Composite modified foamed recycled asphalt and preparation method thereof

Abstract

The invention provides composite modified foamed recycled asphalt and a preparation method thereof, and belongs to the technical field of modified foamed asphalt. The method comprises the following steps: reacting metal oxide powder, a regenerant, water-borne epoxy resin and a modified cross-linking agent to obtain a regenerated copolymer; mixing the aged asphalt, the matrix asphalt, the regenerated cellulose fiber, the regenerated copolymer and water, foaming, and crushing to obtain an asphalt mixture; and mixing the asphalt mixture with aggregate to obtain the composite modified foamed recycled asphalt. The regenerated copolymer is prepared from the modified cross-linking agent, the oxide powder and the water-borne epoxy resin, and then the regenerated copolymer is combined with the regenerated cellulose fibers to prepare the composite modified foamed regenerated asphalt, so that the dynamic stability and the dry-wet splitting strength of the regenerated asphalt are improved, and the penetration degree is reduced; the anti-rutting performance, the anti-shearing performance, the anti-aging performance and the non-deformability of the recycled asphalt are remarkably improved, and the structural durability of the recycled asphalt mortar is enhanced.

Description

Technical Field

[0001] This invention relates to the field of modified foamed asphalt technology, and in particular to a composite modified foamed recycled asphalt and its preparation method. Background Technology

[0002] Foamed asphalt is a special asphalt material made by injecting water into hot asphalt, causing it to expand and form a large amount of asphalt foam, which then bursts within a very short time. When foamed asphalt comes into contact with aggregates, the asphalt foam quickly breaks down into small particles, dispersing on the surface of fine aggregates (especially those with a particle size less than 0.075 mm). This forms a fine-particle joint filler with a large amount of asphalt adhering to it. After mixing and compaction, these fine particles can fill the voids in the wet, cold coarse aggregates and act like mortar, stabilizing the mixture. Asphalt aging is specifically characterized by a decrease in the aromatic content, an increase in the asphaltene content, and changes in the chemical components, leading to changes in the colloidal structure of the asphalt. To ensure road safety, asphalt pavements require frequent maintenance, which generates a large amount of waste asphalt mixture. To recycle waste asphalt mixtures, recycling agents have been developed and used in the recycling process to improve the performance of aged asphalt.

[0003] Traditional recycled asphalt mortar faces key technical bottlenecks in road repair and construction projects, including insufficient elastic recovery and poor fatigue resistance. This is primarily due to the weak interfacial compatibility between conventional modifiers and the asphalt matrix, the difficulty in forming effective chemical bonds through physical blending, and insufficient crosslinking density and network stability. In the treatment of asphalt pavement rutting, load-related cracks, and non-load-related cracks, as well as in major pavement repair projects, existing foamed asphalt mixtures still exhibit problems such as poor early-stage adhesion, low strength, loose aggregates, granulation, and insufficient stability.

[0004] Therefore, it is of great significance to provide a composite modified foamed recycled asphalt with improved mechanical properties and stability and reduced cracking, as well as its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a composite modified foamed recycled asphalt and its preparation method, addressing the shortcomings of existing technologies.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing composite modified foamed recycled asphalt, comprising the following steps: 1) Metal oxide powder, regenerator, waterborne epoxy resin and modified crosslinking agent are reacted to obtain a recycled copolymer; 2) Aged asphalt, base asphalt, regenerated cellulose fiber, regenerated copolymer and water are mixed, foamed and then crushed to obtain asphalt mixture; 3) Mix the asphalt mixture and aggregates to obtain composite modified foamed recycled asphalt.

[0007] Preferably, the regenerator in step 1) is epoxidized soybean oil; and the regenerated cellulose fiber in step 2) is bamboo fiber, cuprammonium fiber, or Tencel fiber.

[0008] Preferably, the mass ratio of the metal oxide powder, regenerator, waterborne epoxy resin and modified crosslinking agent in step 1) is 4~7:10~15:8~12:5~8.

[0009] Preferably, the reaction temperature in step 1) is 60~80℃ and the reaction time is 1~3min.

[0010] Preferably, the modified crosslinking agent in step 1) is prepared by mixing low-density polyethylene, maleic anhydride and dicumyl peroxide and grinding them, and then subjecting the ground particles to a melt grafting reaction to obtain the modified crosslinking agent.

[0011] Preferably, the mass ratio of the low-density polyethylene, maleic anhydride, and dicumyl peroxide is 100:2~3:0.3~0.5; The temperature of the melt grafting reaction is 150~170℃, the rotation speed is 230~300rpm, and the time is 8~15min.

[0012] Preferably, in step 2), the mass ratio of aged asphalt, base asphalt, regenerated cellulose fiber, regenerated copolymer and water is 80~100:10~20:3~5:10~20:5~10; and the mixing and foaming time is 30~45s.

[0013] Preferably, in step 3), the mass ratio of the asphalt mixture to the aggregate is 50-60:20-30; the aggregate is crushed stone with a particle size of 1-3 mm.

[0014] The present invention also provides composite modified foamed recycled asphalt prepared by the preparation method described above.

[0015] The beneficial effects of this invention are: 1) The composite modified foamed recycled asphalt prepared by the method of the present invention improves dynamic stability, fatigue life retention rate, wet-dry splitting strength and wet-dry splitting strength ratio, and reduces penetration; the rutting resistance, shear resistance, aging resistance and deformation resistance of recycled asphalt are significantly improved, enhancing the structural durability of recycled asphalt mortar and reducing cracking.

[0016] 2) Waterborne epoxy resin can coat loose aggregates to form epoxy resin mortar. As the water evaporates, a polymer with strong adhesion and good density is generated, filling the larger voids in the mortar, reducing the number of voids, and improving the density and stability of the structure. The modified crosslinking agent grafts the polar anhydride groups of maleic anhydride onto the LDPE molecular chain. The anhydride groups (-CO-O-CO-) of maleic anhydride form hydrogen bonds or chemical bonds with the gums and asphaltenes in asphalt, significantly improving the compatibility with asphalt. The grafted LDPE has both flexibility and polarity, which can enhance the elastic recovery ability and fatigue resistance of recycled asphalt mortar.

[0017] 3) Regenerated cellulose fibers and metal oxides are beneficial to improving the plastic deformation resistance, rutting resistance and shear resistance of recycled asphalt, and preventing large cracks from appearing in recycled asphalt under external force; metal oxides have a strong ultraviolet masking effect; polymers have functionalization and heat oxidation resistance, effectively preventing secondary aging of recycled asphalt. Detailed Implementation

[0018] This invention provides a method for preparing composite modified foamed recycled asphalt, comprising the following steps: 1) Metal oxide powder, regenerator, waterborne epoxy resin and modified crosslinking agent are reacted to obtain a recycled copolymer; 2) Aged asphalt, base asphalt, regenerated cellulose fiber, regenerated copolymer and water are mixed, foamed and then crushed to obtain asphalt mixture; 3) Mix the asphalt mixture and aggregates to obtain composite modified foamed recycled asphalt.

[0019] In this invention, the regenerating agent in step 1) is preferably epoxidized soybean oil; the regenerated cellulose fiber in step 2) is preferably bamboo fiber, cuprammonium fiber or Tencel fiber.

[0020] In this invention, the preferred mass ratio of the metal oxide powder, regenerator, waterborne epoxy resin and modified crosslinking agent in step 1) is 4~7:10~15:8~12:5~8, more preferably 5~6:11~14:9~11:6~7, and even more preferably 5.5:12~13:10:6.5.

[0021] In this invention, the metal oxide is preferably one or more of titanium oxide, zinc oxide, iron oxide and cerium oxide.

[0022] In this invention, the reaction temperature in step 1) is preferably 60~80℃, more preferably 65~75℃, and even more preferably 70℃, and the reaction time is preferably 1~3min, more preferably 1.5~2.5min, and even more preferably 2min.

[0023] In this invention, the preferred method for preparing the modified crosslinking agent in step 1) is to mix low-density polyethylene, maleic anhydride and dicumyl peroxide and grind them, and then perform a melt grafting reaction on the ground particles to obtain the modified crosslinking agent.

[0024] In this invention, the mass ratio of low-density polyethylene (LDPE), maleic anhydride, and dicumyl peroxide is preferably 100:2~3:0.3~0.5, more preferably 100:2.2~2.8:0.35~0.45, and even more preferably 100:2.5:0.4; The preferred temperature for the melt grafting reaction is 150-170°C, more preferably 155-165°C, and even more preferably 160°C. The preferred rotation speed is 230-300 rpm, more preferably 250-280 rpm, and even more preferably 260-270 rpm. The preferred time is 8-15 min, more preferably 10-14 min, and even more preferably 11-12 min.

[0025] In this invention, the melt grafting reaction is carried out in a twin-screw extruder.

[0026] In this invention, the recycled copolymer improves the compatibility between aged asphalt and base asphalt, reduces the stiffness of aged asphalt, promotes the interaction between macromolecular components, and enhances the flexibility, viscosity, resistance to permanent deformation and elasticity of asphalt, thereby realizing the recycling of asphalt. The recycled copolymer is a cementing material with metal oxide as the core and regenerating agent as the carrier, which effectively improves the comprehensive performance of recycled asphalt.

[0027] In this invention, the mass ratio of aged asphalt, base asphalt, regenerated cellulose fiber, regenerated copolymer and water in step 2) is preferably 80~100:10~20:3~5:10~20:5~10, more preferably 85~95:12~18:3.5~4.5:12~18:6~9, and even more preferably 90:15~16:4:15~16:7~8; the mixing and foaming time is preferably 30~45s, more preferably 32~42s, and even more preferably 35~40s.

[0028] In this invention, the mass ratio of the asphalt mixture and aggregate in step 3) is preferably 50~60:20~30, more preferably 52~58:22~28, and even more preferably 55~56:25~26; the aggregate is preferably crushed stone with a particle size of 1~3mm, more preferably 1.5~2.5mm, and even more preferably 2mm.

[0029] The present invention also provides composite modified foamed recycled asphalt prepared by the preparation method described above.

[0030] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0031] In the examples and comparative examples, the waterborne epoxy resin was EPI-REZ 3510-W-60; the aggregate was crushed stone with a particle size of 1.5~2.5mm; the aged asphalt was asphalt powder recovered by conventional solvent extraction, rotary evaporation, crushing and screening of No. 10 aged asphalt; and the matrix asphalt was SBS modified asphalt from Maoming Zhengcheng Petrochemical Co., Ltd.

[0032] Example 1

[0033] Low-density polyethylene, maleic anhydride, and dicumyl peroxide were mixed in a mass ratio of 100:2.5:0.4 and then ground to obtain particles with a particle size of 2-4 mm. The particles were placed in a twin-screw extruder and subjected to a melt grafting reaction at 160°C and 260 rpm for 12 min to obtain a modified crosslinking agent.

[0034] Titanium oxide powder, epoxidized soybean oil, waterborne epoxy resin and modified crosslinking agent were mixed evenly in a mass ratio of 5:13:10:6. The homogeneous mixture was reacted at 70°C for 2 minutes to obtain the recycled copolymer.

[0035] Aged asphalt, base asphalt, bamboo fiber, recycled copolymer, and deionized water were mixed at a mass ratio of 90:15:4:15:8, foamed for 35 seconds, and then crushed to obtain an asphalt mixture. The asphalt mixture and aggregates were then mixed evenly at a mass ratio of 55:25 to obtain composite modified foamed recycled asphalt.

[0036] Example 2

[0037] Low-density polyethylene, maleic anhydride, and dicumyl peroxide were mixed in a mass ratio of 100:2.2:0.35 and then ground to obtain particles with a particle size of 2-4 mm. The particles were placed in a twin-screw extruder and subjected to a melt grafting reaction at 155°C and 280 rpm for 15 min to obtain a modified crosslinking agent.

[0038] Ferric oxide powder, epoxidized soybean oil, waterborne epoxy resin, and modified crosslinking agent were mixed evenly in a mass ratio of 4:10:8:6. The homogeneous mixture was reacted at 65°C for 3 minutes to obtain a recycled copolymer.

[0039] Aged asphalt, base asphalt, cuprammonium fiber, recycled copolymer, and deionized water were mixed at a mass ratio of 85:12:3:11:6, foamed for 32 seconds, and then crushed to obtain an asphalt mixture. The asphalt mixture and aggregates were then mixed evenly at a mass ratio of 50:22 to obtain composite modified foamed recycled asphalt.

[0040] Example 3

[0041] Low-density polyethylene, maleic anhydride, and dicumyl peroxide were mixed in a mass ratio of 100:2.8:0.45 and then ground to obtain particles with a particle size of 2-4 mm. The particles were placed in a twin-screw extruder and subjected to a melt grafting reaction at 165°C and 240 rpm for 10 min to obtain a modified crosslinking agent.

[0042] Zinc oxide powder, epoxidized soybean oil, waterborne epoxy resin and modified crosslinking agent were mixed evenly in a mass ratio of 6:15:12:7. The homogeneous mixture was then reacted at 75°C for 1 minute to obtain a recycled copolymer.

[0043] Aged asphalt, base asphalt, Tencel fiber, recycled copolymer, and deionized water were mixed at a mass ratio of 95:18:5:18:10, foamed for 40 seconds, and then crushed to obtain an asphalt mixture. The asphalt mixture and aggregates were then mixed evenly at a mass ratio of 58:27 to obtain composite modified foamed recycled asphalt.

[0044] Comparative Example 1

[0045] The bamboo fiber of Example 1 is omitted, as is the preparation of the modified crosslinking agent. The modified crosslinking agent of Example 1 is replaced with dicumyl peroxide, and other process conditions are the same as those of Example 1.

[0046] Comparative Example 2

[0047] The titanium dioxide powder and water-based epoxy resin of Example 1 are omitted, and the other process conditions are the same as those of Example 1.

[0048] Comparative Example 3

[0049] The preparation of the recycled copolymer in Example 2 is omitted. The recycled copolymer in Example 2 is replaced with the crosslinking agent dicumyl peroxide, and other process conditions are the same as in Example 2.

[0050] The performance of the composite modified foamed recycled asphalt in Examples 1-3 and Comparative Examples 1-3 was tested, and the test results are shown in Table 1.

[0051] The dynamic stability (times / mm), penetration (1 / 10mm), and flow value (mm) of recycled asphalt were tested according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025) to evaluate the rutting resistance, shear resistance, and plastic deformation resistance of recycled asphalt.

[0052] The recycled asphalt mortar specimens (size: 50mm×50mm×5mm) of the examples and comparative examples were irradiated with a QUV ultraviolet aging chamber (UVB-313 lamp, 60℃) for 500 hours to carry out ultraviolet aging, and the fatigue life retention rate of the specimens after aging was tested.

[0053] The wet-dry splitting strength ratio (TSR) of recycled asphalt was tested according to the splitting test standard of the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025).

[0054] Table 1 Performance test results of recycled asphalt in the examples and comparative examples

[0055] This invention prepares a recycled copolymer by modifying a crosslinking agent, oxide powder, and water-based epoxy resin, and then combines it with recycled cellulose fibers to prepare a composite modified foamed recycled asphalt. This improves the dynamic stability and wet-dry splitting strength ratio of the recycled asphalt and reduces its penetration. The rutting resistance, shear resistance, aging resistance, and deformation resistance of the recycled asphalt are significantly improved, enhancing the structural durability of the recycled asphalt mortar and reducing cracking.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing composite modified foamed recycled asphalt, characterized in that, It includes the following steps: 1) Metal oxide powder, regenerator, waterborne epoxy resin and modified crosslinking agent are reacted to obtain a recycled copolymer; 2) Aged asphalt, base asphalt, regenerated cellulose fiber, regenerated copolymer and water are mixed, foamed and then crushed to obtain asphalt mixture; 3) Mix the asphalt mixture and aggregates to obtain composite modified foamed recycled asphalt.

2. The preparation method according to claim 1, characterized in that, Step 1) The regenerating agent is epoxidized soybean oil; Step 2) The regenerated cellulose fiber is bamboo fiber, cuprammonium fiber or Tencel fiber.

3. The preparation method according to claim 1 or 2, characterized in that, Step 1) The mass ratio of the metal oxide powder, regenerator, waterborne epoxy resin and modified crosslinking agent is 4~7:10~15:8~12:5~8.

4. The preparation method according to claim 3, characterized in that, Step 1) The reaction temperature is 60~80℃ and the reaction time is 1~3min.

5. The preparation method according to claim 4, characterized in that, Step 1) The modified crosslinking agent is prepared by mixing low-density polyethylene, maleic anhydride and dicumyl peroxide and grinding them. The ground particles are then subjected to a melt grafting reaction to obtain the modified crosslinking agent.

6. The preparation method according to claim 5, characterized in that, The mass ratio of the low-density polyethylene, maleic anhydride, and dicumyl peroxide is 100:2~3:0.3~0.5; The temperature of the melt grafting reaction is 150~170℃, the rotation speed is 230~300rpm, and the time is 8~15min.

7. The preparation method according to claim 6, characterized in that, Step 2) The mass ratio of aged asphalt, base asphalt, regenerated cellulose fiber, regenerated copolymer and water is 80~100:10~20:3~5:10~20:5~10; the mixing and foaming time is 30~45s.

8. The preparation method according to claim 7, characterized in that, Step 3) The mass ratio of the asphalt mixture to the aggregate is 50~60:20~30; the aggregate is crushed stone with a particle size of 1~3mm.

9. The composite modified foamed recycled asphalt prepared by the preparation method according to any one of claims 1 to 8.

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