Double-waste warm-mixing recycled ultra-thin layer asphalt mixture, preparation method and application thereof

Abstract

This invention relates to the field of transportation pavement recycling technology, specifically to a dual-waste material warm-mix recycled ultrathin-layer asphalt mixture, its preparation method, and its application. The dual-waste material warm-mix recycled ultrathin-layer asphalt mixture comprises: asphalt, finely separated old aggregate, new aggregate, mineral powder, warm-mix recycling modifier, and fiber; wherein the old aggregate is milled waste asphalt surface layer material with particle sizes including 0-3mm, 3-5mm, and 5-10mm; the asphalt is waste tire rubber powder / SBS composite modified high-viscosity, high-rubber asphalt. This dual-waste material warm-mix recycled ultrathin-layer asphalt mixture is an environmentally friendly warm-mix recycled ultrathin-layer asphalt mixture with controllable porosity, stability, and durability. The preparation method of this mixture has the advantages of reducing production and construction temperature, activating aged asphalt, enhancing the deep integration of new and old asphalt, improving recycling rate, and improving road performance to the level of virgin materials. Simultaneously, it also has the advantages of low cost, green environmental protection, and broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of transportation pavement recycling technology, specifically to a warm-mix recycled ultrathin layer asphalt mixture made from two waste materials, its preparation method, and its application. Background Technology

[0002] Traditional asphalt pavement waste recycling still faces many practical problems. First, RAP (Recycled Asphalt Powder) is an irregularly shaped multiphase mixture formed by old asphalt bonding multiple aggregate particles. Agglomeration is one of the most prominent characteristics of RAP. The old material exhibits severe pseudo-particle size and large gradation variability, making quality control difficult. Especially for oil-rich recycled asphalt fine aggregates, the high asphalt content makes deep recycling of the old asphalt difficult, resulting in poor integration of new and old asphalt, leading to low utilization rates or reduced quality, poor economic and social benefits, and resource waste. Simultaneously, the corresponding mix design methods lack a skeletal structure and recycling concept. The interaction and tight bonding between new asphalt and aged asphalt in the old material require specific temperature and time conditions to be fully completed, severely affecting the overall road performance of recycled asphalt mixtures. Compared with asphalt mixtures using only virgin aggregates, the various properties are significantly reduced.

[0003] Waste tires, as consumables and waste materials from vehicle use, can become an environmental pollutant if not properly disposed of. However, if processed into waste tire rubber powder and applied to highway pavement engineering, they can be an excellent renewable resource. This can increase the bonding performance between asphalt and aggregates, reduce noise, control cracks, improve the performance of road surfaces, and extend their service life, showing great promise.

[0004] Ultra-thin overlay technology is a rapid paving and preventative maintenance technology. After treating existing pavement defects, a porous, ultra-tough modified asphalt mixture is prepared by adjusting the aggregate gradation based on high-performance special modified asphalt. This mixture is then applied to a non-stick high-performance tack coat surface using traditional asphalt paving and compaction techniques, followed by a 1.2-2.0cm ultra-tough thin overlay. This overcomes the shortcomings of traditional overlay protection methods, giving the pavement excellent resistance to reflective cracking, low-temperature cracking, fatigue cracking, water damage, and high-temperature stability. Simultaneously, the pavement also provides driving comfort, safety, durability, and quietness.

[0005] In summary, regarding how to fully utilize the respective advantages of "full recycling technology" and "ultra-thin overlay technology," explore the recycling potential of waste tire rubber powder and oil-rich asphalt waste fine aggregates, enhance the performance of high-viscosity, high-rubber asphalt prepared by composite modification of waste tire rubber powder and SBS, increase the content of oil-rich recycled asphalt waste fine aggregates, establish a mix design method for thin-layer overlay recycled mixtures, improve the road performance of thin-layer overlay recycled mixtures, and achieve efficient, high-quality, and high-quantity recycling of milled asphalt pavement materials, meeting the road performance requirements of thin-layer overlays while being energy-saving and environmentally friendly, it is necessary to explore a dual-waste warm-mix recycled ultra-thin layer asphalt mixture and its production preparation method. Summary of the Invention

[0006] The purpose of this invention is to address the technical deficiencies of traditional plant-mixed hot recycled asphalt mixtures and, by combining the advantages of hot-mix thin-layer overlay mixtures, to provide a dual-waste material warm-mix recycled ultra-thin-layer asphalt mixture, its preparation method, and its application. This dual-waste material warm-mix recycled ultra-thin-layer asphalt mixture is an environmentally friendly warm-mix recycled ultra-thin-layer asphalt mixture with controllable porosity, stability, and durability. The preparation method of this mixture has the advantages of reducing production and construction temperatures, activating aged asphalt, enhancing the deep integration of new and old asphalt, improving recycling rate, and improving road performance to the level of virgin materials. At the same time, it also has the advantages of low cost, green environmental protection, and broad application prospects.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a dual-waste warm-mix recycled ultrathin layer asphalt mixture, the dual-waste warm-mix recycled ultrathin layer asphalt mixture comprising: asphalt, finely separated old aggregate, new aggregate, mineral powder, warm-mix recycling modifier and fiber;

[0008] The old aggregate is waste asphalt surface layer milled material, with particle sizes including 0~3mm, 3~5mm and 5~10mm;

[0009] The asphalt is a high-viscosity, high-rubber asphalt modified from waste tire rubber powder / SBS.

[0010] Preferably, the preparation method of the waste tire rubber powder / SBS composite modified high viscosity and high rubber asphalt includes: compounding waste tire rubber powder with SBS at a temperature of 180~200℃, adding chemical additives and base asphalt for shearing, stirring and development.

[0011] Preferably, the waste tire rubber powder has a fineness of 80 mesh and an admixture amount of 15-20% of the total mass of waste tire rubber powder / SBS composite modified high-viscosity high-rubber asphalt.

[0012] Preferably, the SBS is a 791h type linear SBS modifier.

[0013] Preferably, the chemical additive comprises the solid thickener sasobit and the liquid dispersant type 1102C.

[0014] Preferably, the base asphalt is 70# base asphalt.

[0015] Preferably, the new aggregate is basalt with a particle size of 3-5 mm and 5-10 mm.

[0016] Preferably, the warm-mix recycling modifier comprises APTL warm-mix agent, modified epoxy polymer emulsion, aromatic oil, waste rubber powder and recycled oil; the dosage is 1 to 4‰ of the mass of the old aggregate.

[0017] Preferably, the fiber is polyester fiber, and the dosage is 0.2~0.4% of the mass of the warm-mix recycled ultrathin layer asphalt mixture.

[0018] Preferably, the amount of asphalt used is 4-5% of the mass of the warm-mix recycled ultrathin layer asphalt mixture, and the asphalt film thickness is 12-15 μm.

[0019] Preferably, the dual-waste warm-mix recycled ultrathin layer asphalt mixture has a skeleton-filled structure, which is composed of new aggregate with a particle size of 5~10mm and old aggregate with a particle size of 3~5mm and 5~10mm to form a skeleton, and then the voids formed in the skeleton structure are filled by old aggregate with a particle size of 0~3mm, mineral powder and asphalt.

[0020] The porosity of the warm-mix recycled ultrathin layer asphalt mixture made from dual waste materials is 12-15%.

[0021] In a second aspect, the present invention provides a method for preparing a warm-mix recycled ultrathin layer asphalt mixture based on two waste materials as described in the first aspect, the method comprising:

[0022] 1) The finely separated old aggregate is heated in a recycling drum at a temperature of 140~150℃, and the new aggregate is heated in a drying drum at a temperature of 200~250℃;

[0023] 2) Add the old aggregate, new aggregate, mineral powder, warm-mix recycling modifier and fiber from step 1) to the mixing tank and dry mix for 10-15 seconds;

[0024] 3) Add waste tire rubber powder / SBS composite modified high-viscosity high-rubber asphalt to the mixing tank and wet mix for 30-35 seconds;

[0025] The total mixing time is less than 50 seconds.

[0026] Preferably, the old aggregate is waste asphalt surface layer milled material with a particle size including 0~3mm, 3~5mm and 5~10mm.

[0027] Preferably, the new aggregate is basalt with a particle size of 3-5 mm and 5-10 mm.

[0028] Preferably, the warm-mix recycling modifier comprises APTL warm-mix agent, modified epoxy polymer emulsion, aromatic oil, waste rubber powder and recycled oil; the dosage is 1 to 4‰ of the mass of the old aggregate.

[0029] Preferably, the fiber is polyester fiber, and the dosage is 0.2~0.4% of the mass of the warm-mix recycled ultrathin layer asphalt mixture.

[0030] Preferably, the amount of asphalt used is 4-5% of the mass of the warm-mix recycled ultrathin layer asphalt mixture, and the asphalt film thickness is 12-15 μm.

[0031] Preferably, the aggregates with two particle size ranges—old aggregates with a particle size of 5-10 mm and mixed old and new aggregates with a particle size of 5-10 mm—form a skeleton structure. The method for determining this structure is to treat the aggregates as equivalent to spheres, with the mixed old and new aggregates with a particle size of 5-10 mm completely enclosed by the old aggregates with a particle size of 3-5 mm. The spatial relationship between the two is shown in equations (a)-(c).

[0032]

[0033] In equations (a)-(c):

[0034] P 12 P3 represents the percentage of new and old mixed aggregates with a particle size of 5-10mm; P4 represents the percentage of RAP aggregates with a particle size of 3-5mm.

[0035] ρ 12 ρ3 represents the apparent relative density of the mixed new and old aggregates with a particle size of 5-10 mm; ρ3 represents the apparent relative density of the RAP aggregates with a particle size of 3-5 mm.

[0036] r i The sieve aperture size is (mm); r i+1 The size of the sieve aperture (mm) of the previous sieve in the i-th sieve;

[0037] Q i For a mixture of new and old aggregates with a particle size of 5~10mm, screen mesh r i sieve residue (%); W i The percentage of old aggregate with a particle size of 3~5mm retained on a sieve with a mesh size of ri.

[0038] d 12 d1 represents the average particle size of the mixed new and old aggregates with a particle size of 5~10mm; d2 represents the average particle size of the old aggregates with a particle size of 3~5mm.

[0039] V 12V1 represents the porosity (%) of the mixed new and old aggregates with a particle size of 5-10 mm, and V2 represents the porosity (%) of the old aggregates with a particle size of 3-5 mm.

[0040] Preferably, the relationship between the proportions of asphalt, new aggregate, old aggregate, and mineral powder and the spatial volume parameters is shown in equations (d)-(g):

[0041]

[0042] P4 represents the percentage of old aggregate with a particle size of 0-3mm; P5 represents the percentage of mineral powder; P6 represents the percentage of asphalt content.

[0043] ρ4 is the relative density of old aggregate with a particle size of 0~3mm; ρ5 is the relative density of mineral powder; ρ6 is the relative density of asphalt; ρ 123 The relative density of the composite aggregate is that of old aggregate with a particle size of 3-5 mm and a mixture of old and new aggregate with a particle size of 5-10 mm; ρ sc The compaction relative density is calculated by combining old aggregates with a particle size of 3-5 mm and a mixture of old and new aggregates with a particle size of 5-10 mm.

[0044] VV is the porosity (%) of asphalt mixture; VCA is the porosity (%) of the skeleton after filling with old aggregate with a particle size of 3~5mm and new and old aggregate mixture with a particle size of 5~10mm.

[0045] The compacted relative density is the density measured by 50 single-sided compaction tests using the Marshall compaction method.

[0046] Preferably, when designing the mix proportion of the warm-mix recycled ultra-thin overlay asphalt mixture, the total asphalt content should be estimated based on the average asphalt film thickness of 13.5 μm (12-15 μm) and the aggregate surface area. The calculation model is shown in equations (h)-(j):

[0047] (h): OAC (%) = Assumed film thickness × aggregate surface area × asphalt density (g / cm³) 3 ) / 10;

[0048] Aggregate surface area (m²) 2 / kg)=(0.41a+0.41b+0.82c+1.64d+2.87e+6.14f+12.29g+32.77h) / 10 2 ;

[0049]

[0050] In equation (h)-(j):

[0051] a, b, c, d, e, f, g, and h represent the percentage of sieve openings (%) with apertures of 9.5 mm, 4.75 mm, 2.36 mm, 1.18 mm, 0.6 mm, 0.3 mm, 0.15 mm, and 0.075 mm, respectively.

[0052] OAC represents the estimated total asphalt usage (%); OAC1 represents the estimated asphalt usage (%); OAC2 represents the asphalt usage of the old aggregate (%).

[0053] R2 represents the asphalt content (%) of old aggregate with a particle size of 5-10 mm; R3 represents the asphalt content (%) of old aggregate with a particle size of 3-5 mm; and R4 represents the asphalt content (%) of old aggregate with a particle size of 0-3 mm.

[0054] Thirdly, the present invention provides an application of the dual-waste warm-mix recycled ultrathin layer asphalt mixture as described in the first aspect in the field of highway maintenance.

[0055] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0056] The present invention relates to a dual-waste warm-mix recycled ultrathin layer asphalt mixture, which addresses the technical defects of traditional plant-mixed hot recycled asphalt mixtures and combines the advantages of hot-mix thin layer overlay mixtures. The old material recovered from milling of the asphalt surface layer is separated by a combination of rigid and flexible fine separation equipment to eliminate the agglomerates of the milled old material, and is finely screened and graded to improve the quality stability of the recycled mixture.

[0057] The dual-waste warm-mix recycled ultrathin layer asphalt mixture of the present invention reduces the production and construction temperature, activates aged asphalt, enhances the deep integration of new and old asphalt, and improves the recycling rate by adding a multi-component composite modifier with warm-mix, recycling and strengthening functions. In particular, it increases the amount of fine aggregate of oil-rich RAP asphalt and improves the road performance to the level of new material.

[0058] Meanwhile, the dual-waste warm-mix recycled ultrathin layer asphalt mixture of the present invention makes full use of the high elasticity and SBS properties of waste tire rubber powder, and produces micro-nano activated rubber through green de-crosslinking technology. It is then combined with the base asphalt through high-temperature shearing, stirring and development to prepare micro-nano rubber / SBS composite to form high-viscosity and high-rubber modified asphalt, which improves the internal grid structure and road performance of the high-viscosity modified asphalt.

[0059] Furthermore, in the dual-waste warm-mix recycled ultrathin layer asphalt mixture of the present invention, the coarse aggregate space adopts a skeleton structure system composed of raw material recycled aggregate + new aggregate, and the fine aggregate is filled with oil-rich milled old fine aggregate to form a skeleton filling structure and establish volume relationship. Multi-element recycled modifier and fiber are added to increase the proportion of structural asphalt, and the relationship between the amount of modifier, new asphalt and the specific surface area of ​​the coated aggregate, mineral powder and fiber is established. The proportion relationship of 5-10mm new material, 5-10mm RAP, 3-5mm RAP, 0-3mm RAP and mineral powder is accurately determined by inverse theoretical formula, forming a mix design method for thin layer overlay warm-mix recycled mixture.

[0060] Furthermore, the preparation method of the dual-waste warm-mix recycled ultrathin layer asphalt mixture of the present invention establishes a mixture modifier dosage design method based on the balance between performance and function by plotting the relationship curve between modifier dosage and high and low temperature performance of the mixture, with the optimal modifier dosage of MD = (MD1 + MD2) / 2 as the balance between high and low temperature performance. This method can ensure the expected performance of the mixture and regulate its performance accordingly.

[0061] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0062] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0063] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0064] The specific plan is as follows:

[0065] (1) The present invention firstly recycles the asphalt surface layer of the highway by separate milling. The recycled old aggregate is separated by a fine separation equipment that combines rigidity and flexibility to remove the clumps of particles, and then finely screened and divided into four grades: 10~15mm, 5~10mm, 3~5mm and 0~3mm.

[0066] (2) Test the old asphalt content, properties and pseudo-particle size of lean coarse aggregate and rich fine aggregate of finely separated old aggregate (hereinafter referred to as "RAP"), and classify finely separated old aggregate into grades I-II for management and application according to indicators such as pseudo-particle size (gradation fluctuation difference) and asphalt content, and establish corresponding standards to ensure the gradation stability of warm-mix recycled thin-layer overlay asphalt mixture during construction and eliminate the impact of milled old aggregate agglomerates on the quality of the mixture.

[0067] (3) Based on the highway grade, traffic volume, old material content and surface wear layer application scenario, select three grades of RAP with particle size of 0~3mm, 3~5mm and 5~10mm and new aggregate with particle size of 5~10mm to form the aggregate of warm mix recycled ultra-thin layer overlay asphalt mixture.

[0068] (4) Based on the performance of the old asphalt detected in step (2), the type and amount of the old material recycling agent are determined by the performance and function balance design method, so as to restore the performance of the old asphalt, activate the aged asphalt, enhance the fusion of new and old asphalt, improve the recycling rate, and improve the road performance to the level of new material.

[0069] (5) Test the performance of the old asphalt after step (4), establish the relationship between the four performance indicators of the old asphalt softening point, ductility, penetration and dynamic viscosity at 60℃ and the type and amount of warm mix recycling modifier, accurately determine the type and amount of warm mix recycling modifier, and improve the performance level of the old asphalt to high viscoelasticity modified new asphalt.

[0070] (6) Waste tire rubber powder / SBS composite modified high-viscosity high-rubber asphalt is a green high-viscosity high-rubber modified asphalt prepared by using waste rubber powder and SBS as modifiers and base asphalt under high temperature conditions (180~200℃) through shearing, stirring and development processes. Its raw material composition usually includes: base asphalt (70#), rubber powder made from waste tires, SBS, and chemical additives. Taking into account the high elasticity properties of rubber, micro-nano activated rubber is produced through green de-crosslinking technology, and then waste tire rubber powder / SBS composite modified high-viscosity high-rubber asphalt is prepared to improve the internal grid structure of high-viscosity modified asphalt.

[0071] (7) Warm-mixed recycled thin-layer overlay asphalt mixture is a skeleton-filled structure. The new aggregate with a particle size of 5~10mm and the RAP with a particle size of 5~10mm are combined to form a mechanism and volume parameters. The relationship between the proportion of new and old asphalt, new and old aggregate, and mineral powder and the spatial volume parameters is established.

[0072] (8) Establish the optimal structure of the asphalt film, and accurately determine the ratio of new and old aggregates and mineral powder in each grade by using parameters such as porosity, asphalt-aggregate ratio, and fiber as control inputs.

[0073] (9) The mixing plant produces warm-mix recycled ultra-thin layer asphalt mixtures of two waste materials. The mixing process is as follows: RAP is heated in the recycling drum at a temperature of 140-150℃, and new aggregate is heated in the drying drum at a temperature of 200-250℃. Then, the heated RAP, new aggregate, mineral powder, warm-mix recycled modifier and fiber are added to the mixing drum and dry-mixed for 10-15s. Then, waste tire rubber powder / SBS composite modified high viscosity and high rubber asphalt is added to the mixing drum and wet-mixed for 30-35s. The total mixing time is not more than 50s, so that the mixture is uniformly mixed and free of white spots.

[0074] In a preferred embodiment of the present invention, the new aggregate is basalt.

[0075] In a preferred embodiment of the present invention, the standard for Grade I old aggregate is as follows: for aggregates ≥3mm, the degree of pseudo-particle size (i.e., the gradation fluctuation value) is within 10%, the old asphalt content is ≤1.5%, the crushing value is <26%, and the content of needle-shaped and flaky particles is <15%; for aggregates <3mm, the degree of pseudo-particle size is within 10%, and the sand equivalent is ≥60%.

[0076] The standard for Class II old aggregate is as follows: for aggregates ≥3mm, the degree of pseudo-particle size (i.e., the gradation fluctuation value) is within 10%~15%, the old asphalt content is ≤2.0%, the crushing value is <30%, and the content of needle-shaped and flaky particles is <20%; for aggregates <3mm, the degree of pseudo-particle size is within 10%~15%, and the sand equivalent is ≥50%.

[0077] In a preferred embodiment of the present invention, oil-rich fine aggregate refers to the portion of old asphalt pavement milled material with a particle size of less than 4.75 mm after fine separation, and oil-lean coarse aggregate refers to the portion of old asphalt pavement milled material with asphalt particles larger than 4.75 mm after fine separation.

[0078] In a preferred embodiment of the present invention, the newly added asphalt is a high-viscosity, high-rubber asphalt modified by waste tire rubber powder / SBS, with an asphalt content of 4% to 5% and an asphalt film thickness of 12 to 15 μm.

[0079] In a preferred embodiment of the present invention, the warm mix regeneration modifier is a mixture of conventional APTL warm mix agent, modified epoxy polymer emulsion, aromatic oil, waste rubber powder, and recycled oil. APTL warm mix agent is a surfactant; under mechanical stirring, the uniformly dispersed surfactant micelle aqueous solution contacts the hot asphalt, forming a large amount of structural water film with lubricating function, increasing the mixing workability and compaction ability of the mixture, thereby achieving the desired mixing and compaction temperature. The addition of aromatic oil, waste rubber powder, and recycled oil replenishes the lightweight components in the old asphalt mixture, improving its penetration and ductility, and enhancing the elastic recovery ability of the old asphalt. The addition of modified epoxy polymer emulsion strengthens the binding force of the old asphalt, allowing the regeneration agent to better exert its reinforcing effect in the mixture, improving the overall strength and stability of the mixture.

[0080] In a preferred embodiment of the present invention, the dosage of the warm-mix recycling modifier is 1 to 3‰ of the RAP mass, thereby improving the performance of the RAP recycled asphalt.

[0081] In a preferred embodiment of the present invention, the fiber is polyester fiber, and the fiber content is 0.2 to 0.4% of the mass of the warm-mix recycled ultrathin layer asphalt mixture.

[0082] In a preferred embodiment of the present invention, the mix design method for warm-mix recycled ultrathin layer asphalt mixtures using dual waste materials establishes the optimal structural asphalt film relationship. By using parameters such as porosity, asphalt-aggregate ratio, and fiber as control inputs, the proportions of new and old aggregates and mineral powder at each grade are precisely determined, as follows:

[0083] In a preferred embodiment of the present invention, two coarse aggregates with a RAP particle size of 5-10 mm and a new aggregate particle size of 5-10 mm form a dense skeleton structure. According to the theory of stepwise filling and particle interference, the RAP aggregate with a particle size of 5-10 mm is filled into the new aggregate with a particle size of 5-10 mm in different proportions, and a relationship curve between the filling ratio and the gap ratio is established. The aggregate ratio corresponding to the minimum gap ratio is selected from the relationship curve as the composition ratio of the old and new aggregates when the interlocking dense structure is formed.

[0084] In a preferred embodiment of the present invention, the two aggregate sizes—RAP with a particle size of 3-5 mm and the mixed new and old aggregate with a particle size of 5-10 mm—form a skeleton structure. This structure is determined by treating the aggregate as an equivalent sphere, with the 5-10 mm particle size completely enclosed by the 3-5 mm particle size aggregate. The spatial relationship between the two is as follows:

[0085]

[0086] In the formula:

[0087] P 12 P3 represents the percentage of new and old mixed aggregates with a particle size of 5-10mm; P4 represents the percentage of RAP aggregates with a particle size of 3-5mm.

[0088] ρ 12 ρ3 represents the apparent relative density of the mixed new and old aggregates with a particle size of 5-10 mm; ρ3 represents the apparent relative density of the RAP aggregates with a particle size of 3-5 mm.

[0089] r i The sieve aperture size is in mm; r i+1 Q represents the sieve aperture size of the previous sieve in the i-th sieve, in mm; i For 5-10mm grade mixed aggregates of new and old materials, the screen aperture is r i The sieve residue, %; W i The residue of 3-5mm RAP aggregate at sieve aperture ri, %

[0090] d 12 The average particle size of the mixed new and old aggregates is 5-10 mm.

[0091] d3 is the average particle size of RAP aggregates in the 3-5mm particle size range.

[0092] V 12 V1 represents the porosity (%) of the mixed new and old aggregates with a particle size of 5-10 mm, and V2 represents the porosity (%) of the old aggregates with a particle size of 3-5 mm.

[0093] In a preferred embodiment of the present invention, the relationship between the proportions of new asphalt, new and old aggregates, and mineral powder and the spatial volume parameters is as follows:

[0094]

[0095] P4 represents the percentage of RAP aggregate with a particle size of 0-3mm; P5 represents the percentage of mineral powder.

[0096] P6 represents the asphalt content (%); ρ4 represents the relative density of RAP particles with a diameter of 0-3 mm.

[0097] ρ5 is the relative density of the mineral powder; ρ6 is the relative density of the newly added asphalt.

[0098] ρ 123 The relative density of the composite aggregate is a mixture of new and old aggregates with a particle size of 3-5 mm (RAP) and 5-10 mm (RAP). sc The compaction relative density is calculated by combining RAP with a particle size of 3-5 mm and a mixture of new and old aggregates with a particle size of 5-10 mm.

[0099] VV represents the porosity (%) of asphalt mixture; VCA represents the porosity (%) of the skeleton of coarse aggregate mixtures with particle sizes of 3~5mm and 5~10mm after filling.

[0100] In a preferred embodiment of the present invention, the density of the new and old mixed aggregates with a particle size of 3-5 mm and a particle size of 5-10 mm is calculated by using two proportions of aggregates to form a skeleton structure. The density measured by the Marshall compaction method after 50 single-sided compaction is the compacted relative density.

[0101] In a preferred embodiment of the present invention, the dual-waste warm-mix recycled ultrathin layer asphalt mixture is a porous asphalt mixture with a porosity of 12-15%.

[0102] In a preferred embodiment of the present invention, when designing the mix proportion of the warm-mix recycled ultrathin layer asphalt mixture using dual waste materials, the total asphalt content should be estimated based on the average asphalt film thickness of 13.5 μm (12-15 μm) and the aggregate surface area. The calculation model is as follows:

[0103] OAC (%) = Assumed film thickness × Aggregate surface area × Asphalt density (g / cm³) 3 ) / 10;

[0104] Aggregate surface area (m²) 2 / kg)=(0.41a+0.41b+0.82c+1.64d+2.87e+6.14f+12.29g+32.77h) / 10 2 ;

[0105] In the formula: a, b, c, d, e, f, g, and h represent the percentage of sieve openings (%) with apertures of 9.5 mm, 4.75 mm, 2.36 mm, 1.18 mm, 0.6 mm, 0.3 mm, 0.15 mm, and 0.075 mm, respectively.

[0106] OAC1 = OAC - OAC2;

[0107] Where: OAC1 is the estimated asphalt usage, %; OAC is the estimated total asphalt usage (%).

[0108] OAC2 represents the asphalt content (%) of RAP;

[0109] OAC2 = P2R2 + P3R3 + P4R4 (%)

[0110] In the formula: R2 is the asphalt content (%) of 5-10mmRAP; R3 is the asphalt content (%) of 3-5mmRAP; R4 is the asphalt content (%) of 0-3mmRAP.

[0111] In a preferred embodiment of the present invention, the dosage of the warm-mix recycled asphalt modifier used in the dual-waste warm-mix recycled ultrathin-layer asphalt mixture is 1-4‰ of the RAP mass. The dosage of the separating waste modifier and the warm-mix recycled agent is determined by a performance-functional balance design method, as follows:

[0112] Indoor rutted slab specimens were prepared by incorporating 1-4‰ warm-mix recycled modifier into RAP. The dynamic stability at 60℃ and the failure strain in a bending tensile test at -10℃ were tested for each modifier dosage, varying by ±1‰. Curves showing the relationship between modifier dosage and dynamic stability and failure strain were plotted. The modifier dosage corresponding to the inflection point of the 60℃ dynamic stability curve is designated as MD1, and the modifier dosage corresponding to the inflection point of the -10℃ bending tensile test failure strain curve is designated as MD2. The optimal modifier dosage MD, representing a balance between high and low temperature performance, is as follows:

[0113] MD = (MD1 + MD2) / 2;

[0114] In a preferred embodiment of the present invention, the road performance of the dual-waste material warm-mix recycled ultra-thin layer asphalt mixture is not lower than the performance standard of the virgin material hot-mix thin layer overlay high viscoelastic asphalt mixture, as shown in Table 1:

[0115] Table 1

[0116]

[0117] The present invention will be described in detail below through examples. In the following examples, the pharmaceuticals and agents are all conventional commercially available products.

[0118] Example 1

[0119] The amount of old aggregate added is pre-specified to be 45%.

[0120] First, the collected AC-13 asphalt pavement milling material from the highway surface layer is separated into old aggregates using a fine separation device. The aggregates have particle sizes of 0-3mm, 3-5mm, and 5-10mm, and asphalt contents of 10.57%, 3.98%, and 1.12%, respectively.

[0121] The old aggregate, new aggregate and mineral powder were screened, and the results of the screening test are shown in Table 2.

[0122] Table 2

[0123]

[0124] Extraction tests were conducted on the RAP material. The old asphalt after extraction was recycled and its performance was tested. The test results are shown in Table 3.

[0125] Table 3

[0126]

[0127] The technical specifications of waste tire rubber powder / SBS composite modified high-viscosity high-rubber asphalt are shown in Table 4.

[0128] Table 4

[0129]

[0130] For road sections with obvious cracks, it is advisable to add fibers as toughening agents for the mixture to improve the crack resistance of the ultra-thin overlay mixture. Polyester fibers should be used, and the fiber content should be taken as the median value, which is 0.3% of the mixture mass.

[0131] The following formula is used to calculate:

[0132] The average particle size of the new aggregate with a particle size of 5-10 mm is d1 = 7.06 mm;

[0133] The average particle size of RAP with a particle size of 5~10mm is d2=6.93mm;

[0134] The average particle size of RAP with a particle size of 3~5mm is d3=3.15mm.

[0135]

[0136] A mineral mixture was prepared by mixing new and old aggregates with a particle size of 5-10 mm (RAP content of 45%) and two grades of RAP aggregates with a particle size of 3-5 mm at a ratio of 3.11:1. The mixture was then compacted 50 times on one side, and its compacted relative density ρsc = 1.56 was measured. The combined relative density of the two grades of aggregates was:

[0137]

[0138] Based on the screening results of the aggregates, the specific surface area is calculated using the following formula:

[0139] SA=(0.41a+0.41b+0.82c+1.64d+2.87e+6.14f+12.29g+32.77h) / 10 2 ;

[0140] The specific surface areas of 5-10mm new and old mixed aggregates, RAP 3-5mm, RAP 0-3mm, and mineral powder were calculated respectively, and the results are as follows:

[0141] S12 = 0.74m 2 / kg,

[0142] S3 = 2.75m 2 / kg,

[0143] S4 = 5.88m 2 / kg,

[0144] S5 = 38.73m 2 / kg.

[0145] With a porosity of 13.5%, an asphalt-aggregate ratio of 6.8%, an asphalt film thickness of 13.5 μm, and a fiber incorporation of 0.3%, these parameters are substituted into the equations relating the proportions of asphalt, aggregates, and mineral powder to the volumetric parameters, and the equations relating the total specific surface area of ​​asphalt coating to the specific surface areas of aggregates, mineral powder, and fibers. The resulting equation set is as follows:

[0146]

[0147] Based on the above system of equations, the calculation results are: P5 = 2.4%; P4 = 13.6%; P3 = 30.4%; P 12 =51.6%;

[0148] Based on the above calculation results, a trial mix was conducted within the gradation range, controlling 4.75mm and 2.36mm as the key sieve apertures. The trial mix results are shown in Table 5.

[0149] Table 5

[0150]

[0151] The method for preparing recycled asphalt mixture according to the present invention involves mixing, and the steps are as follows:

[0152] Pour RAP and recycling agent into the mixing pot and dry mix for 100 seconds. Then add new aggregate and mix for 100 seconds. Finally, add mineral powder and waste tire rubber powder / SBS composite modified high viscosity and high rubber asphalt and mix for 100 seconds. The total mixing time is 300 seconds.

[0153] According to design requirements, the asphalt-aggregate ratio of the mixture was selected as 6.8%, with 0.3% polyester fiber added by mass of the mixture. Marshall specimens were formed using a double-sided compaction method, with 50 passes, a mixing temperature of 160℃, and a compaction temperature of 140~145℃. After indoor molding, the specimens underwent high-temperature performance testing (dynamic stability test) and low-temperature performance testing (low-temperature bending test).

[0154] The composite multi-effect warm-mix recycled asphalt mixture used in the warm-mix recycled thin-layer overlay asphalt mixture has a dosage of 1-4‰ of the RAP material. The dosage of the old material modifier and the warm-mix recycled agent is determined by a performance and function balance design method. The high and low temperature performance test results of the mixture with different warm-mix recycled agent dosages are shown in Table 6.

[0155] Table 6

[0156]

[0157] Indoor rutted slab specimens were prepared by incorporating 1-4‰ of a composite multi-effect warm-mix recycling modifier into RAP material. The modifier dosage was varied by ±1‰, and the dynamic stability at 60℃ and the failure strain in a bending tensile test at -10℃ were tested for each dosage. Curves showing the relationship between modifier dosage and dynamic stability and failure strain were plotted. The modifier dosage corresponding to the inflection point of the 60℃ dynamic stability curve was MD1 = 2.2‰, and the modifier dosage corresponding to the inflection point of the -10℃ bending tensile test failure strain curve was MD2 = 2.6‰. The optimal modifier dosage MD, representing a balance between high and low temperature performance, is as follows:

[0158] The optimal modifier dosage MD is calculated as follows: MD=(MD1+MD2) / 2=(2.2+2.6) / 2=2.4‰;

[0159] With an oil-aggregate ratio of 6.8%, an optimal modifier dosage of MD2.4‰, and 0.3% polyester fiber by mass of the mixture, Marshall specimens were molded using a double-sided compaction method with 50 passes. The mixing temperature was 160℃, and the compaction temperature was 140~145℃. The performance of the recycled mixture was verified, and the test results are shown in Table 7.

[0160] Table 7. Test results of the dual-waste material warm-mix recycled ultrathin layer asphalt mixture in this embodiment.

[0161]

[0162] It is evident that the double-waste warm-mix recycled ultrathin layer asphalt mixture prepared in this embodiment meets the standards.

[0163] Example 2

[0164] The RAP content is pre-specified to be 60%.

[0165] Based on the calculation results of each material grade, 4.75mm and 2.36mm were controlled as the key sieve openings within the gradation range to form a trial gradation. The trial gradation results are shown in Table 8.

[0166] Table 8 Results of the Trial Mixing Proportion of Synthetic Gradients

[0167]

[0168] The composite multi-effect warm-mix recycled asphalt mixture used in the aforementioned warm-mix recycled thin-layer overlay asphalt mixture has a dosage of 1-4‰ of RAP. The dosage of the old material modifier and the warm-mix recycled agent is determined by a performance and function balance design method, and the optimal modifier dosage MD is 2.1‰.

[0169] With an oil-aggregate ratio of 6.8%, an optimal modifier dosage of MD2.1‰, and 0.3% polyester fiber by mass of the mixture, Marshall specimens were molded using a double-sided compaction method with 50 passes. The mixing temperature was 160℃, and the compaction temperature was 140~145℃. The performance of the recycled mixture was verified, and the test results are shown in Table 9.

[0170] Table 9 Test Results of Warm-Mixed Recycled Ultra-Thin Layer Asphalt Mixtures Composed of Two Waste Materials

[0171]

[0172] It is evident that the double-waste warm-mix recycled ultrathin layer asphalt mixture prepared in this embodiment meets the standards.

[0173] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0174] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0175] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A warm-mix recycled ultrathin layer asphalt mixture using two waste materials, characterized in that, The dual-waste warm-mix recycled ultrathin layer asphalt mixture includes: asphalt, finely separated old aggregate, new aggregate, mineral powder, warm-mix recycling modifier, and fiber; The old aggregate is waste asphalt surface layer milled material, with particle sizes including 0~3mm, 3~5mm and 5~10mm; The asphalt is a waste tire rubber powder / SBS composite modified high-viscosity, high-rubber asphalt. The new aggregate is basalt with a particle size of 5-10 mm. The warm-mix recycling modifier comprises APTL warm-mix agent, modified epoxy polymer emulsion, aromatic oil, waste rubber powder and recycled oil; the dosage is 1-4‰ of the mass of old aggregate; The aforementioned dual-waste warm-mix recycled ultrathin layer asphalt mixture has a skeleton-filled structure, consisting of new aggregate with a particle size of 5-10mm and old aggregate with particle sizes of 3-5mm and 5-10mm, forming a skeleton, and then old aggregate with a particle size of 0-3mm, mineral powder and asphalt filling the voids formed in the skeleton structure state. The porosity of the warm-mix recycled ultrathin layer asphalt mixture made from two waste materials is 12-15%. The aggregates with particle sizes of 3-5 mm (old aggregate) and 5-10 mm (mixed new and old aggregate) form a skeleton structure. The method for determining this structure is to treat the aggregates as equivalent to spheres, with the 5-10 mm mixed new and old aggregate completely enclosed by the 3-5 mm old aggregate. The spatial relationship between the two is shown in equations (a)-(c). （a）： ； （b）： ； （c）： ； In equations (a)-(c): P 12 P3 represents the percentage of new and old mixed aggregates with a particle size of 5-10mm; P4 represents the percentage of RAP aggregates with a particle size of 3-5mm. ρ 12 ρ3 represents the apparent relative density of the mixed new and old aggregates with a particle size of 5-10 mm; ρ3 represents the apparent relative density of the RAP aggregates with a particle size of 3-5 mm. r i The sieve aperture size is (mm); r i+1 The size of the sieve aperture (mm) of the previous sieve in the i-th sieve; Q i For a mixture of new and old aggregates with a particle size of 5~10mm, screen mesh r i sieve residue (%); W i The percentage of old aggregate with a particle size of 3~5mm retained on a sieve with a mesh size of ri. d 12 d1 represents the average particle size of the mixed new and old aggregates with a particle size of 5~10mm; d2 represents the average particle size of the old aggregates with a particle size of 3~5mm. V 12 V1 represents the porosity (%) of the mixed new and old aggregates with a particle size of 5-10 mm, and V2 represents the porosity (%) of the old aggregates with a particle size of 3-5 mm.

2. The dual-waste material warm-mix recycled ultrathin layer asphalt mixture according to claim 1, characterized in that, The preparation method of the waste tire rubber powder / SBS composite modified high-viscosity, high-rubber asphalt includes: compounding waste tire rubber powder with SBS at a temperature of 180~200℃, adding chemical additives and subjecting the mixture to shearing, stirring, and development with the base asphalt; and / or, The waste tire rubber powder has a fineness of 80 mesh and is added at a rate of 15-20% of the total mass of waste tire rubber powder / SBS composite modified high-viscosity, high-rubber asphalt; and / or, The SBS is a 791h type linear SBS modifier; and / or, The chemical additives include the solid thickener Sasobit and the liquid dispersant type 1102C; and / or, The base asphalt is 70# base asphalt.

3. The dual-waste warm-mix recycled ultrathin layer asphalt mixture according to claim 1 or 2, characterized in that, The fiber is polyester fiber, and its dosage is 0.2~0.4% of the mass of the warm-mix recycled ultrathin layer asphalt mixture; and / or, The amount of asphalt used is 4-5% of the mass of the warm-mix recycled ultrathin layer asphalt mixture made from waste materials, and the asphalt film thickness is 12-15μm.

4. A method for preparing a warm-mix recycled ultrathin layer asphalt mixture based on any one of claims 1-3, characterized in that, The preparation method includes: 1) The finely separated old aggregate is heated in a recycling drum at a temperature of 140~150℃, and the new aggregate is heated in a drying drum at a temperature of 200~250℃; 2) Add the old aggregate, new aggregate, mineral powder, warm-mix recycling modifier and fiber from step 1) to the mixing tank and dry mix for 10-15 seconds; 3) Add waste tire rubber powder / SBS composite modified high-viscosity high-rubber asphalt to the mixing tank and wet mix for 30-35 seconds; The total mixing time is less than 50 seconds.

5. The preparation method according to claim 4, characterized in that, The old aggregate is milled waste asphalt surface layer material, with particle sizes including 0~3mm, 3~5mm and 5~10mm; and / or, The new aggregate is basalt with a particle size of 5-10 mm; and / or, The warm-mix recycling modifier comprises APTL warm-mix agent, modified epoxy polymer emulsion, aromatic oil, waste rubber powder, and recycled oil; the dosage is 1-4‰ of the old aggregate mass; and / or, The fiber is polyester fiber, and its dosage is 0.2~0.4% of the mass of the warm-mix recycled ultrathin layer asphalt mixture; and / or, The amount of asphalt used is 4-5% of the mass of the warm-mix recycled ultrathin layer asphalt mixture made from waste materials, and the asphalt film thickness is 12-15μm.

6. The preparation method according to claim 4, characterized in that, asphalt The relationship between the proportions of new aggregate, old aggregate, and mineral powder and the spatial volume parameters is shown in equations (d)-(g): (d):P 12 +P3+P4+P5+P6=100; （e）： ； （f）： ； （g）： ； P4 represents the percentage of old aggregate with a particle size of 0-3mm (%); P5 represents the percentage of mineral powder (%); P6 represents the percentage of asphalt content (%). ρ4 is the relative density of old aggregate with a particle size of 0~3mm; ρ5 is the relative density of mineral powder; ρ6 is the relative density of asphalt; ρ 123 The relative density is calculated by combining old aggregates with a particle size of 3-5 mm and mixed old and new aggregates with a particle size of 5-10 mm. ρ sc The compaction relative density is calculated by combining old aggregates with a particle size of 3-5 mm and a mixture of old and new aggregates with a particle size of 5-10 mm. VV is the porosity (%) of asphalt mixture; VCA is the porosity (%) of the skeleton after filling with old aggregate with a particle size of 3~5mm and new and old aggregate mixture with a particle size of 5~10mm. The compacted relative density is the density measured by the Marshall compaction method after 50 compactions on one side.

7. The preparation method according to claim 6, characterized in that, The mix design of the warm-mix recycled ultra-thin overlay asphalt mixture is based on the average asphalt film thickness of 13.5 μm (12~15 μm) and the aggregate surface area to estimate the total asphalt content. The calculation model is shown in equations (h)-(j): (h): OAC (%) = Assumed film thickness × aggregate surface area × asphalt density (g / cm³) 3 ) / 10; Aggregate surface area (m²) 2 / kg)=(0.41a+0.41b+0.82c+1.64d+2.87e+6.14f+12.29g+ 32.77h) / 10 2 ; (i): OAC1 = OAC - OAC2; (j): OAC2=P2R2+P3R3+P4R4; In equation (h)-(j): a, b, c, d, e, f, g, and h represent the percentage of sieve openings (%) with apertures of 9.5 mm, 4.75 mm, 2.36 mm, 1.18 mm, 0.6 mm, 0.3 mm, 0.15 mm, and 0.075 mm, respectively. OAC represents the estimated total asphalt usage (%); OAC1 represents the estimated asphalt usage (%); OAC2 represents the asphalt usage of the old aggregate (%). R2 represents the asphalt content (%) of old aggregate with a particle size of 5-10 mm; R3 represents the asphalt content (%) of old aggregate with a particle size of 3-5 mm; and R4 represents the asphalt content (%) of old aggregate with a particle size of 0-3 mm.

8. The application of a dual-waste warm-mix recycled ultrathin layer asphalt mixture as described in any one of claims 1-3 in the field of highway maintenance.

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