Mixture of waste tire rubber powder composite asphalt recycled fine aggregate and preparation method thereof

Abstract

The application discloses a kind of waste and old tyre rubber powder compound asphalt regeneration fine aggregate mixtures and preparation method thereof, and preparation steps include: using silane coupling agent to the surface treatment of regeneration fine aggregate, using stearic acid to waste and old tyre rubber powder raw material is pre-activated, new asphalt is heated and is sequentially added to pre-activated rubber powder stirring, SBS modifier is added with high-speed shearing, then add tackifying resin high-speed shearing, again add the fine aggregate after pretreatment stirring, and composite modified asphalt binder is prepared;Composite modified asphalt binder, screening after regeneration coarse aggregate, new aggregate, mineral powder are fully mixed, first dry mix again wet mix, and the mixture product is obtained.This preparation method overcomes the deficiency of traditional asphalt regeneration mixture in high and low temperature performance, water damage resistance and durability, and also realizes the synergistic recycling of waste and old tyre rubber powder and asphalt pavement material.The mixture prepared by the method has excellent road performance and low cost, and has important environmental protection and economic value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of recycled asphalt mixture, and particularly relates to a mixture of waste tire rubber powder composite asphalt recycled fine aggregate and a preparation method thereof. BACKGROUND

[0002] With the rapid development of highway construction, the maintenance demand of asphalt pavement is increasing, and a large amount of recycled asphalt mixture (RAP) is generated. How to efficiently utilize these waste resources, reduce the construction cost of asphalt pavement, and reduce environmental pollution has become an important research topic in the field of road engineering. The asphalt pavement recycling technology is a technology of recycling the recycled asphalt mixture through a certain process, and the plant-mixed hot recycling technology is widely used due to its mature process and controllable quality. At present, the research on the recycling of RAP at home and abroad mainly focuses on increasing the RAP content and improving the performance of the recycled mixture. CN113698139B discloses a high-content RAP plant-mixed hot recycled modified asphalt mixture, which realizes the hot recycled mixture with a RAP content of 40%-70% by adding an asphalt recycling agent and a modifier, but the RAP used is mainly coarse aggregate with a particle size of 16mm-30mm. CN113511840A proposes an asphalt recycled material resistant to water damage, which improves the water damage resistance of the recycled mixture by adding special aggregate such as mordenite molecular sieve and nano silicon carbide, but needs to rely on high-priced special aggregate (mordenite and nano silicon carbide), which is high in cost and low in utilization rate of recycled fine aggregate (≤30%), wastes resources, and only improves the water damage resistance without considering the high and low temperature performance and durability; only RAP is used without using waste tires, and the resource recycling is single. In the recycling process of RAP, most of the recycled coarse aggregate is recycled, and the treatment and utilization of the recycled fine aggregate with a particle size of 0-5mm, which accounts for a large proportion in RAP, has always been a technical difficulty and has not been fully utilized, resulting in a large amount of resource waste. On the other hand, waste tires as another important solid waste have attracted much attention in recycling. The waste tire rubber powder (CR) is tried to be used in modified asphalt due to its good elasticity and durability, so as to improve the high-temperature stability and low-temperature crack resistance of the asphalt mixture. CN118184223A introduces a cold recycled asphalt mixture, which realizes the recycling of old asphalt pavement materials by adding a composite modifier containing waste tire rubber powder, but does not solve the core problem of the dispersion of the rubber powder and the balance of the performance of the mixture, the dispersion of the rubber powder is poor, the performance cannot be fully utilized, the high and low temperature performance is poor (high-temperature rutting and low-temperature cracking), and the durability is insufficient.

[0003] In summary, the prior art still has the following problems: first, the old asphalt is aged after long-term use, the penetration decreases, the softening point increases, and direct mixing with new asphalt can easily lead to poor high-temperature stability and weak water damage resistance of the mixture. Second, although the waste tire rubber powder can improve the elasticity of asphalt, under the conventional process, the dispersion of the rubber powder is poor, and it is easy to agglomerate, so it is difficult to fully play its "elastic recovery" and "anti-cracking" performance. Third, in order to ensure the performance of the recycled mixture, it is usually necessary to increase the amount of new asphalt or high-priced modifier, and the utilization rate of the recycled fine aggregate (such as 0-5mm particles in the milling material) is less than 30% due to poor gradation and high clay content, resulting in high comprehensive cost. Therefore, it is urgent to develop a kind of asphalt recycling mixture technology which can efficiently utilize waste tire rubber powder and recycled fine aggregate, and has good road performance and economic efficiency. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a kind of waste tire rubber powder composite asphalt recycled fine aggregate mixture and its preparation method with excellent road performance, low cost and high resource recycling rate.

[0005] In order to solve the above technical problems, the technical scheme adopted by the present application is:

[0006] A kind of preparation method of waste tire rubber powder composite asphalt recycled fine aggregate mixture, comprising the following steps:

[0007] (1) The whole recycled asphalt mixture is screened and impurities are removed, and 0-5mm recycled fine aggregate and 5mm-15mm recycled coarse aggregate are separated, the recycled coarse aggregate is reserved, and the recycled fine aggregate is surface treated with silane coupling agent to obtain pretreated fine aggregate;

[0008] (2) The waste tire rubber powder raw material is dried, and stearic acid is added to obtain pre-activated rubber powder;

[0009] (3) The new asphalt is heated to 160-170 DEG C, the pre-activated rubber powder is added, stirred at a speed of 300-600 rpm for 12-18 min, heated to 180-185 DEG C, SBS modifier is added, sheared at a speed of 3000-6000 rpm for 50-70 min, tackifying resin is added, sheared at a speed of 1500-3000 rpm for 8-12 min, cooled to 155-160 DEG C, and the pretreated fine aggregate is added, stirred at a speed of 300-600 rpm for 12-18 min to obtain composite modified asphalt binder;

[0010] (4) The composite modified asphalt binder, the recycled coarse aggregate after screening and impurity removal, the new aggregate and the mineral powder are mixed, dry mixing is carried out first, then wet mixing is carried out, and the mixture product is obtained.

[0011] The preparation method of the mixture of the waste and old tire rubber powder composite asphalt recycled fine aggregate, preferably, in step (1), the surface treatment is spraying a silane coupling agent aqueous solution on the surface of the recycled fine aggregate, the mass percentage concentration of the silane coupling agent aqueous solution is 3%-10%, and the amount of the silane coupling agent aqueous solution is 0.2%-0.5% of the mass of the recycled fine aggregate.

[0012] The preparation method of the mixture of the waste and old tire rubber powder composite asphalt recycled fine aggregate, preferably, in step (1), the silane coupling agent is a triethoxysilane containing a vinyl group, a styryl group or a C6-C10 alkyl group, the molecular weight is 150 g / mol-300 g / mol, the purity is greater than or equal to 95%, and the hydrolysis degree of a 1% aqueous solution at 25°C is 30%-60%.

[0013] The preparation method of the mixture of the waste and old tire rubber powder composite asphalt recycled fine aggregate, preferably, in step (2), the amount of the stearic acid is 1.5%-3.0% of the mass of the waste and old tire rubber powder.

[0014] The preparation method of the mixture of the waste and old tire rubber powder composite asphalt recycled fine aggregate, preferably, in step (2), the mixing is performed at a rotation speed of 1200 rpm-1600 rpm for 8 min-12 min.

[0015] The preparation method of the mixture of the waste and old tire rubber powder composite asphalt recycled fine aggregate, preferably, in step (4), the dry mixing followed by wet mixing is first dry mixing at a rotation speed of 300 rpm-500 rpm for 25 s-35 s, and then wet mixing at a rotation speed of 400 rpm-600 rpm for 80 s-100 s at a temperature of 155°C-160°C.

[0016] The preparation method of the mixture of the waste and old tire rubber powder composite asphalt recycled fine aggregate, preferably, the waste and old tire rubber powder raw material exists in the form of agglomerates, the size of the agglomerates is 20 mesh-80 mesh, and further preferably 40 mesh-60 mesh; the molecular weight of the SBS modifier is 100,000-300,000, and the block ratio S / B=30 / 70-40 / 60; the softening point of the tackifying resin is 70°C-90°C; and the size of the new aggregate is 0-5 mm.

[0017] The preparation method of the mixture of the waste and old tire rubber powder composite asphalt recycled fine aggregate, preferably, the tackifying resin is a coumarone resin or a terpene resin; and the new aggregate is crushed stone.

[0018] The preparation method of the mixture of the waste tire rubber powder composite asphalt recycled fine aggregate is preferably that, in terms of mass percentage, the raw material composition comprises: 40-60% of the recycled asphalt mixture, wherein 0-5mm recycled fine aggregate accounts for 60-80%, and 5mm-15mm recycled coarse aggregate accounts for 20-40%; 8-18% of new asphalt; 10-15% of waste tire rubber powder raw material; 2-4% of SBS modifier; 2-4% of tackifying resin; 5-15% of new aggregate; and 3-10% of mineral powder.

[0019] As a general technical concept, the application also provides a mixture of waste tire rubber powder composite asphalt recycled fine aggregate prepared by the preparation method.

[0020] Compared with the prior art, the application has the following advantages:

[0021] (1) In view of the problems of performance deterioration of old asphalt after aging, poor dispersibility of waste tire rubber powder in asphalt, and low utilization rate of recycled fine aggregate, which lead to high comprehensive cost, the application provides a preparation method of a mixture of waste tire rubber powder composite asphalt recycled fine aggregate, which synergistically enhances the dispersion and performance release of waste tire rubber powder through a “CR-SBS-resin” composite modification system and a “rubber powder pre-activation-multi-stage blending” process, significantly improves the dispersibility of the rubber powder in the asphalt, and the size of the rubber powder agglomerate is less than 5μm observed by a scanning electron microscope, which is much better than the common 10μm-20μm agglomerate in the traditional process, and much smaller than the size of the waste tire rubber powder raw material agglomerate (about 270μm). The improvement of the microstructure corresponds to the simultaneous improvement of the high-temperature stability (dynamic stability≥6000 times / mm), low-temperature crack resistance (-10℃ breaking strain≥2800με), water damage resistance (TSR≥85%) and durability of the mixture.

[0022] (2) The preparation method of the application increases the content of the recycled fine aggregate to 60-80% of RAP (only 30-40% in the traditional method) through raw material matching, surface modification by a silane coupling agent and a multi-stage blending process, while the content of the new asphalt is reduced to 8-18%, which is 30-40% lower than that in the traditional method, and no high-priced warm-mixing agent or fiber stabilizer is needed, so that the comprehensive cost of the mixture is reduced by 15-25% compared with the conventional plant-mixed hot recycled material.

[0023] (3) The preparation method of the application makes full use of the "elastic recovery" and "anti-cracking" performance of waste tire rubber powder by mutual matching of raw materials, pre-activation of rubber powder and multi-stage blending process, so that the waste tire rubber powder content reaches 10% to 15% (the traditional content is only 3% to 8%), the utilization rate of waste tires is increased by more than 2 times, and the utilization rate of recycled fine aggregate is increased from 30% to 80%. In the prior art, the low content of waste tire rubber powder is affected by other factors in addition to dispersibility. Specifically, poor dispersibility is a surface problem, while interface bonding force, viscosity control, performance synergy, gradation compatibility and cost balance are deep constraints. Poor dispersibility can exacerbate viscosity control and interface separation, leading to performance imbalance, which ultimately requires high-priced auxiliary materials to compensate, forming a vicious cycle and limiting the content of rubber powder. The present application solves all the constraints by "rubber powder pre-activation + fine aggregate surface modification + composite modification system + multi-stage blending process", which realizes the breakthrough of the rubber powder content from 3% to 8% to 10% to 15% while ensuring performance and cost advantages.

[0024] (4) The mixture of the waste tire rubber powder composite asphalt recycled fine aggregate of the application improves the utilization rate of multiple types of waste resources through the synergy of high-content recycled fine aggregate (60% to 80%) and high-content waste tire rubber powder (10% to 15%), which not only improves the road performance of the mixture, but also reduces the cost and improves the resource recycling efficiency. DETAILED DESCRIPTION

[0025] The application will be further described below in conjunction with the specification and specific preferred embodiments, but the protection scope of the application is not limited thereby.

[0026] Example 1

[0027] The preparation method of the mixture of the waste tire rubber powder composite asphalt recycled fine aggregate of the application comprises the following steps:

[0028] S1, recycled fine aggregate pretreatment: screen the whole recycled asphalt mixture (RAP) to remove impurities, separate 0-5mm recycled fine aggregate and 5-15mm recycled coarse aggregate, screen and remove impurities from the 5-15mm recycled coarse aggregate for standby, then spray silane coupling agent aqueous solution on the surface of the recycled fine aggregate, the mass of the silane coupling agent aqueous solution is 0.3% of the mass of the recycled fine aggregate, and then dry treatment. In this step, the silane coupling agent treatment can improve the oil wettability of the surface of the recycled fine aggregate and enhance the adhesion with asphalt, thereby improving the overall performance and durability of the mixture. The concentration of the silane coupling agent aqueous solution is 5%, purchased from Jianghan New Material, model number KH-550.

[0029] S2, rubber powder pre-activation: after drying the waste tire rubber powder (CR) raw material, add stearic acid, the amount of stearic acid is 2% of the mass of CR, use high-speed mixer for high-speed dry mixing, specifically mixing at 1400 rpm for 10 min. This pre-activation treatment can improve the compatibility of rubber powder and asphalt, so that the rubber powder can be better dispersed in the asphalt in the subsequent composite modification process.

[0030] S3, preparation of composite modified asphalt binder: heat the new asphalt to 165℃, add the pre-activated CR and stir at 450 rpm for 15 min, then heat to 183℃ and add SBS modifier, shear at 4500 rpm for 60 min, then add tackifying resin and shear at 2200 rpm for 10 min, finally cool to 160℃, add pretreated fine aggregate and stir at 450 rpm for 10 min. This step controls the temperature and stirring parameters to make various modifiers fully blend with asphalt, forming a composite modified asphalt binder with excellent performance.

[0031] S4, mixture mixing: mix the composite modified asphalt binder, screened and impurity-removed recycled coarse aggregate, new aggregate and mineral powder, dry mix at 400 rpm for 30 s, then wet mix at 500 rpm for 90 s at a temperature of 158℃ to obtain the final mixture. This mixing process ensures uniform mixing of all components and forms a stable mixture with excellent performance.

[0032] The mixture of the waste tire rubber powder composite asphalt recycled fine aggregate of the application is composed of the following raw materials in mass percentage: recycled asphalt mixture (RAP) 50%, of which 0-5mm recycled fine aggregate accounts for 70% of RAP; new asphalt 12%; CR raw material 13%, the size of CR raw material aggregate is 50 mesh; SBS modifier 3%, molecular weight is 200,000, block ratio S / B=35 / 65; tackifying resin 3%, selected from coumarone resin, softening point 80℃; new aggregate (0-5mm crushed stone) 12%; mineral powder 7%, total 100% (since the pretreatment of recycled fine aggregate and the pre-activation of rubber powder have little effect on the mass, they can be ignored).

[0033] The new asphalt used in the mixture of the present embodiment is No. 70 A-grade road petroleum asphalt, the penetration (25℃, 100g, 5s) is 60-100 (0.1mm), and the softening point (ring and ball method) is ≥45℃. The waste tire rubber powder raw material exists in the form of agglomerates, and the equivalent size of the agglomerates is 50 mesh (about 270μm), which is not the true particle size of the single particle rubber powder. Due to the van der Waals force and electrostatic attraction on the surface of the tiny rubber powder single particle, and the viscosity of the rubber itself, the dry rubber will spontaneously aggregate to form "a plurality of single particle clusters". In industry, the particle size of the rubber powder single particle is not usually measured, and the size of the agglomerate can meet the subsequent processing requirements. The size of the agglomerate of the waste tire rubber powder raw material used in the present embodiment is in the range of 20-80 mesh, which is more conducive to the mixing of the rubber powder raw material and the asphalt, and improves the elastic recovery performance and crack resistance of the mixture. The molecular weight of the SBS modifier (styrene-butadiene-styrene block copolymer, purchased from Balin Petrochemical, model YH-791 (1301)) is 200,000, which is in the range of 100,000-300,000, and the block ratio S / B is 35 / 65, which is in the range of 30 / 70-40 / 60. This molecular structure of SBS can form a three-dimensional network structure in the asphalt, significantly improving the high-temperature stability and low-temperature crack resistance of the mixture. The tackifying resin used is coumarone resin, with a softening point of 80℃, which is in the range of 70℃-90℃, which can enhance the adhesion of asphalt and aggregate and improve the water stability of the mixture.

[0034] Example 2

[0035] The preparation method of the mixture of the waste tire rubber powder composite asphalt recycled fine aggregate of the present application is completely the same as that of example 1, the main difference is that the composition of the raw material is different, in this embodiment, the proportion of recycled fine aggregate in RAP is reduced from 70% to 65%, and the proportion of recycled coarse aggregate is 35%, and the other compositions are the same as those of example 1.

[0036] Example 3

[0037] The preparation method of the mixture of the waste tire rubber powder composite asphalt recycled fine aggregate of the present application is completely the same as that of example 1, the main difference is that the composition of the raw material is different, in this embodiment, the proportion of recycled fine aggregate in RAP is reduced from 70% to 75%, and the proportion of recycled coarse aggregate is 25%, and the other compositions are the same as those of example 1.

[0038] Example 4

[0039] The preparation method of the mixture of the waste and old tire rubber powder composite asphalt recycled fine aggregate of the present application is completely same with that of example 1, and the main difference lies in that the raw material composition is different, the amount of CR raw material and SBS modifier and tackifying resin is changed in the present example, when the CR raw material is reduced from 13% to 12%, the amount of SBS modifier and tackifying resin is increased, the loss of elasticity and high temperature stability caused by the reduction of CR raw material is supplemented, and the specific embodiments are as follows:

[0040] The raw material composition used in the present example includes recycled asphalt mixture (RAP) 50%, wherein 0-5mm recycled fine aggregate accounts for 70% of RAP; new asphalt 12%; CR raw material 12%, the size of CR raw material aggregate is 50 mesh; SBS modifier 3.5%, the molecular weight is 200,000, and the block ratio S / B is 35 / 65; tackifying resin 3.5%, the softening point is 80℃, and the new aggregate (0-5mm crushed stone) is 12%; mineral powder 7%, and the total is kept as 100%.

[0041] Example 5

[0042] The preparation method of the mixture of the waste and old tire rubber powder composite asphalt recycled fine aggregate of the present application is completely same with that of example 1, and the main difference lies in that the raw material composition is different, the amount of CR raw material and SBS modifier and tackifying resin is changed in the present example, when the CR raw material is reduced from 13% to 12%, the amount of SBS modifier and tackifying resin is increased, the loss of elasticity and high temperature stability caused by the reduction of CR raw material is supplemented, and the specific embodiments are as follows:

[0043] The raw material composition used in the present example includes recycled asphalt mixture (RAP) 50%, wherein 0-5mm recycled fine aggregate accounts for 70% of RAP; new asphalt 11%; CR raw material 14%, the size of CR raw material aggregate is 50 mesh; SBS modifier 3%, the molecular weight is 200,000, and the block ratio S / B is 35 / 65; tackifying resin 3%, the softening point is 80℃, and the new aggregate (0-5mm crushed stone) is 12%; mineral powder 7%.

[0044] Example 6

[0045] The preparation method of the mixture of the waste and old tire rubber powder composite asphalt recycled fine aggregate of the present application is completely same with that of example 1, and the main difference lies in that the raw material composition is different, the amount of CR raw material and SBS modifier and tackifying resin is changed in the present example. When the CR raw material is increased from 13% to 15%, the amount of new asphalt is reduced to 11%, the amount of SBS modifier is reduced to 2.5%, and the amount of tackifying resin is reduced to 2.5%, and the total is kept as 100%. The specific embodiments are as follows:

[0046] The raw material composition used in this embodiment includes 50% of reclaimed asphalt mixture (RAP), 0-5mm reclaimed fine aggregate accounting for 70% of RAP; 11% of new asphalt; 15% of CR raw material, the size of CR raw material aggregate is 50 mesh; 2.5% of SBS modifier, the molecular weight is 200,000, and the block ratio S / B is 35 / 65; 2.5% of tackifying resin, the softening point is 80°C; 12% of new aggregate (0-5mm gravel); and 7% of mineral powder.

[0047] Comparative Example 1

[0048] A preparation method of a mixture of waste tire rubber powder composite asphalt reclaimed fine aggregate, the raw materials used are basically the same as those in Example 1, and the process steps are basically the same as those in Example 1, the main difference is that steps S2 and S3 are different, and the multi-stage blending process of “rubber powder pre-activation, SBS swelling and shearing, resin viscosity reduction, and fine aggregate compounding” is not used.

[0049] The specific preparation steps of the present comparative example include:

[0050] S1: Reclaimed fine aggregate pretreatment: screen and remove impurities from the RAP as a whole, separate the 0-5mm reclaimed fine aggregate and the 5-15mm reclaimed coarse aggregate, screen and remove impurities from the 5-15mm reclaimed coarse aggregate for standby, then spray a silane coupling agent aqueous solution on the surface of the reclaimed fine aggregate, the mass of the silane coupling agent aqueous solution is 0.3% of the mass of the reclaimed fine aggregate, and then dry treatment is performed.

[0051] S2: Dry the CR raw material directly to a water content of ≤1% for standby.

[0052] S3: Heat the new asphalt to 165°C, directly add the dried CR and SBS modifier, and stir at room temperature at a speed of 450 rpm for 20 min; then add the tackifying resin, continue to stir at the same speed for 10 min, and obtain a simplified asphalt binder.

[0053] S4: Add the simplified asphalt binder, the screened and impurity-removed reclaimed coarse aggregate, the pretreated fine aggregate, the new aggregate (0-5mm gravel), and the mineral powder to the stirring equipment, first dry stir at 400 rpm for 30s to ensure uniform dispersion of all aggregates, and then wet stir at 158°C and 500 rpm for 90s to obtain the final mixture.

[0054] Comparative Example 2

[0055] A preparation method of a mixture of waste tire rubber powder composite asphalt reclaimed fine aggregate, the raw materials used are basically the same as those in Example 1, and the process steps are basically the same as those in Example 1, the main difference is that no tackifying resin is added in step S3.

[0056] Comparative Example 3

[0057] A preparation method of a mixture of waste tire rubber powder composite asphalt recycled fine aggregate, the raw materials used are basically the same as those of example 1, the process steps are basically the same as those of example 1, the main difference is that no SBS modifier is added in step S3.

[0058] Comparative example 4

[0059] A preparation method of a mixture of waste tire rubber powder composite asphalt recycled fine aggregate, the raw materials used are basically the same as those of example 1, the process steps are basically the same as those of example 1, the main difference is that the recycled fine aggregate is not surface treated with silane coupling agent in step S1.

[0060] Comparative example 5

[0061] A preparation method of a mixture of waste tire rubber powder composite asphalt recycled fine aggregate, the raw materials used are basically the same as those of example 1, the process steps are basically the same as those of example 1, the main difference is that the CR raw material is not pre-activated in step S2.

[0062] Performance detection test

[0063] The performance of each example and comparative example is tested according to "Highway Engineering Asphalt and Asphalt Mixture Test Procedures" JTG E20, "Highway Asphalt Pavement Construction Technical Specifications" JTG F40, and the specific data is shown in Table 1.

[0064] Table 1 Performance detection data table

[0065]

[0066] The performance of example 1 is significantly better than that of comparative example 1, the Marshall stability is increased by 71%, the dynamic modulus is increased by 52%, and the-10℃ damage strain is increased by 35%.

[0067] Comparing example 1 with comparative example 2 and comparative example 3, the asphalt 60℃ kinematic viscosity of comparative example 2 without tackifying resin and comparative example 3 without SBS modifier is increased by 51% and 33% respectively, the size of rubber powder aggregate of comparative example 2 and 3 is about 28μm and 15μm, which is 8.8 times and 4.7 times larger than 3.2μm of example 1, because tackifying resin can greatly reduce the viscosity of the system, SBS forms a three-dimensional network structure, which prevents the re-aggregation of rubber powder by physical entanglement, and the two have a synergistic effect, combined with the pre-activation process, to achieve the purpose of uniform dispersion of rubber powder, so that the aggregate size is less than 5μm. The elastic network of SBS and the rubber particles of CR work together to resist rutting, so that the Marshall stability of example 1 is increased by 39% and 22% respectively compared with comparative example 2 and comparative example 3. The tackifying resin can also enhance the interfacial adhesion to avoid performance degradation caused by rubber powder falling off; the elastic segment of CR and the butadiene segment of SBS work together to absorb stress, so that the failure strain of example 1 is increased by 33% and 19% respectively compared with comparative example 2 and comparative example 3. The tackifying resin can also fill the interface gap, so that the TSR of example 1 is increased by 19% compared with comparative example 2. The three are indispensable. Through the synergistic effect of “CR+SBS+tackifying resin” in example 1, it is significantly better than comparative examples containing only two components.

[0068] In the present application, one of the core roles of tackifying resin is to reduce the viscosity of the asphalt mixture system, promote the uniform dispersion of rubber powder, SBS and recycled fine aggregate, and enhance the adhesion through interfacial chemical action, ultimately achieving the purpose of “high content of recycled fine aggregate + low cost + high performance”. Although the name contains “tackifying”, it actually works through the synergistic mechanism of “viscosity reduction-dispersion-adhesion enhancement”, not just increasing the viscosity of the system.

[0069] Comparing example 1 with comparative example 4 and comparative example 5, it can be seen that surface treatment of recycled fine aggregate with silane coupling agent and pre-activation of rubber powder also have important influence on the road performance of the mixture.

[0070] Although the present application is disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any skilled person in the art can make many possible changes and modifications to the technical solutions of the present application, or modify equivalent embodiments with equivalent changes, without departing from the spirit and technical solutions of the present application, by using the disclosed methods and technical contents. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above examples according to the technical essence of the present application, without departing from the technical solutions of the present application, still belongs to the protection scope of the technical solutions of the present application.

Claims

1. A method for preparing a mixture of waste tire rubber powder composite asphalt recycled fine aggregate, characterized in that, Includes the following steps: (1) The recycled asphalt mixture is screened to remove impurities, and recycled fine aggregate of 0-5mm and recycled coarse aggregate of 5mm-15mm are separated. The recycled coarse aggregate is used for later use. The recycled fine aggregate is surface treated with silane coupling agent to obtain pretreated fine aggregate. (2) Dry the waste tire rubber powder raw material, add stearic acid and mix to obtain pre-activated rubber powder; (3) Heat the new asphalt to 160℃~170℃, add the pre-activated rubber powder, stir at 300rpm~600rpm for 12min~18min, raise the temperature to 180℃~185℃, add SBS modifier, shear at 3000rpm~6000rpm for 50min~70min, add tackifying resin, shear at 1500rpm~3000rpm for 8min~12min, cool down to 155℃~160℃, add the pretreated fine aggregate, stir at 300rpm~600rpm for 12min~18min to obtain composite modified asphalt binder; (4) Mix the composite modified asphalt binder, the recycled coarse aggregate after screening and impurity removal, the new aggregate and the mineral powder, first dry mix and then wet mix to obtain the mixture product; By weight percentage, the raw material composition includes: 40%–60% recycled asphalt mixture, of which 60%–80% is recycled fine aggregate of 0–5 mm and 20%–40% is recycled coarse aggregate of 5 mm–15 mm; 8%–18% new asphalt; 10%–15% waste tire rubber powder; 2%–4% SBS modifier; 2%–4% tackifying resin; 5%–15% new aggregate; and 3%–10% mineral powder.

2. The method for preparing the mixture of waste tire rubber powder composite asphalt recycled fine aggregate according to claim 1, characterized in that, In step (1), the surface treatment is to spray an aqueous solution of silane coupling agent onto the surface of the recycled fine aggregate. The mass percentage concentration of the aqueous solution of silane coupling agent is 3% to 10%, and the amount of the aqueous solution of silane coupling agent is 0.2% to 0.5% of the mass of the recycled fine aggregate.

3. The method for preparing the mixture of waste tire rubber powder composite asphalt recycled fine aggregate according to claim 1, characterized in that, In step (1), the silane coupling agent is a triethoxysilane containing vinyl, styrene or C6-C10 alkyl groups, with a molecular weight of 150 g / mol to 300 g / mol, a purity of ≥95%, and a degree of hydrolysis of 30% to 60% in a 1% aqueous solution at 25°C.

4. The method for preparing the mixture of waste tire rubber powder composite asphalt recycled fine aggregate according to claim 1, characterized in that, In step (2), the amount of stearic acid used is 1.5% to 3.0% of the mass of waste tire rubber powder.

5. The method for preparing the mixture of waste tire rubber powder composite asphalt recycled fine aggregate according to claim 1, characterized in that, In step (2), the mixing is carried out at a rotation speed of 1200 rpm to 1600 rpm for 8 min to 12 min.

6. The method for preparing the mixture of waste tire rubber powder composite asphalt recycled fine aggregate according to claim 1, characterized in that, In step (4), the dry mixing followed by wet mixing means first dry mixing at a speed of 300 rpm to 500 rpm for 25 s to 35 s, and then wet mixing at a temperature of 155 ℃ to 160 ℃ at a speed of 400 rpm to 600 rpm for 80 s to 100 s.

7. The method for preparing the mixture of waste tire rubber powder composite asphalt recycled fine aggregate according to claim 1, characterized in that, The waste tire rubber powder raw material exists in the form of agglomerates with a size of 40-60 mesh; the SBS modifier has a molecular weight of 100,000-300,000 and a block ratio of S / B = 30 / 70-40 / 60; the tackifying resin has a softening point of 70℃-90℃; and the new aggregate has a size of 0-5 mm.

8. The method for preparing the mixture of waste tire rubber powder composite asphalt recycled fine aggregate according to claim 7, characterized in that, The tackifying resin is coumarone resin or terpene resin; the new aggregate is crushed stone.

9. A mixture of waste tire rubber powder composite asphalt recycled fine aggregate prepared by the preparation method according to any one of claims 1 to 8.

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