Super-durable self-repairing modified asphalt and preparation method thereof

Abstract

The invention relates to the technical field of asphalt, and particularly discloses super-durable self-repairing modified asphalt and a preparation method thereof. The super-durable self-repairing modified asphalt is prepared from the following raw materials in parts by weight: 50 to 70 parts of composite modified asphalt, 35 to 50 parts of acrylate emulsion, 8 to 14 parts of modified polyacrylonitrile fiber, 11 to 18 parts of filler, 12 to 21 parts of self-repairing microcapsule, 4 to 6 parts of thickening agent and 1 to 3 parts of anti-aging agent. The invention relates to a preparation method of super-durable self-repairing modified asphalt. The preparation method comprises the following steps: S1, melting composite modified asphalt at 120-130 DEG C; s2, then adding the acrylate emulsion, the modified polyacrylonitrile fiber, the filler and the self-repairing microcapsule, and mixing and stirring; s3, adding a thickening agent and an anti-aging agent, mixing and stirring, and cooling to room temperature, so as to obtain the super-durable self-repairing modified asphalt. The super-durable self-repairing modified asphalt prepared by the invention is remarkable in self-repairing effect and good in durability.

Description

Technical Field

[0001] The present application relates to the field of asphalt technology, and in particular to an ultra-durable self-healing modified asphalt and a preparation method thereof. Background Art

[0002] Modified asphalt is an asphalt binder made by adding rubber, resin, high molecular polymer, ground rubber powder or other fillers, or by taking measures such as mild oxidation of asphalt to improve the performance of asphalt or asphalt mixture. There are two mechanisms for modifying asphalt: one is to change the chemical composition of asphalt, and the other is to make the modifier evenly distributed in the asphalt to form a certain spatial network structure.

[0003] Asphalt pavement is prone to cracks due to the combined effects of climate, traffic environment, asphalt aging, etc., which not only destroys the continuity and flatness of the pavement, but also causes water to seep into the roadbed and erode, thus affecting the service life of the pavement. Cracks are the most common type of asphalt pavement disease at home and abroad. The current common treatment measure is still milling and resurfacing, which not only consumes a lot of resources, but also seriously affects the road's traffic capacity and traffic safety.

[0004] In order to deal with the common crack problem of asphalt pavement, the current research trend is to add self-healing microcapsules to asphalt mixtures. When microcracks appear on the pavement, the capsule wall of the microcapsule ruptures and releases the repair material in the capsule core, thereby delaying further damage to the pavement. However, due to the uneven dispersion of microcapsules in the mixture and the difficulty in controlling the release rate of the repair material, the actual effect of this method is not satisfactory. Summary of the invention

[0005] In order to solve at least one of the above technical problems, the present application provides an ultra-durable self-healing modified asphalt and a preparation method thereof.

[0006] On the one hand, the present application provides an ultra-durable self-healing modified asphalt, comprising the following raw materials in parts by weight: 50-70 parts of composite modified asphalt, 35-50 parts of acrylic emulsion, 8-14 parts of modified polyacrylonitrile fiber, 11-18 parts of filler, 12-21 parts of self-healing microcapsules, 4-6 parts of thickener, and 1-3 parts of antioxidant.

[0007] By adopting the above technical scheme, this application improves the durability of asphalt through a carefully designed raw material ratio, and realizes the self-repair efficiency of asphalt after cracking. The composite modified asphalt, as the matrix of the modified asphalt raw material, can improve the low-temperature brittleness and high-temperature fluidity of asphalt, so that it can maintain good elasticity and toughness in a wider temperature range, and improve its durability; the addition of modified polyacrylonitrile fiber can effectively reduce the plastic shrinkage and drying shrinkage of asphalt, thereby reducing the risk of cracking; the microcapsules containing the repair agent in the self-repairing microcapsules will rupture when cracks occur inside the asphalt, release the repair agent, automatically repair the asphalt microcracks, extend the structural life, and improve durability.

[0008] The preparation method of the composite modified asphalt comprises the following steps: A1. Heat the base asphalt at 150-160°C for 1-2h, then add SBS and polyurethane in sequence, and stir at 300-500rpm for 20-30min to obtain a mixture; A2. Subject the mixture obtained in step A1 to high-speed shearing at 150-160° C. for 45-55 minutes, add graphene oxide, and subject it to high-speed shearing at 150-160° C. for 30-40 minutes to obtain the composite modified asphalt.

[0009] By adopting the above technical solution, this application selects SBS, polyurethane and graphene oxide to carry out composite modification of the matrix asphalt, and heats the matrix asphalt to 150-160°C to reduce its viscosity, facilitate the subsequent addition of modifiers and ensure its uniform dispersion. SBS is an elastomer that can improve the elasticity and toughness of asphalt, especially at low temperatures; polyurethane can enhance the adhesion and wear resistance of asphalt; graphene oxide has an extremely high specific surface area and excellent mechanical properties, and its addition can form a network structure in the asphalt matrix, significantly improving the strength and toughness of asphalt.

[0010] Optionally, the weight ratio of the matrix asphalt, SBS, polyurethane and graphene oxide is 100:(10-15):(15-20):(1-5).

[0011] Optionally, the modified polyacrylonitrile fiber is benzyl alcohol modified polyacrylonitrile fiber.

[0012] Optionally, the method for preparing the self-repairing microcapsules comprises the following steps: B1, adding gum arabic to water, mixing, heating to dissolve, then adding montmorillonite, stirring and mixing, and ultrasonically dispersing for 15-20 minutes to obtain a mixture I; diphenylmethane diisocyanate and hexamethylene diisocyanate are stirred and mixed to obtain a mixture II; B2, mixing mixture I and mixture II and stirring for 40-45 minutes, and emulsifying to obtain an emulsion; B3. Add a 0.8% triethylenetetramine solution dropwise into the emulsion, heat and react for 1.5-2 hours, filter, wash, and dry at 45-50° C. for 10-12 hours to obtain the self-repairing microcapsules.

[0013] Through the above technical solution, the present application uses gum arabic and montmorillonite as capsule wall materials, diphenylmethane diisocyanate and hexamethylene diisocyanate as repair agents and core materials to prepare self-repairing microcapsules. When the asphalt is subjected to external forces to produce microcracks, the microcapsules located near the cracks rupture due to stress concentration, releasing the isocyanate repair agent inside. The released isocyanate repair agent comes into contact with the water in the asphalt or the moisture in the air, undergoes a polymerization reaction, and generates high molecular substances such as polyurethane to fill the cracks. The self-repair of the asphalt structure is achieved, the crack resistance of the asphalt is improved, the life of the asphalt is increased, and the maintenance cost is reduced.

[0014] Optionally, in step B1, the weight ratio of gum arabic, water and montmorillonite is (2-4):100:(1-2), and the weight ratio of diphenylmethane diisocyanate and hexamethylene diisocyanate is 1:(4-5).

[0015] Optionally, in step B3, the volume ratio of the triethylenetetramine solution to the emulsion is 1:2.

[0016] Optionally, the weight ratio of the modified polyacrylonitrile fiber to the self-healing microcapsule is 1:(1-1.8).

[0017] Optionally, the weight ratio of the modified polyacrylonitrile fiber to the self-healing microcapsule is 1:1.5.

[0018] Optionally, the sum of the weights of the modified polyacrylonitrile fibers and the self-healing microcapsules accounts for 17.0-22.3% of the total weight of the ultra-durable self-healing modified asphalt raw material.

[0019] By adopting the above-mentioned technical scheme, the present application limits the weight ratio of modified polyacrylonitrile fiber and self-healing microcapsules and the sum of their weights in the asphalt raw material, ensuring that the asphalt has good self-healing ability and avoiding the problem that too little fiber may not be enough to effectively inhibit crack propagation, and too much microcapsule may lead to increased costs and decreased mechanical properties.

[0020] Optionally, the filler comprises talc powder and heavy calcium carbonate in a weight ratio of 1:4-8.

[0021] In a second aspect, the present application provides a method for preparing the above-mentioned ultra-durable self-healing modified asphalt, comprising the following steps: S1. Melting the composite modified asphalt at 120-130°C; S2, adding acrylic emulsion, modified polyacrylonitrile fiber, filler and self-repairing microcapsule, mixing and stirring at 800-1000 rpm for 40-60 min; S3. Add thickener and antioxidant, mix and stir at 800-1000 rpm for 20-30 minutes, cool to room temperature, and obtain the ultra-durable self-healing modified asphalt.

[0022] By adopting the above technical scheme, the preparation method of the present application is simple, and the anti-cracking asphalt obtained has excellent performance and is suitable for popularization and application.

[0023] In summary, the present invention includes at least one of the following beneficial technical effects: 1. This application improves the durability of asphalt and realizes the self-repair efficiency of asphalt after cracking through a carefully designed raw material ratio. The composite modified asphalt, as the matrix of the modified asphalt raw material, can improve the low-temperature brittleness and high-temperature fluidity of asphalt, so that it can maintain good elasticity and toughness in a wider temperature range and improve its durability; the addition of modified polyacrylonitrile fiber can effectively reduce the plastic shrinkage and drying shrinkage of asphalt, thereby reducing the risk of cracking; the microcapsules containing the repair agent in the self-repairing microcapsules will rupture when cracks occur inside the asphalt, release the repair agent, automatically repair the microcracks in the asphalt, extend the life of the structure, and improve durability.

[0024] 2. This application limits the weight ratio of modified polyacrylonitrile fiber and self-healing microcapsules, as well as the weight and proportion of the two in the asphalt raw material, to ensure that the asphalt has good self-healing ability and avoid problems such as too little fiber may not be enough to effectively inhibit crack propagation, and too much microcapsule may lead to increased costs and decreased mechanical properties.

[0025] 3. The preparation method of the present application is simple, and the anti-cracking asphalt obtained has excellent performance and is suitable for popularization and application. DETAILED DESCRIPTION

[0026] The present application is further described in detail below with reference to the embodiments. Specific embodiments

[0027] Preparation Example 1 This preparation example provides a composite modified asphalt, and the preparation method includes the following steps: A1. Heat the base asphalt at 155°C for 1.5h, then add SBS and polyurethane in sequence, and stir at 400rpm for 25min to obtain a mixture; A2. The mixture obtained in step A1 is subjected to high-speed shearing treatment at 150-160° C. for 50 minutes, and then graphene oxide is added and high-speed shearing is carried out at 155° C. for 35 minutes to obtain the composite modified asphalt.

[0028] The weight ratio of matrix asphalt, SBS, polyurethane and graphene oxide is 100:12:18:3.

[0029] Preparation Example 2 This preparation example provides a self-repairing microcapsule, and the preparation method includes the following steps: B1, adding gum arabic to water, mixing, heating to dissolve, then adding montmorillonite, stirring and mixing, and ultrasonically dispersing for 20 minutes to obtain a mixture I; diphenylmethane diisocyanate and hexamethylene diisocyanate were stirred and mixed to obtain a mixture II; B2, mixing mixture I and mixture II and stirring for 45 minutes, and emulsifying to obtain an emulsion; B3. Add a 0.8% triethylenetetramine solution dropwise into the emulsion, heat and react for 2 hours, filter, wash, and dry at 50° C. for 12 hours to obtain the self-repairing microcapsules.

[0030] In step B1, the weight ratio of gum arabic, water and montmorillonite is 3:100:1.5, and the weight ratio of diphenylmethane diisocyanate and hexamethylene diisocyanate is 1:4.5; in step B3, the volume ratio of triethylenetetramine solution and emulsion is 1:2.

[0031] Example 1 The present embodiment provides an ultra-durable self-healing modified asphalt, comprising the following raw materials in parts by weight: 50 parts of composite modified asphalt, 35 parts of acrylic emulsion, 10 parts of modified polyacrylonitrile fiber, 11 parts of filler, 15 parts of self-healing microcapsules, 4 parts of thickener, and 1 part of antioxidant.

[0032] Among them, the composite modified asphalt is prepared by Preparation Example 1, the self-healing microcapsule is prepared by Preparation Example 2, the modified polyacrylonitrile fiber is benzyl alcohol modified polyacrylonitrile fiber, the filler is talcum powder and heavy calcium carbonate in a weight ratio of 1:6, the thickener is hydroxypropyl methylcellulose, and the antioxidant is antioxidant AW.

[0033] The preparation method of the ultra-durable self-healing modified asphalt in this embodiment comprises the following steps: S1. Melting the composite modified asphalt at 125°C; S2, adding acrylic emulsion, modified polyacrylonitrile fiber, filler and self-repairing microcapsule, mixing and stirring at 900 rpm for 50 min; S3. Add thickener and antioxidant, mix and stir at 900 rpm for 25 minutes, cool to room temperature, and obtain the ultra-durable self-healing modified asphalt.

[0034] Embodiment 2-4 Example 2 The difference between this embodiment and embodiment 1 is that when preparing the ultra-durable self-healing modified asphalt, the total weight of the modified polyacrylonitrile fiber and the self-healing microcapsules is 25 parts, and the weight ratio of the modified polyacrylonitrile fiber to the self-healing microcapsules is 1:1.

[0035] Example 3 The difference between this embodiment and embodiment 1 is that when preparing the ultra-durable self-healing modified asphalt, the total weight of the modified polyacrylonitrile fiber and the self-healing microcapsules is 25 parts, and the weight ratio of the modified polyacrylonitrile fiber to the self-healing microcapsules is 1:1.2.

[0036] Example 4 The difference between this embodiment and embodiment 1 is that when preparing the ultra-durable self-healing modified asphalt, the total weight of the modified polyacrylonitrile fiber and the self-healing microcapsules is 25 parts, and the weight ratio of the modified polyacrylonitrile fiber to the self-healing microcapsules is 1:1.8.

[0037] Comparative Examples 1-3 Comparative Example 1 The difference between this comparative example and Example 1 is that no self-healing microcapsules were added when preparing the ultra-durable self-healing modified asphalt.

[0038] Comparative Example 2 The difference between this comparative example and Example 1 is that no modified polyacrylonitrile fiber is added when preparing the ultra-durable self-healing modified asphalt.

[0039] Comparative Example 3 The difference between this comparative example and Example 1 is that modified polyacrylonitrile fibers and self-healing microcapsules are not added when preparing the ultra-durable self-healing modified asphalt.

[0040] Experimental testing: Asphalt concrete test blocks were prepared using the self-repairing asphalt prepared in the examples and comparative examples of the present application in accordance with the relevant technical regulations in the Technical Specifications for Highway Asphalt Pavement Construction (JTG F40-2004).

[0041] Compressive strength test: According to GB / T 50081-2002, the compressive strength of asphalt concrete test blocks was tested, and the 28d compressive strength F of each test block was measured. 1 ; Crack resistance test: The crack resistance test of asphalt concrete test blocks was carried out in accordance with JGJ / T 193-2009; Self-repair ability test: The asphalt concrete test block was pre-compressed and damaged (the pre-compression value was 60% of the compressive strength), and then the compressive strength F of each test block after pre-compression damage was tested. 2 Then the damaged test block was steam oxidized at 50℃ and cured for 3 days. The compressive strength F of the asphalt concrete test block after 3 days of repair was tested. 3, calculate the compressive strength repair rate of each asphalt concrete specimen: W 1 (%)=(F 3 -F 2 ) / F 2 ×100% is used to characterize the self-healing ability of the super durable self-healing modified asphalt.

[0042] The experimental test results of Examples 1-4 and Comparative Examples 1-3 are shown in Table 1.

[0043] Table 1 Experimental test results of Examples 1-4 and Comparative Examples 1-3 Analysis of results: The difference between Examples 2-4 and Example 1 is that when preparing the super-durable self-healing modified asphalt, the total weight of the modified polyacrylonitrile fiber and the self-healing microcapsules is 25 parts, and the weight ratio of the modified polyacrylonitrile fiber and the self-healing microcapsules is different. Combined with the experimental test results in Table 1, it can be seen that when the weight ratio of the modified polyacrylonitrile fiber and the self-healing microcapsules is 1:1.5, the obtained super-durable self-healing modified asphalt has higher compressive strength, better crack resistance, and better self-healing ability. The difference between Comparative Example 1 and Example 1 is that when preparing the super-durable self-healing modified asphalt, no self-healing microcapsules are added. The difference between Comparative Example 2 and Example 1 is that when preparing the super-durable self-healing modified asphalt, no modified polyacrylonitrile fiber is added. The difference between Comparative Example 3 and Example 1 is that when preparing the super-durable self-healing modified asphalt, no modified polyacrylonitrile fiber and self-healing microcapsules are added. Combined with the experimental test results in Table 1, it can be seen that when preparing super-durable self-healing modified asphalt, the compound use of modified polyacrylonitrile fiber and self-healing microcapsule can better improve the comprehensive performance of the super-durable self-healing modified asphalt.

[0044] Embodiment 5-6 Example 5 The difference between Example 5-6 and Example 1 is that the weight fractions of some components are changed when preparing the ultra-durable self-healing modified asphalt. See Table 2 for the differences.

[0045] Table 2 Differences between Examples 5-6 and Example 3 Ingredients (parts by weight) Example 3 Example 5 Example 6 Composite modified asphalt 50 60 70 Acrylic Emulsion 35 40 50 filler 11 15 18 Modified polyacrylonitrile fiber 10 10 10 Self-healing microcapsules 15 15 15 Thickener 4 5 6 Antioxidant 1 2 3 The experimental test results of Examples 5-6 are shown in Table 3.

[0046] Table 3 Experimental test results of Examples 5-6 Example <![CDATA[F 1 (MPa)]]> Crack resistance grade <![CDATA[W 1 (%)]]> Example 1 85.5 LV 22.8 Example 5 87.0 LV 25.6 Example 6 85.9 LV 23.1 Result analysis: The difference between Example 5-6 and Example 1 is that when preparing the ultra-durable self-healing modified asphalt, the weight proportions of some components are different. Combined with the experimental test results in Table 3, it can be seen that when preparing the ultra-durable self-healing modified asphalt, the ultra-durable self-healing modified asphalt prepared in Example 5 has better comprehensive performance.

[0047] Embodiment 7-9 The difference between Example 7-9 and Example 5 is that when preparing the super durable self-healing modified asphalt, based on the premise that the weight ratio of modified polyacrylonitrile fiber and self-healing microcapsule is 1:1.5, the total weight of modified polyacrylonitrile fiber and self-healing microcapsule in the total weight of the super durable self-healing modified asphalt raw material is changed, and the optimal weight ratio is selected.

[0048] In Example 5, the total weight of the modified polyacrylonitrile fiber and the self-healing microcapsules is 25 parts, and the total weight of the ultra-durable self-healing modified asphalt raw material is 147 parts.

[0049] Therefore, it is not difficult to conclude that in Example 5, the modified polyacrylonitrile fiber (referred to as variable 1) and the self-healing microcapsules (referred to as variable 2) account for 17.0% of the total weight of the ultra-durable self-healing modified asphalt raw material (referred to as the matrix).

[0050] The differences between Examples 7-9 and Example 5 are shown in Table 4.

[0051] Proportion = (variable 1 + variable 2) / total weight of matrix * 100%.

[0052] Table 4 Differences between Examples 7-9 and Example 5 The experimental test results of Examples 7-9 are shown in Table 5.

[0053] Table 5 Experimental test results of Examples 7-9 Results analysis: The difference between Examples 7-9 and Example 5 is that when preparing the super-durable self-healing modified asphalt, when the modified polyacrylonitrile fiber (referred to as variable 1) and the self-healing microcapsule (referred to as variable 2) account for 17.0-22.3% of the total weight of the super-durable self-healing modified asphalt raw material (referred to as the matrix), the comprehensive performance of the obtained super-durable self-healing modified asphalt is better. When the modified polyacrylonitrile fiber (referred to as variable 1) and the self-healing microcapsule (referred to as variable 2) account for 19.7% of the super-durable self-healing modified asphalt (referred to as the matrix), the comprehensive performance of the obtained super-durable self-healing modified asphalt is better.

[0054] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A super durable self-repairing modified asphalt, characterized in that: The invention comprises the following raw materials in parts by weight: 50-70 parts of composite modified asphalt, 35-50 parts of acrylic ester emulsion, 8-14 parts of modified polyacrylonitrile fiber, 11-18 parts of filler, 12-21 parts of self-repairing microcapsule, 4-6 parts of thickener and 1-3 parts of antioxidant.

2. The ultra-durable self-healing modified asphalt according to claim 1, characterized in that: The preparation method of the composite modified asphalt comprises the following steps: A1. Heat the base asphalt at 150-160°C for 1-2h, then add SBS and polyurethane in sequence, and stir at 300-500rpm for 20-30min to obtain a mixture; A2. Subject the mixture obtained in step A1 to high-speed shearing at 150-160° C. for 45-55 minutes, add graphene oxide, and subject it to high-speed shearing at 150-160° C. for 30-40 minutes to obtain the composite modified asphalt.

3. The ultra-durable self-healing modified asphalt according to claim 2, characterized in that: The weight ratio of the matrix asphalt, SBS, polyurethane and graphene oxide is 100: (10-15): (15-20): (1-5).

4. The ultra-durable self-healing modified asphalt according to claim 1, characterized in that: The modified polyacrylonitrile fiber is benzyl alcohol modified polyacrylonitrile fiber.

5. The ultra-durable self-healing modified asphalt according to claim 1, characterized in that: The method for preparing the self-repairing microcapsules comprises the following steps: B1, adding gum arabic to water, mixing, heating to dissolve, then adding montmorillonite, stirring and mixing, and ultrasonically dispersing for 15-20 minutes to obtain a mixture I; diphenylmethane diisocyanate and hexamethylene diisocyanate are stirred and mixed to obtain a mixture II; B2, mixing mixture I and mixture II and stirring for 40-45 minutes, and emulsifying to obtain an emulsion; B3. Add a 0.8% triethylenetetramine solution dropwise into the emulsion, heat and react for 1.5-2 hours, filter, wash, and dry at 45-50° C. for 10-12 hours to obtain the self-healing microcapsules.

6. The ultra-durable self-healing modified asphalt according to claim 5, characterized in that: In the step B1, the weight ratio of gum arabic, water and montmorillonite is (2-4):100:(1-2), and the weight ratio of diphenylmethane diisocyanate and hexamethylene diisocyanate is 1:(4-5).

7. The ultra-durable self-healing modified asphalt according to claim 1, characterized in that: The weight ratio of the modified polyacrylonitrile fiber to the self-repairing microcapsule is 1:(1-1.8).

8. The ultra-durable self-healing modified asphalt according to claim 1, characterized in that: The total weight of the modified polyacrylonitrile fiber and the self-repairing microcapsules accounts for 17.0-22.3% of the total weight of the ultra-durable self-repairing modified asphalt raw material.

9. The ultra-durable self-healing modified asphalt according to claim 1, characterized in that: The filler comprises talc powder and heavy calcium carbonate in a weight ratio of 1:4-8.

10. A method for preparing the ultra-durable self-healing modified asphalt according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Melting the composite modified asphalt at 120-130°C; S2, adding acrylic emulsion, modified polyacrylonitrile fiber, filler and self-repairing microcapsule, mixing and stirring at 800-1000 rpm for 40-60 min; S3. Add thickener and antioxidant, mix and stir at 800-1000 rpm for 20-30 minutes, cool to room temperature, and obtain the ultra-durable self-healing modified asphalt.

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