High-elastic and high-viscosity composite modified emulsified asphalt for cold-laying wearing course construction and its preparation method

Abstract

This application relates to the field of asphalt materials, and specifically discloses a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction and its preparation method, which includes the following raw materials: matrix asphalt, 2-5 parts of emulsifier, stabilizer, extender, pH regulator and modifier; the modifier includes a mixture of waste rubber powder, SBR and petroleum resin; its preparation method includes the following steps: first heat the matrix asphalt, then add the modifier, raise the temperature, and then enter a colloid mill for shearing to obtain an asphalt mixture; mix the emulsifier, stabilizer, extender, pH regulator and water, heat and stir to obtain a soap solution; mix the asphalt mixture and the soap solution and then enter a colloid mill for shear emulsification at the same time, and then obtain a highly viscous and highly elastic composite modified emulsified asphalt after cooling; this application has the characteristics of improving the quality of the evaporation residue of emulsified asphalt, especially regarding the dynamic viscosity and elastic recovery quality, and preparing a highly elastic and highly viscous modified emulsified asphalt.

Description

Technical Field

[0001] The present application relates to the field of asphalt materials, and more specifically, to a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction and a preparation method thereof. Background Art

[0002] At present, in road engineering, in order to improve the durability and service performance of the road surface, various types of asphalt materials are widely used in different layers of the road surface. Although traditional hot mix asphalt mixtures have good compaction performance and strength, they have high energy consumption during production and construction and have a greater impact on the environment. Therefore, in recent years, cold paving asphalt has received more and more attention as an energy-saving and environmentally friendly alternative material.

[0003] The common cold paving asphalt materials on the market at present are mainly emulsified asphalt. Emulsified asphalt is obtained by melting viscous asphalt through heat and mechanical action, and dispersing it in water containing emulsifiers and stabilizers in the form of micro-droplets to form an oil-in-water or water-in-oil emulsion. It is mainly used for road surface treatment, bonding layer, penetration layer, sealing layer, etc. to improve the durability and stability of the road. Emulsified asphalt does not require heating during use, and the aggregate does not need to be heated either. It has many advantages such as simple construction, low cost, low carbon and energy saving. The surface course refers to a thin layer of fine aggregate asphalt laid on the original asphalt pavement to improve the service quality of the asphalt pavement, enhance the waterproof, anti-slip ability and flatness of the road surface. With the continuous increase in traffic volume and the increasingly serious problem of road aging, the cold paving surface course, as a fast, efficient and environmentally friendly road maintenance method, will be more widely used.

[0004] The application of emulsified asphalt in the cold paving surface course can avoid the cumbersome process of high-temperature heating and stirring required for hot mix asphalt, thus simplifying the construction process and improving the construction efficiency. As one of the main materials for the cold paving surface course, the performance quality of emulsified asphalt directly affects the construction quality of the cold paving surface course.

[0005] Due to the effects of emulsified asphalt emulsifiers and mechanical stirring, etc., the high-temperature stability, bonding performance, deformation resistance and deformation recovery performance of current emulsified asphalt have decreased, directly affecting the bonding between emulsified asphalt and aggregate during its application in the cold paving surface course and affecting the construction quality. For example, phenomena such as segregation and delamination may occur during the construction process, and its elastic recovery performance will affect the deformation of the subsequent cold paving surface course under vehicle loads, affecting the durability and service life of the road surface.

[0006] Therefore, in order to ensure the quality of the surface course asphalt, it is necessary to modify the emulsified asphalt to improve the quality of the evaporation residue of the emulsified asphalt, especially regarding the dynamic viscosity and elastic recovery quality. The above-mentioned properties directly affect the high-temperature stability and elasticity of the emulsified asphalt, and further affect the final bonding strength and deformation resistance performance with the aggregate. Summary of the Invention

[0007] In order to improve the quality of the evaporation residue of emulsified asphalt, especially with respect to dynamic viscosity and elastic recovery quality, and to prepare a highly elastic and highly viscous modified emulsified asphalt, the present application provides a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction and its preparation method.

[0008] In the first aspect, the present application provides a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction, adopting the following technical solution:

[0009] A highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction, comprising the following raw materials in parts by weight: 70 - 85 parts of base asphalt, 2 - 5 parts of emulsifier, 0.2 - 0.5 parts of stabilizer, 5 - 10 parts of extender, 1 - 3 parts of pH regulator, and 6 - 13 parts of modifier;

[0010] Among them, the modifier includes a mixture of waste rubber powder, SBR, and petroleum resin with a mass ratio of 1:(0.5 - 0.8):(0.2 - 0.4).

[0011] By adopting the above technical solution, the modifier in the present application is added with waste rubber powder, SBR, and petroleum resin. SBR (styrene - butadiene rubber) as a rubber - type modifier can enhance the viscosity and elasticity of asphalt. Petroleum resin as a resin - type modifier can improve the adhesion of base asphalt. In the present application, part of the waste rubber powder is used to replace SBR as the modifier of emulsified asphalt. When the waste rubber powder is mixed with the base asphalt, the two have a large bonding area and strong molecular force, thereby improving the dynamic viscosity of emulsified asphalt through physical mixing. Moreover, during the preparation process of modified emulsified asphalt, under the action of high temperature and mechanical force, the desulfurization reaction of the waste rubber powder causes the macromolecules of the waste rubber powder to break, and the newly generated small - molecule chains dissolve in the asphalt to form a stable three - dimensional network structure, achieving the purpose of modification. In addition, the waste rubber powder can also absorb the light oil components in the base asphalt and undergo a swelling reaction, thereby increasing the viscosity of emulsified asphalt, making it easier to adhere to aggregates, improving the durability of the road surface. And due to the addition and swelling effect of the waste rubber powder, the modified emulsified asphalt also has better elastic recovery performance. Finally, the prepared emulsified asphalt has high - viscosity and high - elasticity properties, significantly improving the performance of emulsified asphalt.

[0012] Optionally, the waste rubber powder is added after being modified by the following method:

[0013] The waste rubber powder is first crushed and then impregnated and dried in hydrogen peroxide solution to obtain pretreated waste rubber powder;

[0014] Then the pretreated waste rubber powder is subjected to pressure impregnation treatment in a mixed modification liquid of vinyl versatate, ruthenium tetroxide, initiator, organobentonite, and water, and then washed and dried to obtain modified waste rubber powder.

[0015] By adopting the above technical solution, due to the relatively high surface energy of waste rubber powder particles and the significant difference in molecular structure between them and matrix asphalt, the waste rubber powder particles are prone to agglomeration and precipitation in the matrix asphalt. Therefore, in this application, hydrogen peroxide oxidant is used to treat the waste rubber powder, causing some chemical bonds on its surface to break, which can effectively reduce the molecular weight of the waste rubber powder and introduce carbonyl and carboxyl groups onto the waste rubber powder. Then, pressure impregnation treatment is carried out in the mixed modification liquid. Under the action of ruthenium tetroxide catalyst, more carboxyl groups are introduced onto the surface of the waste rubber powder. Then, small molecule anti-settling agent organic bentonite is introduced onto the surface of the waste rubber powder through the hydroxyl groups on the organic bentonite. Together with the action of vinyl versatate, vinyl versatate bonds with the double bonds in the waste rubber powder under the action of an initiator, thereby introducing tertiary carbonate groups, and using its steric hindrance effect to further prevent the agglomeration of waste rubber powder particles, which is beneficial to the mixing and dispersion of the modified waste rubber powder in the matrix asphalt and further improves the viscosity and elasticity of the modified emulsified asphalt.

[0016] Optionally, during the preparation of the modified waste rubber powder, the addition amount of the hydrogen peroxide solution is 5 - 8 mass times that of the waste rubber powder, and the mass concentration of the hydrogen peroxide solution is 15 - 30 wt%.

[0017] The addition amount of the mixed modification liquid is 3 - 5 mass times that of the pretreated waste rubber powder, and the mixed modification liquid is prepared by mixing 8 - 12 parts by weight of vinyl versatate, 1 - 3 parts by weight of ruthenium tetroxide, 0.5 - 1.5 parts by weight of initiator, 5 - 10 parts by weight of organic bentonite, and 20 - 30 parts by weight of water.

[0018] By adopting the above technical solution, through the control of the above raw material addition amounts, the dispersion uniformity of the modified waste rubber powder for mixing with matrix asphalt to prepare modified asphalt is better, and the dynamic viscosity and elastic recovery performance of the prepared modified emulsified asphalt are better.

[0019] Optionally, when the waste rubber powder is modified, the conditions for pressure impregnation of the mixed modification liquid are: impregnation pressure is 2.5 - 4 MPa, impregnation temperature is 55 - 65 °C, and impregnation time is 90 - 150 min.

[0020] By adopting the above technical solution, when the pretreated waste rubber powder is pressure impregnated in the above mixed modification liquid, its modification effect is better.

[0021] Optionally, 5 - 8 parts by weight of p-hydroxybenzoic acid are further added to the mixed modification liquid.

[0022] By adopting the above technical solution, p-hydroxybenzoic acid is added to the mixed modifier in the present application. With the addition of p-hydroxybenzoic acid, its hydroxyl group reacts with the activated carboxyl group on the waste rubber powder, thereby introducing a small molecule benzene ring structure onto the waste rubber powder. The benzene ring structure has a high affinity for aromatics, which can not only improve the compatibility with the matrix asphalt, but also enhance the interaction between the matrix asphalt and SBR, enabling the composite modifier of the modified waste rubber powder and SBR to be dispersed in the matrix asphalt in the form of a spatial network, thus greatly improving the performance of the emulsified asphalt.

[0023] Optionally, the modified waste rubber powder is added after being loaded on the polyamide aerogel. The specific operation is as follows:

[0024] After mixing the modified waste rubber powder with water, polyamide aerogel and polyvinyl alcohol are added, and then impregnated under ultrasonic conditions for 20 - 30 minutes and dried.

[0025] By adopting the above technical solution, in the present application, the modified waste rubber powder is loaded on the polyamide aerogel and then added as an additive. Under ultrasonic dispersion conditions, the modified waste rubber powder is filled and loaded on the surface and within the pore structure of the polyamide aerogel. Then, by utilizing the viscosity of polyvinyl alcohol and the formation of chemical bonding between the carboxyl group on the modified waste rubber powder and the polyamide aerogel, the bonding strength between the modified waste rubber powder and the polyamide aerogel is improved, preventing shedding, and realizing a more firm loading effect of the modified waste rubber powder on the polyamide aerogel. By utilizing the elasticity of the polyamide aerogel, the elastic recovery performance and dynamic viscosity of the modified emulsified asphalt are improved. In addition, due to the similarity in chemical structure and good interaction force between the polyamide aerogel and the asphalt matrix, compared with the waste rubber powder, the polyamide aerogel has better compatibility with the asphalt matrix. The polyamide aerogel can be used as a carrier for the waste rubber powder, which can further improve the dispersibility and stability of the waste rubber powder. At the same time, it can also absorb and store the light components in the asphalt through its porous structure, further improving the performance of the asphalt. Finally, the comprehensive performance of the prepared modified emulsified asphalt is better.

[0026] Optionally, when the modified waste rubber powder is loaded on the polyamide aerogel, the mass ratio of the modified waste rubber powder to water added is 1:(5 - 7), the mass ratio of the polyamide aerogel to the added amount of the modified waste rubber powder is 1:(0.4 - 0.6), and the added amount of polyvinyl alcohol is 3 - 5 wt% of the added amount of the modified waste rubber powder.

[0027] Optionally, the stabilizer is selected as a mixture of calcium chloride, microcrystalline wax and WSG - 104H emulsified asphalt stabilizer with a mass ratio of 1:(0.2 - 0.3):(2 - 3).

[0028] By adopting the above technical scheme, the stabilizer in this application is selected on the basis of traditional calcium chloride inorganic salt and WSG-104H emulsified asphalt stabilizer. The WSG-104H emulsified asphalt stabilizer effectively solves the problems of long-term storage precipitation of emulsified asphalt, poor emulsification effect, crusting and demulsification, and significantly improves the quality of emulsified asphalt. The addition of a small amount of microcrystalline wax can form a protective film in the emulsified asphalt to prevent the aggregation and stratification of asphalt particles, thereby improving the stability of the emulsified asphalt. Moreover, the addition of microcrystalline wax can form a tiny elastic network structure in the asphalt, thereby improving the elastic recovery ability of the asphalt, which helps to improve the modified emulsified asphalt road. When subjected to external forces such as vehicle loads, it can better maintain its flatness and durability, and its small addition prevents its asphalt viscosity from decreasing too much.

[0029] Optionally, the emulsifier is a cationic emulsifier, and the pH adjuster is phosphoric acid.

[0030] Optionally, the retardant is a mixture of mineral oil and polyethylene wax in a mass ratio of 1:(0.3-0.5).

[0031] By adopting the above technical solution, oily substances can improve the ductility of emulsified asphalt by improving the fluidity and elasticity of asphalt. The addition of polyethylene wax can significantly reduce the penetration of asphalt while increasing the softening point and ductility of asphalt. When too much polyethylene wax is added, its ductility is reduced. When the amount added in this application is selected, the overall performance of the final emulsified asphalt is better.

[0032] In a second aspect, the present application provides a method for preparing a high-elastic and high-viscosity composite modified emulsified asphalt for cold-laid overlay construction, using the following technical solution:

[0033] A method for preparing a high-elastic and high-viscosity composite modified emulsified asphalt for cold-laid overlay construction comprises the following steps:

[0034] S1. Firstly heat the base asphalt to 170-180°C, then add the modifier, heat to 180-190°C and stir, then put it into the colloid mill for shearing to obtain an asphalt mixture;

[0035] S2, mixing the emulsifier, stabilizer, extending agent, pH adjuster and water, heating to 70-80°C, and stirring to obtain a soap solution;

[0036] S3, mixing the asphalt mixture obtained in step S1 with the soap solution in step S2 and simultaneously entering a colloid mill for shear emulsification, and then cooling to obtain a high-viscosity and high-elastic composite modified emulsified asphalt.

[0037] By adopting the above technical solutions, the method provided by this application is simple and convenient, easy to realize industrialization. In this application, the modifier and the matrix asphalt are first dispersed and then mixed and sheared with the soap solution. How to make the waste rubber powder in the modifier have better mixing and dispersibility with the matrix asphalt is better for improving the performance of the final emulsified asphalt.

[0038] In summary, this application has the following beneficial effects:

[0039] 1. The modifier in this application is added with waste rubber powder, SBR and petroleum resin. In this application, part of the waste rubber powder is used to replace SBR as the modifier of emulsified asphalt. When the waste rubber powder is mixed with the matrix asphalt, the two have a large bonding area and strong molecular force, so as to improve the dynamic viscosity of emulsified asphalt through physical mixing. Moreover, during the preparation process of modified emulsified asphalt, under the action of high temperature and mechanical force, the desulfurization reaction of the waste rubber powder causes the macromolecules of the waste rubber powder to break, and the newly generated small molecular chains dissolve in the asphalt to form a stable spatial network structure, achieving the purpose of modification. In addition, the waste rubber powder can also absorb the light oil components in the matrix asphalt and undergo a swelling reaction, thereby improving the viscosity of the emulsified asphalt, making it easier to adhere to the aggregate, and improving the durability of the road surface. Moreover, due to the addition and swelling effect of the waste rubber powder, the modified emulsified asphalt also has better elastic recovery performance. The finally prepared emulsified asphalt has high viscosity and high elasticity performance, significantly improving the performance of emulsified asphalt;

[0040] 2. In this application, the waste rubber powder is treated with hydrogen peroxide oxidant to break some chemical bonds on its surface, which can effectively reduce the molecular weight of the waste rubber powder, and introduce carbonyl and carboxyl groups on the waste rubber powder. Then, it is subjected to pressure impregnation treatment in the mixed modification liquid. Under the action of ruthenium tetroxide catalyst, more carboxyl groups are introduced on the surface of the waste rubber powder. Then, through the hydroxyl groups on the organobentonite, the small molecule anti-settling agent organobentonite is introduced on the surface of the waste rubber powder. Together with the action of vinyl versatate, vinyl versatate bonds with the double bonds in the waste rubber powder under the action of an initiator, thereby introducing tertiary carbonate groups, and using its steric hindrance effect to further prevent the agglomeration of waste rubber powder particles, which is beneficial to the mixing and dispersion of the modified waste rubber powder in the matrix asphalt, and further improving the viscosity and elasticity of the modified emulsified asphalt;

[0041] 3. In this application, p-hydroxybenzoic acid is added to the mixed modification liquid. The addition of p-hydroxybenzoic acid causes its hydroxyl group to react with the activated carboxyl group on the waste rubber powder, thereby introducing a small molecule benzene ring structure on the waste rubber powder. The benzene ring structure has a high affinity for aromatics, so it can not only improve the compatibility with the matrix asphalt, but also enhance the interaction between the matrix asphalt and SBR, making the composite modifier of the modified waste rubber powder and SBR disperse in the matrix asphalt in the form of a spatial network, thereby greatly improving the performance of emulsified asphalt;

[0042] 4. In this application, the modified waste rubber powder is loaded on polyamide aerogel and then added as an additive. Under ultrasonic dispersion conditions, the modified waste rubber powder is filled and loaded on the surface and within the pore structure of the polyamide aerogel. Then, by utilizing the viscosity of polyvinyl alcohol and the formation of chemical bonding between the carboxyl groups on the modified waste rubber powder and the polyamide aerogel, the bonding strength between the modified waste rubber powder and the polyamide aerogel is improved, preventing detachment, and realizing a more firm loading effect of the modified waste rubber powder on the polyamide aerogel. By utilizing the elasticity of the polyamide aerogel, the elastic recovery performance and dynamic viscosity of the modified emulsified asphalt are improved. In addition, due to the similarity in chemical structure and good interaction between the polyamide aerogel and the asphalt matrix, compared with the waste rubber powder, the polyamide aerogel has better compatibility with the asphalt matrix. Making the polyamide aerogel as a carrier of the waste rubber powder can further improve the dispersibility and stability of the waste rubber powder. At the same time, it can also absorb and store the light components in the asphalt through its porous structure, further improving the performance of the asphalt. Finally, the comprehensive performance of the modified emulsified asphalt is better. Detailed Embodiments

[0043] The following further elaborates on this application in conjunction with embodiments. It should be specifically noted that: for those not specifying specific conditions in the following embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments can all be sourced from ordinary commercial sales.

[0044] In the following embodiments, the matrix asphalt is selected as AH-70 road heavy traffic asphalt;

[0045] The petroleum resin is selected as C9 petroleum resin; the WSG-104H emulsified asphalt stabilizer is selected as the WSG-104H emulsified asphalt stabilizer from Shanghai Wanzhao Fine Chemical Co., Ltd.

[0046] The mineral oil is selected as 55# white oil; the SBR is selected as the styrene-butadiene latex of model SBRL-65 from Xinxiang Longteng Highway Technology Co., Ltd.

[0047] The polyamide aerogel is selected as a polyamide elastomer-based aerogel, which is formed by combining polyamide elastomer and aerogel, and can be sourced from commercial sales or customized. In the following embodiments, the polyamide aerogel is prepared by the following method:

[0048] Take polyamide elastomer and propanol and mix them in a mass ratio of 1:5. After ultrasonic dispersion, heat to 90 °C and stir for 7 h to dissolve and obtain a mixed solution. Then pour the mixed solution into a beaker, place the beaker in a dry ice-ethanol mixture for freezing, the freezing temperature is -30 °C, and the freezing time is 3 h to obtain a solid mixture. Then evacuate the solid mixture in a freeze dryer and perform freeze-drying at -100 °C for 80 h. After freeze-drying, the polyamide elastomer-based aerogel is prepared.

[0049] Example 1

[0050] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold-laying surface course construction, comprising the following steps:

[0051] S1. First heat 75 g of matrix asphalt to 175 °C, then add 10 g of modifier, raise the temperature to 185 °C and stir, and then enter a colloid mill for shearing. The rotation speed of the colloid mill is 5500 r / min to obtain an asphalt mixture;

[0052] Among them, the modifier is obtained by mixing waste rubber powder, SBR and C9 petroleum resin according to a mass ratio of 1:0.6:0.3;

[0053] S2. Mix 3 g of emulsifier, 0.3 g of stabilizer, 8 g of extender, 2 g of pH regulator and 62 g of water, heat to 75 °C, and stir and mix to obtain a soap solution;

[0054] Among them, the emulsifier is selected as octadecyl trimethyl ammonium chloride cationic emulsifier, the pH regulator is selected as phosphoric acid; the extender is selected as a mixture of mineral oil and polyethylene wax with a mass ratio of 1:0.4, and the stabilizer is selected as a mixture of calcium chloride, microcrystalline wax and WSG-104H emulsified asphalt stabilizer with a mass ratio of 1:0.2:2.5;

[0055] S3. Mix the asphalt mixture obtained in step S1 with the soap solution in step S2 and simultaneously enter a colloid mill for shear emulsification. The rotation speed of the colloid mill is 3800 r / min, and then cool to obtain a highly viscous and highly elastic composite modified emulsified asphalt.

[0056] Example 2

[0057] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold-laying surface course construction, comprising the following steps:

[0058] S1. First heat 70 g of matrix asphalt to 170 °C, then add 6 g of modifier, raise the temperature to 180 °C and stir, and then enter a colloid mill for shearing. The rotation speed of the colloid mill is 5000 r / min to obtain an asphalt mixture;

[0059] Among them, the modifier is obtained by mixing waste rubber powder, SBR and C9 petroleum resin according to a mass ratio of 1:0.5:0.2;

[0060] S2. Mix 2 g of emulsifier, 0.2 g of stabilizer, 5 g of extender, 1 g of pH regulator and 55 g of water, heat to 70 °C, and stir and mix to obtain a soap solution;

[0061] Among them, the emulsifier is selected as octadecyl trimethyl ammonium chloride cationic emulsifier, the pH regulator is selected as phosphoric acid; the extender is selected as a mixture of mineral oil and polyethylene wax with a mass ratio of 1:0.3, and the stabilizer is selected as a mixture of calcium chloride, microcrystalline wax and WSG-104H emulsified asphalt stabilizer with a mass ratio of 1:0.2:2;

[0062] S3. Mix the asphalt mixture obtained in step S1 with the soap solution in step S2 and then enter a colloid mill for shear emulsification simultaneously. The rotation speed of the colloid mill is 3500 r / min, and then high-viscosity and high-elasticity composite modified emulsified asphalt is obtained after cooling.

[0063] Example 3

[0064] A preparation method of high-elasticity and high-viscosity composite modified emulsified asphalt for cold paving surface course construction includes the following steps:

[0065] S1. First heat 85 g of matrix asphalt to 180 °C, then add 13 g of modifier, raise the temperature to 190 °C and stir, and then enter a colloid mill for shearing. The rotation speed of the colloid mill is 6000 r / min to obtain an asphalt mixture;

[0066] Among them, the modifier is obtained by mixing waste rubber powder, SBR and C9 petroleum resin according to a mass ratio of 1:0.8:0.4;

[0067] S2. Mix 5 g of emulsifier, 0.5 g of stabilizer, 10 g of extender, 3 g of pH regulator and 70 g of water, heat to 80 °C, and stir and mix to obtain a soap solution;

[0068] Among them, the emulsifier is selected as octadecyl trimethyl ammonium chloride cationic emulsifier, the pH regulator is selected as phosphoric acid; the extender is selected as a mixture of mineral oil and polyethylene wax with a mass ratio of 1:0.5, and the stabilizer is selected as a mixture of calcium chloride, microcrystalline wax and WSG-104H emulsified asphalt stabilizer with a mass ratio of 1:0.3:3;

[0069] S3. Mix the asphalt mixture obtained in step S1 with the soap solution in step S2 and then enter a colloid mill for shear emulsification simultaneously. The rotation speed of the colloid mill is 4000 r / min, and then high-viscosity and high-elasticity composite modified emulsified asphalt is obtained after cooling.

[0070] Example 4

[0071] A preparation method of high-elasticity and high-viscosity composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 1, the difference is that the waste rubber powder in the modifier in step S1 is modified by the following method and then added:

[0072] The waste rubber powder is first crushed and then impregnated and dried in a hydrogen peroxide solution to obtain pretreated waste rubber powder. The addition amount of the hydrogen peroxide solution is 6 times the mass of the waste rubber powder, and the mass concentration of the hydrogen peroxide solution is 20 wt%.

[0073] Then, the pretreated waste rubber powder is subjected to pressure impregnation treatment in a mixed modification liquid of vinyl versatate, ruthenium tetroxide, initiator, organic bentonite and water. The impregnation pressure is 3 MPa, the impregnation temperature is 60 °C, and the impregnation time is 120 min. Then, it is washed with water and dried to obtain modified waste rubber powder.

[0074] The addition amount of the mixed modification liquid is 4 times the mass of the pretreated waste rubber powder. Based on the mixed modification liquid, the mixed modification liquid is prepared by mixing 10 g of vinyl versatate, 2 g of ruthenium tetroxide, 1 g of initiator potassium persulfate, 8 g of organic bentonite and 25 g of water.

[0075] Example 5

[0076] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 1. The difference is that the waste rubber powder in the modifier in step S1 is added after being modified by the following method:

[0077] The waste rubber powder is first crushed and then impregnated and dried in a hydrogen peroxide solution to obtain pretreated waste rubber powder. The addition amount of the hydrogen peroxide solution is 5 times the mass of the waste rubber powder, and the mass concentration of the hydrogen peroxide solution is 15 wt%.

[0078] Then, the pretreated waste rubber powder is subjected to pressure impregnation treatment in a mixed modification liquid of vinyl versatate, ruthenium tetroxide, initiator, organic bentonite and water. The impregnation pressure is 2.5 MPa, the impregnation temperature is 55 °C, and the impregnation time is 150 min. Then, it is washed with water and dried to obtain modified waste rubber powder.

[0079] The addition amount of the mixed modification liquid is 3 times the mass of the pretreated waste rubber powder. Based on the mixed modification liquid, the mixed modification liquid is prepared by mixing 8 g of vinyl versatate, 1 g of ruthenium tetroxide, 0.5 g of initiator potassium persulfate, 5 g of organic bentonite and 20 g of water.

[0080] Example 6

[0081] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 1. The difference is that the waste rubber powder in the modifier in step S1 is added after being modified by the following method:

[0082] The waste rubber powder is first crushed and then impregnated and dried in a hydrogen peroxide solution to obtain pretreated waste rubber powder. The addition amount of the hydrogen peroxide solution is 8 times the mass of the waste rubber powder, and the mass concentration of the hydrogen peroxide solution is 30 wt%.

[0083] Then, the pretreated waste rubber powder is subjected to pressure impregnation treatment in a mixed modification liquid of vinyl versatate, ruthenium tetroxide, initiator, organic bentonite and water. The impregnation pressure is 4 MPa, the impregnation temperature is 65 °C, and the impregnation time is 90 min. Then, it is washed with water and dried to obtain the modified waste rubber powder.

[0084] Among them, the addition amount of the mixed modification liquid is 3 - 5 mass times that of the pretreated waste rubber powder. Based on the mixed modification liquid, the mixed modification liquid is prepared by mixing 12 g of vinyl versatate, 3 g of ruthenium tetroxide, 1.5 g of initiator potassium persulfate, 10 g of organic bentonite and 30 g of water.

[0085] Example 7

[0086] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 4, except that vinyl versatate is not added to the mixed modification liquid.

[0087] Example 8

[0088] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 4, except that 5 g of p-hydroxybenzoic acid is further added to the mixed modification liquid.

[0089] Example 9

[0090] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 4, except that 8 g of p-hydroxybenzoic acid is further added to the mixed modification liquid.

[0091] Example 10

[0092] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 4, except that after the prepared modified waste rubber powder is loaded on polyamide aerogel and then added. The specific operation is as follows:

[0093] The modified waste rubber powder and water are mixed according to a mass ratio of 1:6, then polyamide aerogel and polyvinyl alcohol are added. The mass ratio of polyamide aerogel to the addition amount of modified waste rubber powder is 1:0.5, and the addition amount of polyvinyl alcohol is 4 wt% of the addition amount of modified waste rubber powder. After impregnation for 25 min under ultrasonic conditions, it is dried.

[0094] Example 11

[0095] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 4, except that after the prepared modified waste rubber powder is loaded on polyamide aerogel and then added. The specific operation is as follows:

[0096] After mixing the modified waste rubber powder and water in a mass ratio of 1:5, polyamide aerogel and polyvinyl alcohol are added. The mass ratio of polyamide aerogel to the added amount of modified waste rubber powder is 1:0.4, and the added amount of polyvinyl alcohol is 3 wt% of the added amount of modified waste rubber powder. After impregnation for 20 min under ultrasonic conditions, it is dried.

[0097] Example 12

[0098] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 4. The difference is that the prepared modified waste rubber powder is added after being loaded on polyamide aerogel. The specific operation is as follows:

[0099] After mixing the modified waste rubber powder and water in a mass ratio of 1:7, polyamide aerogel and polyvinyl alcohol are added. The mass ratio of polyamide aerogel to the added amount of modified waste rubber powder is 1:0.6, and the added amount of polyvinyl alcohol is 5 wt% of the added amount of modified waste rubber powder. After impregnation for 30 min under ultrasonic conditions, it is dried.

[0100] Comparative Example 1

[0101] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 1. The difference is that no modifier is added to the raw materials.

[0102] Comparative Example 2

[0103] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 1. The difference is that the modifier is waste rubber powder.

[0104] Comparative Example 3

[0105] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 1. The difference is that SBR in the modifier is replaced with SBS in equal amount.

[0106] Comparative Example 4

[0107] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 1. The difference is that microcrystalline wax is not added to the stabilizer.

[0108] Comparative Example 5

[0109] A preparation method of a highly elastic and highly viscous composite modified emulsified asphalt for cold paving surface course construction is carried out according to the method in Example 1. The difference is that microcrystalline wax in the stabilizer is replaced with paraffin in equal amount.

[0110] Performance Detection

[0111] First, refer to T0620 to detect the 60°C dynamic viscosity and elastic recovery (25°C) performance of the evaporated residues of the modified emulsified asphalt prepared in the examples and comparative examples of this application. The detection results are shown in Table 1 below.

[0112] Table 1:

[0113]

[0114] Referring to the detection results in Table 1 above, the modified emulsified asphalt prepared in the examples of this application has excellent 60°C dynamic viscosity and elastic recovery performance. The 60°C dynamic viscosity reflects the fluidity, stability of the emulsified asphalt under high-temperature conditions, and the bonding strength with the aggregate, while the elastic recovery property reflects the ability of the emulsified asphalt to return to its original shape after being stressed, directly indicating that it can quickly return to its original shape after being subjected to vehicle loads, reducing permanent pavement deformation.

[0115] Referring to the detection results of Example 1 and Examples 4-6 of this application, it can be seen that after the waste rubber powder is modified, the dynamic viscosity and elasticity of the prepared emulsified asphalt are significantly improved. Combining with the detection results of Example 7, when vinyl versatate is not added to the mixed modifier, it has an impact on the dispersion and distribution of the waste rubber powder in the matrix asphalt, thus reducing the performance of the final emulsified asphalt; combining with the detection results of Examples 8-9, when p-hydroxybenzoic acid is also added to the mixed modifier, its performance is further improved. Combining with the detection results of Examples 10-12, when the waste rubber powder is loaded and added on polyamide aerogel, its performance is significantly improved.

[0116] Combining with the detection results of Example 1 and Comparative Example 1, when no modifier is added to the raw materials, its dynamic viscosity and elastic recovery properties are significantly reduced. When the modifier is directly replaced with waste rubber powder in Comparative Example 2, its elastic recovery performance is significantly reduced. Although the dynamic viscosity is higher than that in Comparative Example 1, it is still much lower than that in Example 1. Combining with the detection results of Comparative Example 3, when SBS and waste rubber powder are compounded as the modifier, its elastic recovery performance is much lower than that in Example 1. Combining with the detection results in Examples 4 and 5, when microcrystalline wax is not added or replaced with paraffin in the stabilizer, its elastic recovery performance is also reduced. When microcrystalline wax is compounded with the traditional stabilizer, the performance of the final modified emulsified asphalt is better.

[0117] In addition, the modified emulsified asphalt prepared in Example 4 of this application is subjected to the detection in Table 2 below, and the detection results are shown in Table 2 below.

[0118] Table 2:

[0119]

[0120] Referring to the test results in Table 2 above, the performance of the modified emulsified asphalt prepared in this application meets the requirements. Moreover, the modified emulsified asphalt prepared in this application is used for the construction of the cold-laid wearing course, and there is no need to mill the original road surface. It is widely applicable to the corrective maintenance of expressways, urban expressways and highways of all grades, quickly improving the road condition level. It can also be used for preventive maintenance. Moreover, there is no flue gas emission during construction at normal temperature, and the energy consumption is reduced by 80% compared with that of the hot mix ultra-thin wearing course. The carbon dioxide emission per ton of mixture is reduced by 2.5 kg, and the sulfur dioxide emission is reduced by 0.3 kg.

[0121] Moreover, the modified emulsified asphalt prepared in this application is used in the modified super-strong wearing course asphalt mixture, and the test value after soaking in water at 25°C for 1 h in the wet wheel abrasion test is 0 g / m 2 , far exceeding the required value of ≤540 g / m 2 , and the test value after soaking in water at 25°C for 6 d is 174.6 g / m 2 , far exceeding the required value of ≤800 g / m 2 , and the water damage resistance performance of the constructed asphalt pavement is excellent.

[0122] This specific embodiment is only an explanation of this application, and it is not a limitation of this application. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of this application, it is protected by the patent law.

Claims

1. A high-elastic and high-viscosity composite modified emulsified asphalt for cold-laid overlay construction, characterized in that: It includes the following raw materials in parts by weight: 70-85 parts of base asphalt, 2-5 parts of emulsifier, 0.2-0.5 parts of stabilizer, 5-10 parts of extender, 1-3 parts of pH regulator and 6-13 parts of modifier; The modifier includes a mixture of waste rubber powder, SBR and petroleum resin in a mass ratio of 1: (0.5-0.8): (0.2-0.4); The waste rubber powder is modified and added by the following method: After the waste rubber powder is crushed, it is first immersed in a hydrogen peroxide solution for drying to obtain pretreated waste rubber powder; Then the pretreated waste rubber powder is subjected to pressure immersion treatment in a mixed modification liquid of tert-butyl vinyl carbonate, ruthenium tetraoxide, initiator, organic bentonite and water, and then washed with water and dried to obtain modified waste rubber powder; Parahydroxybenzoic acid is also added to the mixed modified liquid; The stabilizer is a mixture of calcium chloride, microcrystalline wax and WSG-104H emulsified asphalt stabilizer in a mass ratio of 1: (0.2-0.3): (2-3).

2. The high-elastic and high-viscosity composite modified emulsified asphalt for cold-laid overlay construction according to claim 1, characterized in that: During the preparation of the modified waste rubber powder, the amount of hydrogen peroxide solution added is 5-8 times the mass of the waste rubber powder, and the mass concentration of the hydrogen peroxide solution is 15-30wt%; The amount of the mixed modified liquid added is 3-5 times the mass of the pretreated waste rubber powder, and the mixed modified liquid is prepared by mixing 8-12 parts by weight of versatate vinyl carbonate, 1-3 parts by weight of ruthenium tetroxide, 0.5-1.5 parts by weight of initiator, 5-10 parts by weight of organic bentonite and 20-30 parts by weight of water.

3. The high-elastic and high-viscosity composite modified emulsified asphalt for cold-laid overlay construction according to claim 1, characterized in that: When the waste rubber powder is modified, the conditions for pressurized impregnation of the mixed modified liquid are: impregnation pressure is 2.5-4MPa, impregnation temperature is 55-65℃, and impregnation time is 90-150min.

4. The high-elasticity and high-viscosity composite modified emulsified asphalt for cold-laid overlay construction according to claim 2, characterized in that: 5-8 parts by weight of p-hydroxybenzoic acid are also added to the mixed modified liquid.

5. The high-elasticity and high-viscosity composite modified emulsified asphalt for cold-laid overlay construction according to claim 2, characterized in that: The modified waste rubber powder is loaded on the polyamide aerogel and then added, and the specific operation is as follows: After the modified waste rubber powder is mixed with water, polyamide aerogel and polyvinyl alcohol are added, and the mixture is immersed in ultrasonic conditions for 20-30 minutes and then dried.

6. The high-elasticity and high-viscosity composite modified emulsified asphalt for cold-laid overlay construction according to claim 5, characterized in that: When the modified waste rubber powder is loaded on the polyamide aerogel, the mass ratio of the modified waste rubber powder to water is 1:(5-7), the mass ratio of the polyamide aerogel to the modified waste rubber powder is 1:(0.4-0.6), and the amount of polyvinyl alcohol added is 3-5wt% of the amount of the modified waste rubber powder added.

7. The high-elasticity and high-viscosity composite modified emulsified asphalt for cold-laid overlay construction according to claim 1, characterized in that: The emulsifier is a cationic emulsifier, and the pH adjuster is phosphoric acid; The retardant is a mixture of mineral oil and polyethylene wax in a mass ratio of 1: (0.3-0.5).

8. The method for preparing a high-elastic and high-viscosity composite modified emulsified asphalt for cold-laid overlay construction as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Firstly, heat the base asphalt to 170-180°C, then add the modifier, heat to 180-190°C and stir, then put it into the colloid mill for shearing to obtain an asphalt mixture; S2, mixing the emulsifier, stabilizer, extending agent, pH adjuster and water, heating to 70-80° C., and stirring to obtain a soap solution; S3, mixing the asphalt mixture obtained in step S1 with the soap solution in step S2 and simultaneously entering into a colloid mill for shear emulsification, and then cooling to obtain a high-viscosity and high-elasticity composite modified emulsified asphalt.

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