Double-waste-material warm-mixing regenerated ultrathin-layer asphalt mixture as well as preparation method and application thereof

Abstract

The invention relates to the technical field of traffic and transportation pavement regeneration, in particular to a double-waste-material warm-mixing regenerated ultra-thin-layer asphalt mixture and a preparation method and application thereof.The double-waste-material warm-mixing regenerated ultra-thin-layer asphalt mixture comprises asphalt, finely-separated old aggregate, new aggregate, mineral powder, a warm-mixing regenerated modifier and fibers; wherein the old aggregate is a waste asphalt upper surface layer milling material, and the particle sizes of the old aggregate include 0-3 mm, 3-5 mm and 5-10 mm; the asphalt is waste tire rubber powder / SBS composite modified high-viscosity high-glue asphalt. The double-waste-material warm-mixing regenerated ultrathin-layer asphalt mixture is an environment-friendly warm-mixing regenerated ultrathin-layer asphalt mixture which is controllable in gap, stable and durable, and the preparation method of the mixture has the advantages that the production and construction temperature is reduced, the aged asphalt is activated, the deep fusion of new asphalt and old asphalt is enhanced, the regeneration utilization rate is increased, and the service life of the mixture is prolonged. Meanwhile, the low-cost environment-friendly pavement material also has the advantages of low cost, environment friendliness and wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of transportation pavement regeneration, and in particular to a double-waste material warm-mix recycled ultra-thin layer asphalt mixture, and a preparation method and application thereof. Background Art

[0002] The recycling of waste asphalt pavement materials from traditional construction still faces numerous practical challenges. First, RAP is an irregularly shaped, multiphase mixture composed of old asphalt bonded to multiple aggregate particles. Agglomeration is one of the most notable characteristics of RAP, and the old material exhibits severe false particle size and gradation variability, making quality difficult to control. This is especially true for oil-rich recycled asphalt, which contains a high asphalt content and is difficult to deeply regenerate. The resulting poor fusion of new and old asphalt results in low utilization rates or reduced quality, poor economic and social benefits, and wasted resources. Furthermore, the corresponding mix design methods lack a framework structure and recycling philosophy. The interaction and close bonding between the new asphalt and the aged asphalt in the old material require specific temperature and time conditions to fully complete, severely impacting the overall road performance of the recycled asphalt mixture. Compared to asphalt mixtures made entirely of new material, various properties are significantly reduced.

[0003] Waste tires are fragile objects and waste used in vehicles. If they are not handled properly, they will become an environmental pollutant. However, if they are processed into waste tire rubber powder and used in highway pavement projects, they will become an excellent renewable resource. They can increase the bonding performance between asphalt and aggregate, reduce noise, control cracks, improve road pavement performance, and extend service life. They have broad prospects.

[0004] Ultra-thin overlay technology is a rapid, preventative paving and 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, specially modified asphalt. Traditional asphalt pavement paving and compaction processes are applied to a base surface sprayed with a high-performance, non-stick wheel tack coat, and a 1.2-2.0cm ultra-tough overlay is applied. This overcomes the shortcomings of traditional maintenance overlay protection methods, resulting in a pavement with excellent resistance to reflective cracking, low-temperature cracking, fatigue cracking, water damage, and high-temperature stability. Furthermore, the pavement offers driving comfort, safety, durability, and quietness.

[0005] In summary, how to fully utilize the respective advantages of "full recycling technology" and "ultra-thin overlay technology", tap the recycling potential of waste tire rubber powder and oil-rich asphalt waste fine materials, enhance the performance of high-viscosity and high-rubber asphalt prepared by composite modification of waste tire rubber powder and SBS, increase the dosage of oil-rich recycled asphalt waste fine materials, establish a mix ratio design method for thin-layer overlay recycled mixture, improve the road performance of thin-layer overlay recycled mixture, realize the efficient, high-quality and high-quantity recycling of asphalt pavement milling waste materials, meet the road performance requirements of thin-layer overlay pavement, and save energy and be environmentally friendly. Against this background, it is necessary to explore a double-waste warm-mix recycled ultra-thin layer asphalt mixture and its production and preparation method. Summary of the Invention

[0006] The purpose of the present invention is to provide a double-waste material warm-mix recycled ultra-thin layer asphalt mixture and its preparation method and application in response to the technical defects of traditional factory-mixed hot-recycled asphalt mixtures, combined with the advantages of hot-mixed thin-layer overlay mixtures. The double-waste material warm-mix recycled ultra-thin layer asphalt mixture is a void-controllable, stable and durable environmentally friendly warm-mix recycled ultra-thin layer asphalt mixture. The preparation method of the mixture has the advantages of lowering the production and construction temperature, activating aged asphalt, enhancing the deep fusion of new and old asphalt, improving the recycling utilization rate, and improving the road performance to the level of new materials. At the same time, it is low in cost, green and environmentally friendly, and has broad application prospects.

[0007] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a double-waste material warm-mix recycled ultra-thin layer asphalt mixture, wherein the double-waste material warm-mix recycled ultra-thin layer asphalt mixture comprises: asphalt, finely separated old aggregate, new aggregate, mineral powder, warm-mix recycled modifier and fiber;

[0008] Wherein, the old aggregate is waste asphalt top layer milling material, and the particle size includes 0~3mm, 3~5mm and 5~10mm;

[0009] The asphalt is waste tire rubber powder / SBS composite modified high-viscosity and high-rubber asphalt.

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

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

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

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

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

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

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

[0017] Preferably, the fiber is polyester fiber, and the mixing amount is 0.2-0.4% of the mass of the double-waste warm-mixing recycled ultra-thin layer asphalt mixture.

[0018] Preferably, the amount of asphalt is 4-5% of the mass of the double-waste warm-mixing recycled ultra-thin layer asphalt mixture, and the asphalt film thickness is 12-15μm.

[0019] Preferably, the double-waste warm-mixing recycled ultra-thin layer asphalt mixture is a skeleton filling 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 the voids in the skeleton structure are filled by old aggregate with a particle size of 0-3mm, mineral powder and asphalt.

[0020] Preferably, the void ratio of the double-waste warm-mixing recycled ultra-thin layer asphalt mixture is 12-15%.

[0021] In the second aspect, the application provides a preparation method of the double-waste warm-mixing recycled ultra-thin layer asphalt mixture.

[0022] 1) heating the old aggregate after fine separation in a recycling drum at a temperature of 140-150℃, and heating the new aggregate in a drying drum at a temperature of 200-250℃;

[0023] 2) adding the old aggregate, new aggregate, mineral powder, warm-mixing recycled modifier and fiber in step 1) into a mixing cylinder for dry mixing for 10-15s;

[0024] 3) adding the waste tire rubber powder / SBS composite modified high-viscosity high-adhesion asphalt into the mixing cylinder for wet mixing for 30-35s;

[0025] Preferably, the total mixing time is less than 50s.

[0026] Preferably, the old aggregate is waste old asphalt upper layer milling material, and the particle size includes 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 regeneration modifier comprises APTL warm mix agent, modified epoxy polymer emulsion, aromatic oil, waste rubber powder and recycled oil; the addition amount is 1~4‰ of the mass of the old aggregate.

[0029] Preferably, the fiber is polyester fiber, and the addition amount is 0.2-0.4% of the mass of the double waste material warm mix recycled ultra-thin layer asphalt mixture.

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

[0031] Preferably, the skeleton structure relationship is formed by the old aggregate with a particle size of 5-10 mm and the old and new mixed aggregate with a particle size of 5-10 mm. The determination method is to regard the aggregate as equivalent to a sphere, and the old and new mixed aggregate with a particle size of 5-10 mm is completely wrapped by the old aggregate with a particle size of 3-5 mm. The spatial relationship between the two is shown in formulas (a)-(c):

[0032] In formulas (a)-(c):

[0033] P 12 P is the proportion of new and old mixed aggregate with a particle size of 5-10 mm (%); P3 is the proportion of RAP aggregate with a particle size of 3-5 mm (%);

[0034] ρ 12 is the apparent relative density of new and old mixed aggregate with a particle size of 5-10 mm; ρ3 is the apparent relative density of RAP aggregate with a particle size of 3-5 mm;

[0035] r i is the sieve hole size (mm); r i+1 is the mesh size of the previous gear of gear i (mm);

[0036] Q i The new and old mixed aggregate with a particle size of 5~10mm is i The sieve residue (%); W i is the sieve residue of old aggregate with a particle size of 3~5mm at the sieve hole ri (%);

[0037] d 12 is the average particle size of new and old mixed aggregate with a particle size of 5~10mm; d3 is the average particle size of old aggregate with a particle size of 3~5mm;

[0038] V 12V3 is the void ratio (%) of old and new mixed aggregate with a particle size of 5 to 10 mm, and V3 is the void ratio (%) of old aggregate with a particle size of 3 to 5 mm.

[0039] Preferably, the relationship between the proportions of asphalt, new aggregate, old aggregate, mineral powder and spatial volume parameters is as shown in formulas (d)-(g):

[0040] P4 is the proportion of old aggregate with a particle size of 0-3 mm (%); P5 is the proportion of mineral powder (%); P6 is the amount of asphalt used (%);

[0041] 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 ρ is the composite relative density of old aggregate with a particle size of 3-5 mm and new and old mixed aggregate with a particle size of 5-10 mm; sc The relative density of the old aggregate with a particle size of 3-5 mm and the new and old mixed aggregate with a particle size of 5-10 mm;

[0042] VV is the void ratio of asphalt mixture (%); VCA is the void ratio of the asphalt skeleton after filling with the mixture of old aggregate with a particle size of 3-5 mm and new and old aggregate with a particle size of 5-10 mm (%);

[0043] The compacted relative density is the density measured by 50 compaction cycles on one side using the Marshall compaction method.

[0044] Preferably, when designing the mix ratio of the warm-mix recycled ultra-thin layer overlay asphalt mixture, the total asphalt consumption should be estimated based on the asphalt film thickness (average value of 13.5 μm) of 12-15 μm and the aggregate surface area. The calculation model is shown in formulas (h)-(j):

[0045] (h): OAC (%) = assumed film thickness × aggregate surface area × asphalt density (g / cm 3 ) / 10;

[0046] Aggregate surface area (m 2 / kg)=(0.41a+0.41b+0.82c+1.64d+2.87e+6.14f+12.29g+32.77h) / 10 2 ;

[0047] In formulas (h)-(j):

[0048] a, b, c, d, e, f, g, and h represent the passing percentages (%) of sieves with pore sizes 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;

[0049] OAC is the estimated total asphalt content (%); OAC1 is the estimated asphalt content (%); OAC2 is the asphalt content of the old aggregate (%);

[0050] R2 is the asphalt content (%) of old aggregate with a particle size of 5~10mm; R3 is the asphalt content (%) of old aggregate with a particle size of 3~5mm; R4 is the asphalt content (%) of old aggregate with a particle size of 0~3mm.

[0051] In a third aspect, the present invention provides an application of the double-waste material warm mix recycled ultra-thin layer asphalt mixture as described in the first aspect in the field of highway maintenance.

[0052] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0053] The double-waste material warm-mix recycled ultra-thin layer asphalt mixture of the present invention addresses the technical defects of traditional factory-mixed hot-recycled asphalt mixtures and combines the advantages of hot-mix thin-layer overlay mixtures. The old materials recovered from the milling of the asphalt top layer use a combination of rigid and flexible fine separation equipment to eliminate the agglomerated particles of the milled old materials, and are finely screened and graded to improve the quality stability of the recycled mixture.

[0054] The double-waste warm-mix recycled ultra-thin layer asphalt mixture of the present invention reduces the production and construction temperature, activates aged asphalt, enhances the deep fusion of new and old asphalt, and improves the recycling rate by adding a multi-component composite modifier with warm-mix, regeneration and enhancement functions. In particular, it increases the amount of oil-rich RAP asphalt fine aggregate and improves the road performance to the level of new materials.

[0055] At the same time, the double-waste warm-mix recycled ultra-thin layer asphalt mixture of the present invention fully utilizes the high elasticity and SBS properties of waste tire rubber powder, and produces micro-nano activated rubber through green de-crosslinking technology, which is sheared, stirred, and developed with the matrix asphalt at high temperature to prepare micro-nano rubber / SBS composite to form high-viscosity and high-rubber modified asphalt, thereby improving the internal grid structure and road performance of the high-viscosity modified asphalt.

[0056] Further, in the double-waste warm-mixing regenerated ultra-thin-layer asphalt mixture of the present application, the space of coarse aggregate is filled with raw material regenerated aggregate + new aggregate to form a skeleton structure system, and the fine aggregate is filled with oil-rich milled old fine aggregate to form a skeleton filling structure and establish a volume relationship, and a multi-element regeneration modifier and fiber are added to increase the proportion of structural asphalt, and the relationship between the modifier, new asphalt dosage and wrapped aggregate, mineral powder and fiber specific surface area is established, and the precise proportion relationship of 5-10mm new material, 5-10mm RAP, 3-5mm RAP, 0-3mm RAP and mineral powder is determined through theoretical formula inversion, and a thin-layer overlay warm-mixing regenerated mixture mix proportion design method is formed.

[0057] In addition, the preparation method of the double-waste warm-mixing regenerated ultra-thin-layer asphalt mixture of the present application draws a relationship curve between the modifier content and the high and low temperature performance of the mixture, and establishes a mixture modifier content design method based on performance and function balance with the high and low temperature performance balance as the best modifier content MD=(MD1+MD2) / 2, which can ensure the expected performance of the mixture and regulate the performance accordingly.

[0058] Other features and advantages of the present application will be described in detail in the following specific embodiments. DETAILED DESCRIPTION

[0059] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0060] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values should be interpreted as approximately between the stated values and include values near the stated values. For ranges, the endpoints are included between the stated limit values and the individual points are included within the stated ranges. New ranges can be created by combining the endpoints of the ranges or individual points with each other. These new ranges are to be considered disclosed herein.

[0061] The specific scheme is as follows:

[0062] (1) The present application first separately mills and recycles the asphalt upper layer of the expressway, and the recycled old aggregate is stripped of the granules of the knot by the fine separation equipment of rigid-flexible combination, and then is finely screened and graded into four grades of 10-15mm, 5-10mm, 3-5mm and 0-3mm.

[0063] (2) The old asphalt content, performance and pseudo-particle size of the oil-poor coarse aggregate and oil-rich fine aggregate of the finely separated old aggregate (abbreviated as "RAP") are tested, and the finely separated old aggregate is divided into grades I-II for management and application according to the pseudo-particle size (gradation fluctuation difference) and asphalt content, and corresponding standards are established to ensure the gradation stability of the warm-mix recycled thin-layer overlay asphalt mixture during construction and eliminate the influence of the agglomerated particles of the milled old aggregate on the quality of the mixture.

[0064] (3) According to the highway grade, traffic volume, the amount of old material and the application scenario of the surface wearing layer, three grades of RAP with a particle size of 0-3 mm, 3-5 mm and 5-10 mm and new aggregate with a particle size of 5-10 mm are selected to form the aggregate of the warm-mix recycled ultra-thin layer overlay asphalt mixture.

[0065] (4) Based on the performance of the old asphalt tested in step (2), the performance and function balance design method is adopted to determine the type and amount of the regeneration agent for separating the old material, restore the performance of the old asphalt, activate the aged asphalt, enhance the fusion of the new and old asphalt, improve the recycling rate, and improve the road performance to the level of new material.

[0066] (5) After testing the performance of the old asphalt restored in step (4), establish the relationship between the four major performance indicators of the old asphalt softening point, ductility, needle penetration and 60°C dynamic viscosity 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 the high viscoelastic modified new asphalt.

[0067] (6) Waste tire rubber powder / SBS composite modified high-viscosity and high-rubber asphalt is a green high-viscosity and high-rubber modified asphalt prepared by shearing, stirring and developing waste rubber powder and SBS as a modifier under high temperature conditions (180~200℃). Its raw materials generally include: base asphalt (70#), rubber powder prepared from waste tires, SBS, and chemical additives. Taking into account the high elasticity of rubber, micro-nano activated rubber is produced through green de-crosslinking technology, and then waste tire rubber powder / SBS composite modified high-viscosity and high-rubber asphalt is prepared to improve the internal grid structure of high-viscosity modified asphalt.

[0068] (7) Warm mix recycled thin layer asphalt overlay mixture is a skeleton filling structure. New aggregate with a particle size of 5~10mm and RAP with a particle size of 5~10mm together constitute the mechanism and volume parameters. The relationship between the proportion of new and old asphalt, new and old aggregate, mineral powder and spatial volume parameters is established.

[0069] (8) Establish the relationship between the optimal structure of asphalt membrane, and accurately determine the ratio of new and old aggregates and mineral powder in each grade by controlling the input parameters such as void ratio, oil-stone ratio, and fiber.

[0070] (9) The mixing station produces and mixes double-waste material warm-mix recycled ultra-thin layer asphalt mixture. The mixing process is as follows: heat the RAP in the recycling drum at a temperature of 140-150℃, heat the new aggregate in the drying drum at a temperature of 200-250℃, then add the heated RAP, new aggregate, mineral powder, warm-mix recycled modifier and fiber into the mixing tank and dry mix for 10-15s; then add the waste tire rubber powder / SBS composite modified high-viscosity and high-glue asphalt into the mixing tank and wet mix for 30-35s. The total mixing time is no more than 50s, so that the mixture is evenly mixed and free of white material.

[0071] In a preferred embodiment of the present invention, the new aggregate is basalt.

[0072] In a preferred embodiment of the present invention, the standards for Class I old aggregate are: the pseudo-particle size of aggregate ≥3mm, i.e., the grading fluctuation value is within 10%, the old asphalt content is ≤1.5%, the crushing value is <26%, and the needle-like particle content is <15%; the pseudo-particle size of aggregate <3mm is within 10%, and the sand equivalent is ≥60%.

[0073] The standards for Grade II old aggregate are: for aggregates ≥3mm, the pseudo-particle size, i.e., the grading fluctuation value, is within 10%~15%, the old asphalt content is ≤2.0%, the crushing value is <30%, and the needle-like particle content is <20%; for aggregates <3mm, the pseudo-particle size is within 10%~15%, and the sand equivalent is ≥50%.

[0074] In a preferred embodiment of the present invention, the oil-rich fine aggregate refers to the part of the old asphalt pavement milling material with a particle size less than 4.75 mm after fine separation, and the oil-poor coarse aggregate refers to the part of the old asphalt pavement milling material with a particle size greater than 4.75 mm after fine separation.

[0075] In a preferred embodiment of the present invention, the newly added asphalt is waste tire rubber powder / SBS composite modified high-viscosity and high-rubber asphalt, the asphalt dosage is 4% to 5%, and the asphalt film thickness is 12 to 15 μm.

[0076] 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 to form a large amount of structural water film with lubricating function, which increases the mixing workability and easy compaction ability of the mixture, thereby achieving the mixing and compaction temperature. The addition of aromatic oil, waste rubber powder, and recycled oil supplements the light components in the old asphalt mixture to a certain extent, improves its needle penetration and ductility, and improves the elastic recovery ability of the old asphalt. The addition of modified epoxy polymer emulsion enhances the binding force of the old asphalt, so that the regeneration agent can better play a reinforcing role in the mixture and improve the overall strength and stability of the mixture.

[0077] In a preferred embodiment of the present invention, the dosage of the warm mix regeneration modifier is 1-3‰ of the mass of RAP, which improves the performance of RAP regenerated asphalt.

[0078] In a preferred embodiment of the present invention, the fiber is polyester fiber, and the fiber content is 0.2-0.4% of the mass of the double waste material warm mix recycled ultra-thin layer asphalt mixture.

[0079] In a preferred embodiment of the present invention, the method for designing the mix ratio of a double-waste material warm-mix recycled ultra-thin layer asphalt mixture establishes a relationship for the optimal structure of the asphalt film. By using parameters such as void ratio, oil-stone ratio, and fiber as control inputs, the ratio of the new and old aggregates and the mineral powder in each grade is accurately determined as follows:

[0080] In a preferred embodiment of the present invention, two grades of coarse aggregates with RAP particle size of 5~10mm and new aggregate particle size of 5~10mm constitute a skeleton dense structure relationship. According to the step-by-step filling theory and particle interference theory, RAP aggregate with particle size of 5~10mm is filled into new aggregate with particle size of 5~10mm in different proportions, and a relationship curve between filling ratio and gap ratio is established. The aggregate ratio corresponding to the minimum gap ratio on the relationship curve is selected as the composition ratio of new and old aggregates in the embedded dense structure.

[0081] In a preferred embodiment of the present invention, the skeleton structure relationship is formed by two aggregates: RAP with a particle size of 3-5 mm and new and old mixed aggregate with a particle size of 5-10 mm. The method for determining the relationship is to treat the aggregate as a sphere, with the particle size of 5-10 mm completely surrounded by the particle size of 3-5 mm. The spatial relationship between the two is as follows:

[0082] Where:

[0083] P 12 P is the proportion of new and old mixed aggregate with a particle size of 5 to 10 mm (%); P3 is the proportion of RAP aggregate with a particle size of 3 to 5 mm (%);

[0084] ρ 12 is the apparent relative density of new and old mixed aggregate with a particle size of 5 to 10 mm; ρ3 is the apparent relative density of RAP aggregate with a particle size of 3 to 5 mm;

[0085] r i is the sieve hole size, mm; r i+1 is the mesh size of the previous gear of gear i, mm; Q i The new and old mixed aggregates are 5-10mm in size and the mesh size is r i Screen residue, % W i The sieve residue of 3-5mm grade RAP aggregate on the sieve hole ri, %;

[0086] d 12 The average particle size of new and old mixed aggregates is 5 to 10 mm;

[0087] d3 is the average particle size of RAP aggregate in the range of 3 to 5 mm.

[0088] V 12 V3 is the void ratio (%) of old and new mixed aggregate with a particle size of 5 to 10 mm, and V3 is the void ratio (%) of old aggregate with a particle size of 3 to 5 mm.

[0089] In a preferred embodiment of the present invention, the relationship between the proportion of new asphalt, new and old aggregates, and mineral powder and the spatial volume parameter is as follows:

[0090] P4 is the proportion of RAP aggregate with a particle size of 0-3 mm (%); P5 is the proportion of mineral powder (%);

[0091] P6 is the asphalt dosage (%); ρ4 is the relative density of RAP with a particle size of 0-3 mm;

[0092] ρ5 is the relative density of mineral powder; ρ6 is the relative density of newly added asphalt;

[0093] ρ 123 is the composite relative density of RAP with a particle size of 3-5 mm and new and old mixed aggregate with a particle size of 5-10 mm; ρ sc The relative density of the composite compaction of RAP with a particle size of 3-5 mm and new and old mixed aggregate with a particle size of 5-10 mm;

[0094] VV is the void ratio of asphalt mixture (%); VCA is the void ratio of the skeleton after filling with coarse aggregate mixture with particle size of 3~5mm and 5~10mm (%).

[0095] In a preferred embodiment of the present invention, the composite density of RAP with a particle size of 3 to 5 mm and new and old mixed aggregate with a particle size of 5 to 10 mm is prepared by using a two-grade ratio calculated based on the relationship between the skeleton structure of the two-grade aggregates to prepare the mineral mixture, and the density measured by 50 times of single-sided compaction using the Marshall compaction method is the compaction relative density.

[0096] In a preferred embodiment of the present invention, the double-waste material warm-mix recycled ultra-thin layer asphalt mixture is a porous asphalt mixture with a void ratio of 12 to 15%.

[0097] In a preferred embodiment of the present invention, when designing the mix ratio of the double-waste material warm-mix recycled ultra-thin layer asphalt mixture, it is appropriate to estimate the total asphalt consumption based on the asphalt film thickness of 13.5 μm (average value of 12-15 μm) and the aggregate surface area. The calculation model is as follows:

[0098] OAC (%) = assumed film thickness × aggregate surface area × asphalt density (g / cm 3 ) / 10;

[0099] Aggregate surface area (m 2 / kg)=(0.41a+0.41b+0.82c+1.64d+2.87e+6.14f+12.29g+32.77h) / 10 2 ;

[0100] Wherein: a, b, c, d, e, f, g, h represent the passing percentage (%) of sieve holes 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.

[0101] OAC1=OAC-OAC2;

[0102] Where: OAC1 is the estimated asphalt usage (%); OAC is the estimated total asphalt usage (%);

[0103] OAC2 is the asphalt content of RAP (%);

[0104] OAC2=P2R2+P3R3+P4R4(%);

[0105] Where: R2 is the asphalt content (%) of 5-10mm RAP; R3 is the asphalt content (%) of 3-5mm RAP; R4 is the asphalt content (%) of 0-3mm RAP;

[0106] In a preferred embodiment of the present invention, the dosage of the warm mix regeneration modifier used in the double waste material warm mix regeneration ultra-thin layer asphalt mixture is 1-4‰ of the RAP mass, and the dosage of the separation waste material modifier and the warm mix regeneration agent is determined based on the performance and function balance design method, as follows:

[0107] Indoor rutting board specimens were prepared by adding 1-4‰ warm-mix recycled modifier to RAP. The modifier dosage was varied by ±1‰. Dynamic stability at 60°C and failure strain in a -10°C low-temperature flexural tensile test were tested for various dosages. Curves were plotted showing the relationship between modifier dosage, dynamic stability, and failure strain. The modifier dosage corresponding to the inflection point of the 60°C dynamic stability curve was designated MD1, and the modifier dosage corresponding to the inflection point of the -10°C low-temperature flexural tensile test failure strain curve was designated MD2. The optimal modifier dosage, MD, was determined to achieve a balance between high and low-temperature performance, as follows:

[0108] MD=(MD1+MD2) / 2;

[0109] In a preferred embodiment of the present invention, the road performance of the double-waste material warm-mix recycled ultra-thin layer asphalt mixture is not lower than the performance standard of the hot-mix thin layer overlay high viscoelastic asphalt mixture of virgin material, as shown in Table 1:

[0110] Table 1

[0111] The present invention will be described in detail below by way of examples. In the following examples, the drugs and pharmaceuticals are all conventional commercial products.

[0112] Example 1

[0113] The pre-specified amount of old aggregate is 45%.

[0114] Firstly, the collected AC-13 asphalt pavement milling materials from the upper layer of the highway were separated by fine separation equipment to produce old aggregates with particle sizes of 0-3mm, 3-5mm and 5-10mm, and their asphalt contents were 10.57%, 3.98% and 1.12% respectively.

[0115] The old aggregate, new aggregate and mineral powder were screened, and the screening test results are shown in Table 2;

[0116] Table 2

[0117] The RAP material was subjected to an extraction test, and the old asphalt after the extraction test was recovered and subjected to a performance test. The test results are shown in Table 3.

[0118] Table 3

[0119] The technical indicators of waste tire rubber powder / SBS composite modified high-viscosity and high-rubber asphalt are shown in Table 4.

[0120] Table 4

[0121] For road sections with obvious cracks, it is advisable to add fiber as a mixture toughening agent to improve the crack resistance of the ultra-thin overlay mixture. The fiber used is polyester fiber, and the fiber content is an intermediate value, which is 0.3% of the mixture mass.

[0122] Calculated according to the following formula:

[0123] The average particle size of new aggregate with a particle size of 5 to 10 mm is d1 = 7.06 mm;

[0124] The average particle size of RAP with a particle size of 5 to 10 mm is d2 = 6.93 mm;

[0125] The average particle size of RAP with a particle size of 3~5mm is d3=3.15mm.

[0126]

[0127] The mineral mixture was prepared by mixing old and new mixed aggregates with a particle size of 5-10 mm (RAP content of 45%) and two grades of aggregates with a particle size of 3-5 mm RAP at a ratio of 3.11:1. The mixture was 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 is:

[0128] According to the screening results of the aggregate, the specific surface area is calculated according to the formula:

[0129] SA=(0.41a+0.41b+0.82c+1.64d+2.87e+6.14f+12.29g+32.77h) / 10 2 ;

[0130] The specific surface areas of 5-10mm old and new mixed aggregate, RAP3-5mm, RAP0-3mm, and mineral powder were calculated respectively. The results are as follows:

[0131] S12=0.74m 2 / kg,

[0132] S3=2.75m 2 / kg,

[0133] S4=5.88m 2 / kg,

[0134] S5=38.73m 2 / kg.

[0135] The porosity is 13.5%, the oil-stone ratio is 6.8%, the asphalt film thickness is 13.5 μm, and the fiber content is 0.3%. Substituting these parameters into the relationship between the proportion of asphalt, aggregate, and mineral powder and the spatial volume parameter, and the relationship between the total specific surface area of ​​asphalt coating and the specific surface areas of aggregate, mineral powder, and fiber, the following equations are obtained:

[0136] According to the above equations, the calculation results are: P5 = 2.4%; P4 = 13.6%; P3 = 30.4%; P 12 =51.6%;

[0137] According to the above calculation results, 4.75mm and 2.36mm are used as key sieve holes to make trial gradations within the gradation range. The trial grading results are shown in Table 5:

[0138] Table 5

[0139] The preparation method of the regenerated asphalt mixture of the present invention is mixed, and the steps are as follows:

[0140] RAP and regeneration agent were poured into the mixing pot and dry mixed for 100 seconds, then new aggregate was added and mixed for 100 seconds, and finally mineral powder and waste tire rubber powder / SBS composite modified high-viscosity and high-glue asphalt were added and mixed for 100 seconds. The total mixing time was 300 seconds.

[0141] Based on design requirements, the asphalt-to-stone ratio of the mixture was selected to be 6.8%, with polyester fiber added at 0.3% of the mixture's mass. Marshall specimens were formed by double-sided compaction 50 times, with a mixing temperature of 160°C and a compaction temperature of 140-145°C. After indoor molding, the specimens were subjected to high-temperature performance (dynamic stability testing) and low-temperature performance (low-temperature bending testing).

[0142] The amount of the composite multi-effect warm mix recycled modifier used in the warm mix recycled thin layer overlay asphalt mixture is 1-4‰ of the RAP material. The amount of the separated old material modifier and the warm mix recycled agent is determined by a design method based on performance and function balance. The high and low temperature performance test results of the mixture with different warm mix recycled modifier amounts are shown in Table 6.

[0143] Table 6

[0144] Indoor rutting board specimens were prepared by adding 1-4‰ of a composite multi-effect warm-mix regeneration modifier to RAP material. The modifier dosage was varied by ±1‰, and the 60°C dynamic stability and -10°C low-temperature flexural tensile test failure strain at various dosages were tested. Curves were plotted showing the relationship between modifier dosage, dynamic stability, and failure strain. The modifier dosage corresponding to the inflection point of the 60°C dynamic stability curve for the mixture was MD1 = 2.2‰, and the modifier dosage corresponding to the inflection point of the -10°C low-temperature flexural tensile test failure strain curve was MD2 = 2.6‰. The optimal modifier dosage, MD, achieved a balance between high and low-temperature performance, as shown below:

[0145] The optimal modifier dosage MD is calculated as follows: MD = (MD1 + MD2) / 2 = (2.2 + 2.6) / 2 = 2.4‰;

[0146] The performance of the recycled mixture was verified using a Marshall specimen with an oil-to-stone ratio of 6.8%, an optimal modifier dosage of 2.4‰, and 0.3% polyester fiber added to the mixture by weight. The specimens were compacted 50 times on both sides at a mixing temperature of 160°C and a compaction temperature of 140-145°C. The test results are shown in Table 7:

[0147] Table 7 Test results of double waste material warm mix recycled ultra-thin layer asphalt mixture in this embodiment

[0148] It can be seen that the double-waste material warm-mixing regenerated ultra-thin layer asphalt mixture prepared in the embodiment meets the standard.

[0149] Example 2

[0150] The RAP material content is 60% in advance.

[0151] According to the calculation results of each file, the gradation is tried to match in the range of the key sieve hole of 4.75 mm and 2.36 mm, and the trial matching results are shown in Table 8.

[0152] Table 8 Matching proportion results of the synthesized gradation

[0153] The warm-mixing regenerated thin layer overlay asphalt mixture uses the composite multi-effect warm-mixing regeneration modifier with a content of 1-4‰ of RAP, and the content of the separation old material modifier and the warm-mixing regeneration agent is determined by using the performance and function balance design method to obtain the optimal modifier content MD of 2.1‰.

[0154] The oil-stone ratio is 6.8%, the optimal modifier content MD is 2.1‰, and the polyester fiber with a mass of 0.3% is added to the mixture. The Marshall test piece is formed by double-sided compaction for 50 times, the mixing temperature is 160℃, the compaction temperature is 140-145℃, the performance of the regenerated mixture is verified, and the test results are shown in Table 9.

[0155] Table 9 Test results of the double-waste material warm-mixing regenerated ultra-thin layer asphalt mixture

[0156] It can be seen that the double-waste material warm-mixing regenerated ultra-thin layer asphalt mixture prepared in the embodiment meets the standard.

[0157] The preferred embodiments of the application are described in detail above, but the application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the application within the technical concept of the application, and these simple modifications all belong to the protection scope of the application.

[0158] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the application will not describe various possible combinations.

[0159] In addition, various different embodiments of the application can also be combined in any manner, as long as it does not deviate from the idea of the application, and it should be considered as disclosed by the application.

Claims

1. A double waste material warm mix recycled ultra-thin layer asphalt mixture, characterized in that: The double waste material warm mix recycled ultra-thin layer asphalt mixture comprises: asphalt, finely separated old aggregate, new aggregate, mineral powder, warm mix recycled modifier and fiber; Wherein, the old aggregate is waste asphalt top layer milling material, and the particle size includes 0~3mm, 3~5mm and 5~10mm; The asphalt is waste tire rubber powder / SBS composite modified high-viscosity and high-rubber asphalt.

2. The double waste material warm mix recycled ultra-thin layer asphalt mixture according to claim 1, characterized in that: The preparation method of the waste tire rubber powder / SBS composite modified high-viscosity and high-rubber asphalt comprises: compounding the waste tire rubber powder with SBS at a temperature of 180-200° C., adding chemical additives and shearing, stirring and developing with the base asphalt; and / or, The fineness of the waste tire rubber powder is 80 mesh, and the amount thereof is 15-20% of the total mass of the waste tire rubber powder / SBS composite modified high-viscosity and high-rubber asphalt; and / or, The SBS is a 791h type linear SBS modifier; and / or, The chemical additives include solid tackifier sasobit and liquid dispersant 1102C type; and / or, The matrix asphalt is 70# matrix asphalt.

3. The double waste material warm mix recycled ultra-thin layer asphalt mixture according to claim 1 or 2, characterized in that: The new aggregate is basalt with a particle size of 5 to 10 mm; and / or, The warm mix regeneration 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 the old aggregate; and / or, The fiber is polyester fiber, and the amount thereof is 0.2-0.4% of the mass of the double waste material warm mix recycled ultra-thin layer asphalt mixture; and / or, The amount of asphalt used is 4-5% of the mass of the double waste material warm mix recycled ultra-thin layer asphalt mixture, and the asphalt film thickness is 12-15 μm.

4. The double waste material warm mix recycled ultra-thin layer asphalt mixture according to claim 1, characterized in that: The double-waste material warm mix recycled ultra-thin layer asphalt mixture has a skeleton filling structure, with new aggregate with a particle size of 5-10mm and old aggregate with particle sizes of 3-5mm and 5-10mm forming the skeleton, and then the gaps formed in the skeleton structure are filled with old aggregate with a particle size of 0-3mm, mineral powder and asphalt; The void ratio of the double-waste material warm-mix recycled ultra-thin layer asphalt mixture is 12-15%.

5. A method for preparing a warm-mix recycled ultra-thin layer asphalt mixture of double waste materials according to any one of claims 1 to 4, characterized in that: The preparation method comprises: 1) The finely separated old aggregate is heated in a regeneration drum at a temperature of 140-150°C, and the new aggregate is heated in a drying drum at a temperature of 200-250°C; 2) Add the old aggregate, new aggregate, mineral powder, warm mix regeneration modifier and fiber from step 1) into the mixing tank and dry mix for 10 to 15 seconds; 3) Add waste tire rubber powder / SBS composite modified high-viscosity and high-rubber asphalt into the mixing tank and wet mix for 30 to 35 seconds; Among them, the total mixing time is less than 50s.

6. The preparation method according to claim 5, characterized in that The old aggregate is waste asphalt top layer milling material, with particle sizes ranging from 0 to 3 mm, 3 to 5 mm and 5 to 10 mm; and / or, The new aggregate is basalt with a particle size of 5 to 10 mm; and / or, The warm mix regeneration 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 the old aggregate; and / or, The fiber is polyester fiber, and the amount thereof is 0.2-0.4% of the mass of the double waste material warm mix recycled ultra-thin layer asphalt mixture; and / or, The amount of asphalt used is 4-5% of the mass of the double waste material warm mix recycled ultra-thin layer asphalt mixture, and the asphalt film thickness is 12-15 μm.

7. The preparation method according to claim 5 or 6, characterized in that: The skeleton structure relationship of the aggregates in the two particle size ranges of 5-10 mm old aggregate and 5-10 mm old and new mixed aggregate is determined by equating the aggregates to spheres. The old and new mixed aggregates with particle sizes of 5-10 mm are completely wrapped by the old aggregates with particle sizes of 3-5 mm. The spatial relationship between the two is shown in formulas (a)-(c): （a）： ； （b）： ； （c）： ； In formulas (a)-(c): P 12 P is the proportion of new and old mixed aggregate with a particle size of 5-10 mm (%); P3 is the proportion of RAP aggregate with a particle size of 3-5 mm (%); ρ 12 is the apparent relative density of new and old mixed aggregate with a particle size of 5-10 mm; ρ3 is the apparent relative density of RAP aggregate with a particle size of 3-5 mm; r i is the sieve hole size (mm); r i+1 is the mesh size of the previous gear of gear i (mm); Q i The new and old mixed aggregate with a particle size of 5~10mm is i The sieve residue (%); W i is the sieve residue of old aggregate with a particle size of 3~5mm at the sieve hole ri (%); d 12 is the average particle size of new and old mixed aggregates with a particle size of 5-10 mm; d3 is the average particle size of old aggregates with a particle size of 3-5 mm; V 12 V3 is the void ratio (%) of old and new mixed aggregate with a particle size of 5 to 10 mm, and V3 is the void ratio (%) of old aggregate with a particle size of 3 to 5 mm.

8. The preparation method according to claim 5, characterized in that asphalt The relationship between the proportion of new aggregate, old aggregate, mineral powder and spatial volume parameters is shown in formulas (d)-(g): (d):P 12 +P3+P4+P5+P5=100; （e）： ； （f）： ； （g）： ； P4 is the proportion of old aggregate with a particle size of 0-3 mm (%); P5 is the proportion of mineral powder (%); P6 is the amount of asphalt used (%); 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 old aggregate with a particle size of 3-5 mm and the new and old mixed aggregate with a particle size of 5-10 mm; ρ sc The relative density of the old aggregate with a particle size of 3-5 mm and the new and old mixed aggregate with a particle size of 5-10 mm; VV is the void ratio of asphalt mixture (%); VCA is the void ratio of the asphalt skeleton after filling with the mixture of old aggregate with a particle size of 3-5 mm and new and old aggregate with a particle size of 5-10 mm (%); The compacted relative density is the density measured by 50 compaction cycles on one side using the Marshall compaction method.

9. The preparation method according to claim 5, characterized in that When designing the mix proportion of the warm-mix recycled ultra-thin overlay asphalt mixture, the total asphalt consumption should be estimated based on the asphalt film thickness (average value of 13.5 μm, which is 12 to 15 μm) and the aggregate surface area. The calculation model is shown in formulas (h)-(j): (h): OAC (%) = assumed film thickness × aggregate surface area × asphalt density (g / cm 3 ) / 10; Aggregate surface area (m 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 formulas (h)-(j): a, b, c, d, e, f, g, and h represent the passing percentages (%) of sieves with pore sizes 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 is the estimated total asphalt content (%); OAC1 is the estimated asphalt content (%); OAC2 is the asphalt content of the old aggregate (%); R2 is the asphalt content (%) of old aggregate with a particle size of 5~10mm; R3 is the asphalt content (%) of old aggregate with a particle size of 3~5mm; R4 is the asphalt content (%) of old aggregate with a particle size of 0~3mm.

10. Use of the double-waste material warm mix recycled ultra-thin layer asphalt mixture as claimed in any one of claims 1 to 4 in the field of highway maintenance.

Images