High-strength asphalt concrete and preparation method thereof

Abstract

The invention relates to the technical field of asphalt concrete, in particular to high-strength asphalt concrete and a preparation method thereof. The high-strength asphalt concrete is prepared from the following raw materials in parts by weight: 27 to 40 parts of waste asphalt mixture, 10 to 17 parts of asphalt, 8 to 15 parts of aggregate, 1 to 5 parts of modifier, 0.1 to 0.3 part of antioxidant and 0.03 to 0.08 part of weather-resistant agent. The high-strength asphalt concrete contains the modifier, the weather-resistant agent and other components, and test results show that the modifier can effectively enhance the mechanical properties of the asphalt concrete, and the weather-resistant agent can make the asphalt concrete have a longer service life.

Description

Technical Field

[0001] The present invention relates to the technical field of asphalt concrete, and particularly relates to a high-strength asphalt concrete and a preparation method thereof. Background Art

[0002] In recent years, the urban construction in China has shown a trend of rapid development, and transportation has become the top priority in the development of urban infrastructure in China. This has put forward new requirements for the performance of pavement materials, which not only need to have excellent mechanical properties but also need to have a long service life.

[0003] Currently, the material of pavement materials is usually asphalt. However, traditional asphalt pavements often have problems such as poor mechanical properties, that is, low compressive strength and flexural strength, and short service life. Based on the above problems, scholars have proposed using asphalt concrete instead of asphalt as pavement materials. Asphalt concrete, also known as bituminous concrete, is made by artificially selecting mineral materials with a certain gradation (such as crushed stone or crushed gravel), stone chips or sand, mineral powder, etc., and mixing them with a certain proportion of road asphalt under specific conditions. Research shows that asphalt concrete combines the excellent properties of asphalt and concrete. However, existing asphalt concrete has the problem that it cannot combine excellent mechanical properties and a long service life. Based on this, the present application provides an asphalt concrete that combines excellent mechanical properties and a long service life, which is of great significance for improving the overall performance of pavement materials. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, one of the purposes of the present invention is to provide a high-strength asphalt concrete with excellent mechanical properties and weather resistance.

[0005] Another purpose of the present invention is to provide a preparation method of the high-strength asphalt concrete, and the preparation method has simple steps.

[0006] One of the purposes of the present invention is achieved by adopting the following technical solutions: A high-strength asphalt concrete, comprising the following raw materials in parts by weight: 27-40 parts of waste asphalt mixture, 10-17 parts of asphalt, 8-15 parts of aggregate, 1-5 parts of modifier, 0.1-0.3 parts of antioxidant, and 0.03-0.08 parts of weathering agent; The preparation process of the modifier is as follows: (1) Add bentonite into water, then add cetylmethyldihydroxyethylammonium bromide and stir for reaction, and obtain pretreated bentonite after purification; (2) Add the pretreated bentonite obtained in step (1) into water, then add lignin and basalt fiber, and carry out hydrothermal reaction, and obtain the modifier after purification.

[0007] Further, the mass ratio of the pretreated bentonite, lignin, and basalt fiber in step (2) is 1:(0.2 - 0.5):(0.5 - 1).

[0008] Further, the temperature of the hydrothermal reaction in step (2) is 220 - 260 °C, and the time of the hydrothermal reaction is 14 - 16 h.

[0009] Further, the mass ratio of the bentonite and cetylmethyldihydroxyethylammonium bromide in step (1) is 1:(0.5 - 1); the temperature of the stirring reaction is 55 - 70 °C, and the time of the stirring reaction is 1.5 - 3 h.

[0010] Further, the preparation process of the weathering agent is as follows: Mix nano-titanium dioxide and polyurethane, then carry out a heating reaction, then cool down and add water, perform ultrasonic oscillation and then filtration by suction, and dry the solid phase to obtain it.

[0011] Further, the dosage ratio of the nano-titanium dioxide, polyurethane, and water is 1 g:(400 - 600) g:(12 - 18) mL; the average particle size of the nano-titanium dioxide is 20 - 40 nm.

[0012] Further, the temperature of the heating reaction is 130 - 140 °C, and the time of the heating reaction is 1 - 3 h; cool down to 40 - 50 °C.

[0013] Further, the waste asphalt mixture is the waste material generated by milling the asphalt pavement and obtained by screening, wherein the proportion of the particle size of 0 - 45 mm is 10 - 15%, the proportion of the particle size of 4.5 - 10 mm is 25 - 40%, the proportion of the particle size of 10 - 18.5 mm is 30 - 40%, and the proportion of the particle size of 18.5 - 31 mm is 10 - 27%.

[0014] Further, the aggregate consists of primary coarse aggregate with a particle size of 19 - 38 mm, secondary coarse aggregate with a particle size of 9 - 19 mm, tertiary coarse aggregate with a particle size of 4 - 9 mm, and stone chips. The mass ratio of the primary coarse aggregate, secondary coarse aggregate, tertiary coarse aggregate, and stone chips is 4:6:3:4; the antioxidant is antioxidant 1010 or antioxidant 168.

[0015] The second object of the present invention is achieved by the following technical solution: The preparation method of the above high-strength asphalt concrete includes the following steps: Mix each raw material evenly at 130 - 150 °C according to the described weight ratio.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a high-strength asphalt concrete, which contains components such as a modifier and a weathering agent. Among them, the modifier is obtained by pretreating bentonite with cetyl methyldihydroxyethyl ammonium bromide, and then carrying out a hydrothermal carbonization reaction on the pretreated bentonite, lignin, and basalt fiber. Further analysis of this preparation method shows that the pretreatment of bentonite is to increase the interlayer spacing inside the bentonite, which is beneficial to the uniform distribution of basalt fiber in the bentonite; the hydrothermal carbonization reaction is to carbonize lignin on the surfaces of the bentonite and basalt fiber. In addition, lignin contains abundant active groups such as alcohol hydroxyl groups and phenolic hydroxyl groups, which can not only improve the dispersion of basalt fiber in the asphalt concrete and increase the strength, but also improve the compatibility between the new and old asphalt and extend the service life of the asphalt concrete. The weathering agent of the present invention is obtained by modifying nano-titanium dioxide with polyurethane. The above modification method can improve the dispersion of nano-titanium dioxide in the asphalt concrete, thereby enhancing the weather resistance of the asphalt concrete. In addition, this weathering agent also has good viscosity, which is beneficial to enhancing the bonding between the new and old asphalt, thereby improving the performance of the asphalt concrete. Detailed implementation manners

[0017] The following combines the detailed implementation manners to further describe the present invention. It should be noted that on the premise of no conflict, the following described embodiments or technical features can be combined arbitrarily to form new embodiments. The specific conditions not specified in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are all conventional products obtained through commercial channels without special instructions.

[0018] In the present invention, the length of the basalt fiber is 3-20 mm; the asphalt is 70# base asphalt; The aggregate is composed of a first-grade coarse aggregate with a particle size of 19-38 mm, a second-grade coarse aggregate with a particle size of 9-19 mm, a third-grade coarse aggregate with a particle size of 4-9 mm, and stone chips. The mass ratio of the first-grade coarse aggregate, the second-grade coarse aggregate, the third-grade coarse aggregate, and the stone chips is 4:6:3:4.

[0019] (I) Embodiment Embodiment 1 Embodiment 1 provides a high-strength asphalt concrete, which is composed of the following raw materials in parts by weight: 33 parts of waste asphalt mixture, 14 parts of 70# base asphalt, 12 parts of aggregate, 3 parts of modifier, 0.2 part of antioxidant 1010, and 0.05 part of weathering agent; Among them, the waste asphalt mixture is the waste material generated by milling the asphalt pavement and obtained by screening. The proportion of particles with a particle size of 0-45 mm is 12%, the proportion of particles with a particle size of 4.5-10 mm is 28%, the proportion of particles with a particle size of 10-18.5 mm is 33%, and the proportion of particles with a particle size of 18.5-31 mm is 27%; The preparation process of the modifier is as follows: (1) According to the mass ratio of bentonite to cetylmethyldihydroxyethylammonium bromide of 1:0.8, add bentonite to water, then add cetylmethyldihydroxyethylammonium bromide, and stir and react at 60°C for 2 h. After filtration and drying, pretreated bentonite is obtained; (2) According to the mass ratio of pretreated bentonite, lignin, and basalt fiber of 1:0.3:0.7, add the pretreated bentonite obtained in step (1) to water, then add lignin and basalt fiber, and carry out hydrothermal reaction at 240°C for 15 h. After filtration, washing, and drying, the modifier is obtained.

[0020] The preparation process of the weather-resistant agent is as follows: According to the dosage ratio of nano-titanium dioxide, polyurethane, and water of 1 g:500 g:15 mL, mix nano-titanium dioxide with an average particle size of 30 nm and polyurethane, then heat and react at 135°C for 2 h. After cooling to 45°C, add water, carry out ultrasonic oscillation and then filtration, and dry the solid phase to obtain it.

[0021] Example 1 also provides the preparation method of the above high-strength asphalt concrete, which is specifically as follows: Weigh each raw material according to the described weight ratio, and then mix them evenly at 140°C. That's it.

[0022] Example 2 Example 2 provides a high-strength asphalt concrete, which is composed of the following raw materials in parts by weight: 27 parts of waste asphalt mixture, 10 parts of 70# base asphalt, 8 parts of aggregate, 1 part of modifier, 0.1 part of antioxidant 168, and 0.03 part of weather-resistant agent; Among them, the waste asphalt mixture is the waste material generated by milling the asphalt pavement and obtained through screening, in which the proportion of particles with a size of 0 - 45 mm is 15%, the proportion of particles with a size of 4.5 - 10 mm is 40%, the proportion of particles with a size of 10 - 18.5 mm is 30%, and the proportion of particles with a size of 18.5 - 31 mm is 15%; The preparation process of the modifier is as follows: (1) According to the mass ratio of bentonite to cetylmethyldihydroxyethylammonium bromide of 1:0.5, add bentonite to water, then add cetylmethyldihydroxyethylammonium bromide, and stir and react at 55°C for 3 h. After filtration and drying, pretreated bentonite is obtained; (2) According to the mass ratio of pretreated bentonite, lignin, and basalt fiber of 1:0.2:0.5, add the pretreated bentonite obtained in step (1) to water, then add lignin and basalt fiber, and carry out hydrothermal reaction at 220°C for 16 h. After filtration, washing, and drying, the modifier is obtained.

[0023] The preparation process of the weather-resistant agent is as follows: Mix nano-titanium dioxide with an average particle size of 20 nm and polyurethane in a weight ratio of 1 g: 400 g: 12 mL, heat the mixture at 130 °C for 3 h, cool it to 40 °C, add water, filter by ultrasonic oscillation, and dry the solid phase to obtain the product.

[0024] Example 2 also provides a method for preparing the above high-strength asphalt concrete, which is as follows: Weigh each raw material according to the above weight ratio, and then mix them evenly at 130 °C.

[0025] Example 3 Example 3 provides a high-strength asphalt concrete, which is composed of the following raw materials in parts by weight: 40 parts of waste asphalt mixture, 17 parts of 70# base asphalt, 15 parts of aggregate, 5 parts of modifier, 0.3 part of antioxidant 1010, and 0.08 part of weathering agent. Among them, the waste asphalt mixture is the waste material generated by milling the asphalt pavement and obtained by screening. The proportion of particles with a size of 0 - 45 mm is 10%, the proportion of particles with a size of 4.5 - 10 mm is 40%, the proportion of particles with a size of 10 - 18.5 mm is 40%, and the proportion of particles with a size of 18.5 - 31 mm is 10%. The preparation process of the modifier is as follows: (1) Add bentonite to water according to the mass ratio of bentonite to cetylmethyldihydroxyethylammonium bromide of 1:1, then add cetylmethyldihydroxyethylammonium bromide, stir and react at 70 °C for 1.5 h, filter and dry to obtain pretreated bentonite. (2) Add the pretreated bentonite obtained in step (1) to water according to the mass ratio of pretreated bentonite, lignin, and basalt fiber of 1:0.5:1, then add lignin and basalt fiber, carry out hydrothermal reaction at 260 °C for 14 h, filter, wash, and dry to obtain the modifier.

[0026] The preparation process of the weathering agent is as follows: Mix nano-titanium dioxide with an average particle size of 40 nm and polyurethane in a weight ratio of 1 g: 600 g: 18 mL, heat the mixture at 140 °C for 1 h, cool it to 50 °C, add water, filter by ultrasonic oscillation, and dry the solid phase to obtain the product.

[0027] Example 3 also provides a method for preparing the above high-strength asphalt concrete, which is as follows: Weigh each raw material according to the above weight ratio, and then mix them evenly at 150 °C.

[0028] (II) Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that: a mixture of bentonite, lignin, and basalt fiber is used to replace the modifier, and the amounts of bentonite, lignin, and basalt fiber are the same as those in Example 1, and the rest is the same as Example 1.

[0029] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that: a mixture of nano-titanium dioxide and polyurethane is used to replace the weathering agent, and the amounts of nano-titanium dioxide and polyurethane are the same as those in Example 1, and the rest is the same as Example 1.

[0030] The properties of the concrete prepared in Examples 1-3 and Comparative Examples 1-2 are described below.

[0031] Mechanical properties: Referring to the standard of GB / T50784-2013, the mechanical properties of the concrete prepared in Examples 1-3 and Comparative Examples 1-2 were tested, and the results are shown in Table 1.

[0032] Weather resistance: Referring to JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the immersion residual stability, dynamic stability, and fatigue resistance of the concrete prepared in Examples 1-3 and Comparative Examples 1-2 were tested, and the test results are shown in Table 2.

[0033] Table 1 Table 2 The higher the immersion residual stability, the higher the water stability of the asphalt concrete; the higher the dynamic stability, the stronger the high-temperature rutting resistance of the asphalt concrete; the higher the fatigue life, the less the cracking situation accumulated by the asphalt concrete under repeated traffic loads.

[0034] As can be seen from Tables 1-2, the asphalt concrete obtained in Examples 1-3 of the present invention has excellent mechanical properties and weather resistance.

[0035] Compared with Examples 1-3, in Comparative Example 1, a mixture of bentonite, lignin, and basalt fiber was used to replace the modifier, and the mechanical properties of the obtained concrete were significantly reduced. The above results indicate that the modifier obtained by the present invention can effectively enhance the mechanical properties of asphalt concrete. The modifier of the present invention is obtained by pretreating bentonite with cetylmethyldihydroxyethylammonium bromide and then performing a hydrothermal carbonization reaction on the pretreated bentonite, lignin, and basalt fiber. Further analysis of this preparation method shows that the pretreatment of bentonite is to increase the interlayer spacing inside bentonite, which is beneficial to the uniform distribution of basalt fiber in bentonite; the hydrothermal carbonization reaction is to carbonize lignin on the surfaces of bentonite and basalt fiber. In addition, lignin contains abundant active groups such as alcohol hydroxyl groups and phenolic hydroxyl groups, which can not only improve the dispersion of basalt fiber in asphalt concrete and increase the strength, but also improve the compatibility between new and old asphalt and extend the service life of asphalt concrete.

[0036] Compared with Examples 1-3, in Comparative Example 2, a mixture of nano-titanium dioxide and polyurethane was used to replace the weathering agent, and the weather resistance of the obtained concrete was significantly reduced. The above results indicate that the weathering agent obtained by the present invention can endow asphalt concrete with a longer service life. The present invention uses polyurethane to modify nano-titanium dioxide to obtain a weathering agent. The above modification method can improve the dispersion of nano-titanium dioxide in asphalt concrete, thereby enhancing the weather resistance of asphalt concrete. In addition, this weathering agent also has good viscosity, which is beneficial to enhancing the bonding between new and old asphalt, thus improving the performance of asphalt concrete.

[0037] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantive changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection required by the present invention.

Claims

1. A high-strength asphalt concrete, characterized in that: The raw materials include the following parts by weight: 27-40 parts of waste asphalt mixture, 10-17 parts of asphalt, 8-15 parts of aggregate, 1-5 parts of modifier, 0.1-0.3 parts of antioxidant, and 0.03-0.08 parts of weathering agent; The preparation process of the modifier is as follows: (1) adding bentonite into water, then adding hexadecylmethyl dihydroxyethyl ammonium bromide to carry out stirring reaction, and obtaining pretreated bentonite after purification; (2) adding the bentonite pretreated in step (1) into water, and then adding lignin and basalt fiber, performing a hydrothermal reaction, and obtaining a modifier after purification; The preparation process of the weathering agent is as follows: nano titanium dioxide and polyurethane are mixed and heated for reaction, then cooled and water is added, ultrasonically shaken and filtered, and the solid phase is dried to obtain the weathering agent.

2. The high-strength asphalt concrete according to claim 1, characterized in that: The mass ratio of the pretreated bentonite, lignin and basalt fiber in step (2) is 1: (0.2-0.5): (0.5-1).

3. The high-strength asphalt concrete according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step (2) is 220-260° C., and the time of the hydrothermal reaction is 14-16 hours.

4. The high-strength asphalt concrete according to claim 1, characterized in that: The mass ratio of bentonite to hexadecylmethyl dihydroxyethyl ammonium bromide in step (1) is 1:(0.5-1); the stirring reaction temperature is 55-70°C, and the stirring reaction time is 1.5-3h.

5. The high-strength asphalt concrete according to claim 1, characterized in that: The dosage ratio of the nano titanium dioxide, polyurethane and water is 1 g: (400-600) g: (12-18) mL; the average particle size of the nano titanium dioxide is 20-40 nm.

6. The high-strength asphalt concrete according to claim 1, characterized in that: The temperature of the heating reaction is 130-140°C, and the heating reaction time is 1-3h; the temperature is lowered to 40-50°C.

7. The high-strength asphalt concrete according to claim 1, characterized in that: The waste asphalt mixture is waste material generated by milling asphalt pavement and is obtained by screening, wherein the proportion of particle size 0-45mm is 10-15%, the proportion of particle size 4.5-10mm is 25-40%, the proportion of particle size 10-18.5mm is 30-40%, and the proportion of particle size 18.5-31mm is 10-27%.

8. The high-strength asphalt concrete according to claim 1, characterized in that: The aggregate consists of primary coarse aggregate with a particle size of 19-38 mm, secondary coarse aggregate with a particle size of 9-19 mm, tertiary coarse aggregate with a particle size of 4-9 mm and stone chips, and the mass ratio of the primary coarse aggregate, the secondary coarse aggregate, the tertiary coarse aggregate and the stone chips is 4:6:3:4; the antioxidant is antioxidant 1010 or antioxidant 168.

9. The method for preparing high-strength asphalt concrete according to any one of claims 1 to 8, characterized in that: The following steps are involved: According to the weight ratio, the raw materials are mixed uniformly at 130-150°C.

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