A high-content RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture and its preparation process

Abstract

This invention belongs to the field of asphalt mixture technology, and relates to a high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture and its preparation process. The low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components by weight: 50-60 parts recycled asphalt mixture; 30-40 parts modified steel slag aggregate; 3-5 parts SBS modified asphalt; 0.02-0.06 parts low-temperature asphalt modifier; 3-8 parts slag powder; 0.2-0.5 parts lignin fiber; and 1-2 parts self-made asphalt recycling agent. This invention breaks through the limitations of traditional RAP dosage, with a maximum dosage of 70%. The steel slag recycled aggregate replaces natural aggregate, significantly reducing the consumption of virgin materials and waste emissions, which aligns with the new era's dual-carbon strategy and sustainable development goals. It is particularly suitable for winter construction, heavy-duty traffic roads, and green road construction in steel industry areas, combining technological advancement and engineering practicality.

Description

Technical Field

[0001] This invention belongs to the field of asphalt mixture technology, and relates to a high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture and its preparation process. Background Technology

[0002] With the increasing emphasis placed on energy conservation, emission reduction, and recycled materials by the state, reclaimed asphalt pavement (RAP) has become an increasingly important recycling material in the transportation industry and is being used more and more.

[0003] Studies have shown that compared to asphalt pavements paved with new materials, using recycled pavements with a RAP content of 20%–50% can reduce the total project cost by 14%–50%. Currently, domestic research on recycled materials for plant-mixed hot asphalt mixtures with low RAP content is relatively comprehensive and has been applied in many projects, with a utilization rate generally below 30%, indicating low utilization of old materials. Research on the application of recycled materials for plant-mixed hot asphalt mixtures with a RAP content greater than 30% has found that conventional recycling temperatures require 160–180℃, resulting in high energy consumption and further exacerbating aging. Poor fusion between new and old materials leads to water damage and fatigue cracking, especially when the recycled material content in the asphalt mixture is too high, which will reduce the low-temperature crack resistance and water damage resistance of the mixture. On the other hand, if the content is too low, the old asphalt pavement material cannot be fully utilized, increasing maintenance costs.

[0004] Meanwhile, steel slag, a byproduct of the metallurgical industry, has high hardness and compressive strength (typically higher than natural stone), which can significantly improve the rutting resistance of asphalt mixtures, making it particularly suitable for heavy-duty traffic roads. The multi-faceted and rough surface of steel slag particles results in strong adhesion to asphalt, enhancing the internal friction and shear resistance of the mixture and reducing the risk of aggregate stripping. Furthermore, as aggregate, it can reduce the mining of natural stone, minimizing environmental damage and aligning with the concept of a circular economy. Therefore, this study aims to investigate the recycling effect of plant-mixed hot asphalt mixture recycled material with a high RAP (Recycled Asphalt Powder) content, determining the optimal dosage of recycled asphalt mixture and steel slag aggregate, and their corresponding road performance. This is of great significance for optimizing the mix design of low-temperature plant-mixed hot asphalt mixture recycled material and improving road maintenance quality. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture and its preparation process. This method fully utilizes the characteristics of reclaimed asphalt (RAP) and steel slag aggregate to improve the overall performance of the plant-mixed hot recycled SMA-13 ​​(Stone Mastic Asphalt or Stone Matrix Asphalt, with a maximum nominal particle size of 13 mm) asphalt mixture. The specific technical solution is as follows:

[0006] The first objective of this invention is to provide a high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture, comprising the following components by weight:

[0007] 50-60 parts of recycled asphalt mixture (RAP); 30-40 parts of modified steel slag aggregate; 3-5 parts of SBS modified asphalt; 0.02-0.06 parts of low-temperature asphalt modifier; 3-8 parts of slag powder; 0.2-0.5 parts of lignin fiber; 1-2 parts of self-made asphalt recycling agent;

[0008] The modified steel slag aggregate is prepared by soaking steel slag aggregate in phosphoric acid solution, surface drying, and then spraying with a silane coupling agent.

[0009] The self-made asphalt recycling agent comprises the following components in parts by weight:

[0010] 52-60 parts naphthenic oil; 10-20 parts SBS rubber powder; 3-8 parts tall oil fatty acid; 2-7 parts silane coupling agent; 1-3 parts antioxidant; 0.3-0.5 parts anti-stripping agent; 10-15 parts plasticizer; 4-7 parts silica sol.

[0011] This invention utilizes SMA-13 ​​asphalt mixture recycled material, containing no less than 50% recycled asphalt mixture. Furthermore, the high-temperature performance of the SMA-13 ​​asphalt mixture recycled material improves with increasing content. This is because the aged asphalt film in the RAP (recycled asphalt mixture) coats the aggregate, providing initial strength. Asphalt ages, its internal molecular structure changes, with lightweight components volatilizing and heavyweight components increasing, making the asphalt more brittle and hard. Simultaneously, the recycled asphalt mixture exhibits good angularity. When aged asphalt from the recycled asphalt mixture is mixed with virgin modified steel slag aggregate for recycling, this aggregate composition increases the stiffness modulus of the recycled asphalt mixture. Therefore, increasing the content of recycled asphalt mixture significantly improves its high-temperature rutting resistance, making it more suitable for use in high-temperature regions of southern my country.

[0012] This invention uses modified steel slag recycled aggregate. Steel slag aggregate not only has excellent angularity and its rutting resistance is superior to that of natural aggregate, but also has high hardness (crushing value ≤15%), which compensates for the defect of decreased roughness with increasing RAP particle size and dosage. In addition, the porosity of the surface provides good adsorption of asphalt. Furthermore, the modified steel slag also solves the contradiction that steel slag aggregate is prone to swelling when exposed to water. The silane coupling agent sprayed on the surface further enhances the bonding between steel slag and asphalt, resulting in stronger adsorption and coating capabilities.

[0013] This invention employs a composite modification of low-temperature asphalt modifier and SBS-modified asphalt, synergistically combining the light oil components and plasticizers in a self-made asphalt recycling agent. This further improves the low-temperature plastic penetration of aged asphalt mixtures, restores the colloidal structure, and enhances the road performance of recycled asphalt mixtures. Furthermore, it lowers the mixing and compaction temperature of the recycled mixture, reducing the construction temperature to 120–135℃, compared to the conventional hot recycling mixing temperature of over 160℃. This reduces energy consumption, pollution emissions, and the risk of accelerated asphalt aging. The use of SBS-modified asphalt in this invention allows for a balance between high and low temperature performance in recycled asphalt mixtures. This is because the SBS elastic network not only improves the crack resistance of recycled asphalt mixtures (bending strain ≥2500με at -20℃) but also enhances their rutting resistance (dynamic stability ≥4000 cycles / mm). Additionally, the enhanced adhesion of low-temperature SBS-modified asphalt further improves its chemical bonding with the modified layer on the surface of steel slag aggregate.

[0014] This invention employs a self-made asphalt recycling agent, which is co-compounded and synergistically modified with low-temperature SBS-modified asphalt, thereby improving the high and low temperature performance, water stability, and freeze-thaw resistance of the recycled asphalt mixture. The naphthenic oil incorporated into the self-made asphalt recycling agent has strong dissolving power, capable of penetrating aged asphalt and restoring its rheological properties. Simultaneously, polymer synergistic modification and SBS rubber powder provide elasticity and enhance crack resistance. Plasticizers, in conjunction with naphthenic oil and SBS rubber powder, lower the low-temperature brittle point of the mixture (below -20℃), while nano-silica in the silica sol enhances high-temperature stability, i.e., rutting resistance, achieving a balance between low temperature performance and durability. Tall oil fatty acids and silane coupling agents strengthen the encapsulation of the low-temperature SBS-modified asphalt, improving the adhesion between steel slag and asphalt and significantly reducing water damage.

[0015] Furthermore, the high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components by weight:

[0016] 55 parts of reclaimed asphalt mixture (RAP); 35 parts of modified steel slag aggregate; 3.5 parts of SBS modified asphalt; 0.04 parts of low-temperature asphalt modifier; 4.5 parts of slag powder; 0.3 parts of lignin fiber; 1.16 parts of self-made asphalt recycling agent.

[0017] Furthermore, the reclaimed asphalt mixture (RAP) comprises the following components in parts by weight:

[0018] 55-65 parts of recycled asphalt mixture with a particle size of 5mm-10mm; 10-20 parts of recycled asphalt mixture with a particle size of 3mm-5mm; and 20-30 parts of recycled asphalt mixture with a particle size of less than 3mm.

[0019] The reclaimed asphalt mixture (RAP) is produced by using asphalt-aggregate separation technology, which involves crushing and screening the material through physical collision, selecting three particle sizes: 5mm-10mm, 3mm-5mm, and 0mm-3mm.

[0020] For each particle size range of 5mm~10mm, 3mm~5mm, and 0mm~3mm, the smallest value is not included in the range, while the largest value is included.

[0021] Furthermore, the preparation method of the modified steel slag aggregate includes the following steps:

[0022] A1: Further crush the steel slag aggregate after magnetic separation and screen it into four grades with target particle sizes of 10mm~16mm, 5mm~10mm, 3mm~5mm, and 0mm~3mm.

[0023] A2: Soak steel slag aggregates with four particle sizes of 10mm-16mm, 5mm-10mm, 3mm-5mm, and 0mm-3mm in a 3%-6% phosphoric acid solution for 20-30 hours respectively;

[0024] A3: After soaking treatment, the four grades of materials with particle sizes of 10mm~16mm, 5mm~10mm, 3mm~5mm and 0mm~3mm are air-dried or dried in a forced-air drying oven until they are surface dry.

[0025] A4: The four grades of surface-dried aggregate with particle sizes of 10mm-16mm, 5mm-10mm, 3mm-5mm, and 0mm-3mm are diluted with silane coupling agent at a ratio of 0.5%-1.5% and sprayed onto the surface of steel slag. The total amount of silane coupling agent used accounts for 3-5% of the weight of steel slag. After turning and spraying 2-3 times, modified steel slag aggregate is obtained.

[0026] Furthermore, the steel slag aggregate in A2 comprises the following components in parts by weight:

[0027] 50-60 parts of steel slag aggregate with a particle size of 10mm-15mm; 15-25 parts of steel slag aggregate with a particle size of 5mm-10mm; 10-20 parts of steel slag aggregate with a particle size of 3mm-5mm; 10-20 parts of steel slag aggregate with a particle size of 0mm-3mm.

[0028] For each particle size range of 10mm~16mm, 5mm~10mm, 3mm~5mm, and 0mm~3mm, the smallest value is not included in the range, while the largest value is included.

[0029] Furthermore, the preparation method of the self-made asphalt recycling agent includes the following steps:

[0030] B1: Pass the SBS rubber powder through a 40-mesh sieve to remove impurities and preheat it to 50-70℃; adjust the pH value of the silica sol to 8-10 with ammonia; dehydrate the naphthenic oil to a moisture content of ≤0.1%, i.e., heat it to 105℃±5℃ using a modified asphalt mixing equipment and stir for 20-50 minutes.

[0031] B2: Add naphthenic oil to a reactor containing an inert protective gas and heat to 80-90°C; slowly add SBS rubber powder, maintain the temperature at 90-100°C, and stir for 1-2 hours until the particles are completely dissolved to form a homogeneous solution.

[0032] B3: Cool solution one to 70-80℃, add tall oil fatty acid and silane coupling agent in sequence, and stir for 15-30 minutes; then add antioxidant and anti-stripping agent, and stir for 30-50 minutes to obtain solution two;

[0033] B4: Cool solution two to 50-60℃, slowly add silica sol and plasticizer, and stir at 3000-5000 rpm for 20-30 minutes until uniformly dispersed to obtain the self-made asphalt recycling agent; seal and store in a dark glass bottle for later use.

[0034] The self-made asphalt rejuvenator has the following characteristics: viscosity 200–500 mPa·s (25℃, Brookfield viscometer); flash point ≥180℃ (Cleveland open cup method); softening point difference ≤2.5℃ after mixing with aged asphalt (ring and ball method).

[0035] Furthermore, the inert gas protective gas is one or more of nitrogen, argon, or helium.

[0036] Furthermore, the silane coupling agent is one or more of KH-550, KH-560, or KH-570.

[0037] Further, the antioxidant is one or both of octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; the anti-stripping agent is SA-3 type asphalt anti-stripping agent produced by Jiangsu Subote New Material Co., Ltd.; and the plasticizer is dioctyl phthalate (DOP).

[0038] Furthermore, the SBS modified bitumen can be commercially available.

[0039] Furthermore, the density of the low-temperature asphalt modifier is 0.94–0.98 g / mm³. 3 Flash point 180~220℃, ash content <1.0; such as USP-H low temperature asphalt modifier produced by Shandong Luzhixing New Material Co., Ltd.

[0040] Furthermore, the specific surface area of ​​the slag powder is 400–500 m². 2 / kg, such as S95 or higher grade blast furnace slag powder produced by Shandong Lubi Building Materials Co., Ltd.

[0041] Furthermore, the density of the lignin fiber is 1.5 g·cm³. -3 The oil absorption ratio is 5 to 9 times the fiber mass, and the ash content is 18±5, such as the loose, fluffy wood fiber produced by Jiangsu Sheyang Siding Fiber Manufacturing Co., Ltd.

[0042] The second objective of this invention is to provide a preparation process for the above-mentioned high-content RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture, comprising the following steps:

[0043] S1: Mix the dry asphalt mixture recycled material (RAP), modified steel slag aggregate, and slag powder. The mixing temperature is controlled at 120-130℃ and the mixing time is 15-20 seconds until the aggregate is uniform and free of lumps to obtain the mixture.

[0044] S2: Heat the homemade asphalt recycling agent to 60-70℃, and spray it evenly into the mixture through an atomizing nozzle, and stir for 10-15 seconds;

[0045] S3: Add low-temperature SBS modified asphalt, with a stirring temperature of not less than 120℃, and stir for 20-30 seconds to ensure that the asphalt completely coats the aggregate; the preparation method of the low-temperature SBS modified asphalt is to premix the low-temperature modifier with SBS modified asphalt, with a stirring temperature of 140℃-150℃, and stir for not less than 30 minutes until the mixture is uniform to obtain low-temperature SBS modified asphalt.

[0046] S4: Slowly and disperse the lignin fiber to avoid clumping. The stirring temperature should not be lower than 120℃. Stir for 15-20 seconds until the fiber is evenly dispersed, the asphalt film is uniform, and there are no white speckles. This will give you a high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture.

[0047] The beneficial effects of this invention are:

[0048] This invention provides a low-temperature plant-mixed hot-recycled SMA-13 ​​asphalt mixture with a RAP content of ≥50%. Testing shows that its Marshall stability reaches a maximum of 17.3 kN, its residual Marshall stability after immersion in water is ≥90%, its dynamic stability (DS) is ≥5000 cycles / mm, reaching a maximum of 8500 cycles / mm, its low-temperature flexural strain is ≥3000 με, and its freeze-thaw splitting strength ratio (TSR) is ≥90%. These indicators far exceed the corresponding technical requirements for SBS modified asphalt mixtures in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTGF40-2004).

[0049] This invention breaks through the traditional limitations of RAP content (usually ≤30%), with a maximum content of 70%. Combined with recycled steel slag aggregate, it completely replaces natural aggregate, significantly reducing the consumption of virgin materials and waste emissions. It is particularly suitable for winter construction, heavy-duty traffic roads, and green road construction in steel industry areas, combining advanced technology with engineering practicality. Attached Figure Description

[0050] Figure 1 A photograph of a Marshall compaction specimen of low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture prepared in Example 1 of this invention. Detailed Implementation

[0051] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0052] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0053] Low-temperature asphalt modifier: USP-H low-temperature asphalt modifier produced by Shandong Luzhixing New Material Co., Ltd., with a density of 0.94~0.98g / mm³. 3 Flash point 180~220℃, ash content <1.0%.

[0054] Blast furnace slag powder: S95 grade or higher blast furnace slag powder produced by Shandong Lubi Building Materials Co., Ltd., with a specific surface area of ​​400-500 m². 2 / kg.

[0055] Lignin fiber: Loose, flocculent wood fiber produced by Jiangsu Sheyang Siding Fiber Manufacturing Co., Ltd., with a density of 1.5 g·cm³. -3 It has an oil absorption ratio of 5 to 9 times the fiber mass and an ash content of 18±5%.

[0056] Anti-stripping agent: SA-3 type asphalt anti-stripping agent produced by Jiangsu Subote New Material Co., Ltd.;

[0057] Recycled asphalt mixture (RAP): Utilizing asphalt-aggregate separation technology, it is crushed and screened through physical impact, selecting particle sizes of 5mm-10mm, 3mm-5mm, and 0mm-3mm; it includes the following components by weight:

[0058] 60 parts of recycled asphalt mixture with a particle size of 5mm to 10mm; 15 parts of recycled asphalt mixture with a particle size of 3mm to 5mm; and 25 parts of recycled asphalt mixture with a particle size of 0mm to 3mm.

[0059] The preparation method of modified steel slag aggregate includes the following steps:

[0060] A1: Further crush the steel slag after magnetic separation and screen it into four grades with target particle sizes of 10mm~16mm, 5mm~10mm, 3mm~5mm, and 0mm~3mm.

[0061] A2: Four grades of steel slag aggregate with particle sizes of 10mm-16mm, 5mm-10mm, 3mm-5mm, and 0mm-3mm were soaked in a 4% phosphoric acid solution for 24 hours to generate a stable calcium phosphate or magnesium phosphate reinforced surface layer, which blocks the expansion path; among them, there were 55 parts of steel slag aggregate with a particle size of 10mm-15mm; 20 parts of steel slag aggregate with a particle size of 5mm-10mm; 15 parts of steel slag aggregate with a particle size of 3mm-5mm; and 15 parts of steel slag aggregate with a particle size of 0mm-3mm.

[0062] A3: After soaking treatment, the four grades of materials with particle sizes of 10mm~16mm, 5mm~10mm, 3mm~5mm and 0mm~3mm are naturally air-dried until surface dry;

[0063] A4: After surface drying, the four grades of aggregate with particle sizes of 10mm-16mm, 5mm-10mm, 3mm-5mm, and 0mm-3mm are spread out and sprayed onto the surface of the steel slag with silane coupling agent KH-550 diluted at a ratio of 1%. The total amount of silane coupling agent KH-550 is 4% of the weight of the steel slag. After turning over and spraying three times, modified steel slag aggregate is obtained.

[0064] Homemade asphalt recycling agent, comprising the following components in parts by weight:

[0065] 57 parts naphthenic oil; 15 parts SBS rubber powder; 5 parts tall oil fatty acid; 4 parts silane coupling agent KH-550; 1.8 parts Irganox 1010 hindered phenolic antioxidant; 0.4 parts anti-stripping agent; 12 parts dioctyl phthalate (DOP) plasticizer; 4.8 parts silica sol;

[0066] The preparation method of the self-made asphalt recycling agent includes the following steps:

[0067] B1: Raw material preparation:

[0068] ① Pass the SBS rubber powder through a 40-mesh sieve to remove impurities and preheat it to 60℃;

[0069] ② Adjust the pH of the silica sol to 9 using ammonia;

[0070] ③ The purchased naphthenic oil is dehydrated and heated to 105℃ using a modified asphalt mixing equipment, and stirred for 30 minutes until the moisture content is ≤0.1%;

[0071] B2: Add naphthenic oil to a reactor containing an inert protective gas and heat to 85°C; slowly add SBS rubber powder, maintain the temperature at 100°C, and stir at 200 rpm for 2 hours until the particles are completely dissolved to form a homogeneous solution.

[0072] B3: Cool solution one to 70℃, add tall oil fatty acid and silane coupling agent KH-550 in sequence, stir for 20 min; then add antioxidant and anti-stripping agent, stir for 40 min to obtain solution two;

[0073] B4: Cool solution 2 to 60℃, slowly add silica sol and plasticizer, stir with a high-speed shear mixer at 3500 rpm for 30 minutes until uniformly dispersed to obtain the self-made asphalt recycling agent;

[0074] According to the test results, the self-made asphalt recycling agent should meet the following indicators: viscosity 300 mPa·s (25℃, Brookfield viscometer); flash point: ≥180℃ (Cleveland open cup method); softening point difference after mixing with aged asphalt ≤2.5℃ (ring and ball method); and be stored in a dark glass bottle for later use.

[0075] The above-mentioned substances are used in the following examples or comparative examples.

[0076] Example 1:

[0077] A high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components by weight:

[0078] 55 parts of reclaimed asphalt mixture (RAP); 35 parts of modified steel slag aggregate; 4 parts of SBS modified asphalt; 0.04 parts of low-temperature asphalt modifier; 4.5 parts of slag powder; 0.3 parts of lignin fiber; 1.16 parts of self-made asphalt recycling agent.

[0079] The preparation process of the high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture includes the following steps:

[0080] S1: Add the dried RAP, modified steel slag aggregate, and slag powder to the asphalt mixture mixer and mix. The mixing temperature is controlled at 120℃ and the mixing time is 15s until the aggregate is uniform and free of lumps to obtain the mixture.

[0081] S2: Heat the homemade asphalt recycling agent to 70°C, spray it evenly into the mixture through an atomizing nozzle, and stir for 15 seconds;

[0082] S3: Add low-temperature SBS modified asphalt, stir at 125℃ for 30 seconds to ensure that the asphalt completely coats the aggregate; the preparation method of the low-temperature SBS modified asphalt is to premix the low-temperature modifier with SBS modified asphalt, stir for 50 minutes at 145℃ until the mixture is uniform to obtain low-temperature SBS modified asphalt.

[0083] S4: Slowly and disperse the lignin fiber to avoid clumping. Stir at 125℃ for 20 seconds until the fiber is evenly dispersed, the asphalt film is uniform, and there are no white speckles. This will give you a high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture.

[0084] The method for preparing Marshall compaction specimens of low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture includes the following steps:

[0085] G1: Mold preparation: Heat the Marshall test mold (φ101.6mm×63.5mm) and the compaction hammer to 110℃, and apply a small amount of glycerin release agent;

[0086] G2: Loading: Load the mixture in two batches, each time taking about 750g of the mixture. Use a spatula to tamp along the perimeter 15 times and in the center 10 times to remove air bubbles.

[0087] G3: Compaction: Use double-sided compaction method, 50 compactions per side (standard Marshall compaction count, hammer weight 4.53kg, drop height 457mm); the height of the specimen after compaction should be 63.5mm±1.3mm, otherwise adjust the amount of material used;

[0088] G4: Demolding: After compaction, use a demolding device to push out the specimen while it is still hot to avoid deformation;

[0089] G5: Specimen curing and storage: Specimens should be left to stand at room temperature for 24 hours, avoiding direct sunlight, and cooled to room temperature; the specimen number, proportion, and molding date should be marked.

[0090] In this embodiment, the RAP content of the low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture prepared was 55%, and the prepared Marshall compaction specimens were as follows: Figure 1 As shown, the test results show that its Marshall stability is 15.7 kN, the residual Marshall stability after immersion in water is 92.5%, the dynamic stability (DS) is 7500 cycles / mm, the low-temperature bending strain is 3455 με, and the freeze-thaw splitting strength ratio (TSR) is 92.3%. All relevant indicators exceed the corresponding technical requirements for SBS modified asphalt mixtures in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTGF40-2004).

[0091] Example 2:

[0092] A high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components by weight:

[0093] 60 parts of reclaimed asphalt mixture (RAP); 30 parts of modified steel slag aggregate; 4 parts of SBS modified asphalt; 0.04 parts of low-temperature asphalt modifier; 4.5 parts of slag powder; 0.3 parts of lignin fiber; 1.16 parts of self-made asphalt recycling agent.

[0094] The preparation methods for the high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture and the preparation methods for Marshall compaction specimens are the same as in Example 1, and will not be repeated here.

[0095] Compared to Example 1, this embodiment maintains the same total aggregate amount, but increases the recycled asphalt mixture (RAP) to 60 parts and reduces the modified steel slag aggregate to 30 parts, while keeping the remaining components and their mass percentages unchanged. Testing of the above mixture specimens showed a Marshall stability of 15.3 kN, a water-immersed Marshall residual stability of 87.5%, a dynamic stability (DS) of 5500 cycles / mm, a low-temperature flexural strain of 3010 με, and a freeze-thaw splitting strength ratio (TSR) of 90.3%. These indicators still exceed the corresponding technical requirements for SBS modified asphalt mixtures in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTGF40-2004). This demonstrates that even with a high RAP utilization rate of 60%, the specification requirements are still met, proving that the addition of low-temperature SBS modified asphalt and recycling agents can effectively restore the performance of aged asphalt.

[0096] Example 3:

[0097] A high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components by weight:

[0098] 50 parts of reclaimed asphalt mixture (RAP); 36 parts of modified steel slag aggregate; 4 parts of SBS modified asphalt; 0.04 parts of low-temperature asphalt modifier; 8 parts of slag powder; 0.3 parts of lignin fiber; 1.66 parts of self-made asphalt recycling agent.

[0099] The preparation methods for the high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture and the preparation methods for Marshall compaction specimens are the same as in Example 1, and will not be repeated here.

[0100] Compared to Example 1, this embodiment reduced the amount of reclaimed asphalt mixture (RAP) to 50 parts, increased the modified steel slag aggregate to 36 parts, increased the slag powder to 8 parts, and appropriately increased the dosage of the self-made asphalt recycling agent. Testing of the above mixture specimens showed a Marshall stability of 17.3 kN, a water-immersed Marshall residual stability of 94.0%, a dynamic stability (DS) of 8500 cycles / mm, a low-temperature flexural strain of 3100 με, and a freeze-thaw splitting strength ratio (TSR) of 95.0%. All relevant indicators exceeded the corresponding technical requirements for SBS modified asphalt mixtures in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTGF40-2004). It is evident that when the RAP utilization rate is 50%, the slag powder filling effect improves the density, achieving a Marshall stability of 17.3 kN and a record-breaking dynamic stability of 8500 cycles / mm. Low-temperature performance slightly decreased, but still met the specification requirements. Therefore, a balance between high-temperature and low-temperature requirements should be struck based on material properties and road load levels.

[0101] Example 4:

[0102] A high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components by weight:

[0103] 55 parts of reclaimed asphalt mixture (RAP); 35 parts of modified steel slag aggregate; 4 parts of SBS modified asphalt; 0.06 parts of low-temperature asphalt modifier; 4.5 parts of slag powder; 0.3 parts of lignin fiber; 1.64 parts of self-made asphalt recycling agent.

[0104] The mixing temperature in step S4 of the method for preparing high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture is 120℃.

[0105] The preparation method of the Marshall compaction specimen is the same as in Example 1, and will not be repeated here.

[0106] Compared to Example 1, this embodiment increased the low-temperature asphalt modifier to 0.06 parts and appropriately reduced the dosage of the self-made asphalt recycling agent. The mixing temperature in S4 was reduced to 120℃. Testing of the above mixture specimens showed a Marshall stability of 16.1 kN, a water-immersion Marshall residual stability of 90.9%, a dynamic stability (DS) of 5300 cycles / mm, a low-temperature flexural strain of 3560 με, and a freeze-thaw splitting strength ratio (TSR) of 91.5%. All relevant indicators exceeded the corresponding technical requirements for SBS modified asphalt mixtures in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTGF40-2004). This embodiment demonstrates the feasibility of low-temperature construction, i.e., mixing at 120℃ still meets all the indicators.

[0107] Example 5:

[0108] A high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components by weight:

[0109] 55 parts of reclaimed asphalt mixture (RAP); 36 parts of modified steel slag aggregate; 3.0 parts of SBS modified asphalt; 0.04 parts of low-temperature asphalt modifier; 4 parts of slag powder; 0.3 parts of lignin fiber; and 1.66 parts of self-made asphalt recycling agent.

[0110] The preparation methods for the high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture and the preparation methods for Marshall compaction specimens are the same as in Example 1, and will not be repeated here.

[0111] Compared to Example 1, this embodiment reduced the amount of SBS modified asphalt to 3 parts, slag powder to 4 parts, and correspondingly increased the amount of modified steel slag aggregate to 36 parts. Testing of the above mixture specimens showed a Marshall stability of 15.1 kN, a water-immersed Marshall residual stability of 91.2%, a dynamic stability (DS) of 5500 cycles / mm, a low-temperature flexural strain of 3100 με, and a freeze-thaw splitting strength ratio (TSR) of 92.7%. All relevant indicators exceeded the corresponding technical requirements for SBS modified asphalt mixtures in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTGF40-2004). This embodiment demonstrates that the elastic network of SBS modified asphalt plays a crucial role in improving the mechanical properties of recycled asphalt mixtures.

[0112] Comparative Example 1:

[0113] A low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components in parts by weight:

[0114] 55 parts of recycled asphalt mixture (RAP); 35 parts of basalt aggregate; 4 parts of SBS modified asphalt; 4.5 parts of slag powder; 0.3 parts of lignin fiber; 1.2 parts of self-made asphalt recycling agent;

[0115] The basalt aggregate comprises the following components in parts by weight: 18.3 parts of basalt aggregate with a particle size of 10mm to 15mm; 6.7 parts of basalt aggregate with a particle size of 5mm to 10mm; 5 parts of basalt aggregate with a particle size of 3mm to 5mm; and 5 parts of basalt aggregate with a particle size of 0mm to 3mm.

[0116] The preparation process of the low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture includes the following steps:

[0117] S1: Add the dried RAP, basalt aggregate, and slag powder to the asphalt mixture mixer and mix. The mixing temperature is controlled at 173℃ and the mixing time is 15s until the aggregate is uniform and free of lumps to obtain the mixture.

[0118] S2: Heat the homemade asphalt recycling agent to 70°C, spray it evenly into the mixture through an atomizing nozzle, and stir for 15 seconds;

[0119] S3: Add SBS modified asphalt, mix at 168℃ for 30 seconds to ensure that the asphalt completely coats the aggregate.

[0120] S4: Slowly and disperse the lignin fiber to avoid clumping. Stir at 168℃ for 20 seconds until the fiber is evenly dispersed, the asphalt film is uniform, and there are no white speckles. This will give you the low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture.

[0121] The preparation method of the Marshall compaction specimen is the same as in Example 1, and will not be repeated here.

[0122] This comparative example uses a commercially available low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture. Compared to Example 1, the modified steel slag aggregate is replaced with natural basalt aggregate, with the corresponding mass fraction remaining unchanged. No low-temperature asphalt modifier is added, and all other components and mass fractions remain the same. The mixing temperature of this comparative asphalt mixture is 173℃. Testing of the above mixture specimens showed a Marshall stability of 13.2 kN, a water-immersed Marshall residual stability of 79.3%, a dynamic stability (DS) of 3500 cycles / mm, a low-temperature flexural strain of 3200 με, and a freeze-thaw splitting strength ratio (TSR) of 73.9%. Compared to Example 1, the high-temperature mixing caused secondary aging of the RAP asphalt, resulting in significant performance degradation, especially a substantial decrease in the freeze-thaw splitting strength ratio (TSR).

[0123] Comparative Example 2:

[0124] A low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components in parts by weight:

[0125] 55 parts of reclaimed asphalt mixture (RAP); 35 parts of unmodified steel slag aggregate; 4 parts of SBS modified asphalt; 4.5 parts of slag powder; 0.04 parts of low-temperature asphalt modifier; 0.3 parts of lignin fiber; 1.2 parts of asphalt recycling agent (HR-R series produced by Shandong Expressway Huarui Road Materials Technology Co., Ltd.).

[0126] Unmodified steel slag aggregate comprises the following components in parts by weight: 55 parts of steel slag aggregate with a particle size of 10mm to 15mm; 20 parts of steel slag aggregate with a particle size of 5mm to 10mm; 15 parts of steel slag aggregate with a particle size of 3mm to 5mm; and 15 parts of steel slag aggregate with a particle size of 0mm to 3mm.

[0127] The preparation process of the low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture includes the following steps:

[0128] S1: Add the dried RAP, unmodified steel slag aggregate, and slag powder to the asphalt mixture mixer and mix. The mixing temperature is controlled at 173℃ and the mixing time is 15s until the aggregate is uniform and free of lumps to obtain the mixture.

[0129] S2: Heat the asphalt recycling agent to 70℃, spray it evenly into the mixture through an atomizing nozzle, and stir for 15 seconds;

[0130] S3: Add low-temperature SBS modified asphalt, stir at 168℃ for 20-30 seconds to ensure that the asphalt completely coats the aggregate; the preparation method of the low-temperature SBS modified asphalt is to premix the low-temperature modifier with SBS modified asphalt, stir for no less than 30 minutes at a stirring temperature of 145℃ until the mixture is uniform to obtain low-temperature SBS modified asphalt.

[0131] S4: Slowly and disperse the lignin fiber to avoid clumping. Stir at 168℃ for 20 seconds until the fiber is evenly dispersed, the asphalt film is uniform, and there are no white speckles. This will give you the low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture.

[0132] The preparation method of the Marshall compaction specimen is the same as in Example 1, and will not be repeated here.

[0133] Compared to Example 1, this comparative example replaced the modified steel slag aggregate with unmodified steel slag aggregate, while keeping the other components, mass fractions, and processing technology unchanged. Testing of the resulting mixture specimens showed a Marshall stability of 12.5 kN, a water-immersed Marshall residual stability of 82%, a dynamic stability (DS) of 4500 cycles / mm, a low-temperature flexural strain of 2600 με, and a freeze-thaw splitting strength ratio (TSR) of 81.5%. Compared to Example 1, the unmodified steel slag aggregate exhibited poor adhesion to asphalt; when the RAP content was too high, the unmodified steel slag powder could not compensate for the weak interfacial areas, resulting in insufficient water stability.

[0134] Comparative Example 3:

[0135] A low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components in parts by weight:

[0136] 55 parts of reclaimed asphalt mixture (RAP); 35 parts of modified steel slag aggregate; 4 parts of SBS modified asphalt; 4.5 parts of slag powder; 0.3 parts of lignin fiber; 1.16 parts of asphalt recycling agent (HR-R series produced by Shandong Expressway Huarui Road Materials Technology Co., Ltd.).

[0137] The preparation process of the low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture includes the following steps:

[0138] S1: Add the dried RAP, modified steel slag aggregate, and slag powder to the asphalt mixture mixer and mix. The mixing temperature is controlled at 175℃ and the mixing time is 15s until the aggregate is uniform and free of lumps to obtain the mixture.

[0139] S2: Heat the asphalt recycling agent to 70℃, spray it evenly into the mixture through an atomizing nozzle, and stir for 15 seconds;

[0140] S3: Add SBS modified asphalt, mix at 170℃ for 30 seconds to ensure that the asphalt completely coats the aggregate;

[0141] S4: Slowly and disperse the lignin fiber to avoid clumping. Stir at 170℃ for 20 seconds until the fiber is evenly dispersed, the asphalt film is uniform, and there are no white speckles. This will give you the low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture.

[0142] The preparation method of the Marshall compaction specimen is the same as in Example 1, and will not be repeated here.

[0143] Compared to Example 1, this comparative example no longer added a low-temperature asphalt modifier, and replaced the self-made asphalt rejuvenator with a commercially available asphalt rejuvenator. With all other components and their mass percentages unchanged, the mixing temperature of the asphalt mixture in this comparative example was 175°C. Testing of the mixture specimens showed a Marshall stability of 12.6 kN, a water-immersion Marshall residual stability of 77.6%, a dynamic stability (DS) of 3400 cycles / mm, a low-temperature flexural strain of 2800 με, and a freeze-thaw splitting strength ratio (TSR) of 72.1%. Compared to Example 1, the overall performance of the asphalt mixture specimens in this comparative example decreased due to secondary aging of the RAP asphalt caused by high-temperature mixing and the corresponding performance differences of the commercially available asphalt rejuvenator, especially the Marshall stability, which no longer met the specifications.

[0144] Comparative Example 4:

[0145] A low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components in parts by weight:

[0146] 55 parts of reclaimed asphalt mixture (RAP); 33.66 parts of modified steel slag aggregate; 4 parts of SBS modified asphalt; 0.04 parts of low-temperature asphalt modifier; 4.5 parts of slag powder; 0.3 parts of lignin fiber; and 2.5 parts of self-made asphalt recycling agent.

[0147] The mixing temperature in step S1 of the method for preparing high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture is 125℃.

[0148] The preparation method of the Marshall compaction specimen is the same as in Example 1, and will not be repeated here.

[0149] Compared to Example 1, the self-made asphalt recycling agent in this comparative example was increased to 2.5 parts, and the modified steel slag aggregate was correspondingly reduced. With all other components and their mass percentages remaining unchanged, the mixing temperature of the asphalt mixture in this comparative example was 125℃. Testing of the mixture specimens showed a Marshall stability of 11.2 kN, a water-immersed Marshall residual stability of 73.2%, a dynamic stability (DS) of 2800 cycles / mm, a low-temperature flexural strain of 3260 με, and a freeze-thaw splitting strength ratio (TSR) of 62.1%. Compared to Example 1, Control Group 1 showed decreased high-temperature stability and failed to meet the specifications for Marshall stability due to excessive self-made recycling agent (containing aromatic oil and activator).

[0150] Comparative Example 5:

[0151] A low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture comprises the following components in parts by weight:

[0152] 55 parts of reclaimed asphalt mixture (RAP); 37.5 parts of modified steel slag aggregate; 1 part of SBS modified asphalt; 0.04 parts of low-temperature asphalt modifier; 4.5 parts of slag powder; 0.3 parts of lignin fiber; 1.66 parts of self-made asphalt recycling agent.

[0153] In the preparation method of the high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture, the stirring temperature in S1 is reduced to 125℃.

[0154] The preparation method of the Marshall compaction specimen is the same as in Example 1, and will not be repeated here.

[0155] Compared to Example 1, the comparative example reduced the SBS modified asphalt to 1 part and correspondingly increased the amount of modified steel slag aggregate, while keeping the other components and their mass percentages unchanged. The mixing temperature of the asphalt mixture in this comparative example was 125℃. Testing of the mixture specimens showed a Marshall stability of 7.5 kN, a water-immersed Marshall residual stability of 53.1%, a dynamic stability (DS) of 2100 cycles / mm, a low-temperature flexural strain of 1360 με, and a freeze-thaw splitting strength ratio (TSR) of 45.2%. Compared to Example 1, the control group 1 had insufficient SBS asphalt to balance high and low temperature performance; at excessively low temperatures, it lacked sufficient resistance to rutting at high temperatures, and other indicators also failed to meet specifications. Therefore, the amount of SBS modified asphalt used should be reasonably controlled.

[0156] The performance testing of the low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture of the present invention is based on the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20-2011), and other indicators are tested and evaluated in accordance with the "Technical Specifications for Construction of Highway Asphalt Pavement" (JTGF40-2004).

[0157] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture, characterized in that, Includes the following components by weight: 50-60 parts recycled asphalt mixture; 30-40 parts modified steel slag aggregate; 3-5 parts SBS modified asphalt; 0.02-0.06 parts low-temperature asphalt modifier; 3-8 parts slag powder; 0.2-0.5 parts lignin fiber; 1-2 parts self-made asphalt recycling agent; The modified steel slag aggregate is prepared by soaking steel slag aggregate in phosphoric acid solution, surface drying, and then spraying with a silane coupling agent. The self-made asphalt recycling agent comprises the following components in parts by weight: 52-60 parts naphthenic oil; 10-20 parts SBS rubber powder; 3-8 parts tall oil fatty acid; 2-7 parts silane coupling agent; 1-3 parts antioxidant; 0.3-0.5 parts anti-stripping agent; 10-15 parts plasticizer; 4-7 parts silica sol.

2. The high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture according to claim 1, characterized in that, The recycled asphalt mixture comprises the following components in parts by weight: 55-65 parts of recycled asphalt mixture with a particle size of 5mm-10mm; 10-20 parts of recycled asphalt mixture with a particle size of 3mm-5mm; and 20-30 parts of recycled asphalt mixture with a particle size of less than 3mm.

3. The high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture according to claim 1, characterized in that, The method for preparing the modified steel slag aggregate includes the following steps: A1: Further crush the steel slag aggregate after magnetic separation and screen it into four grades with target particle sizes of 10mm~16mm, 5mm~10mm, 3mm~5mm, and 0mm~3mm. A2: Soak steel slag aggregates with four particle sizes of 10mm-16mm, 5mm-10mm, 3mm-5mm, and 0mm-3mm in a 3%-6% phosphoric acid solution for 20-30 hours respectively; A3: After soaking treatment, the four grades of materials with particle sizes of 10mm~16mm, 5mm~10mm, 3mm~5mm and 0mm~3mm are air-dried or dried in a forced-air drying oven until they are surface dry. A4: The four grades of surface-dried aggregate with particle sizes of 10mm-16mm, 5mm-10mm, 3mm-5mm, and 0mm-3mm are diluted with silane coupling agent at a ratio of 0.5%-1.5% and sprayed onto the surface of steel slag. The total amount of silane coupling agent used accounts for 3-5% of the weight of steel slag. After turning and spraying 2-3 times, modified steel slag aggregate is obtained.

4. The high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture according to claim 3, characterized in that, The steel slag aggregate in A2 comprises the following components in parts by weight: 50-60 parts of steel slag aggregate with a particle size of 10mm-15mm; 15-25 parts of steel slag aggregate with a particle size of 5mm-10mm; 10-20 parts of steel slag aggregate with a particle size of 3mm-5mm; 10-20 parts of steel slag aggregate with a particle size of 0mm-3mm.

5. The high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture according to claim 1, characterized in that, The preparation method of the self-made asphalt recycling agent includes the following steps: B1: Pass the SBS rubber powder through a 40-mesh sieve to remove impurities and preheat it to 50-70℃; adjust the pH value of the silica sol to 8-10 with ammonia; dehydrate the naphthenic oil to a moisture content of ≤0.1%; B2: Add naphthenic oil to a reactor containing an inert protective gas and heat to 80-90°C; slowly add SBS rubber powder, maintain the temperature at 90-100°C, and stir for 1-2 hours until the particles are completely dissolved to form a homogeneous solution. B3: Cool solution one to 70-80℃, add tall oil fatty acid and silane coupling agent in sequence, and stir for 15-30 minutes; then add antioxidant and anti-stripping agent, and stir for 30-50 minutes to obtain solution two; B4: Cool solution two to 50-60℃, slowly add silica sol and plasticizer, and stir at 3000-5000 rpm for 20-30 minutes until uniformly dispersed to obtain the self-made asphalt recycling agent; seal and store in a dark glass bottle for later use.

6. The high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture according to claim 5, characterized in that, The inert protective gas is one or more of nitrogen, argon, or helium.

7. The high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture according to claim 1, characterized in that, The silane coupling agent is one or more of KH-550, KH-560 or KH-570.

8. The high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture according to claim 1, characterized in that, The antioxidant is one or both of octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; the anti-stripping agent is SA-3 type asphalt anti-stripping agent produced by Jiangsu Subote New Material Co., Ltd.; and the plasticizer is dioctyl phthalate.

9. The high-dosage RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture according to claim 1, characterized in that, The density of the low-temperature asphalt modifier is 0.94–0.98 g / mm³. 3 The flash point is 180–220℃, and the ash content is <1.0%. The specific surface area of ​​the slag powder is 400–500 m². 2 / kg; the density of the lignin fiber is 1.5 g·cm³. -3 It has an oil absorption ratio of 5 to 9 times the fiber mass and an ash content of 18±5%.

10. A preparation process for high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Mix the dried asphalt mixture recycled material, modified steel slag aggregate, and slag powder. The mixing temperature is controlled at 120-130℃ and the mixing time is 15-20 seconds until the aggregate is uniform and free of lumps to obtain the mixture. S2: Heat the homemade asphalt recycling agent to 60-70℃, and spray it evenly into the mixture through an atomizing nozzle, and stir for 10-15 seconds; S3: Add low-temperature SBS modified asphalt, stir at a temperature not lower than 120℃ for 20-30 seconds to ensure that the asphalt completely coats the aggregate; the preparation method of the low-temperature SBS modified asphalt is to premix the low-temperature modifier with SBS modified asphalt, stir for not less than 30 minutes until the mixture is uniform, and stir at a temperature of 140℃-150℃ to obtain low-temperature SBS modified asphalt. S4: Slowly and disperse the lignin fiber to avoid clumping. The stirring temperature should not be lower than 120℃. Stir for 15-20 seconds until the fiber is evenly dispersed, the asphalt film is uniform, and there are no white speckles. This will give you a high-volume RAP low-temperature plant-mixed hot recycled SMA-13 ​​asphalt mixture.

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