Coated asphalt warm mixing reinforcing agent as well as preparation method and application thereof

Abstract

The invention discloses a coated asphalt warm mixing reinforcing agent as well as a preparation method and application thereof, the reinforcing agent takes surfactant modified kapok fiber as a network framework, and a phase change material is coated on the surface of the framework. The preparation method comprises the following steps: heating and melting the phase-change material, and spraying to the surface of the modified kapok fiber to obtain a wrapped product; and crushing and screening the product to obtain the granular reinforcing agent. During application, the additive accounts for 0.3-5% of the mass of asphalt. By virtue of the advantages of environmental friendliness, porosity, good mechanical support and the like of natural kapok fibers, the interfacial compatibility of the natural kapok fibers and asphalt is modified and optimized, the temperature of the composite phase change material is controlled, the mixing and compacting temperature of an asphalt mixture can be reduced, the high-temperature rut resistance and low-temperature crack resistance of the asphalt mixture can be improved, and the dual technical targets of'cost reduction by warm mixing 'and'performance enhancement' are realized; the core technology pain point of a traditional warm mixing agent is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of asphalt modifier, and particularly relates to a coated asphalt warm-mixing enhancer as well as a preparation method and application thereof. BACKGROUND

[0002] In the field of asphalt pavement engineering, the core application value of the warm-mixing agent as a key asphalt modifying additive lies in that multiple technical benefits are achieved by reducing the mixing, paving and compaction working temperature of asphalt and asphalt mixture, on the one hand, the construction environment can be significantly improved (such as reducing the safety risk caused by high-temperature operation, reducing the labor intensity of construction personnel), the uniformity of the mixture and the compaction degree are improved, and thus the engineering quality of the asphalt pavement is ensured; on the other hand, the emission of volatile organic compounds (VOCs) and energy consumption in the high-temperature heating process of asphalt can be effectively reduced, which meets the development needs of green road construction, and thus the warm-mixing agent is increasingly widely applied in highway maintenance and new construction engineering.

[0003] However, the traditional asphalt warm-mixing agents (such as emulsified type, organic viscosity-reducing type, etc.) widely used in the current industry still have two key technical bottlenecks, which restrict the application effect and the range of promotion: first, the interface compatibility and dispersion stability are insufficient; the interface combination ability of the traditional warm-mixing agent and the asphalt matrix is weak, and the dispersion is poor and the particle agglomeration phenomenon easily occurs in the mixing process of the mixture, which not only makes it difficult to uniformly play the role of temperature reduction, but also may damage the colloid structure of asphalt, resulting in problems such as segregation, strength reduction and the like of the mixture, which directly affects the bearing performance and durability of the asphalt pavement; second, the single function limitation; the action mechanism of the existing warm-mixing agent is mainly focused on “physical viscosity reduction” or “interface lubrication”, which can only realize the single function of reducing the construction temperature, and cannot meet the enhancement requirements of the road performance of the asphalt mixture. The asphalt pavement needs to bear complex environmental loads such as high-temperature rutting and low-temperature cracking in the service process, and the traditional warm-mixing agent lacks the role of improving the high and low temperature performance, so that the pavement using the warm-mixing agent is difficult to meet the durability requirements in long-term service. In view of the above technical defects of the prior art, it is urgent to develop a new type of asphalt warm-mixing agent with “warm-mixing function” and “performance enhancement function” in the industry to break through the technical limitations of the traditional products. SUMMARY

[0004] The technical problem solved by the present application is to overcome the deficiencies in the prior art, and provide a coated asphalt warm-mixing enhancer, a preparation method and application thereof.The coated asphalt warm-mixing enhancer has a coating structure, can reduce the asphalt mixing temperature, and improve the asphalt pavement performance.Innovatively, natural kapok fibers are used as a structural framework (the natural kapok fibers have environmental friendliness, porous structure adaptability and mechanical support capacity, and provide a basis for functional compounding), the interface compatibility of the modified kapok fibers with asphalt is optimized through a surfactant modification, and a phase change material is compounded to strengthen the temperature control capacity, so that a composite material with a unique coating structure is finally formed; the design can not only significantly reduce the mixing and compaction temperature of the asphalt mixture through the temperature control effect of the phase change material, but also rely on the physical reinforcement effect of the kapok fibers to simultaneously improve the high-temperature anti-rutting performance and low-temperature anti-cracking performance of the asphalt mixture, so that the dual technical targets of 'warm-mixing cost reduction' and 'performance enhancement' are achieved, and the core technical pain points of the traditional warm-mixing agent are solved.

[0005] To solve the above technical problem, the present application provides a coated asphalt warm-mixing enhancer, in which a surfactant-modified kapok fiber is used as a network framework, and a phase change material is wrapped on the surface of the network framework.

[0006] The coated asphalt warm-mixing enhancer is further prepared by the following method: mixing the kapok fibers with a surfactant solution, stirring at 40-70 DEG C for 1-4 hours, and drying to obtain the surfactant-modified kapok fibers.

[0007] The coated asphalt warm-mixing enhancer is further prepared by the following method: mixing the kapok fibers with a surfactant solution, stirring at 40-70 DEG C for 1-4 hours, and drying to obtain the surfactant-modified kapok fibers.

[0008] The coated asphalt warm-mixing enhancer is further prepared by the following method: mixing the kapok fibers with a surfactant solution, stirring at 40-70 DEG C for 1-4 hours, and drying to obtain the surfactant-modified kapok fibers.

[0009] The coated asphalt warm-mixing enhancer is further prepared by the following method: mixing the kapok fibers with a surfactant solution, stirring at 40-70 DEG C for 1-4 hours, and drying to obtain the surfactant-modified kapok fibers.

[0010] The coated asphalt warm-mixing enhancer is further prepared by the following method: mixing the kapok fibers with a surfactant solution, stirring at 40-70 DEG C for 1-4 hours, and drying to obtain the surfactant-modified kapok fibers.

[0011] The coated asphalt warm-mixing enhancer is further prepared by the following method: mixing the kapok fibers with a surfactant solution, stirring at 40-70 DEG C for 1-4 hours, and drying to obtain the surfactant-modified kapok fibers.

[0012] Based on one general technical concept, the application further provides a preparation method of the coated asphalt warm-mixing enhancer, comprising the following steps: S1, heating the phase change material to a molten state, and then spraying it to the surface of the surfactant-modified kapok fiber to obtain a coated product; S2, crushing and screening the coated product to obtain a granular coated asphalt warm-mixing enhancer.

[0013] In the above preparation method, further, the spraying adopts a pressure spraying mode, the spraying pressure is 0.2 MPa-1.0 MPa, and the surfactant-modified kapok fiber is in a mechanical stirring or fluidized state during the spraying process; and / or, the granular coated asphalt warm-mixing enhancer has a particle size in the range of 0.1 mm-5 mm.

[0014] Based on one general technical concept, the application further provides an application of the coated asphalt warm-mixing enhancer in preparing asphalt, and the application method comprises: adding the coated asphalt warm-mixing enhancer into asphalt at 0.3%-5% of the mass of the asphalt.

[0015] The technical principle of the application is that: The application innovatively constructs a coated asphalt warm-mixing agent which takes natural kapok fiber as a structural skeleton, is modified by a surfactant, and is compounded with a phase change material. The core mechanism is that: first, the kapok fiber is modified by a surfactant to significantly enhance the compatibility and dispersibility of the kapok fiber with asphalt; then, the molten phase change material is uniformly coated on the surface of the fiber to effectively reduce the asphalt mixing and construction temperature by using the endothermic / exothermic effect of the phase change material at a specific temperature. The unique hollow structure of the kapok fiber not only provides a stable carrier for the phase change material to prevent it from leaking and agglomerating, but also can form a three-dimensional network reinforcing structure in the asphalt mixture, thereby simultaneously improving the high-temperature stability and low-temperature crack resistance of the material, and finally realizing the dual functions of warm-mixing and enhancement.

[0016] Compared with the prior art, the application has the following advantages: (1) The application provides a coated asphalt warm-mixing enhancer, which overcomes the limitation of single function of the traditional warm-mixing agent, and integrates the functions of warm-mixing and enhancement. The phase change material effectively reduces the construction temperature, and the reinforcing effect of the kapok fiber significantly improves the high- and low-temperature performance and fatigue resistance of the asphalt mixture, thereby realizing the synergistic effect of temperature reduction and enhancement.

[0017] (2) The application provides a coated asphalt warm-mixing enhancer, which has a unique "fiber skeleton-phase change material coating layer" structure and effectively solves the technical problems of easy agglomeration, poor compatibility with asphalt, easy phase separation and leakage of traditional warm-mixing agents or phase change materials, and ensures the uniform dispersion and long-term performance stability of the product in asphalt.

[0018] (3) The application further provides a preparation method of the coated asphalt warm-mixing enhancer, which is simple in process, easy for industrial production, does not require complex and expensive equipment, and has excellent industrial production potential and application prospect. DETAILED DESCRIPTION

[0019] The application will be further described below in combination with specific preferred embodiments, but the protection scope of the application is not limited by this.

[0020] The materials, reagents and instruments used in the following examples can be obtained from commercial channels. The experimental methods in the following examples and comparative examples are conventional methods in the field, unless otherwise specified.

[0021] Example 1 A coated asphalt warm-mixing enhancer, which has a unique "fiber skeleton-phase change material coating layer" structure and effectively solves the technical problems of easy agglomeration, poor compatibility with asphalt, easy phase separation and leakage of traditional warm-mixing agents or phase change materials, and ensures the uniform dispersion and long-term performance stability of the product in asphalt. (1) Preparation of a precursor: 20 g of kapok fibers with a length of 1-5 mm and a hollow tube diameter of 10-20 μm are weighed, 1 g of cetyltrimethylammonium bromide is dissolved in 200 mL of deionized water, and stirring is carried out at 300 r / min at 50℃ for 2 h; after the reaction is completed, filtration is carried out, and drying is carried out in an 80℃ oven for 6 h to obtain modified kapok fiber precursor.

[0022] (2) Melt coating: the paraffin is heated to 80℃ to melt, the paraffin is weighed according to a mass ratio of paraffin to modified kapok fiber precursor of 1:10, and the paraffin is uniformly sprayed to the surface of the precursor in a continuous mechanical stirring state by using a pressure spraying device (spraying pressure 0.3 MPa) to realize complete coating to obtain a coated product.

[0023] (3) Crushing and screening: after the coated product is preliminarily crushed by a mechanical crusher, screening is carried out, and the particle product with a particle size of 0.5-2 mm is taken to obtain the coated asphalt warm-mixing enhancer.

[0024] The coated asphalt warm-mixing enhancer is mixed into 70# base asphalt at 0.5% of the mass of the asphalt, and test results show that the asphalt mixture mixing temperature can be reduced by about 39℃, the Marshall stability is increased by 18%, and the freeze-thaw splitting strength ratio is increased by 15%.

[0025] Example 2 A coated asphalt warm-mixing enhancer, with sodium dodecyl sulfate modified kapok fiber as a network skeleton, polyethylene glycol and polyethylene wax wrapped on the surface of the network skeleton. Its preparation method comprises the following steps: (1) Preparation of precursor: 50 g of kapok fiber with a length of 10-15 mm and a hollow tube diameter of 30-40 μm is weighed, 5 g of sodium dodecyl sulfate is dissolved in 400 mL of deionized water, and the mixture is stirred at 60°C for 3 h; after the reaction is completed, the mixture is filtered and dried at 85°C for 8 h to obtain modified kapok fiber precursor.

[0026] (2) Melt coating: polyethylene glycol (molecular weight 6000) and polyethylene wax are mixed in a mass ratio of 1:1, heated to 95°C to melt, and weighed in a mass ratio of 1:8 of the total mass of the phase change material to the mass of the modified kapok fiber precursor, and sprayed onto the precursor in a fluidized state in the fluidized bed under a spraying pressure of 0.5 MPa to achieve uniform coating to obtain a coated product.

[0027] (3) Crushing and screening: the obtained coated product is mechanically crushed and screened, and the product particle size is controlled between 1-3 mm to obtain the coated asphalt warm-mixing enhancer.

[0028] The coated asphalt warm-mixing enhancer is applied in SBS modified asphalt at a dosage of 3% of the mass of asphalt, which can reduce the mixing temperature by about 35°C, increase the dynamic stability of the mixture by 22%, and increase the low-temperature bending strain by 12%, showing excellent warm-mixing and enhancement synergistic effect.

[0029] Example 3 A coated asphalt warm-mixing enhancer, with fatty amine polyoxyethylene ether modified kapok fiber as a network skeleton, and fatty acid wrapped on the surface of the network skeleton. Its preparation method comprises the following steps: (1) Preparation of precursor: 100 g of kapok fiber with a length of 15-20 mm and a hollow tube diameter of 40-50 μm is weighed, 8 g of fatty amine polyoxyethylene ether is dissolved in 600 mL of deionized water, and the mixture is stirred at 70°C at 250 r / min for 4 h; after the reaction is completed, the mixture is filtered and dried at 90°C for 10 h to obtain the modified kapok fiber precursor.

[0030] (2) Melt coating: a mixture of fatty acid (lauric acid: stearic acid = 1:1) is heated to 75°C to melt, and weighed in a mass ratio of 1:6 of the phase change material to the modified kapok fiber precursor, and sprayed and coated on the surface of the precursor by a pressure spraying device (spraying pressure 0.8 MPa) under the condition of strong mechanical stirring.

[0031] (3) Crushing and screening: the coated product is treated by a crusher, and particles with a particle size of 2-5 mm are screened and taken as the final product.

[0032] The coated asphalt warm mix reinforcing agent obtained in this embodiment is added at 1.5% of the asphalt mass and used in high modulus asphalt mixtures. The measured mixing temperature is reduced by more than 38°C, the compressive strength is increased by 20%, and the residual stability reaches more than 90%, which significantly improves the comprehensive road performance and durability of the mixture.

[0033] Comparative Example 1 Take 100 g of kapok fiber with a length of 15-20 mm and a hollow tube diameter of 40-50 μm. Heat a mixture of fatty acids (lauric acid:stearic acid = 1:1) to 75℃ to melt it. Weigh it according to the mass ratio of phase change material to modified kapok fiber of 1:6. Spray it onto the surface of the precursor using a pressure spraying device (spray pressure 0.8 MPa) under strong mechanical stirring. Process the coated product with a crusher and screen it to obtain particles with a particle size of 2-5 mm as the final product.

[0034] The coated asphalt warm mix reinforcing agent obtained in this comparative example was added at 1.5% of the asphalt mass and used in high-modulus asphalt mixtures. Comparing the effects of Example 3 and Comparative Example 1, Example 3 showed a 50% reduction in mixing temperature, a 15% increase in compressive strength, and a 57% improvement in residual stability.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A coated asphalt warm mix enhancer characterized by, The surface active agent modified kapok fiber is used as a network skeleton, and a phase change material is wrapped on the surface of the network skeleton.

2. The coated asphalt warm mix enhancer of claim 1, wherein, The surface active agent modified kapok fiber is prepared by mixing the kapok fiber with a surface active agent solution, stirring and reacting at 40-70 DEG C for 1-4 hours, and drying to obtain the surface active agent modified kapok fiber.

3. The coated asphalt warm mix enhancer of claim 2, wherein, The surface active agent includes one or a mixture of several of cationic surfactant, anionic surfactant and nonionic surfactant, and / or the kapok fiber is a hollow tube with a length of 1-20 mm and a diameter of 10-50 μm.

4. The coated asphalt warm mix enhancer of claim 2, wherein, The surface active agent includes one or a mixture of several of cetyl trimethyl ammonium bromide, fatty amine polyoxyethylene ether and sodium dodecyl sulfate.

5. The coated asphalt warm mix enhancer of claim 2, wherein, The mass ratio of the surface active agent to the kapok fiber is 1:5-20.

6. The coated asphalt warm mix enhancer of any one of claims 1 to 5, wherein, The phase change material includes one or a mixture of several of paraffin, polyethylene wax, fatty acid and polyethylene glycol.

7. The coated asphalt warm mix enhancer of any one of claims 1 to 5, wherein, The mass ratio of the phase change material to the network skeleton is 1:5-15.

8. A method of producing the coated asphalt warm mix enhancer of any one of claims 1 to 7, characterized in that, The preparation method includes the following steps: S1, heating the phase change material to a molten state, and then spraying it to the surface of the surface active agent modified kapok fiber to obtain a coated product; S2, crushing and screening the coated product to obtain a granular coated asphalt warm-mixing enhancer.

9. The production method according to claim 8, characterized by, The spraying uses a pressure spraying method, the spraying pressure is 0.2-1.0 MPa, and the surface active agent modified kapok fiber is in a mechanical stirring or fluidized state during the spraying process; and / or the granular coated asphalt warm-mixing enhancer has a particle size of 0.1-5 mm.

10. Use of the coated asphalt warm mix enhancer according to any one of claims 1 to 7 for the preparation of an asphalt, characterized in that, The application method includes adding the coated asphalt warm-mixing enhancer to asphalt at a content of 0.3-5 wt% based on the mass of the asphalt.