Low temperature cold patch asphalt mixture and method of making same

Abstract

This application provides a low-temperature cold-repair asphalt mixture and its preparation method, which is composed of elastically modified asphalt, composite aggregate, epoxy fatty acid methyl ester, antioxidant, cyclopentadiene, and fumed silica. Based on the total mass of the composite aggregate, the composite aggregate consists of diabase, basalt, limestone manufactured sand, high-energy activated rice husk ash, and composite fibers. This application introduces high-energy activated rice husk ash into the composite aggregate and modifies its interface, thereby introducing a three-dimensional network structure into the asphalt mixture, thus improving the low-temperature performance of the mixture, reducing the compaction difficulty, and enhancing the interfacial bonding performance between the components. After construction, the asphalt mixture can effectively improve the repair effect of the road surface and meet the repair needs of heavy-load roads. This application can effectively improve the emergency response capability of roads and has the advantages of scientific formulation, simple preparation process, low implementation cost, wide applicability, and ease of promotion and implementation.

Description

Technical Field

[0001] This application belongs to the field of building materials technology, specifically relating to a low-temperature cold repair asphalt mixture and its preparation method. Background Technology

[0002] In existing technologies, low-temperature cold-repair asphalt mixtures play a crucial role in emergency repair and preventative maintenance of road surface potholes. They eliminate the need for high-temperature mixing and heating during construction, allowing for direct paving and compaction in low-temperature environments. This rapidly addresses road damage, prevents water erosion, ensures road safety, significantly reduces energy consumption during maintenance, and improves construction efficiency and emergency response capabilities. However, current low-temperature cold-repair asphalt mixtures on the market still have many shortcomings in terms of formulation and performance.

[0003] In existing technologies, traditional solvent-based cold repair asphalt mixtures, while having a fast molding speed and meeting the emergency road repair needs under normal working conditions, exhibit poor adaptability to extreme low temperatures. They are prone to slow initial strength development and poor compaction, and also suffer from drawbacks such as easy hardening and failure during storage, and environmental hazards caused by the volatilization of organic solvents. Modified emulsified cold repair asphalt mixtures, while having better environmental performance and room temperature storage stability and adaptable to maintenance operations at normal temperatures, are prone to demulsification and failure at low temperatures. They also have weak adhesion to the original pavement interface, leading to cracking and detachment at the repair site, insufficient repair durability, and poor bonding stability between the components, making them unsuitable for the high requirements of high-grade heavy-duty roads. Furthermore, existing mixtures generally suffer from the core shortcoming of difficulty in achieving synergistic high and low temperature performance.

[0004] Therefore, in order to comprehensively improve the low-temperature workability, strength stability, interfacial adhesion, repair durability and storage stability of low-temperature cold repair asphalt mixtures, it is urgent to make systematic improvements to break through existing technical bottlenecks and improve the construction quality and long-term service performance of road repair projects. Summary of the Invention

[0005] This application aims to address the shortcomings of existing solvent-based cold repair asphalt mixtures, such as poor adaptability to extreme low temperatures, difficulty in compaction, poor pavement strength after repair, poor storage stability, and easy clumping failure after long-term storage. It also addresses the technical problems of emulsified cold repair asphalt mixtures, such as easy demulsification failure under low-temperature conditions, weak bonding with the original pavement interface, easy cracking and detachment at the repair site, insufficient repair durability, and poor bonding stability between the components of the mixture, making it difficult to meet the requirements of high-grade heavy-duty roads. Therefore, this application proposes a low-temperature cold repair asphalt mixture.

[0006] In order to solve the technical problems proposed in this application, this application also proposes a method for preparing low-temperature cold repair asphalt mixture.

[0007] This application adopts the following scheme: a low-temperature cold repair asphalt mixture, which is composed of the following components by weight: 15-23 parts of elastic modified asphalt, 66-80 parts of composite aggregate, 3-7 parts of epoxy fatty acid methyl ester, 2-5 parts of antioxidant, 2-5 parts of cyclopentadiene, and 1-2 parts of fumed silica, wherein the type of antioxidant is 1010;

[0008] Based on the total mass of the composite aggregate, the composite aggregate is composed of the following components by mass parts: 15-22 parts diabase, 28-36 parts basalt, 22-28 parts limestone manufactured sand, 10-16 parts high-energy activated rice husk ash, and 5-8 parts composite fiber. The composite aggregate has undergone interface modification treatment.

[0009] In some feasible embodiments, based on the total mass of the elastically modified asphalt, the elastically modified asphalt is composed of the following components by mass parts: 55-65 parts of base asphalt, 5-7 parts of linear SBS, 3-6 parts of hydrogenated SEBS, 2-3 parts of styrene-butadiene rubber powder, 2-3 parts of maleic anhydride, 5-7 parts of epoxy fatty acid methyl ester, and 3-4 parts of terpene phenolic resin. The base asphalt is 90# Grade A road petroleum asphalt. The linear SBS (styrene-butadiene-styrene linear block copolymer) was purchased from Sinopec Baling Petrochemical Co., Ltd., and the hydrogenated SEBS (hydrogenated styrene-ethylene-butene-styrene linear block copolymer) was purchased from Shandong Dawn Polymer Materials Co., Ltd.

[0010] In some feasible embodiments, the method for preparing the elastic modified asphalt includes the following steps: Step 101. Divide the base asphalt into two equal parts, and take one part of the base asphalt, linear SBS, hydrogenated SEBS, styrene-butadiene rubber powder, maleic anhydride, epoxy fatty acid methyl ester and terpene phenolic resin into a reaction vessel in sequence. After dispersing at 150℃-160℃ and 1500rpm-1800rpm for 40min-60min, the elastic modification precursor is obtained. Step 102. The elastic modified precursor prepared in step 101 and another portion of base asphalt are sequentially put into a high-speed shearing reactor and sheared at high speed for 60 min-80 min at 175℃-185℃ and 2800 rpm-3300 rpm to obtain the elastic modified asphalt.

[0011] In some feasible embodiments, the preparation method of the high-energy activated rice husk ash includes the following steps: Step 201. Put the pretreated rice husks into a muffle furnace and calcine them at a constant temperature of 600℃-800℃ for 85min-95min. After cooling to room temperature, the crude rice husk ash is obtained. Step 202. Transfer the crude rice husk ash prepared in step 201 to a dry ball mill and ball mill it to 0.065mm-0.075mm to obtain high-energy activated rice husk ash.

[0012] In some feasible embodiments, step 201, the pretreatment method of rice husk includes the following steps: rice husk and sulfuric acid solution with a mass fraction of 1% are added into a stirring vessel in a mass ratio of 1:(48-52), stirred for 2.5 hours at 25°C and 300-400 rpm, and then filtered, washed with clean water, and dried at a constant temperature to obtain the pretreated rice husk.

[0013] In some feasible embodiments, the mass fraction of amorphous silica in the high-energy activated rice husk ash is 94.8%-95.5%.

[0014] In some feasible embodiments, the composite aggregate contains diabase with a particle size of 13.2 mm to 15.9 mm, basalt with a particle size of 4.7 mm to 8.8 mm, and limestone manufactured sand with a particle size of 1.2 mm to 3.6 mm. The composite fiber is obtained by mixing basalt fiber and polyester fiber at a mass ratio of 2:1.

[0015] In some feasible embodiments, the basalt fiber has a length of 5mm-7mm and a diameter of 11µm-15µm, the polyester fiber has a length of 2mm-4mm and a diameter of 18µm-22µm.

[0016] In some feasible embodiments, the interface modification method of the composite aggregate includes the following steps: diabase, basalt, limestone manufactured sand, high-energy activated rice husk ash and composite fiber are sequentially added into a twin-shaft horizontal mixing pot according to a preset ratio, and stirred for 60min-90min at 35℃-45℃ and 300rpm-500rpm. During the mixing process, under the conditions of output pressure of 0.8MPa-1.0MPa, output flow rate of 1.5L / min-2.0L / min, and atomization cone angle of 60°, the interface modifier is sprayed into the composite aggregate through a high-pressure atomizing nozzle; The interface modifier is obtained by mixing dodecyl phosphate monoester and anhydrous ethanol at a mass ratio of 1:30, and the amount of dodecyl phosphate monoester used is 0.3%-0.7% of the total mass of the dry composite aggregate.

[0017] To address the technical problems raised in this application, this application also provides a method for preparing low-temperature cold-repair asphalt mixture, which includes the following steps: Step 301. Add the elastic modified asphalt, epoxy fatty acid methyl ester, antioxidant, cyclopentadiene, and fumed silica into the mixer in the preset ratio. Mix for 60 min to 90 min at 35℃-45℃ and 1500 rpm-1800 rpm to obtain the repair adhesive. Step 302. Add the repair adhesive prepared in step 301 into the mixing tank according to the preset ratio, then divide the composite aggregate into three equal parts and add them into the mixing tank in three batches. Stir at room temperature and a speed of 1000rpm-1200rpm. The stirring time after each addition is 40min-60min. After all the materials are added and stirred, the low temperature cold repair asphalt mixture is obtained.

[0018] To address the technical problems raised in this application, this application also provides a construction method for low-temperature cold-repair asphalt mixtures, which includes the following steps: Step 401. Treatment of pothole defects The pit is cut into a regular rectangle using a cutting machine, with the cutting range extending 5cm-10cm beyond the edge of the defect and the cutting depth ≥5cm, ensuring that the pit walls are vertical, flat, and free of loose or damaged material. Loose asphalt, debris, water, and snow are removed from the pit using a pneumatic hammer / milling machine until a solid base layer is exposed. In low-temperature environments (≤0℃), a hot air gun is used to completely melt and dry the snow on the pit walls and bottom, ensuring that there is no free water or dust in the pit. Step 402. Pretreatment of the interface between new and old road surfaces The repair adhesive prepared in step 301 of this application is evenly applied to the walls and bottom of the pit as an interface adhesive, at a dosage of 0.3 kg / m². 2 -0.6kg / m 2 In low-temperature environments (≤0℃), the repair adhesive needs to be preheated to 40℃-50℃ before application to ensure fluidity. After application, let it stand for 3-5 minutes until the repair adhesive is fully soaked and penetrates into the micro-cracks of the old road surface to form an adhesive interface before paving. Step 403. Layered paving When the pothole depth is greater than 6cm, layered paving should be adopted, with a single layer thickness of ≤6cm; the loose paving coefficient should be controlled at 1.2-1.4 in normal temperature environment and increased to 1.3-1.5 in low temperature environment (≤0℃); when paving, the material should be evenly spread from the center to the surrounding area, and the paved surface should be 1.2cm-1.4cm higher than the original road surface; in extreme low temperature environment, the low temperature cold repair asphalt mixture should be preheated to 10℃-18℃ in the heat preservation warehouse in advance; Step 404. Gradient compaction After paving, compaction should begin immediately. First, lightly compact the surface with a small plate compactor 2-3 times to compact the edges of potholes and the junction between the new and old pavement. Second, heavily compact the surface with a vibratory plate compactor / small roller 4-6 times, increasing the number of compaction passes by 2-3 times in low-temperature environments to ensure a compaction degree ≥95% (≥96% at normal temperatures). Third, statically compact the surface with a smooth-drum roller 1-2 times to eliminate wheel tracks and ensure that the flatness deviation between the repaired pavement and the original pavement is ≤3mm. Step 405. Road surface repair and reopening to traffic After compaction, repair the road surface, remove excess mixture, and ensure that the road surface is flat and free of loose material. In normal temperature environment (≥0℃), allow the road to stand for 1-2 hours after compaction before opening to traffic; in low temperature environment (0℃-10℃), allow the road to stand for 2-4 hours before opening to traffic; in extreme low temperature environment (<0℃), allow the road to stand for 4-6 hours before opening to traffic; in emergency repair scenarios, the road can be opened to traffic immediately after compaction.

[0019] Compared with the prior art, this application has the following beneficial effects: This application provides a low-temperature cold-repair asphalt mixture, which, by weight, consists of 15-23 parts of elastic modified asphalt, 66-80 parts of composite aggregate, 3-7 parts of epoxy fatty acid methyl ester, 2-5 parts of antioxidant, 2-5 parts of cyclopentadiene, and 1-2 parts of fumed silica. Based on the total mass of the composite aggregate, which is composed of diabase, basalt, limestone manufactured sand, high-energy activated rice husk ash, and composite fibers, and undergoes interface modification treatment, this mixture can be directly laid and compacted in low-temperature environments for emergency repair and preventative maintenance of road surface potholes. By optimizing the proportions of each component and performing interface modification treatment on the composite aggregate, the high and low temperature adaptability of the mixture can be synergistically improved, thereby solving the defects of traditional solvent-based mixtures such as poor extreme low-temperature adaptability, easy compaction and hardening, poor storage stability, and environmental hazards. It also overcomes the problems of modified emulsified mixtures, such as easy demulsification and failure at low temperatures, weak interfacial bonding, insufficient repair durability, and difficulty in adapting to high-grade heavy-load roads. This application can effectively ensure the low-temperature workability and strength stability of the mixture, significantly improve interfacial adhesion and long-term storage stability, extend the service life of road repair parts, reduce maintenance construction energy consumption, and improve the emergency response capability of road maintenance. It has the advantages of scientific and reasonable formula, simple preparation and operation, low implementation cost, wide applicability, and easy promotion and implementation. Attached Figure Description

[0020] Figure 1 The bar chart shows the test results of Examples 1-3 and Comparative Examples 8-11.

[0021] Figure 2 These are the test results for Example 2, Comparative Examples 1-4.

[0022] Figure 3These are the test results for Example 2, Comparative Examples 5-7.

[0023] Figure 4 These are radar charts showing the test results of Examples 1-3 and Comparative Examples 8-11. Detailed Implementation

[0024] The technical solutions provided in this application are further illustrated in conjunction with the contents shown in Examples 1-3 and Comparative Examples 1-11.

[0025] Example 1 (1) The preparation method of elastic modified asphalt includes the following steps. Step 101. According to the elastic modified asphalt component table shown in Table 1, divide the base asphalt into two equal parts, and take one part of the base asphalt, linear SBS, hydrogenated SEBS, styrene-butadiene rubber powder, maleic anhydride, epoxy fatty acid methyl ester and terpene phenolic resin into the reactor in sequence. After dispersing at 150℃ and 1500rpm for 40min, the elastic modified precursor is obtained. Step 102. The elastic modified precursor prepared in step 101 and another portion of base asphalt are sequentially put into a high-speed shearing reactor and sheared at 175°C and 2800 rpm for 60 minutes to obtain the elastic modified asphalt.

[0026] (2) The preparation method of high-energy activated rice husk ash includes the following steps. Step 201. Put the pretreated rice husks into a muffle furnace and calcine them at 700℃ for 85 minutes. After cooling to room temperature, the crude rice husk ash is obtained. Step 202. Transfer the crude rice husk ash prepared in step 201 to a dry ball mill and ball mill it to 0.07 mm to obtain high-energy activated rice husk ash.

[0027] In step 201, the pretreatment method for rice husks includes the following steps: rice husks and a 1% sulfuric acid solution are added to a stirring vessel at a mass ratio of 1:48. The mixture is stirred at 25°C and 300 rpm for 2.5 hours. Then, the mixture is filtered, washed with clean water, and dried at a constant temperature to obtain the pretreated rice husks.

[0028] (3) The interface modification method of composite aggregates includes the following steps. Diabase, basalt, limestone manufactured sand, high-energy activated rice husk ash, and composite fiber were sequentially added to a twin-shaft horizontal mixing pot according to a preset ratio and stirred for 60 minutes at 35℃ and 300 rpm. During the stirring process, the interface modifier was sprayed into the composite aggregate through a high-pressure atomizing nozzle under the conditions of an output pressure of 0.8 MPa, an output flow rate of 1.5 L / min, and an atomization cone angle of 60°. The interface modifier is obtained by mixing dodecyl phosphate monoester and anhydrous ethanol at a mass ratio of 1:30, and the amount of dodecyl phosphate monoester is 0.4% of the total mass of the dry composite aggregate.

[0029] (4) The preparation method of low-temperature cold repair asphalt mixture includes the following steps. Step 301. According to the composition table of low temperature cold repair asphalt mixture shown in Table 2, add the elastic modified asphalt, epoxy fatty acid methyl ester, antioxidant, cyclopentadiene and fumed silica into the mixer in the preset ratio. Mix for 60 minutes at 35℃ and 1500rpm to obtain the repair adhesive. Step 302. Add the repair adhesive and composite aggregate prepared in step 301 into the mixing tank in sequence according to the preset ratio, and stir at room temperature and 1000 rpm. The composite aggregate is divided into three parts and added into the mixing tank in batches. The stirring time for each batch is 40 min. After stirring is completed, the low temperature cold repair asphalt mixture is obtained.

[0030] Example 2 (1) The preparation method of elastic modified asphalt includes the following steps. Step 101. According to the elastic modified asphalt component table shown in Table 1, divide the base asphalt into two equal parts, and take one part of the base asphalt, linear SBS, hydrogenated SEBS, styrene-butadiene rubber powder, maleic anhydride, epoxy fatty acid methyl ester and terpene phenolic resin into the reactor in sequence. After dispersing at 155℃ and 1650rpm for 50min, the elastic modified precursor is obtained. Step 102. The elastic modified precursor prepared in step 101 and another portion of base asphalt are sequentially put into a high-speed shearing reactor and sheared at 180°C and 3000 rpm for 70 minutes to obtain the elastic modified asphalt.

[0031] (2) The preparation method of high-energy activated rice husk ash includes the following steps. Step 201. Put the pretreated rice husks into a muffle furnace and calcine them at 700℃ for 90 minutes. After cooling to room temperature, the crude rice husk ash is obtained. Step 202. Transfer the crude rice husk ash prepared in step 201 to a dry ball mill and ball mill it to 0.07 mm to obtain high-energy activated rice husk ash.

[0032] In step 201, the pretreatment method for rice husks includes the following steps: rice husks and a 1% sulfuric acid solution are added to a stirring vessel at a mass ratio of 1:50. The mixture is stirred at 25°C and 350 rpm for 2.5 hours. Then, the mixture is filtered, washed with clean water, and dried at a constant temperature to obtain the pretreated rice husks.

[0033] (3) The interface modification method of composite aggregates includes the following steps. Diabase, basalt, limestone manufactured sand, high-energy activated rice husk ash, and composite fiber were sequentially added to a twin-shaft horizontal mixing pot according to a preset ratio and stirred for 80 minutes at 40℃ and 400 rpm. During the stirring process, the interface modifier was sprayed into the composite aggregate through a high-pressure atomizing nozzle under the conditions of an output pressure of 0.9 MPa, an output flow rate of 1.8 L / min, and an atomization cone angle of 60°. The interface modifier is obtained by mixing dodecyl phosphate monoester and anhydrous ethanol at a mass ratio of 1:30, and the amount of dodecyl phosphate monoester used is 0.5% of the total mass of the dry composite aggregate.

[0034] (4) The preparation method of low-temperature cold repair asphalt mixture includes the following steps. Step 301. According to the composition table of low temperature cold repair asphalt mixture shown in Table 2, add the elastic modified asphalt, epoxy fatty acid methyl ester, antioxidant, cyclopentadiene and fumed silica into the mixer in the preset ratio. Mix for 80 minutes at 40℃ and 1700rpm to obtain the repair adhesive. Step 302. The repair adhesive and composite aggregate prepared in step 301 are added into the mixing tank in sequence according to the preset ratio and stirred at room temperature and 1100 rpm. The composite aggregate is divided into three parts and added into the mixing tank in batches. The stirring time for each batch is 50 min. After stirring is completed, the low temperature cold repair asphalt mixture is obtained.

[0035] Example 3 (1) The preparation method of elastic modified asphalt includes the following steps. Step 101. According to the elastic modified asphalt component table shown in Table 1, divide the base asphalt into two equal parts, and take one part of the base asphalt, linear SBS, hydrogenated SEBS, styrene-butadiene rubber powder, maleic anhydride, epoxy fatty acid methyl ester and terpene phenolic resin into the reactor in sequence. After dispersing at 160℃ and 1800rpm for 60min, the elastic modified precursor is obtained. Step 102. The elastic modified precursor prepared in step 101 and another portion of base asphalt are sequentially put into a high-speed shearing reactor and sheared at 185°C and 3300 rpm for 80 minutes to obtain the elastic modified asphalt.

[0036] (2) The preparation method of high-energy activated rice husk ash includes the following steps. Step 201. Put the pretreated rice husks into a muffle furnace and calcine them at 700℃ for 95 minutes. After cooling to room temperature, the crude rice husk ash is obtained. Step 202. Transfer the crude rice husk ash prepared in step 201 to a dry ball mill and ball mill it to 0.07 mm to obtain high-energy activated rice husk ash.

[0037] In step 201, the pretreatment method for rice husks includes the following steps: rice husks and a 1% sulfuric acid solution are added to a stirring vessel at a mass ratio of 1:52. The mixture is stirred at 25°C and 400 rpm for 2.5 hours. Then, the mixture is filtered, washed with clean water, and dried at a constant temperature to obtain the pretreated rice husks.

[0038] (3) The interface modification method of composite aggregates includes the following steps. Diabase, basalt, limestone manufactured sand, high-energy activated rice husk ash, and composite fiber were sequentially added to a twin-shaft horizontal mixing pot according to a preset ratio and stirred for 90 minutes at 45℃ and 500 rpm. During the stirring process, the interface modifier was sprayed into the composite aggregate through a high-pressure atomizing nozzle under the conditions of an output pressure of 1.0 MPa, an output flow rate of 2.0 L / min, and an atomization cone angle of 60°. The interface modifier is obtained by mixing dodecyl phosphate monoester and anhydrous ethanol at a mass ratio of 1:30, and the amount of dodecyl phosphate monoester is 0.6% of the total mass of the dry composite aggregate.

[0039] (4) The preparation method of low-temperature cold repair asphalt mixture includes the following steps. Step 301. According to the composition table of low temperature cold repair asphalt mixture shown in Table 2, add the elastic modified asphalt, epoxy fatty acid methyl ester, antioxidant, cyclopentadiene and fumed silica into the mixer in the preset ratio. After mixing for 90 minutes at 45℃ and 1800rpm, the repair adhesive is obtained. Step 302. The repair adhesive and composite aggregate prepared in step 301 are added into the mixing tank in sequence according to the preset ratio and stirred at room temperature and 1200 rpm. The composite aggregate is divided into three parts and added into the mixing tank in batches. The stirring time for each batch is 60 min. After stirring is completed, the low temperature cold repair asphalt mixture is obtained.

[0040] Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that the calcination temperature of the rice husk in step 201 is adjusted to 500°C, while the processes of the other components remain unchanged.

[0041] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that the calcination temperature of the rice husk in step 201 is adjusted to 600°C, while the processes of the other components remain unchanged.

[0042] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that the calcination temperature of the rice husk in step 201 is adjusted to 800°C, while the processes of the other components remain unchanged.

[0043] Comparative Example 4 The difference between Comparative Example 4 and Example 2 is that the calcination temperature of the rice husk in step 201 is adjusted to 900°C, while the processes for the other components remain unchanged.

[0044] Comparative Example 5 The difference between Comparative Example 5 and Example 2 is that the 1% sulfuric acid solution in the rice husk pretreatment process was replaced with water, while the process for the remaining components remained unchanged.

[0045] Comparative Example 6 The difference between Comparative Example 6 and Example 2 is that the 1% sulfuric acid solution in the rice husk pretreatment process was replaced with a 3% sulfuric acid solution, while the other components and processes remained unchanged.

[0046] Comparative Example 7 The difference between Comparative Example 7 and Example 2 is that the 1% sulfuric acid solution in the rice husk pretreatment process was replaced with a 5% sulfuric acid solution, while the other components and processes remained unchanged.

[0047] Comparative Example 8 The difference between Comparative Example 8 and Example 2 is that all the elastic modified asphalt was replaced with ordinary 90# Grade A road petroleum asphalt, while the process of the remaining components remained unchanged.

[0048] Comparative Example 9 The difference between Comparative Example 9 and Example 2 is that the high-energy activated rice husk ash in the composite aggregate was removed and replaced with an equal amount of limestone manufactured sand, while the process of the remaining components remained unchanged.

[0049] Comparative Example 10 The difference between Comparative Example 10 and Example 2 is that the composite fibers in the composite aggregate were removed and replaced with an equal amount of limestone manufactured sand, while the process of the remaining components remained unchanged.

[0050] Comparative Example 11 The difference between Comparative Example 11 and Example 2 is that the composite aggregate interface modification step is removed, while the processes for the other components remain unchanged.

[0051] Table 1. Components of Elastic Modified Asphalt

[0052] Table 2. Components of Asphalt Mixture for Low-Temperature Cold Repair

[0053] Continued from Table 2

[0054] The low-temperature cold-repair asphalt mixtures prepared in Examples 1-3 and Comparative Examples 1-11 were subjected to the following tests: Test 1: According to the test method T0709-2011 in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the low-temperature cold repair asphalt mixtures prepared in Examples 1-3 and Comparative Examples 1-11 were prepared into corresponding test specimens, and the initial Marshall stability of the test specimens was tested. After curing the test specimens at 60℃ for 48h, their molding Marshall stability was tested again according to the same standard to evaluate the immediate repair performance and long-term load-bearing performance of the cold repair asphalt mixtures after molding.

[0055] Test 2 (Extreme Low Temperature Condition Simulation Experiment A): The low-temperature cold repair asphalt mixtures prepared in Examples 1-3 and Comparative Examples 1-11 were prepared into standard Marshall specimens of the same size (diameter 101.6 mm, height 63.5 mm). All specimens were placed in a constant temperature environment of -10℃ for 6 hours. After the insulation was completed, the low-temperature splitting strength of each specimen at -10℃ was tested according to the standard T0716-2011 in JTGE20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" to evaluate its low-temperature bonding performance and crack resistance.

[0056] Test 3 (Extreme Low Temperature Condition Simulation Experiment B): The low-temperature cold repair asphalt mixtures prepared in Examples 1-3 and Comparative Examples 1-11 were prepared into standard small beam specimens of the same size (250mm×30mm×35mm). The specimens were simultaneously placed in a constant temperature environment of -10℃ for 6 hours. After the insulation was completed, the low-temperature bending failure strain and splitting stiffness modulus of each specimen at -10℃ were tested according to the standards T0715-2011 and T0716-2011 of JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" to evaluate their low-temperature resistance to deformation and cracking.

[0057] Test 4: The low-temperature cold-repair asphalt mixtures prepared in Examples 1-3 and Comparative Examples 1-11 were prepared into standard Marshall specimens of the same size (diameter 101.6 mm, height 63.5 mm). Each specimen was then subjected to a freeze-thaw cycle treatment of vacuum saturation, freezing at -18℃, and thawing in a 60℃ water bath. After the cycle treatment was completed, the freeze-thaw splitting residual strength ratio (TSR) of each specimen was tested according to the standard T0729-2000 in JTGE20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" to evaluate its water loss resistance and long-term weather resistance.

[0058] Test 5: The low-temperature cold repair asphalt mixtures prepared in Examples 1-3 and Comparative Examples 1-11 were prepared into standard rut plate specimens of the same size (300mm long, 300mm wide, and 50mm thick). All specimens were placed in a constant temperature environment of 60℃ for 8 hours. After the insulation was completed, the dynamic stability of each specimen at 60℃ was tested according to the standard T0719-2011 in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" to evaluate its high-temperature deformation resistance and long-term service stability.

[0059] Test 6: According to the standard of GB / T 30451-2013 "Chemical Analysis Methods for Silica Ash", the mass fraction of amorphous silica in the high-energy activated rice husk ash used in Examples 1-3 and Comparative Examples 1-11 was measured. The test results are shown in Table 3 below.

[0060] Table 3 Results of Tests 1-6

[0061] Continued from Table 3

[0062] From Table 3, Figure 1 , Figure 4Test results show that the cold-repair asphalt mixtures in Examples 1-3, composed of elastically modified asphalt, composite aggregates (diabase, basalt, limestone manufactured sand, high-energy activated rice husk ash, composite fibers), epoxy fatty acid methyl esters, antioxidant 1010, cyclopentadiene, and fumed silica, are prepared by calcining at 700℃ and acid leaching with 1% sulfuric acid. The composite aggregates are interface-modified with dodecyl phosphate monoester, and the elastically modified asphalt is prepared by crosslinking with linear SBS and hydrogenated SEBS. This process significantly improves the low-temperature crack resistance, high-temperature rutting resistance, water stability, and load-bearing durability of the cold-repair asphalt mixture while ensuring its immediate workability. During the preparation of the cold-repair asphalt mixture, the pozzolanic effect and filling effect of the high-energy activated rice husk ash, and the three-dimensional reinforcement effect of the composite fibers contribute to its superior performance. The compatibility optimization effect of the interface-modified aggregate can effectively improve the interfacial adhesion between asphalt mastic and aggregate, reducing the risk of moisture intrusion. On the other hand, it can effectively promote the formation of a composite microstructure of cross-linked elastic network-rigid aggregate skeleton-filler modification-interfacial reinforcement within the mixture, improving the synergistic effect efficiency and homogenization degree of each component, thereby effectively improving the comprehensive mechanical properties and long-term durability of the mixture. By applying this cold-repair asphalt mixture to road cold-repair projects, it can effectively solve the technical problems of existing ordinary cold-repair mixtures such as easy cracking at low temperatures, easy rutting at high temperatures, severe water loss, and insufficient load-bearing capacity. It can significantly extend the service life of road repair parts, adapt to complex climates such as severe cold, rainy, and high temperature alternation, and light to medium load road scenarios. At the same time, it can realize the resource utilization of rice husk agricultural waste, combining environmental protection and economic advantages.

[0063] In Comparative Example 1, the organic matter such as cellulose and lignin in the rice husk was not completely decomposed during calcination at 500℃. The residual organic matter coated the surface of silica, resulting in insufficient release of amorphous SiO2, with a content of only 82.3% (a decrease of 13.6% compared to Example 2), and a significant reduction in activity. On the one hand, the decrease in amorphous SiO2 content reduced the activity of rice husk ash, preventing it from undergoing an effective pozzolanic reaction with the active groups in the asphalt mastic and failing to form stable Si-OC covalent bonds. This led to weakened adhesion at the asphalt-aggregate interface and insufficient intermolecular forces. Furthermore, the residual organic matter reduced the compatibility between rice husk ash and asphalt, resulting in uneven dispersion of rice husk ash particles in the asphalt mastic. This prevented effective filling of micropores in the aggregate, increased porosity within the mixture, and significant stress concentration. On the other hand, the incompletely decomposed organic matter is prone to aging and degradation during long-term use of the mixture, leading to voids within the mixture and further reducing its strength and durability.

[0064] From Table 3, Figure 2It can be seen that, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 1 was 2.87 kN (a decrease of 30.8%), and the formed Marshall stability was 7.21 kN (a decrease of 30.1%), indicating a significant decrease in load-bearing capacity; the low-temperature splitting strength at -10℃ was 2.89 MPa (a decrease of 31.4%), and the bending failure strain was 2315 με (a decrease of 28.7%), indicating a significant deterioration in low-temperature crack resistance; the freeze-thaw splitting TSR was 78.2% (a decrease of 14.3%), indicating a significant decrease in water stability; and the dynamic stability at 60℃ was 2186 cycles·mm. -1 (Decreased by 27.7%), with significantly insufficient high-temperature rutting resistance and a marked reduction in overall performance.

[0065] In Comparative Example 2, when calcined at 600℃, the organic matter in the rice husk was basically decomposed, but a small amount remained. The content of amorphous SiO2 increased to 91.7% (a decrease of 3.7% compared to Example 2). The activity of rice husk ash was improved but did not reach its peak. On the one hand, the small amount of residual organic matter still slightly inhibited the pozzolanic effect of amorphous SiO2, resulting in insufficient chemical bonding strength between rice husk ash and asphalt mortar, and the interfacial adhesion was slightly lower than that in Example 2. Furthermore, the filling effect of amorphous SiO2 was not optimal, the micropores of the aggregate were not completely filled, the density of the mixture was slightly lower, and the effect of relieving internal stress was limited. At the same time, although the dispersibility of rice husk ash particles was better than that of Comparative Example 1, a small amount of agglomeration still existed, affecting the synergistic effect between the components.

[0066] From Table 3, Figure 2 It can be seen that, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 2 is 3.52 kN (a decrease of 15.2%), the forming Marshall stability is 8.95 kN (a decrease of 13.3%), the low-temperature splitting strength at -10℃ is 3.56 MPa (a decrease of 15.4%), the bending failure strain is 2782 με (a decrease of 14.3%), the freeze-thaw splitting TSR is 85.7% (a decrease of 6.1%), and the dynamic stability at 60℃ is 2579 cycles·mm. -1 (Decrease of 14.7%), the core performance of the test specimen was better than that of Comparative Example 1, but still lower than that of Example 2.

[0067] In Comparative Example 3, at 800℃, the amorphous SiO2 in rice husk ash underwent a crystal transformation, generating inert crystalline SiO2. The content of amorphous SiO2 decreased to 90.5% (a decrease of 4.9% compared to Example 2), and the activity of rice husk ash decreased significantly. On the one hand, crystalline SiO2 could not react with asphalt mastic to form a pozzolanic reaction and could not form chemical bonds, only playing a weak physical filling role. The adhesion of the asphalt-aggregate interface was significantly weakened, and the intermolecular forces were only van der Waals forces, resulting in low bonding strength. Furthermore, during the crystal transformation process, the rice husk ash particles showed slight sintering and agglomeration, resulting in poor dispersibility, poor filling effect, increased porosity inside the mixture, and obvious stress concentration. Moreover, the rigidity of crystalline SiO2 was too strong and did not match the flexibility of asphalt mastic, which easily led to microcracks at the interface, further reducing the performance of the mixture.

[0068] From Table 3, Figure 2 It can be seen that, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 3 is 3.68 kN (a decrease of 11.3%), the forming Marshall stability is 9.03 kN (a decrease of 12.5%), the low-temperature splitting strength at -10℃ is 3.62 MPa (a decrease of 14.0%), the bending failure strain is 2815 με (a decrease of 13.3%), the freeze-thaw splitting TSR is 86.1% (a decrease of 5.7%), and the dynamic stability at 60℃ is 2605 cycles·mm. -1 (Decreased by 13.9%), the performance was slightly better than Comparative Examples 1 and 2, but lower than Example 2, and the high-temperature rutting resistance decreased significantly, indicating that excessively high calcination temperature would cause rice husk ash to deactivate, thus failing to exert the core modifying effect of rice husk ash.

[0069] In Comparative Example 4, at 900℃, the crystal transformation of amorphous SiO2 was more complete, the content of crystalline SiO2 increased significantly, and the content of amorphous SiO2 was only 84.6% (a decrease of 11.1% compared to Example 2), further reducing the activity of rice husk ash. On the one hand, the inertness of crystalline SiO2 was more obvious, making it difficult for rice husk ash to react chemically with asphalt mortar. Its physical filling effect was also greatly weakened due to the severe sintering and agglomeration of the internal particles of rice husk ash, resulting in a significant increase in the internal porosity of the mixture. Furthermore, the sintered and agglomerated rice husk ash particles also disrupted the continuity of the asphalt-aggregate interface, leading to a sharp decrease in interfacial adhesion and easy interfacial delamination. Moreover, agglomerated particles became stress concentration points, which easily caused microcrack propagation at low temperatures and exacerbated deformation at high temperatures.

[0070] From Table 3, Figure 2It can be seen that, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 4 is 3.02 kN (a decrease of 27.2%), the forming Marshall stability is 7.58 kN (a decrease of 26.5%), the low-temperature splitting strength at -10℃ is 3.05 MPa (a decrease of 27.6%), the bending failure strain is 2403 με (a decrease of 26.0%), the freeze-thaw splitting TSR is 79.5% (a decrease of 12.9%), and the dynamic stability at 60℃ is 2217 cycles·mm. -1 (Decrease of 26.7%) The overall performance of the test specimen was better than that of Comparative Example 1, but lower than that of Comparative Examples 2 and 3. This further illustrates that excessively high calcination temperature will lead to the deactivation of rice husk ash and exacerbate agglomeration, which seriously affects the overall performance of the mixture.

[0071] In Comparative Example 5, the rice husk ash was washed with water without acid leaching pretreatment. Water could not remove impurities such as potassium, sodium, and calcium from the rice husk, leaving these impurities on the surface. On one hand, these impurities inhibited the activity of amorphous SiO2, hindering its pozzolanic reaction with asphalt mortar, resulting in an amorphous SiO2 content of only 86.4% (a decrease of 9.2% compared to Example 2). This weakened chemical bonding and reduced the adhesion between the asphalt and aggregate interface. Furthermore, the residual metal impurities promoted the crystallization of amorphous SiO2 during calcination, further reducing its activity. At the same time, the impurities increased the hydrophilicity of the rice husk ash particles, damaging the compatibility of the asphalt-aggregate interface and leading to poorer asphalt adhesion to the aggregate, making interface peeling more likely. On the other hand, the metal impurities reduced the consistency of the asphalt mortar, affecting its anti-aging and anti-deformation properties, weakening the intermolecular forces within the mixture, and decreasing cohesion.

[0072] From Table 3, Figure 3 It can be seen that, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 5 is 3.12 kN (a decrease of 24.8%), the forming Marshall stability is 7.85 kN (a decrease of 24.0%), the low-temperature splitting strength at -10℃ is 3.14 MPa (a decrease of 25.4%), the bending failure strain is 2456 με (a decrease of 24.4%), the freeze-thaw splitting TSR is 80.3% (a decrease of 12.0%), and the dynamic stability at 60℃ is 2268 cycles·mm. -1 (Decrease of 25.0%), all core properties of the test specimens decreased significantly, with the water stability of the test specimens showing the most significant decrease. This indicates that without acid leaching pretreatment, impurities cannot be removed, leading to a decrease in the activity of rice husk ash, a deterioration in interfacial compatibility, and an inability to exert the core modifying effect of rice husk ash. The performance of the test specimens was far lower than that of Examples 1-3.

[0073] In Comparative Example 6, the acid concentration of rice husk ash was increased to 3%. The excessively high acid concentration corroded the silica skeleton in the rice husk ash, resulting in a decrease in the amorphous SiO2 content to 92.1% (a decrease of 3.3% compared to Example 2), and a slight decrease in the activity of the rice husk ash. On the one hand, the structure of the corroded silica skeleton was incomplete and could not form a stable chemical bond with the asphalt mastic, resulting in a slightly lower interfacial adhesion than in Example 2. On the other hand, the residual acid radicals would be adsorbed on the surface of the rice husk ash, damaging the compatibility of the asphalt-aggregate interface, leading to a poorer coating effect of the asphalt on the aggregate and easy interface peeling. At the same time, the excessively high acid concentration would cause slight dissolution of the rice husk ash particles, reducing dispersibility and affecting the filling effect, resulting in a slightly lower density of the mixture.

[0074] From Table 3, Figure 3 It can be seen that, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 6 is 3.76 kN (a decrease of 9.4%), the forming Marshall stability is 9.24 kN (a decrease of 10.5%), the low-temperature splitting strength at -10℃ is 3.78 MPa (a decrease of 10.2%), the bending failure strain is 2907 με (a decrease of 10.5%), the freeze-thaw splitting TSR is 87.2% (a decrease of 4.5%), and the dynamic stability at 60℃ is 2632 cycles·mm. -1 (Decrease of 12.9%) The performance of the test specimen was better than that of Comparative Example 5, but lower than that of Example 2, indicating that excessively high acid leaching concentration can damage the rice husk ash skeleton, reduce its activity, and have a negative impact on its filling effect.

[0075] In Comparative Example 7, the acid leaching concentration of rice husk ash was increased to 5%, and the silica skeleton in the rice husk ash was severely corroded, with the amorphous SiO2 content decreasing to 88.5% (a decrease of 7.0% compared to Example 2), and the activity significantly decreased. On the one hand, the corroded silica skeleton was broken and could not play an effective filling role, and the chemical bonding with the asphalt mastic was greatly weakened, resulting in a sharp decrease in interfacial adhesion. On the other hand, a large number of residual acid radicals would severely damage the compatibility of the asphalt-aggregate interface, causing the asphalt and aggregate to fail to bond effectively, making it easy for interfacial peeling to occur, and the cohesion of the mixture to decrease significantly. At the same time, the rice husk ash particles after dissolution had extremely poor dispersibility, resulting in severe agglomeration and the formation of stress concentration points, which were prone to cracking at low temperatures and deformation at high temperatures.

[0076] From Table 3, Figure 3 It can be seen that, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 7 is 3.35 kN (a decrease of 19.3%), the forming Marshall stability is 8.31 kN (a decrease of 19.5%), the low-temperature splitting strength at -10℃ is 3.42 MPa (a decrease of 18.8%), the bending failure strain is 2624 με (a decrease of 19.2%), the freeze-thaw splitting TSR is 82.6% (a decrease of 9.5%), and the dynamic stability at 60℃ is 2415 cycles·mm.-1 (Decrease of 20.1%), the performance was better than Comparative Example 5, but lower than Comparative Example 6 and Example 2, further demonstrating that excessively high acid leaching concentration will seriously damage the performance of rice husk ash, thereby leading to a decrease in the overall performance of the mixture.

[0077] In Comparative Example 8, the elastic modified asphalt was replaced with ordinary 90# base asphalt. Ordinary unmodified asphalt lacks a cross-linked elastic network, has a linear molecular chain structure, low entanglement density, and poor double bond activity. On the one hand, the interaction force between linear molecular chains is only van der Waals force, without chemical bonding. At low temperatures, the molecular chains cannot extend freely and are prone to breakage. At high temperatures, the molecular chains are prone to slippage and plastic deformation. Furthermore, ordinary unmodified asphalt has poor compatibility with interface-modified aggregates and cannot form a strong interfacial bond with the modifier. The interfacial adhesion decreases sharply, and interfacial delamination is prone to occur. At the same time, ordinary unmodified asphalt has poor anti-aging properties, and the molecular chains are prone to degradation during long-term use, leading to a continuous decline in the performance of the mixture and making it impossible to form a synergistic effect with rice husk ash and composite fibers.

[0078] As shown in Table 3, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 8 was 2.15 kN (a decrease of 48.2%), and the formed Marshall stability was 5.62 kN (a decrease of 45.5%), indicating a sharp drop in load-bearing capacity; the splitting strength at -10℃ was 1.87 MPa (a decrease of 55.6%), and the bending failure strain was 1246 με (a decrease of 61.6%), indicating extremely poor low-temperature crack resistance and inability to adapt to low-temperature winter environments; the freeze-thaw splitting TSR was 62.5% (a decrease of 31.5%), indicating a significant decrease in water stability and susceptibility to water damage; the dynamic stability at 60℃ was 1128 cycles·mm. -1 (Decreased by 62.7%), with extremely poor high-temperature rutting resistance, prone to rutting deformation, and the overall performance of the test specimen was far lower than that of Examples 1-3, and even failed to meet the basic requirements for cold repair.

[0079] In Comparative Example 9, the amount of high-energy activated rice husk ash in the composite aggregate was 0, and there was no filling and pozzolanic effect of high-energy activated rice husk ash. On the one hand, the limestone manufactured sand could only play a simple physical filling role and could not form a chemical bond with the asphalt mastic. The asphalt-aggregate interface adhesion was only van der Waals force, with low bonding strength and easy interface delamination. Furthermore, the micropores of the aggregate could not be filled by nano-sized rice husk ash particles, the porosity of the mixture increased, the stress concentration phenomenon was obvious, and the cohesion decreased. At the same time, without the cross-linking effect of highly active amorphous SiO2, the consistency and deformation resistance of the asphalt mastic decreased, and it could not form a synergistic effect with composite fibers and elastic modified asphalt, resulting in a loose microstructure of the mixture.

[0080] Table 3 shows that, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 9 was 3.06 kN (a decrease of 26.3%), the forming Marshall stability was 7.64 kN (a decrease of 26.0%), the low-temperature splitting strength at -10℃ was 3.02 MPa (a decrease of 28.3%), the bending failure strain was 2287 με (a decrease of 29.6%), the freeze-thaw splitting TSR was 76.4% (a decrease of 16.3%), and the dynamic stability at 60℃ was 2095 cycles·mm. -1 (Decrease of 30.7%), the overall performance of the test specimens decreased significantly, with the most significant decreases in water stability and high-temperature rutting resistance.

[0081] In Comparative Example 10, the composite fiber content in the composite aggregate was 0, and there was no three-dimensional reinforcing network formed by composite fibers in the asphalt mixture. On the one hand, the lack of rigid skeleton support from basalt fibers reduced the intermolecular cohesion of the mixture, weakened its load-bearing capacity, and made it unable to effectively resist external forces. On the other hand, the lack of flexible crack-resistant effect from polyester fibers meant that the internal stress inside the mixture could not be released at low temperatures, the molecular chains were prone to breakage, and microcracks were easily generated and rapidly expanded. At the same time, it could not inhibit the plastic deformation of the asphalt mastic at high temperatures. Furthermore, without the bridging effect of composite fibers, the microcracks at the asphalt-aggregate interface could not be blocked and were prone to develop into macrocracks, further reducing the performance of the mixture and making it impossible to form a synergistic crack-resistant effect with the elastic modified asphalt and rice husk ash.

[0082] Table 3 shows that, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 10 was 3.58 kN (a decrease of 13.7%), the forming Marshall stability was 8.87 kN (a decrease of 14.1%), the low-temperature splitting strength at -10℃ was 3.24 MPa (a decrease of 23.0%), and the bending failure strain was 1863 με (a decrease of 42.6%), with the most significant decrease in low-temperature crack resistance; the freeze-thaw splitting TSR was 81.2% (a decrease of 11.1%); and the dynamic stability at 60℃ was 2247 cycles·mm. -1 (Decrease of 25.7%) The overall performance of the test specimen was better than that of Comparative Example 8 and Comparative Example 9, but lower than that of Examples 1-3, indicating that composite fibers can effectively improve low-temperature crack resistance and load-bearing capacity.

[0083] In Comparative Example 11, the composite aggregate was not subjected to the interface modification treatment specified in the patent. The surface of the unmodified composite aggregate is hydrophilic, resulting in poor compatibility with the oleophilic asphalt mastic. On the one hand, the aggregate surface lacks a hydrophobic modification layer, allowing moisture to easily penetrate the asphalt-aggregate interface, disrupting the van der Waals forces and chemical bonds between molecules, leading to interfacial delamination. Simultaneously, the aggregate surface lacks an interfacial transition layer formed by the modifier, resulting in only physical adhesion between the asphalt and aggregate, significantly reducing interfacial bonding strength. Furthermore, the active hydroxyl groups on the surface of the unmodified aggregate cannot form chemical bonds with the modifier, reducing the cohesion of the mixture and making it prone to particle shedding. At the same time, poor interfacial compatibility leads to uneven asphalt adhesion to the aggregate, forming localized stress concentration points. This can easily cause microcracks at low temperatures and exacerbate deformation at high temperatures, making it impossible to form a synergistic effect with the elastic modified asphalt, rice husk ash, and composite fibers.

[0084] As shown in Table 3, compared with Example 2, the initial Marshall stability of the test specimen corresponding to Comparative Example 11 was 3.22 kN (a decrease of 22.4%), the forming Marshall stability was 8.10 kN (a decrease of 21.5%), the low-temperature splitting strength at -10℃ was 3.12 MPa (a decrease of 25.9%), the bending failure strain was 2108 με (a decrease of 35.1%), the freeze-thaw splitting TSR was 75.3% (a decrease of 17.5%), and the water stability showed the most significant decrease; the dynamic stability at 60℃ was 2124 cycles·mm. -1 (Decrease of 29.8%), the overall performance of the test piece decreased significantly.

[0085] In summary, this application, by optimizing the proportions of each component and modifying the interface of the composite aggregate, can synergistically improve the high and low temperature compatibility of the mixture, thereby solving the defects of traditional solvent-based mixtures, such as poor extreme low-temperature compatibility, easy caking and difficulty in compaction, poor storage stability, and environmental hazards. It also overcomes the problems of modified emulsified mixtures, such as easy demulsification and failure at low temperatures, weak interfacial adhesion, insufficient repair durability, and difficulty in adapting to high-grade heavy-duty roads. This application can effectively ensure the low-temperature workability and strength stability of the mixture, significantly improve interfacial adhesion and long-term storage stability, extend the service life of road repair areas, reduce maintenance energy consumption, and improve the emergency response capability of road maintenance. It has the advantages of scientific and reasonable formulation, simple preparation and operation, low implementation cost, wide applicability, and ease of promotion and implementation.

[0086] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A low-temperature cold-repair asphalt mixture, characterized in that, The composition by weight is as follows: 15-23 parts of elastic modified asphalt, 66-80 parts of composite aggregate, 3-7 parts of epoxy fatty acid methyl ester, 2-5 parts of antioxidant, 2-5 parts of cyclopentadiene, and 1-2 parts of fumed silica. Based on the total mass of the composite aggregate, the composite aggregate is composed of the following components by mass parts: 15-22 parts diabase, 28-36 parts basalt, 22-28 parts limestone manufactured sand, 10-16 parts high-energy activated rice husk ash, and 5-8 parts composite fiber. The composite aggregate has undergone interface modification treatment.

2. The low-temperature cold-repair asphalt mixture according to claim 1, characterized in that, Based on the total mass of the elastic modified asphalt, the elastic modified asphalt is composed of the following components by mass parts: 55-65 parts of base asphalt, 5-7 parts of linear SBS, 3-6 parts of hydrogenated SEBS, 2-3 parts of styrene-butadiene rubber powder, 2-3 parts of maleic anhydride, 5-7 parts of epoxy fatty acid methyl ester, and 3-4 parts of terpene phenolic resin.

3. The low-temperature cold-repair asphalt mixture according to claim 2, characterized in that, The preparation method of the elastic modified asphalt includes the following steps: Step 101. Divide the base asphalt into two equal parts, and take one part of the base asphalt, linear SBS, hydrogenated SEBS, styrene-butadiene rubber powder, maleic anhydride, epoxy fatty acid methyl ester and terpene phenolic resin into a reaction vessel in sequence. After dispersing at 150℃-160℃ and 1500rpm-1800rpm for 40min-60min, the elastic modification precursor is obtained. Step 102. The elastic modified precursor prepared in step 101 and another portion of base asphalt are sequentially put into a high-speed shearing reactor and sheared at high speed for 60 min-80 min at 175℃-185℃ and 2800 rpm-3300 rpm to obtain the elastic modified asphalt.

4. The low-temperature cold-repair asphalt mixture according to claim 1, characterized in that, The preparation method of the high-energy activated rice husk ash includes the following steps: Step 201. Put the pretreated rice husks into a muffle furnace and calcine them at a constant temperature of 600℃-800℃ for 85min-95min. After cooling to room temperature, the crude rice husk ash is obtained. Step 202. Transfer the crude rice husk ash prepared in step 201 to a dry ball mill and ball mill it to 0.065mm-0.075mm to obtain high-energy activated rice husk ash.

5. The low-temperature cold-repair asphalt mixture according to claim 4, characterized in that, In step 201, the pretreatment method for rice husks includes the following steps: rice husks and a 1% sulfuric acid solution are added to a stirring vessel in a mass ratio of 1:(48-52). The mixture is stirred for 2.5 hours at 25°C and 300-400 rpm. Then, the mixture is filtered, washed with clean water, and dried at a constant temperature to obtain the pretreated rice husks.

6. The low-temperature cold-repair asphalt mixture according to claim 1, characterized in that, The mass fraction of amorphous silica in the high-energy activated rice husk ash is 94.8%-95.5%.

7. The low-temperature cold-repair asphalt mixture according to claim 1, characterized in that, In the composite aggregate, the particle size of diabase is 13.2mm-15.9mm, the particle size of basalt is 4.7mm-8.8mm, the particle size of limestone manufactured sand is 1.2mm-3.6mm, and the composite fiber is obtained by mixing basalt fiber and polyester fiber at a mass ratio of 2:

1.

8. The low-temperature cold-repair asphalt mixture according to claim 7, characterized in that, The basalt fiber has a length of 5mm-7mm and a diameter of 11µm-15µm, the polyester fiber has a length of 2mm-4mm and a diameter of 18µm-22µm.

9. A low-temperature cold-repair asphalt mixture according to claim 1, characterized in that, The interface modification method of the composite aggregate includes the following steps: diabase, basalt, limestone manufactured sand, high-energy activated rice husk ash and composite fiber are sequentially added into a twin-shaft horizontal mixing pot according to a preset ratio, and stirred for 60min-90min at 35℃-45℃ and 300rpm-500rpm. During the stirring process, the interface modifier is sprayed into the composite aggregate through a high-pressure atomizing nozzle under the conditions of output pressure of 0.8MPa-1.0MPa, output flow rate of 1.5L / min-2.0L / min and atomization cone angle of 60°. The interface modifier is obtained by mixing dodecyl phosphate monoester and anhydrous ethanol at a mass ratio of 1:30, and the amount of dodecyl phosphate monoester used is 0.3%-0.7% of the total mass of the dry composite aggregate.

10. A method for preparing a low-temperature cold-repair asphalt mixture according to any one of claims 1-9, characterized in that, Includes the following steps: Step 301. Add the elastic modified asphalt, epoxy fatty acid methyl ester, antioxidant, cyclopentadiene, and fumed silica into the mixer in the preset ratio. Mix for 60 min to 90 min at 35℃-45℃ and 1500 rpm-1800 rpm to obtain the repair adhesive. Step 302. Add the repair adhesive prepared in step 301 into the mixing tank according to the preset ratio, then divide the composite aggregate into three equal parts and add them into the mixing tank in three batches. Stir at room temperature and a speed of 1000rpm-1200rpm. The stirring time after each addition is 40min-60min. After all the materials are added and stirred, the low temperature cold repair asphalt mixture is obtained.

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