oil, tall oil, and lanolin. In some embodiments, crude sterols comprise bio-derived sources or partial distillation residues of bio-derived sources. In some embodiments, crude sterol sources include tall oil pitch, soybean oil, or corn oil.

[0065] Any oil residue or bitumen from the disclosed plant sources is a suitable source of crude sterols. U.S. Patent No. 2,715,638, issued to Albrecht on August 16, 1955, discloses a method for recovering sterols from tall oil bitumen, wherein fatty acid impurities are removed by a neutralization process. Subsequently, the sterol esters are saponified; then the free sterols are recovered and washed with isopropanol and dried.

[0066] Crude sterols are preferably obtained from plant sources. Crude sterols may include components other than the desired sterols or sterols. Exemplary plant sources for crude sterols include tall oil pitch, crude tall oil, sugarcane oil, hot well skimming, cottonseed pitch, soybean pitch, corn oil pitch, wheat germ oil, or rye germ oil. In some embodiments, tall oil pitch is a source of crude sterols. Tall oil pitch may include about 30% to 40% unsaponifiable molecules. Unsaponifiables are molecules that do not react with alkali metal hydroxides. The fats and rosin acids retained in tall oil pitch readily react with potassium hydroxide or sodium hydroxide, thus the unsaponifiables can be easily separated. It has been shown that 45% of the unsaponifiable fraction may include sitosterols. Therefore, a tall oil pitch sample may contain about 13.5% to 18% by weight of sterol molecules. In some embodiments, crude sterols may have a purity lower than that of food grade (e.g., less than 85 wt% sterols) or contain more than 85 wt% sterols, but may also contain impurities or contaminants that make the material unsuitable for use in food.

[0067] In some embodiments, crude sterols may be of animal origin. In some embodiments, crude sterols are cholesterol.

[0068] It should be understood that the disclosed sterols can be used in any combination, including animal-derived, plant-derived, pure, or crude. For example, in some embodiments, the sterol is a pure sterol derived from a plant. In some embodiments, the sterol is a pure sterol that is a combination of plant-derived and animal-derived sterols. In some embodiments, the sterol is a crude sterol derived from a combination of plant-derived and animal-derived sterols.

[0069] The sterols added to the asphalt binder may be, for example, about 0.5 wt% to about 15 wt%, about 1 wt% to about 10 wt%, or about 1 wt% to about 3 wt% of the binder in the asphalt. In some embodiments, the sterols added to the asphalt binder may be, for example, about 0.5 wt% to about 15 wt%, about 1 wt% to about 10 wt%, or about 1 wt% to about 3 wt% of the original binder in the asphalt.

[0070] In some embodiments, the sterols are mixtures of sterols, wherein the pure sterols added to the asphalt binder: the crude sterol mixture may be, for example, from about 0.5 wt% to about 15 wt%, or from about 1 wt% to about 10 wt%, or from about 1 wt% to about 3 wt% of the original binder in the asphalt composition. In some embodiments, the sterol mixture comprises a pure sterol to crude sterol in a ratio of 10:90 to 90:10. In some embodiments, the sterol mixture comprises a pure sterol to crude sterol in a ratio of at least 20:80, 30:70, or 40:60, and in some embodiments, comprises a pure sterol to crude sterol in a ratio of less than 80:20, 70:30, or 60:40.

[0071] In some embodiments, sterols can alter, reduce, or delay the degradation of rheological properties caused by the aging of binders containing a combination of recycled bitumen materials (such as RAS and / or RAP) and softeners, such as REOB, virgin paraffinic or naphthenic oils, untreated or unrefined waste oil or waste engine oil materials, vacuum tower bitumen extenders, paraffinic or naphthenic processing oils, or lubricating base oils.

[0072] In some embodiments, sterols can alter, reduce, or delay the degradation of rheological properties caused by the aging of binders containing a combination of recycled bitumen materials (such as RAS and / or RAP) and softeners (such as bio-derived oils) or additives. Such bio-derived oils or additives include oils or esters derived from natural or biological resources, including derivatives or modifiers thereof. Non-limiting examples of bio-derived oils or additives include one or more of vegetable oils or esters thereof, seed oils or esters thereof, soybean oil or esters thereof, corn oil or esters thereof, cashew oil or esters thereof, palm oil or esters thereof, rapeseed oil or esters thereof, safflower oil or esters thereof, sunflower oil or esters thereof, citrus oil or esters thereof, pine oil or esters thereof, rosin oil or esters thereof, or bio-derived fatty acid esters. Exemplary commercially available bio-derived oils or additives include those from Cargill Incorporated available in Agri-Pure Gold™ (e.g., Agri-Pure Gold 53, 55, 63S, 67, 135, 142S, 200, 500, 750S, and 2000) and Anova™ brand bitumen bio-derived agents.

[0073] In the embodiments, sterols can alter, reduce, or delay the degradation of rheological properties caused by the aging of binders containing recycled bitumen materials (such as RAP, RAS, or combinations of RAP and RAS) or by the aging of softeners combined with RAP, RAS, or combinations of RAP and RAS.

[0074] adhesive

[0075] The adhesives used in this application may include any adhesives known in the art that are naturally occurring or manufactured in any region. Bituminous adhesives include petroleum-based adhesives. Suitable bituminous or bituminous adhesives include those conforming to ASTM D-6373, D-3387, D-946, AASHTO M320, M332, M226, or M20.

[0076] Some asphalt pavements may include recycled materials, such as RAP and RAS, as components of the asphalt pavement. Typically, RAP concentrations can be as high as 50%, and RAS concentrations can be as high as 6% by weight of the pavement mixture. Typical binder RAP content ranges from 4% to 6% by weight, and typical binder RAS content ranges from 20% to 25% by weight. Therefore, a mixture containing 50% RAP by weight will contain 2.5% to 3% RAP binder in the final binder mixture, while a binder mixture containing 6% RAS by weight will contain 1.2% to 1.5% RAS binder in the final binder mixture.

[0077] The sterol-containing binders disclosed in this application can provide recycled bitumen (e.g., RAP or RAS) with improved physical and rheological properties, such as reduced hardness, a more effective temperature range, and desirable low-temperature properties.

[0078] Other additives

[0079] In addition to the disclosed sterol-containing asphalt binder, the asphalt may also contain other components. These other components may include elastomers, non-asphalt binders, adhesion promoters, softeners, regenerators, and other suitable components.

[0080] Useful elastomers include, for example, ethylene-vinyl acetate copolymers, polybutadiene, ethylene-propylene copolymers, ethylene-propylene-diene terpolymers, reactive ethylene terpolymers (such as ELVALOY™), butadiene-styrene block copolymers, styrene-butadiene-styrene (SBS) block copolymers, isoprene-styrene block copolymers, and styrene-isoprene-styrene (SIS) block copolymers, chloroprene polymers (such as chloroprene rubber), etc. Cured elastomer additives may include waste tire rubber materials. For example, see the California Standards Specification 2015 (Section 37, page 423) and Section 39 on Hot Mix Asphalt (starting from page 447), available at http: / / www.dot.ca.gov / dist1 / d1lab / SECTION%2039%20%20HMA.pdf and http: / / caltrans-opac.ca.gov / publicat.htm.

[0081] Asphalt binders can be prepared by mixing or blending sterols with a binder (e.g., a primary binder) to form a mixture or blend. In some embodiments, the mixture or blend can be added to recycled asphalt materials (e.g., RAS and / or RAP) and aggregates. Those skilled in the art will understand that it is possible to add and mix the components in any order. In some embodiments, a method of preparing an asphalt mixture includes mixing or blending sterols with primary asphalt at a temperature of about 100°C to about 250°C or about 130°C to about 200°C. In some embodiments, sterols are mixed with primary asphalt at a temperature of about 125°C to about 175°C, or 180°C to 205°C. In some embodiments, primary asphalt is combined with sterols and a softener. In other embodiments, a primary binder is combined and blended with sterols and aggregates to form an asphalt pavement material. In other embodiments, a primary binder is combined and blended with a binder, sterols, and aggregates extracted from RAP, RAS, or a combination of RAP and RAS to form an asphalt pavement material.

[0082] A mixture of suitable aggregates, including stones, gravel, and sand, is heated to a high temperature of approximately 132°C to 187°C and mixed with a sterol-containing asphalt binder of similar heat until the aggregate particles are coated with the binder. Pavement mixtures produced within this temperature range are typically referred to as hot mixes. The asphalt and aggregate mixture is then applied to a surface using a paving machine, which is typically rolled while still hot using additional equipment. The compacted aggregates and asphalt binder eventually harden upon cooling to form the pavement.

[0083] The disclosed sterol-containing asphalt binder can be applied to the top asphalt layer of a road surface via other processes such as cold mixing, where cold and wet aggregates are mixed with a hot or cold binder. This binder can be an emulsion obtained by dispersing asphalt in water using a suitable surfactant, or a mixture of asphalt and a suitable hydrocarbon solvent (e.g., naphtha, #1 oil, or #2 oil, commonly referred to as lightweight asphalt, to name a few). The emulsified asphalt particles coat and bind the aggregates and remain after the water evaporates. When lightweight asphalt is used, the hydrocarbon solvent evaporates at different rates depending on the solvent's volatility. Regardless of the solvent's volatility, what remains is the paving material, in which the asphalt components gradually harden or stiffen over time as the solvent is removed (e.g., through evaporation).

[0084] Binders can also be foamed and mixed with aggregates to improve coating effectiveness. Some emulsions utilize hydrocarbon solvents in addition to water to produce materials suitable for specific applications. Warm mix technology can also be used to form pavements in which the top asphalt layer includes a sterol-containing asphalt binder.

[0085] In one embodiment, a method for manufacturing a road surface is disclosed, comprising providing a sterol-containing asphalt binder, wherein sterols are added to the original asphalt binder at 0.5 wt% to 15 wt% based on the original asphalt binder; combining the sterol-containing asphalt binder with aggregates to form an asphalt pavement material; applying the asphalt pavement material to an asphalt pavement layer; and compacting the applied asphalt pavement material to form a road surface. In some embodiments, the asphalt pavement material may be compacted to form a road surface to a suitable density, typically 89% or higher of the maximum theoretical density depending on the aggregate gradation and location within the pavement layer, to form the road surface.

[0086] In another embodiment, a method of treating an asphalt-containing surface includes providing a surface treatment comprising an asphalt binder containing sterols, wherein sterols are added to the asphalt binder at a concentration of 0.5 wt% to 15 wt% based on the asphalt binder; and the surface treatment is applied to the surface of an existing pavement.

[0087] In some embodiments, the binder comprises a binder mixture. In some embodiments, the binder mixture comprises a virgin binder and a binder extracted from recycled bitumen. For example, the binder extracted from RAS material may be extracted from manufacturer's asphalt shingle waste, consumer's asphalt shingle waste, or a mixture of binders extracted from both. In some embodiments, the binder mixture may comprise about 60 wt% to about 95 wt% of the virgin binder and sterols, and about 0.5 wt% to about 15.0 wt% of the virgin bitumen. In some embodiments, the binder mixture may further comprise 5 wt% to about 40 wt% of a binder extracted from recycled bitumen (such as RAP or RAS, or a combination of RAP and RAS). It has been shown that sterol additives can improve the high-temperature and low-temperature properties and PG grading of RAP- or RAS-containing bitumen binder mixtures at both the low-temperature and high-temperature ends.

[0088] Asphalt pavement material can be used as the top layer of a road surface, with an average thickness, for example, up to about 38 mm or up to about 65 mm. In some embodiments, asphalt pavement material is used as the top layer of a road surface, with an average thickness, for example, up to about 12 mm or up to about 38 mm.

[0089] The parameter Delta Tc (ΔTc) is a measure of the effective response of different binders to aging or the effective influence of different additives on the binder's response to aging. ΔTc is calculated by subtracting the m-critical temperature from the S-critical temperature. Anderson et al., in their 2011 paper, showed that larger ΔTc values ​​were closely related to fatigue cracking in asphalt pavements. Specifically, this study indicated that cracking was likely to occur when ΔTc was 5°C or greater. Anderson et al. used the method of subtracting the S-critical temperature from the m-critical temperature, so a larger positive ΔTc value represented a greater likelihood of fatigue cracking. Since 2011, the asphalt research community has overturned this calculation, and now a larger negative ΔTc value indicates lower binder performance. More recently, research presented by Reinke et al. at the 2016 EE Conference in Prague, Czech Republic, showed that larger negative ΔTc values ​​were closely related to fatigue cracking in two research projects in Minnesota, USA. (Reinke, Hanz, Anderson, Impact of re-refined engine oil bottoms on binder properties and mix performance on two pavements in Minnesota, 6th Eurasphalt and Eurobitume Congress, Prague, June 1-3, 2016, DOI: dx.doi.org / 10.14211 / EE.2016.284). Therefore, in industrial and application use, the ΔTc warning limit is -3°C, and the potential failure value is -5°C. In other words, -5°C is a larger negative value than -3°C, therefore the ΔTc value at -5°C is inferior to the ΔTc value at -3°C.

[0090] To determine the ΔTc parameter, the 4 mm DSR testing procedure and data analysis method from the Western Research Institute were used as described above. The DSR testing procedure and method are also disclosed in international applications PCT / US16 / 37077, filed June 10, 2016; PCT / US2016 / 064950, filed December 5, 2016; and PCT / US2016 / 064961, filed December 5, 2016, all of which are incorporated herein by reference in their entirety.

[0091] The ΔTc parameter can also be determined using a bending beam rheometer (BBR) test procedure based on AASHTO T313 or ASTM D6648. Importantly, when using the BBR test procedure, the test must be performed at a sufficient number of temperatures to obtain results at a hardness failure criterion of 300 MPa and a creep or m-value failure criterion of 0.300, such that one result is below the failure criterion and the other is above the failure criterion. In some cases, for adhesives with ΔTc values ​​less than -5°C, this may require BBR testing at three or more test temperatures. ΔTc values ​​calculated from data that do not meet the above BBR standard requirements may be inaccurate.

[0092] In embodiments, sterol-containing asphalt binders can provide asphalt binder compositions having a ΔTc greater than or equal to -5.0°C. In some embodiments, sterol-containing asphalt binders can provide asphalt binders having a ΔTc greater than or equal to -5.0°C after aging at 75°C for 27, 60, 90, and 152 hours. In other embodiments, when compared to asphalt binders with similar aging levels that do not contain sterols, sterol-containing asphalt binders can provide asphalt binders with a smaller negative ΔTc and a reduced R value after aging. In embodiments, the addition of sterol-containing asphalt binders can provide asphalt binder compositions, pavements, or surface treatments with a ΔTc of -5.0°C to +5°C, -4°C to +4°C, or -3°C to +5°C.

[0093] lotion

[0094] While asphalt-containing emulsions can be used in road construction, emulsions are typically used for applying asphalt surface treatments. Typical emulsions include aqueous emulsions, in which asphalt binder particles are dispersed in water containing one or more emulsifiers.

[0095] Emulsifiers used in emulsions can include any known cationic, anionic, nonionic, or amphoteric surfactant. In paving applications, asphalt emulsions are classified in ASTM D977 and D2397 according to the time required for “setting” or “curing”: fast setting (RS), medium setting (MS), or slow setting (SS). Emulsions cure by evaporating water. Some emulsions, such as cationic emulsions, also cure by electrochemical deposition of dispersed asphalt particles on the aggregate surface. This is a coagulation process, as asphalt particles migrate to the aggregate surface and then aggregate to form a uniform asphalt layer. This can be considered a chemical “breakdown.” In any case, before the emulsion can cure or set, it typically breaks down by separating water from the asphalt particles. The demulsification time is determined by the stability of the emulsion; the more stable the emulsion, the longer the demulsification time. Emulsifiers can also be classified as cationic, anionic, nonionic, or amphoteric based on their surface charge (or lack thereof). By combining surface charge properties with setting time, emulsifiers used in paving applications can be classified, for example, into cationic fast setting (CRS), cationic medium setting (CMS), and cationic slow setting (CSS). These classifications are known in the art and can be readily measured according to ASTM D977 and D2397.

[0096] The asphalt emulsion may contain other reagents, such as the polymers, solvents and other additives described in this application.

[0097] The surface treatment disclosed in this application is an aqueous emulsion comprising a sterol-containing asphalt binder. The binder can be formed by mixing sterols into an asphalt binder (e.g., a primary binder). The sterol-containing binder is then dispersed in a continuous aqueous phase with the aid of an emulsifier. The emulsifier and preheated asphalt are typically pumped into a colloid mill, where high-shear mixing produces an asphalt emulsion with asphalt droplets dispersed in water.

[0098] In microsurface formulations, and optionally in slurry seal operations, the asphalt emulsion is polymer-modified, for example, to increase the strength and durability of the resulting asphalt-based cold-pave formulations and to reduce the curing time of these formulations.

[0099] Suitable polymer lattices for microsurface layer formulations include cationic SBR (styrene-butadiene rubber) lattices, natural rubber lattices, and polychloroprene lattices (e.g., NEOPRENE available from Denka Performance Elastomer LLC). TM(Crystal lattice). SBS (poly(styrene-butadiene-styrene)) block copolymers and copolymers such as ethylene, ethylene vinyl acetate (EVA), glycidyl methacrylate terpolymers or ethylene, n-butyl acrylate (nBA), glycidyl methacrylate terpolymers can also be used, but they must typically be added slowly to heated asphalt (e.g., 160°C–170°C) followed by high-shear mixing to disperse the polymer in the asphalt before forming an asphalt emulsion. Commercially available terpolymers include ELVALOY™ from EIDuPont de Nemour.

[0100] The sterol-containing emulsion preferably comprises about 0.1 wt% to about 10 wt% of a surfactant, 55 wt% to 95 wt% of a sterol-containing bituminous binder, and water to make up the total amount. Before applying the emulsion, the surface to be treated is typically cleaned to remove excess surface dirt, weeds, and contaminants by, for example, brushing, spraying with compressed air, or washing the surface.

[0101] The emulsion can be applied to a porous surface using any suitable method, such as brushing, wiping, scratching, or spraying. Spraying is a preferred method for emulsion application because a thin emulsion layer can be applied in a short time. The emulsion is preferably applied at a temperature between 10°C (15°F) and 93°C (200°F) or between 15°C (60°F) and 87°C (190°F). Ideally, the emulsion has a viscosity at the application temperature that allows it to be sprayed onto the surface, and preferably a viscosity of 1 to 5 centipoise.

[0102] In-situ cold recycling

[0103] The sterol-containing asphalt binder disclosed in this application can also be used in any cold in-situ recycling (CIR) process known in the art. CIR involves removing, reprocessing, and reusing a portion of an existing asphalt surface without using heat. CIR processes can be economical because they can reduce costs, for example, by reusing existing materials, minimizing the use of new materials, reducing material transport and delivery requirements, and by not heating the materials. CIR may include removing the top few inches of an existing asphalt pavement. Among other things, CIR can be used to form new pavement layers using old pavement, remove cracks, ruts, and potholes, and repair pavements. In some embodiments, the top 1 inch, or more, up to the top 6 inches, or less may be removed. Removal in CIR is typically performed by milling or grinding. Ideally, milling is performed using a milling machine or a machine called a recycling machine.

[0104] As the name suggests, CIR (Continuous In-Process) gradation is performed in a continuous process. The removed material typically passes through a crusher, which is part of a CIR paving machine series, before being mixed with the emulsion or foamed asphalt. The removed material can then be crushed and / or graded to produce the desired gradation. The desired gradation can be specified only by the maximum particle size. One example of gradation is when the nominal size of the removed material is less than 1¼ inches. Another example is when the nominal size of the removed material is less than 1 inch. The original aggregate can be added to the removed material.

[0105] The material can then be mixed with an asphalt emulsion containing a sterol-based asphalt binder, lime, Portland cement, or fly ash. This mixing can be carried out using any machine known in the art, including but not limited to milling machines or mixers. The material can then be returned to a milled surface and graded. Examples of machines that can be used for these steps are asphalt pavers and electric graders.

[0106] Lightweight

[0107] In some embodiments, the sterol-containing bitumen binder is diluted with a solvent or "lightened" as part of a composite composition or network, which may further include functional additives (e.g., polymers and surfactants) and inert additives (e.g., filler clays and cellulose fibers). These additives are included in the lightened formulation to provide a composition with specific functional properties, such as viscosity, elastic adhesion, and curing rate.

[0108] Lighter bitumen is used because its viscosity is lower than that of net bitumen, making it suitable for low-temperature applications. After the application of lighter bitumen, the solvent evaporates at varying rates depending on the volatility of the solvent used to produce it. As the solvent evaporates, the viscosity of the remaining bitumen binder increases, leading to a more stable mixture with the aggregate. The process of lighter bitumen "curing" occurs when the petroleum solvent has evaporated.

[0109] Exemplary light solvents include petroleum solvents, light cycle oil (LCO), and #2 diesel fuel oil naphtha, #1 oil, or #2 oil, to name just a few.

[0110] The types of lightweight bitumen are defined by the American Society for Testing and Materials (ASTM) as follows:

[0111] SC = Slow-curing type (paving asphalt): ASTM D-2026-72

[0112] MC = Medium-speed curing type: ASTM D-2027-76

[0113] RC = Fast Curing Type: ASTM D-2028-76

[0114] Lightweight asphalt may contain, for example, 50 wt% to 96 wt% asphalt binder, 70 wt% to 90 wt% asphalt binder, or 75 wt% to 85 wt% asphalt binder, with the remainder being lightweight solvents. Furthermore, lightweight asphalt may contain conventional amounts of anti-adhesion agents or other additives.

[0115] mezzanine

[0116] The disclosed sterol-containing bitumen binder can also be used as a sandwich layer. Figure 1C The diagram illustrates an interlayer that can be placed between an old asphalt pavement and a newly applied asphalt layer. Interlayers are typically asphalt mixtures with a high binder content.

[0117] In one exemplary embodiment, the interlayer mixture contains 6% to 12% polymer-modified binder and 88% to 94% pulverized aggregate. The binder is produced by modifying the original binder with an elastomer and a mixture of 0.5% to 15% sterols. Examples of material requirements can be found in Iowa DOT Specification SS-15006, “Supplemental Specifications for Hot Mix Asphalt Interlayer.” In some embodiments, the bitumen binder (modified or unmodified polymer) contains the disclosed sterols.

[0118] Example

[0119] The following study shows that, compared to untreated and compacted samples, the presence of sterols in the base bitumen binder used to produce the emulsion delayed the aging of the binder in the top 1 / 2 inch of the compacted sample.

[0120] The asphalt mixture samples used were Wisconsin-grade 3 million equivalent uniaxial load (ESAL) mixtures containing recycled asphalt pavement (RAP), using 4.5 wt% virgin PG 58S-28 asphalt binder to achieve a binder replacement rate of 0.2, resulting in a total binder content of 5.6%. These asphalt mixtures were compacted to the target air void level of 6% to 8% using two rotary compactors (designated T and P according to their initials). The rotary compactor marked T was manufactured by Troxler Electronic Laboratories, Inc. (Research Triangle Park, North Carolina). The rotary compactor marked P was manufactured by Pine Instruments, Inc. (Grove City, Pennsylvania).

[0121] Compact all samples to a height of 95 mm and a diameter of 150 mm. Insert all samples into a sleeve approximately 97 mm high, cut from a 6-inch inner diameter drain pipe with a nominal 1 / 8-inch wall thickness. Leave the top and bottom of the samples exposed. Divide the compacted samples into 3 groups of 20 samples each (10T and 10P). The 20 samples in Group I were not treated and were either oven-aged or naturally aged. Use the equivalent of 0.2 gallons / yd 2 Twenty samples from Group II were treated with a cationic rapid coagulation (CQS) emulsion produced using PG 64S-22 base binder. The concentration was equivalent to 0.2 gallons / day. 2 Twenty samples from Group III were treated with a cationic rapid coagulation (CQS) emulsion produced by PG 64S-22, with 5% phytosterol added prior to emulsification. In each case, the residual percentage of the CQS emulsion was between 65% and 66%. The emulsion was applied by weight to the top of a rotating sample inserted into a drain tube using a foam brush. The top of the rotating sample was the top of a compacted sample removed from a rotating mold. Air voids in all samples were determined using an AASHTO T-166, and a unique alpha numerical identifier assigned to each sample was recorded. The external markings of the drain tube containing each sample were “Untreated,” “CQS,” or “CQS + Sterol,” followed by a T or P followed by the unique numerical identifier assigned to that particular sample.

[0122] The three sample groups (20 samples per group) were further divided into three subgroups of 10 samples each. Each subgroup of 10 samples contained 10 untreated samples, 10 CQS-treated samples, and 10 CQS+sterol-treated samples, and each subgroup of 10 samples contained 5 T samples and 5 P samples. One subgroup of 30 samples was aged in a forced-air oven maintained at 75°C, while the other subgroup of 30 samples was left to age naturally in the open air. After conditioning at 75°C for 27, 60, 90, and 152 days, the oven-conditioned samples were removed from the oven.

[0123] The aging of the samples is accelerated by conditioning them in an oven to stimulate real-world road surface conditions as closely as possible. In real-world conditions, the temperature of the road surface layer decreases with increasing depth from the surface. By encasing the test samples in a PVC sleeve, oxygen is prevented from penetrating the sidewalls of the sample, thus stimulating real-world road surface conditions.

[0124] Tables 1 through 5 summarize the test data obtained from the top ½-inch layer of the binder samples after compaction of untreated CQS emulsion samples and mixtures of CQS emulsions produced from bitumen containing 5% phytosterols.

[0125] Table 1 presents the baseline or control data for all treatments. The data in Table 1 were recovered from a compacted, untreated, and unaged mixed sample.

[0126] Table 1 Properties of untreated and unaged recycled adhesives

[0127]

[0128] Tables 2 through 5 summarize the data for the recovered binder after aging in a forced-air furnace at 75°C for 27, 60, 90, and 152 days. PG gradations at 1.0 kPa and 2.2 kPa provide an indication of the relative change in binder hardness. The higher the temperature at which the binder reaches a hardness of 1.0 kPa or 2.2 kPa, the more aged the binder becomes. The low-temperature hardness critical temperature (S-critical) and relaxation critical temperature (m-critical) tracked changes in the low-temperature gradation of the recovered binder. These values ​​were determined using a 4 mm dynamic shear rheometer, following the method of Sui et al. cited in this application. The parameter denoted as ΔTc is determined by subtracting the m-critical from the S-critical. The more negative the ΔTc result, the more prone the mixture containing that binder becomes to fatigue cracking. A ΔTc value less than -5°C indicates that the mixture is prone to fatigue cracking. The R-value parameter is an indicator of the binder's ability to relax stress. Binders with higher R-values ​​are more difficult to relax stress and therefore more prone to cracking.

[0129] Table 2. Properties of the recycled binder at the top ½ inch of all treated compacted samples after aging at 75°C for 27 days.

[0130]

[0131] Table 3. Properties of the recycled binder at the top ½ inch of all treated compacted samples after aging at 75°C for 60 days.

[0132]

[0133] Table 4. Properties of the recycled binder at the top ½ inch of compacted samples after all treatments were aged at 75°C for 90 days.

[0134]

[0135] Table 5. Properties of the recycled binder at the top ½ inch of all treated compacted samples after aging at 75°C for 152 days.

[0136]

[0137] The data summarized in these tables indicate that, compared to the other two treatments, the binder recovered from the CQS emulsion-treated samples produced from a base binder containing 5% sterols had the lowest m-critical temperature, the smallest negative ΔTc value, and the lowest R value. In each aging step, the sterol-containing treatment delayed the effects of aging caused by temperature regulation and oxidative hardening.

[0138] Figures 2 to 6 The data in Tables 1 through 5, plotted in the figures for ease of interpretation, are shown. For aged asphalt binders, the low-temperature m-critical value ( Figure 2 The m-critical temperature is determined by the low-temperature PG classification of the binder. The m-critical slope is obtained from the slope measured at 60 seconds on the master relaxation modulus curve. The m-critical slope value can be obtained from a bending beam rheometer or test (ASTM D6648) or a 4mm DSR test, as shown in the study by Sui and Farrar of the Western Institute. The easier the binder is to relax stress, the lower its failure temperature. The addition of sterols has been shown to improve the binder's ability to relax stress at both low and medium temperatures.

[0139] Figure 3 This is a graph showing the low-temperature S-critical or hardness critical values ​​at different aging times. Figure 3 The results show that there is a slight variation in the S-critical value between treatments at any given aging time. It is also worth emphasizing that although the S-critical temperature is lower than the m-critical temperature, the PG adhesive specification for the low-temperature failure grade is based on the higher of these two low-temperature values. Therefore, if the additive can slow down the rate of m-critical value degradation, then the adhesive will have better low-temperature performance.

[0140] Figure 4 This is a graph showing the ΔTc values ​​at different aging times. Figure 4 The initial addition (at 27 days) of CQS and CQS+sterol emulsions to the mixed samples improved the initial ΔTc values ​​of both treatments relative to time zero. The recovered binder from the untreated samples showed a ΔTc reduction of more than 2°C, while the ΔTc reduction of the standard CQS-treated samples was only about 0.5°C. The ΔTc value of the CQS+sterol-treated samples increased by 0.6°C. The additional bitumen binder added to the initial samples resulted in a lower aging rate for the CQS-treated samples, and this additional bitumen binder, combined with the effect of the sterols, led to an improvement in the ΔTc of the recovered binder after 27 days of aging relative to the zero-day aged mixture. After 60 and 90 days of aging, the ΔTc values ​​of the binder recovered from the CQS+sterol-treated samples remained greater than -5°C compared to the ΔTc of the untreated and CQS-treated samples. Even after 152 days of aging, the CQS+sterol-treated samples still exhibited better ΔTc values ​​compared to the other treatments.

[0141] Figure 5 This is a plot of the rheological index, or R-value, of the adhesive under different treatments. The R-value is another indicator of the adhesive's ability to relax stress. As the R-value increases, the adhesive's ability to relax stress decreases. Ideally, the R-value should be kept below 3; and as... Figure 5 As shown, the initial application of emulsion treatment lowered the R values ​​for both treatments, but after 60 hours of aging, both the untreated and CQS-treated samples had values ​​greater than 3. Throughout the aging process, the CQS+sterol-treated samples consistently showed superior values ​​compared to the other treatments.

[0142] Figure 6 This is a graph showing the high-temperature PG grading of adhesives recovered from various treatments as a function of aging time. The data shows that the high-temperature grading changes relatively little with aging; however, the CQS+sterol treatment consistently exhibits the lowest high-temperature values. Provided the adhesive's hardness is sufficient to withstand rutting and for a typical Midwestern US climate, all these adhesives possess adequate hardness, the high-temperature properties of the adhesives are not particularly significant.

[0143] Tables 6 and 7 show the properties of the binder recovered from the second ½ inch of the compacted samples after 60 and 152 days of aging. These data were obtained at the aforementioned intervals to show a comparison of the aging of the binder in these layers with that in the top ½ inch of the mixture layer. Except for the ΔTc value of the binder from the second ½ inch of the untreated samples, the properties of these recovered binders were similar at 60 and 152 days. The ΔTc of the untreated samples at 60 days was -3.80 °C, likely due to a higher S-critical value compared to CQS and CQS+sterol treatments. A higher S-critical temperature indicates greater aging relative to the hardness failure temperature of the treated samples and is likely due to more oxygen migration to the second ½ inch of the mixture. Because the untreated samples did not undergo any emulsification treatment, the surface half inch of those untreated samples was more likely to be permeated by oxygen into the mixture. The R-value of the untreated 60-day recycled adhesive was similar to that of the other two treatments, consistent with the similarity of its relaxation properties, and also consistent with the m-critical properties of all three treatments of the second ½-inch recycled adhesive.

[0144] Figure 7 Bar graphs show a comparison of S-critical and m-critical data between the top ½ inch and the second ½ inch of reclaimed adhesive after 60 days of aging. Figure 8 The comparison of ΔTc and R-value properties of the same adhesive after 60 days of aging is shown. Figure 9 and Figure 10 A similar corresponding drawing shows the adhesive recovered from the top and second 1 / 2 inch after aging for 152 days.

[0145] For any treatment, the S-critical value showed almost no change relative to depth, and the CQS+sterol treated m-critical value for the top ½ inch exhibited a lower m-critical value 2.4 °C better than the second ½ inch binder. The fact that the CQS-treated sample exhibited an m-critical value 0.6 °C better than the second half inch recycled binder suggests that the additional binder added to the mixture was not the cause of the greater improvement in the m-critical value in the CQS+sterol sample, and indicates that the fog-sealing application of the sterol-containing emulsion was present in the top half inch layer.

[0146] Figure 8 The data plotted show the ΔTc values ​​of the adhesive for the top and second half-inches after 60 days. The R value for the top half-inch of the sterol-treated mixture was also lower than that for the second half-inch.

[0147] Figure 9 A comparison of S-critical and m-critical values ​​after 152 days of aging is shown. For all treatments in both layers, the S-critical data were very similar. The m-critical values ​​showed significant differences. The second half-inch layer was very similar to the untreated sample, with a slightly warmer m-critical temperature. Compared to the second half-inch, the CQS-treated sample had a 2.67°C lower (i.e., better) m-critical value in the top half-inch (-10.09°C vs. -7.42°C). This can be attributed to the additional bitumen added during fog sealing. However, the CQS+sterol-treated sample had a 2.7°C lower (i.e., better) m-critical value in the top half-inch than the CQS-treated sample alone and a 5.7°C lower (i.e., better) than the second layer of the CQS+sterol-treated sample. This indicates that the sterol-treated sample was present in the top half-inch. The results for the CQS treatment also show that fog sealing is generally present in the top half-inch, highlighting that applying bitumen emulsion alone does not provide the same aging retardation effect as the presence of sterol additives in the treatment.

[0148] Figure 10 The ΔTc and R values ​​of the three treatments were compared after 152 days of conditioning. The ΔTc values ​​of the two layers of the untreated samples and the second half-inch of the CQS and CQS+sterol treated samples were similar, with the emulsion-treated samples showing slightly better values, most likely due to the addition of bitumen to the surface of the samples. The ΔTc of the top half-inch layer of the CQS-treated samples was 2.2°C better than that of the second half-inch binder, but the ΔTc of the top half-inch layer of the CQS+sterol treated samples was 5°C better than that of the second half-inch layer. The R value data also showed similar relative performance. The untreated samples had almost identical R values, while the CQS-treated samples showed a 0.25 R value improvement in the top half-inch binder compared to the second half-inch binder, and the CQS+sterol-treated samples showed a 0.74 R value improvement in the top half-inch binder compared to the binder in the second half-inch.

Claims

1. A method of restoring an existing aged bituminous road surface comprising: constructing a surface treatment of a sterol-containing bituminous binder on a top surface of the existing aged bituminous road surface to provide a surface treated road surface, the constructing comprising the step of applying a sterol-containing bituminous binder emulsion to the top surface of the existing aged bituminous road surface; wherein the bituminous binder emulsion comprises a bituminous binder and 0.5 wt% to 15 wt% sterol additive based on the weight of the bituminous binder; wherein the surface treatment of the sterol-containing bituminous binder comprises the sterol additive and wherein the sterol additive in the surface treatment retards or slows the rate of aging of the underlying layers of the existing aged bituminous road surface, wherein the sterol additive comprises a sterol mixture of pure sterol: crude sterol in a weight ratio of 10:90 to 90:

10.

2. The method of claim 1, wherein, the surface treatment is a microsurfacing layer.

3. The method of claim 1, wherein, the surface treatment is a slurry seal.

4. The method of claim 1, wherein, the surface treatment is a chip seal.

5. The method of claim 1, wherein, the surface treatment is applied as a tack coat.

6. The method of claim 1, wherein, the surface treatment is applied as a fog seal.

7. The method according to any one of claims 1 to 6, characterized in that, the sterol additive is 1 wt% to 10 wt% of the weight of the bituminous binder.

8. The method according to any one of claims 1 to 6, characterized in that, the sterol additive is 1 wt% to 3 wt% of the weight of the bituminous binder.

9. The method according to any one of claims 1 to 6, characterized in that, the sterol additive comprises pure sterol.

10. The method of claim 9, wherein, the pure sterol comprises cholesterol.

11. The method of claim 9, wherein, the pure sterol comprises a mixture of phytosterol and cholesterol.

12. The method according to any one of claims 1 to 6, characterized in that, the sterol additive comprises crude sterol.

13. The method of claim 12, wherein, the crude sterol comprises cholesterol.

14. The method of claim 12, wherein, the crude sterol is obtained from a biologically derived source or from a distillation residue of the biologically derived source.

15. The method of claim 12, wherein, the crude sterol source comprises tall oil pitch.

16. The method of claim 12, wherein, the crude sterol source comprises crude sterol derived from soybean oil.

17. The method of claim 12, wherein, the crude sterol source comprises corn oil.

18. The method of any one of claims 1 to 6, wherein, the sterol-containing bituminous binder emulsion further comprises a recycled bituminous binder selected from a recycled bituminous road surface (RAP), a recycled bituminous shingles (RAS), or a combination of RAP and RAS.

19. The method of claim 18, wherein, the recycled bituminous binder comprises a softening agent.

20. The method of claim 19, wherein, the softening agent is selected from REOB, virgin paraffinic or naphthenic oil, unprocessed or unrefined waste residual oil or waste motor oil material, vacuum tower pitch extender, paraffinic or naphthenic process oil or lubricating base oil or biologically derived oil.

21. The method of claim 1, wherein, the surface treatment is an overlay having a thickness of 12 mm (0.5 inch) to 38 mm (1.5 inch).

22. The method of claim 1, wherein, the surface treatment is an overlay having a thickness of 12 mm (0.5 inch) to 19 mm (0.75 inch).

23. The method of claim 1, wherein, the surface treatment further comprises aggregate.

24. The method of claim 23, wherein, the surface treatment is further compacted.

25. A road surface made according to the method of any one of claims 1 to 24.

Images