Warm-mixed, low-carbon asphalt mixture for improving low-temperature performance of asphalt and preparation method thereof

Abstract

The application discloses a warm-mixed low-carbon asphalt mixture for improving low-temperature performance of asphalt and a preparation method thereof, and belongs to the technical field of engineering construction. The warm-mixed low-carbon asphalt mixture for improving low-temperature performance of asphalt comprises 70-90 parts of asphalt, 10-20 parts of devulcanized rubber powder, 3-8 parts of a warm-mixing agent, 10-20 parts of zeolite and 1-2.5 parts of a surfactant; the warm-mixing agent is a mixture of polyethylene wax and modified polyethylene wax; and the modified polyethylene wax is polyethylene wax modified by methacryloyloxyethyl ammonium chloride. The warm-mixing agent and the surfactant are added into the mixture of the asphalt, the rubber powder and the zeolite, so that the mixing and construction temperature of the modified asphalt mixture is reduced, the high-temperature stability, the low-temperature anti-cracking performance and the water stability of the asphalt mixture are improved, and the warm-mixed low-carbon asphalt mixture is suitable for heavy-traffic roads such as expressways and asphalt roads.

Description

Technical Field

[0001] This invention belongs to the field of engineering construction technology, specifically relating to a warm-mix, low-carbon asphalt mixture with improved low-temperature performance and its preparation method. Background Technology

[0002] In the process of paving asphalt roads, the asphalt and its ingredients are typically heated to 160-170℃ before being laid on the road surface. Mechanical construction methods such as paving and compaction are then used to deliver the road for use. However, during the asphalt and ingredient mixing process, the increased temperature releases large amounts of carbon dioxide, carbon monoxide, sulfides, and nitrogen oxides, directly impacting the construction environment and personnel safety. Based on this problem, the concept of warm-mix asphalt emerged. Warm-mix asphalt lowers the temperature during the asphalt and ingredient mixing process through physical or chemical methods, adding auxiliary materials to the asphalt to achieve a uniform mixing temperature of around 140℃. The asphalt performance is similar to that of high-temperature mixed asphalt, but energy consumption is reduced, resources are saved, and the release of toxic gases during production and construction is decreased, thus reducing environmental pollution.

[0003] Currently, by adding modifiers that easily soften asphalt, adding binders, or using chemical modifiers or water to foam the asphalt, asphalt can be easily mixed with aggregates even at low temperatures and can be practically applied in this field. However, most existing warm-mix asphalts suffer from complex compositions. For example, patent CN117720822A discloses a modified warm-mix rubber asphalt and its preparation method. The raw materials for the modified warm-mix rubber asphalt include 70# base asphalt, rubber powder I, rubber powder II, rubber powder III, modified admixture I, modified admixture II, and modified admixture III. Among them, modified admixture I, modified admixture II, and modified admixture III are composed of multiple components. Even if it can reduce the mixing temperature of asphalt, the complexity of its composition increases the difficulty of practical application and construction, which is not conducive to further promotion and application.

[0004] Adding low-melting-point waxes to asphalt to reduce its viscosity is a widely used technique. Examples include adding polyethylene wax or using viscosity-reducing components such as paraffin wax, microcrystalline wax, polyethylene wax, and EVA wax. However, waxes can cause asphalt mixtures to shrink and become brittle at low temperatures, weakening the low-temperature crack resistance of asphalt pavements. Therefore, improving the low-temperature crack resistance of wax-modified asphalt is a problem that urgently needs to be solved. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a warm-mix, low-carbon asphalt mixture and its preparation method for improving the low-temperature performance of asphalt. This invention improves the high-temperature stability, low-temperature crack resistance, and water stability of asphalt mixtures by adding warm-mix agents and surfactants to a mixture of asphalt, rubber powder, and zeolite, thereby reducing the mixing and construction temperature of the modified asphalt mixture. This invention is achieved through the following technical solution: In a first aspect, the present invention provides a warm-mix, low-carbon asphalt mixture for improving the low-temperature performance of asphalt, comprising the following raw materials in parts by weight: 70-90 parts asphalt, 10-20 parts desulfurized rubber powder, 3-8 parts warm-mix agent, 10-20 parts zeolite, and 1-2.5 parts surfactant. The warm-mixing agent is a mixture of polyethylene wax and modified polyethylene wax; The modified polyethylene wax is a polyethylene wax modified with methacryloyloxyethylammonium chloride.

[0006] Furthermore, the mass ratio of the polyethylene wax to the modified polyethylene wax is 1:2~5.

[0007] Furthermore, the method for preparing the modified polyethylene wax is as follows: 1) Place polyethylene wax in xylene, heat to dissolve, add initiator under nitrogen atmosphere, and mix well; 2) Dissolve methacryloyloxyethyl ammonium chloride in xylene; 3) At 80~90℃, slowly add the solution from step 2) to step 1), and complete the addition in 1~2 hours. After the addition is complete, keep the temperature for 3~6 hours. After the reaction is complete, add ethanol to the reaction solution to precipitate, filter, wash, and dry to obtain modified polyethylene wax.

[0008] Further, the mass of the methacryloxyethyl ammonium chloride mentioned in step 2) is 5 to 12% of the mass of polyvinyl chloride.

[0009] Further, in step 1), the mass ratio of polyethylene wax to toluene is 1:2~4, and the heating and dissolving temperature is 120~140℃; in step 2), the mass ratio of methacryloyloxyethyl ammonium chloride to xylene is 1:3~6.

[0010] Furthermore, the initiator is benzoyl peroxide, and the amount of initiator added is 1-5% of the mass of polyethylene wax.

[0011] Furthermore, the desulfurized rubber powder is waste tire rubber powder. The waste tires are crushed and passed through a 40-mesh sieve, and then microwave desulfurized at 900~1000MHz and 250~280℃ for 5~10 minutes.

[0012] Furthermore, the zeolite is zeolite with a particle size of 0.1~0.3mm; the asphalt is 70# base asphalt; and the surfactant is sodium dodecyl sulfate or sodium dodecyl sulfonate.

[0013] In a second aspect, the present invention provides a method for preparing a warm-mix, low-carbon asphalt mixture with improved low-temperature performance of asphalt. The method involves mixing asphalt and zeolite, adding a warm-mix agent, heating to 130-135°C, stirring continuously for 10-30 minutes, adding desulfurized rubber powder and a surfactant, raising the temperature to 140-150°C, and continuing to stir for 20-40 minutes to obtain a warm-mix, low-carbon asphalt mixture with improved low-temperature performance of asphalt.

[0014] Furthermore, the stirring rate during continuous stirring is 1000~1200 r / min, and the stirring rate during continued stirring is 1600~1800 r / min.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: (1) The modified polyethylene wax and polyethylene wax in this invention can melt at a mixing temperature of 130~150℃, significantly reducing the viscosity of asphalt and lowering the mixing temperature by 25~35℃, thereby reducing the emission of greenhouse gases and asphalt fumes and achieving energy conservation and emission reduction.

[0016] (2) The present invention uses a warm mix agent composed of modified polyethylene wax and polyethylene wax, which can simultaneously improve the high temperature stability and low temperature crack resistance of asphalt pavement and improve water stability while reducing the asphalt mixing temperature. After the modified polyethylene wax and polyethylene wax are compounded, they have better compatibility with the asphalt matrix and generate electrostatic adsorption and chemical bonding with polar materials (asphalt, etc.). The polar groups make the asphalt more flexible at low temperature, with greater low temperature bending strain and better crack resistance. The compounding of the two adjusts the overall polarity of the asphalt material, especially the high temperature stability, low temperature crack resistance and water stability, so that the high temperature stability and low temperature crack resistance of the asphalt mixture are improved simultaneously.

[0017] (3) The warm-mix, low-carbon asphalt mixture prepared by the present invention has a simple composition, the raw materials are easy to add, and it can achieve low-temperature crack resistance, high-temperature stability, and easy mixing during construction. It is suitable for heavy traffic roads such as highways and asphalt roads. Detailed Implementation

[0018] The present invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods not specifically described in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. All reagents and materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions.

[0020] In the following examples and comparative examples, the number of parts is by weight.

[0021] Example 1 1. Preparation method of modified polyethylene wax: 1) Place polyethylene wax in 4 times its weight of xylene, heat to 120°C to dissolve, and add benzoyl peroxide (the amount of benzoyl peroxide added is 2% of the weight of polyethylene wax) under a nitrogen atmosphere and mix well. 2) Dissolve methacryloyloxyethyl ammonium chloride (the mass of methacryloyloxyethyl ammonium chloride is 8% of the mass of polyethylene wax) in 5 times its volume of xylene; 3) At 85±5℃, slowly add the solution from step 2) to step 1), and complete the addition in 1.5h. After the addition is complete, keep the temperature for 5h. After the reaction is complete, add ethanol to the reaction solution to precipitate, filter, wash, and dry to obtain modified polyethylene wax.

[0022] 2. Preparation of desulfurized rubber powder: Waste tires are crushed and passed through a 40-mesh sieve, and then microwaved at 1000MHz and 260℃ for 10 minutes to obtain desulfurized rubber powder.

[0023] Unless otherwise specified, the modified polyethylene wax and desulfurized rubber powder used in the following examples and comparative examples were prepared in Example 1; the zeolite was zeolite with a particle size of 0.1~0.3mm; the asphalt was 70# base asphalt; and the surfactant was sodium dodecyl sulfonate.

[0024] Example 2 Composition of warm mix, low carbon asphalt mixture to improve the low temperature performance of asphalt: 80 parts asphalt, 15 parts desulfurized rubber powder, 5 parts warm mix agent (the mass ratio of polyethylene wax and modified polyethylene wax is 1:3), 15 parts zeolite, and 2 parts surfactant. Preparation method of warm-mix, low-carbon asphalt mixture to improve the low-temperature performance of asphalt: Mix asphalt and zeolite, add warm-mix agent, heat to 130~135℃, stir continuously at 1000~1200r / min for 10~30min, add desulfurized rubber powder and surfactant, raise the temperature to 140~150℃, increase the stirring rate to 1600~1800 r / min and continue stirring for 20~40min to obtain warm-mix, low-carbon asphalt mixture to improve the low-temperature performance of asphalt.

[0025] Example 3 Compared with Example 2, the mass ratio of polyethylene wax and modified polyethylene wax in the warm mixing agent of Example 3 is 1:2, and the other raw materials are the same as those in Example 2; The preparation method of warm-mix, low-carbon asphalt mixture with improved low-temperature performance is the same as in Example 2.

[0026] Example 4 Compared with Example 2, the mass ratio of polyethylene wax and modified polyethylene wax in the warm mixing agent of Example 4 is 1:4, and the other raw materials are the same as those in Example 2; The preparation method of warm-mix, low-carbon asphalt mixture with improved low-temperature performance is the same as in Example 2.

[0027] Example 5 Compared with Example 2, the mass ratio of polyethylene wax and modified polyethylene wax in the warm mixing agent of Example 5 is 1:5, and the other raw materials are the same as those in Example 2; The preparation method of warm-mix, low-carbon asphalt mixture with improved low-temperature performance is the same as in Example 2.

[0028] Example 6 Composition of warm mix, low carbon asphalt mixture to improve the low temperature performance of asphalt: 90 parts asphalt, 10 parts desulfurized rubber powder, 6 parts warm mix agent (the mass ratio of polyethylene wax and modified polyethylene wax is 1:3), 20 parts zeolite, and 2 parts surfactant. The preparation method of warm-mix, low-carbon asphalt mixture with improved low-temperature performance is the same as in Example 2.

[0029] Comparative Example 1 Unlike Example 2, the warm mix agent in Comparative Example 1 contains only polyethylene wax, while the other raw materials are the same as in Example 2. The preparation method of the asphalt mixture in Comparative Example 1 is the same as that in Example 2.

[0030] Comparative Example 2 Unlike Example 2, the warm mix agent in Comparative Example 2 contains only modified polyethylene wax, while the other raw materials are the same as in Example 1. The preparation method of the asphalt mixture in Comparative Example 2 is the same as that in Example 2.

[0031] Comparative Example 3 Unlike Example 2, in Comparative Example 3, the mass ratio of polyethylene wax to modified polyethylene wax in the warm mixing agent is 1:1, and the remaining raw materials are the same as in Example 2. The preparation method of the asphalt mixture in Comparative Example 3 is the same as that in Example 2.

[0032] Asphalt mixture performance testing: The asphalt mixtures prepared in Examples 2-6 and Comparative Examples 1-3 were laid and compacted. The dynamic stability at 60°C, maximum flexural strain at -10°C, residual stability after immersion in water, and freeze-thaw splitting strength ratio were calculated according to the test methods described in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The results are shown in Table 1 below. Table 1 Comparison of Asphalt Mixture Performance Tests As shown in Table 1, the asphalt mixture prepared by this invention can not only reduce the mixing temperature of the asphalt mixture (130~150℃), but also meet the requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" for dynamic stability at 60°C, maximum flexural strain at -10°C, residual stability after immersion in water, and freeze-thaw splitting strength ratio. In particular, the asphalt mixture prepared in Example 2 has dynamic stability at 60°C, maximum flexural strain at -10°C, residual stability after immersion in water, and freeze-thaw splitting strength ratio of 4315 times / mm, 3243με, 91.7%, and 93.9%, respectively, indicating that a mass ratio of polyethylene wax to modified polyethylene wax of 1:3 in the warm mix agent achieves better technical results.

[0033] The asphalt mixture warm mix additive prepared in Comparative Example 1, which does not contain modified polyethylene wax, exhibits significantly weakened low-temperature crack resistance. Similarly, the asphalt mixture warm mix additive prepared in Comparative Example 2, also lacking polyethylene wax, shows a certain degree of attenuation in both high-temperature stability and low-temperature crack resistance, particularly a significant reduction in high-temperature stability. Adjusting the ratio of polyethylene wax to modified polyethylene wax to 1:1 further weakens its low-temperature crack resistance compared to Example 2. These results indicate that the polyethylene wax and modified polyethylene wax in the asphalt mixture of this invention work synergistically to enhance both the low-temperature and high-temperature properties of the asphalt mixture. Modified polyethylene wax has a significant impact on the low-temperature performance of the asphalt mixture and also affects its residual stability after water immersion.

[0034] In summary, the warm mix additive of this invention can significantly reduce the mixing temperature of asphalt mixtures, reduce the emission of greenhouse gases and asphalt fumes, and improve the high-temperature stability, low-temperature crack resistance and water stability of warm mix asphalt, especially the crack resistance at low temperatures. This is of great significance for improving the quality of road engineering and extending service life, and is suitable for heavy traffic roads such as highways and asphalt roads.

[0035] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A warm-mix, low-carbon asphalt mixture for improving the low-temperature performance of asphalt, characterized in that, The raw materials include the following parts by weight: 70-90 parts asphalt, 10-20 parts desulfurized rubber powder, 3-8 parts warm mix agent, 10-20 parts zeolite, and 1-2.5 parts surfactant; The warm-mixing agent is a mixture of polyethylene wax and modified polyethylene wax; The modified polyethylene wax is a polyethylene wax modified with methacryloyloxyethylammonium chloride.

2. The warm-mix, low-carbon asphalt mixture for improving the low-temperature performance of asphalt according to claim 1, characterized in that, The mass ratio of the polyethylene wax and the modified polyethylene wax is 1:2~5.

3. The warm-mix, low-carbon asphalt mixture for improving the low-temperature performance of asphalt according to claim 1, characterized in that, The method for preparing the modified polyethylene wax is as follows: 1) Place polyethylene wax in xylene, heat to dissolve, add initiator under nitrogen atmosphere, and mix well; 2) Dissolve methacryloyloxyethyl ammonium chloride in xylene; 3) At 80~90℃, slowly add the solution from step 2) to step 1), and complete the addition in 1~2 hours. After the addition is complete, keep the temperature for 3~6 hours. After the reaction is complete, add ethanol to the reaction solution to precipitate, filter, wash, and dry to obtain modified polyethylene wax.

4. The warm-mix, low-carbon asphalt mixture for improving the low-temperature performance of asphalt according to claim 3, characterized in that, The mass of the methacryloyloxyethyl ammonium chloride mentioned in step 2) is 5-12% of the mass of polyvinyl chloride.

5. The warm-mix, low-carbon asphalt mixture for improving the low-temperature performance of asphalt according to claim 3, characterized in that, In step 1), the mass ratio of polyethylene wax to toluene is 1:2~4, and the heating and dissolution temperature is 120~140℃; in step 2), the mass ratio of methacryloyloxyethyl ammonium chloride to xylene is 1:3~6.

6. The warm-mix, low-carbon asphalt mixture for improving the low-temperature performance of asphalt according to claim 3, characterized in that, The initiator is benzoyl peroxide, and the amount of initiator added is 1-5% of the mass of polyethylene wax.

7. The warm-mix, low-carbon asphalt mixture for improving the low-temperature performance of asphalt according to claim 1, characterized in that, The desulfurized rubber powder is waste tire rubber powder. The waste tires are crushed and passed through a 40-mesh sieve, and then microwave desulfurized at 900~1000MHz and 250~280℃ for 5~10 minutes.

8. The warm-mix, low-carbon asphalt mixture for improving the low-temperature performance of asphalt according to claim 1, characterized in that, The zeolite is zeolite with a particle size of 0.1~0.3mm; the asphalt is 70# base asphalt; and the surfactant is sodium dodecyl sulfate or sodium dodecyl sulfonate.

9. A method for preparing a warm-mix, low-carbon asphalt mixture with improved low-temperature performance as described in any one of claims 1 to 7, characterized in that, Mix asphalt and zeolite, add warm mix agent, heat to 130~135℃, stir continuously for 10~30min, add desulfurized rubber powder and surfactant, raise the temperature to 140~150℃, and continue stirring for 20~40min to obtain a warm mix, low carbon asphalt mixture that improves the low temperature performance of asphalt.

10. The method for preparing warm-mix, low-carbon asphalt mixture with improved low-temperature performance according to claim 9, characterized in that, The stirring rate during continuous stirring is 1000~1200 r / min, and the stirring rate during continued stirring is 1600~1800 r / min.

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