Anti-cracking asphalt concrete and preparation method thereof

Abstract

The invention relates to the technical field of concrete, and provides anti-cracking asphalt concrete and a preparation method thereof.The anti-cracking asphalt concrete is prepared from, by weight, 30-50 parts of asphalt, 40-50 parts of cement, 10-15 parts of natural sand, 8-12 parts of slag and 10-15 parts of silica fume composite aramid fiber pulp; raw materials of the silica fume composite aramid fiber pulp comprise silica fume and aramid fiber pulp. By means of the technical scheme, the problem that asphalt concrete is prone to cracking in the prior art is solved.

Description

Technical Field

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

[0002] In the field of highway transportation, asphalt concrete is widely used in the paving of roads at all levels. Whether it is an expressway or an urban arterial road, due to extremely high requirements for flatness and durability, high-quality asphalt concrete is required to ensure the smoothness and safety of vehicles traveling at high speeds; moreover, it has to withstand the frequent starting and stopping of a large number of vehicles and different types of loads. Asphalt concrete, with its good anti-skid property and flexibility, reduces the risk of traffic accidents and improves driving comfort. However, under the repeated action of daily traffic loads, fatigue stress is easily generated inside asphalt concrete, resulting in the initiation and expansion of microcracks, and finally the formation of macroscopic cracks. The frequent starting and stopping of vehicles, sudden braking, and the heavy pressure of heavy trucks will all exacerbate this process. In cold regions, the low temperature in winter causes asphalt concrete to shrink, and internal stress concentration is also extremely likely to cause cracking of asphalt concrete; therefore, it is urgent to develop a crack-resistant asphalt concrete to improve the durability and safety of roads, reduce maintenance costs, and meet the growing traffic demand. Summary of the Invention

[0003] The present invention provides a crack-resistant asphalt concrete and a preparation method thereof, which solve the problem that asphalt concrete in related technologies is prone to cracking.

[0004] The technical solution of the present invention is as follows: The present invention provides a crack-resistant asphalt concrete, which comprises raw materials in the following parts by weight: 30 - 50 parts of asphalt, 40 - 50 parts of cement, 10 - 15 parts of natural sand, 8 - 12 parts of slag, and 10 - 15 parts of silica fume composite aramid fiber pulp; the raw materials of the silica fume composite aramid fiber pulp include silica fume and aramid fiber pulp.

[0005] As a further technical solution, the mass ratio of the silica fume to the aramid fiber pulp is 1:2 - 4, for example, it can be 1:2, 1:3, 1:4, and preferably 1:3.

[0006] As a further technical solution, the particle size of the silica fume is less than 1250 mesh, for example, it can be 2000 mesh, 3000 mesh, 5000 mesh, 8000 mesh, 10000 mesh.

[0007] In the present invention, when the particle size of silica fume is less than 1250 mesh, for the silica fume composite aramid fiber pulp system, the small particle size silica fume can better wrap the aramid fiber pulp, increasing the contact area and adhesion between the aramid fiber pulp and the matrix. Physical adsorption is formed between the silica fume and the surface of the aramid fiber pulp, enabling the fiber to better play its reinforcing role in concrete. When the concrete is subjected to external forces, stress can be more effectively transmitted to the aramid fiber pulp through the silica fume, improving the reinforcing efficiency of the aramid fiber pulp, and thus enhancing the anti-cracking performance of the asphalt concrete.

[0008] As a further technical solution, the silica fume composite aramid fiber pulp further includes polyvinyl acetate.

[0009] In the present invention, polyvinyl acetate has good adhesiveness. In the silica fume composite aramid fiber pulp system, it can form an adhesive bridge between the silica fume, the aramid fiber pulp, and other components of the asphalt concrete. The ester groups in its molecular structure can undergo physical adsorption with the hydroxyl groups on the surface of the silica fume and the polar groups on the surface of the aramid fiber, thus significantly enhancing the interfacial adhesion between the components. When micro-cracks appear inside the asphalt concrete, polyvinyl acetate can form a bridging effect at the cracks. Its flexible molecular chain can span the cracks, preventing the cracks from further expanding. At the same time, polyvinyl acetate and the silica fume, aramid fiber pulp act together to enhance the toughness of the concrete, enabling the concrete to still maintain a certain load-bearing capacity after cracks appear, and improving the anti-cracking performance and durability of the asphalt concrete.

[0010] As a further technical solution, the mass ratio of the polyvinyl acetate to the aramid fiber pulp is 1 - 5:24, for example, it can be 1:24, 1:12, 1:8, 1:6, 5:24.

[0011] As a further technical solution, the weight-average molecular weight of the polyvinyl acetate is 200,000 - 400,000.

[0012] In the present invention, due to the decrease in the viscosity of asphalt and the weakening of the adhesion to aggregates at high temperatures, polyvinyl acetate with a weight-average molecular weight of 200,000 - 400,000 can form a transition layer with high bonding strength at the asphalt-aggregate interface. Its ester groups physically combine with the components in the asphalt and the substances on the surface of the aggregates, strengthening the adhesion between the asphalt and the aggregates. Under high-temperature heavy traffic, it can effectively maintain the structural integrity of the asphalt concrete and ensure its normal service performance in a high-temperature environment.

[0013] As a further technical solution, the natural sand includes one or both of river sand and sea sand.

[0014] As a further technical solution, the cement is Portland cement.

[0015] As a further technical solution, the preparation method of the silica fume composite aramid fiber pulp includes the following steps: After ball-milling the silica fume and aramid fiber pulp, the silica fume composite aramid fiber pulp is obtained.

[0016] As a further technical solution, the rotation speed of the ball-milling is 300 - 400 rpm, and the time of the ball-milling is 5 - 7 h.

[0017] As a further technical solution, the preparation method of the silica fume composite aramid fiber pulp includes the following steps: Add the silica fume and aramid fiber pulp into a solvent, then add polyvinyl acetate and mix. After drying, the silica fume composite aramid fiber pulp is obtained.

[0018] As a further technical solution, the temperature of the mixing is 35 - 45 °C, and the time of the mixing is 1 - 3 h.

[0019] As a further technical solution, the solvent includes one or more of ethanol, acetone, and toluene.

[0020] As a further technical solution, the mass ratio of the solvent to the aramid fiber pulp is 3:2.

[0021] The present invention also provides a preparation method of crack-resistant asphalt concrete. For preparing the crack-resistant asphalt concrete, it includes the following steps: S1. Weigh the raw materials according to the components in parts by weight. S2. Heat the asphalt to 160 - 180 °C and then add the remaining other components for mixing to obtain the crack-resistant asphalt concrete.

[0022] The working principle and beneficial effects of the present invention are as follows: In the present invention, the silica fume composite aramid fiber pulp is added to the asphalt concrete. The silica fume has a high specific surface area and high activity, which can fill the pores in the cement paste, making it more dense and improving the strength of the cement stone. The aramid fiber pulp has excellent tensile strength. After the two are compounded, a reinforcing framework is formed in the asphalt concrete. When the concrete is subjected to tensile stress, the silica fume composite aramid fiber pulp can effectively bear the tensile force, limit the generation and expansion of cracks, and significantly improve the crack resistance of the asphalt concrete. Specific Embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0024] In the following examples and comparative examples: Asphalt, model 90#; cement, Portland cement po 42.5; aramid fiber pulp, model: 1414; aramid fiber, diameter: 10 - 30 μm, length: 3 mm; river sand, particle size: 100 mesh; sea sand, particle size: 80 mesh; slag, particle size: 325 mesh.

[0025] Example 1 A preparation method of crack-resistant asphalt concrete, comprising the following steps: Heat 50 parts of asphalt to 160 °C, then add 40 parts of cement, 10 parts of river sand, 8 parts of slag, and 12 parts of silica fume composite aramid fiber pulp, and mix evenly to obtain crack-resistant asphalt concrete; Preparation method of silica fume composite aramid fiber pulp: Silica fume (3000 mesh) and aramid fiber pulp are ball-milled at a speed of 400 rpm for 5 h to obtain; the mass ratio of silica fume to aramid fiber pulp is 1:2.

[0026] Example 2 A preparation method of crack-resistant asphalt concrete, comprising the following steps: Heat 40 parts of asphalt to 170 °C, then add 45 parts of cement, 12 parts of mountain sand, 10 parts of slag, and 15 parts of silica fume composite aramid fiber pulp, and mix evenly to obtain crack-resistant asphalt concrete; Preparation method of silica fume composite aramid fiber pulp: Silica fume (5000 mesh) and aramid fiber pulp are ball-milled at a speed of 350 rpm for 6 h to obtain; the mass ratio of silica fume to aramid fiber pulp is 1:3.

[0027] Example 3 A preparation method of crack-resistant asphalt concrete, comprising the following steps: Heat 30 parts of asphalt to 180 °C, then add 50 parts of cement, 15 parts of sea sand, 12 parts of slag, and 10 parts of silica fume composite aramid fiber pulp, and mix evenly to obtain crack-resistant asphalt concrete; Preparation method of silica fume composite aramid fiber pulp: Silica fume (5000 mesh) and aramid fiber pulp are ball-milled at a speed of 300 rpm for 7 h to obtain; the mass ratio of silica fume to aramid fiber pulp is 1:4.

[0028] Example 4 This example is different from Example 2 only in that the preparation method of silica fume composite aramid fiber pulp: Add silica fume and aramid fiber pulp to ethanol, then add polyvinyl acetate (weight average molecular weight of 100,000) and heat at 35 °C for 3 h, and obtain silica fume composite aramid fiber pulp after drying; the mass ratio of silica fume, aramid fiber pulp, polyvinyl acetate, and ethanol is 8:24:1:36.

[0029] Example 5 Compared with Example 2, the only difference in this example lies in the preparation method of silica fume composite aramid fiber pulp: silica fume and aramid fiber pulp are added to acetone, and then polyvinyl acetate (weight average molecular weight is 100,000) is added and heated at 40 °C for 2 h. After drying, silica fume composite aramid fiber pulp is obtained; the mass ratio of silica fume, aramid fiber pulp, polyvinyl acetate, and acetone is 8:24:3:36.

[0030] Example 6 Compared with Example 2, the only difference in this example lies in the preparation method of silica fume composite aramid fiber pulp: silica fume and aramid fiber pulp are added to toluene, and then polyvinyl acetate (weight average molecular weight is 100,000) is added and heated at 45 °C for 1 h. After drying, silica fume composite aramid fiber pulp is obtained; the mass ratio of silica fume, aramid fiber pulp, polyvinyl acetate, and toluene is 8:24:5:36.

[0031] Example 7 Compared with Example 5, the only difference in this example lies in replacing polyvinyl acetate with a weight average molecular weight of 100,000 with an equal amount of polyvinyl acetate with a weight average molecular weight of 500,000.

[0032] Example 8 Compared with Example 5, the only difference in this example lies in replacing polyvinyl acetate with a weight average molecular weight of 100,000 with an equal amount of polyvinyl acetate with a weight average molecular weight of 200,000.

[0033] Example 9 Compared with Example 5, the only difference in this example lies in replacing polyvinyl acetate with a weight average molecular weight of 100,000 with an equal amount of polyvinyl acetate with a weight average molecular weight of 400,000.

[0034] Comparative Example 1 50 parts of asphalt are heated to 160 °C and then 40 parts of cement, 10 parts of river sand, 8 parts of slag, 4 parts of silica fume (3000 mesh), and 8 parts of aramid fiber pulp are added and mixed evenly to obtain crack-resistant asphalt concrete.

[0035] Comparative Example 2 Compared with Example 1, the only difference in this comparative example lies in replacing aramid fiber pulp with an equal amount of aramid fiber.

[0036] Comparative Example 3 Compared with Example 1, the only difference in this comparative example lies in replacing silica fume composite aramid fiber pulp with an equal amount of silica fume (3000 mesh).

[0037] Comparative Example 4 Compared with Example 1, the only difference in this comparative example lies in replacing silica fume composite aramid fiber pulp with an equal amount of aramid fiber pulp.

[0038] Experimental Example 1 The splitting tensile strength of the crack-resistant asphalt concrete prepared in Examples 1 to 6 and Comparative Examples 1 to 4 was tested according to the method in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The test temperature was 15°C ± 0.5°C, and the loading rate was 50 mm / min. The test results are shown in Table 1.

[0039] Table 1 Test Results of the Crack Resistance Performance of Asphalt Concrete

[0040] As can be seen from Table 1, the splitting tensile strength of the asphalt concrete prepared in Examples 1 to 6 is higher than that in Comparative Examples 1 to 4, indicating that adding silica fume composite aramid fiber pulp can improve the crack resistance of asphalt concrete.

[0041] Experimental Example 2 The dynamic stability of the asphalt concrete prepared in Examples 5, 7 to 9 was tested according to the method in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The wheel ground pressure was 0.7 MPa, and the temperature was 60°C. The test results are shown in Table 2.

[0042] Table 2 Test Results of the Dynamic Stability of Asphalt Concrete

[0043] As shown in Table 2, the dynamic stability of the asphalt concrete prepared in Examples 8 to 9 is higher than that in Examples 5 and 7, indicating that adding polyvinyl acetate with a weight-average molecular weight of 200,000 to 400,000 to the silica fume composite aramid fiber pulp can improve the high-temperature stability of asphalt concrete.

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. An anti-cracking asphalt concrete, characterized in that, Raw materials comprising the following components by weight: 30 - 50 parts of asphalt, 40 - 50 parts of cement, 10 - 15 parts of natural sand, 8 - 12 parts of slag, 10 - 15 parts of silica fume composite aramid fiber pulp; the raw materials of the silica fume composite aramid fiber pulp include silica fume and aramid fiber pulp.

2. The anti-cracking asphalt concrete according to claim 1, wherein The mass ratio of the silica fume to the aramid fiber pulp is 2 - 4:

1.

3. An anti-cracking asphalt concrete according to claim 1, wherein The particle size of the silica fume is less than 1250 mesh.

4. An anti-cracking asphalt concrete according to claim 2, characterized in that, The silica fume composite aramid fiber pulp further comprises polyvinyl acetate.

5. An anti-cracking asphalt concrete according to claim 4, characterized in that, The mass ratio of the polyvinyl acetate to the aramid fiber pulp is 1 - 5:

24.

6. The anti-cracking asphalt concrete according to claim 5, characterized in that, The weight-average molecular weight of the polyvinyl acetate is 200,000 - 400,000.

7. An anti-cracking asphalt concrete according to claim 6, characterized in that, The preparation method of the silica fume composite aramid fiber pulp comprises the following steps: adding silica fume and aramid fiber pulp into a solvent, then adding polyvinyl acetate and mixing, and obtaining the silica fume composite aramid fiber pulp after drying.

8. An anti-cracking asphalt concrete according to claim 7, characterized in that, The solvent includes one or more of ethanol, acetone, and toluene.

9. An anti-cracking asphalt concrete according to claim 1, characterized in that, The natural sand includes one or both of river sand and sea sand.

10. A preparation method of crack-resistant asphalt concrete for preparing the crack-resistant asphalt concrete according to any one of claims 1 to 9, characterized in that, Comprising the following steps: S1. Weigh the raw materials according to the components by weight. S2. Heat the asphalt to 160 - 180 °C and then add the remaining other components for mixing to obtain crack-resistant asphalt concrete.

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