Phosphogypsum whisker composite modified asphalt and preparation method thereof

Abstract

The invention relates to the technical field of asphalt modification, and discloses ardealite whisker composite modified asphalt and a preparation method thereof. The ardealite whiskers subjected to surface treatment are used as a base material and can enhance the high-temperature performance and structural stability of the base asphalt when being uniformly dispersed into the asphalt; the plasticizer can promote the uniform dispersion of the ardealite whiskers in the asphalt and reduce the adverse effect of the ardealite whiskers on the low-temperature performance of the asphalt due to the characteristics of powder materials; the dispersing agent can further enhance the dispersion uniformity of the ardealite whiskers under the synergistic effect of the plasticizer and promote the ardealite whiskers to form a cross-linked structure in the asphalt, so that the reinforcing effect on the asphalt is achieved; the stabilizer can enhance the storage stability of the modified asphalt, and the storage stability of the modified asphalt is enhanced by doping the stabilizer; the matrix asphalt is used as a main body material of the modified asphalt, and the service performance of the modified asphalt can be further enhanced through doping and synergistic effects of various modified materials, so that the modified asphalt can be better applied to asphalt pavements.

Description

Technical Field

[0001] The invention relates to the technical field of asphalt modification, and in particular to a phosphogypsum whisker composite modified asphalt and a preparation method thereof. Background Art

[0002] Asphalt pavement is a type of pavement widely used in road engineering. With the increasing traffic volume and vehicle load and the long-term effects of the external natural environment, asphalt pavement diseases such as rutting, cracking, looseness, and peeling have gradually appeared. The base asphalt pavement can no longer meet the increasingly severe traffic environment. The research on asphalt pavement has gradually developed towards modified asphalt pavement. For the research on modified asphalt, researchers have achieved rich research results, such as SBS modified asphalt, SBR modified asphalt, fiber modified asphalt and various compound modified asphalt, which have significantly improved the performance of a certain aspect of the base asphalt to a certain extent. However, the modification cost of most modified asphalts such as SBS modified asphalt is relatively high, especially the price of SBS modifier is very expensive. Although it can significantly improve the service performance of asphalt pavement, it is difficult to achieve better economic benefits. At present, with the continuous development of society, resources are gradually in short supply. Therefore, it is particularly important to explore a new type of modifier with better modification effect and lower economic cost, so as to improve the service performance of asphalt pavement while reducing its economic cost. This can not only meet the use requirements of asphalt pavement, but also meet the requirements of high-quality development of social economy.

[0003] In recent years, researchers have gradually begun to pay attention to the application of solid waste in asphalt pavement. By mixing solid waste with asphalt, waste resources can be effectively utilized, the consumption of new resources can be reduced, the pressure on the environment caused by the accumulation of solid waste can be reduced, and the cost of building and maintaining roads can be reduced. In addition, solid waste can significantly improve the service performance of asphalt and asphalt mixtures due to its unique physical and chemical properties. When used as a modified material for asphalt pavement, it can effectively reduce the cost of modified asphalt, which has significant economic and environmental benefits. The resource utilization of solid waste in asphalt can not only effectively reduce the waste of resources, but also improve the service performance of asphalt and asphalt mixtures, which has huge economic and environmental benefits. As a product of secondary refining of phosphogypsum, phosphogypsum whiskers have the advantages of high temperature resistance, high strength, good toughness, low price, and low toxicity. However, they are currently mainly used as reinforcing agents for materials such as papermaking and resins, and their application prospects have not received significant attention. Asphalt pavement projects are huge in size, and a large amount of asphalt materials will be consumed in construction, repair and maintenance. The application of phosphogypsum whiskers in asphalt modification materials can not only reduce the construction cost of modified asphalt, but also reduce the use of expensive modifiers. In addition, as a toxic solid waste, the accumulation of phosphogypsum will not only waste land resources, but also pollute water sources and soil, and have a serious impact on the ecosystem. Promoting the application of phosphogypsum whiskers in asphalt pavement can further accelerate the transformation of phosphogypsum, and then promote the resource utilization of solid waste, which is conducive to improving economic and environmental benefits. Summary of the invention

[0004] In view of the technical problems in the prior art, the purpose of the present invention is to provide a composite modified asphalt of phosphogypsum whiskers, which solves the problems of poor conversion utilization rate of phosphogypsum and high cost of modified asphalt, and effectively reduces environmental pollution and saves land resources. That is, the composite modified asphalt of phosphogypsum whiskers in the present invention can provide a sustainable utilization method for the conversion and utilization of solid wastes such as phosphogypsum, and makes the modified asphalt have excellent construction and workability and storage stability, good permeability and excellent modification effect. At the same time, the present invention provides a preparation method thereof.

[0005] To achieve the above purpose, the technical solution provided by the present invention is:

[0006] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0007] PSW 6-15 parts, plasticizer 1-10 parts, dispersant 1-10 parts, stabilizer 0.1-1 parts and base asphalt 200-250 parts.

[0008] The present invention provides a phosphogypsum whisker composite modified asphalt. Compared with the modified asphalt in the prior art, the various modified materials have good compatibility with the base asphalt, have excellent construction and workability and storage stability, good permeability and excellent modification effect. In addition, the main material used in the modified asphalt prepared in the present invention is PSW, which can enhance the service performance of the modified asphalt and provide a sustainable utilization method for the value-added application of solid waste in asphalt pavement. The softening point difference of this modified asphalt under the separation test is much lower than 2.5°C, indicating that it has excellent storage stability; it has a lower rotational viscosity at 135°C, indicating that it has excellent construction and workability; although its needle penetration at 25°C is slightly lower than that of the base asphalt, the difference is low, indicating that the synergistic effect of multiple modified materials effectively weakens the influence of PSW on the low-temperature permeability grade of asphalt; its ductility value at 15°C is significantly higher than that of the base asphalt, indicating that the synergistic effect of other modified materials effectively promotes the uniform dispersion of PSW inside the asphalt, and the modified asphalt has excellent low-temperature ductility. Therefore, the modified asphalt of the present invention has good compatibility with the base asphalt, excellent construction workability and storage stability, good permeability and excellent modification effect.

[0009] During the preparation process, the surface of the phosphogypsum whisker needs to be organically treated by surface modification technology to improve its compatibility with asphalt; then the four materials of PSW, plasticizer, dispersant and stabilizer are mixed with the matrix asphalt in proportion to prepare phosphogypsum whisker composite modified asphalt. The modifier for modified asphalt can ensure that PSW is evenly dispersed in the modified asphalt and has good storage stability through the synergistic effect of the four materials; in addition, the uniform dispersion of PSW inside the asphalt can form a certain network structure to enhance the structural stability of the modified asphalt, and the reinforcement effect and heat resistance of PSW can enhance the stiffness and high temperature performance of the modified asphalt. More importantly, the synergistic effect of other modified materials effectively alleviates the adverse effects of PSW as a powder material on the low temperature performance of modified asphalt.

[0010] Specifically, the PSW, as a base material of modified asphalt, has the advantages of high temperature resistance, high strength and good toughness, and can enhance the high temperature performance and structural stability of the base asphalt when uniformly dispersed in the asphalt; the plasticizer can promote the uniform dispersion of phosphogypsum whiskers in the asphalt, reduce the adverse effects of the phosphogypsum whiskers on the low temperature performance of the asphalt due to the characteristics of the powder material, and supplement some lightweight components absorbed by the phosphogypsum whiskers in the asphalt; the dispersant can further enhance the dispersion uniformity of the phosphogypsum whiskers under the synergistic effect of the plasticizer, reduce the possibility of agglomeration of the phosphogypsum whiskers in the asphalt, and promote the phosphogypsum whiskers to form a cross-linked structure in the asphalt, thereby reinforcing the asphalt; the stabilizer can enhance the storage stability of the modified asphalt, and the phosphogypsum whiskers are compatible with the asphalt through surface modification, but are very likely to be segregated during storage or transportation, so the storage stability of the modified asphalt is enhanced by adding a stabilizer; the base asphalt is the main material of the modified asphalt, and the incorporation and synergistic effect of multiple modified materials can further enhance its service performance, so that it can be better applied to asphalt pavement.

[0011] On the basis of the above technical scheme, the PSW is a surface-modified phosphogypsum whisker, wherein the surface modification process is to dissolve 5% of a silane coupling agent into an aqueous solution with a mass ratio of anhydrous ethanol to water of 9:1 by an organic coating method, and then the aqueous solution and phosphogypsum are mixed in a mass ratio of 9:1 to form a suspension, and then an ultrasonic vibrator is used to perform ultrasonic vibration modification on the suspension. The modification time is 60 minutes, and the modification temperature is 50°C. Finally, the filtered modified solution is dried in an oven at 50°C for 24 hours, and then the dried solid is crushed with a ball mill and passed through a sieve with a diameter of 25 μm. The final material is PSW. The density of PSW is 2.69 mg / cm 3 , with a diameter of 25 μm, a melting point of 1450°C, and a Mohs hardness of 4. The PSW is a base material for modified asphalt, has the advantages of high temperature resistance, high strength and good toughness, and can enhance the high temperature performance and structural stability of the base asphalt when evenly dispersed inside the asphalt.

[0012] Based on the above technical solution, the plasticizer is one of dioctyl phthalate and dioctyl adipate or a mixture of the two. The plasticizer can promote the uniform dispersion of phosphogypsum whiskers in the asphalt, reduce the adverse effects of phosphogypsum whiskers on the low-temperature performance of asphalt due to the powder material characteristics, and supplement part of the light components absorbed by the phosphogypsum whiskers in the asphalt.

[0013] Based on the above technical solution, the dispersant is one or a mixture of alkylphenol polyoxyethylene ether and nonylphenol polyoxyethylene ether. Such dispersants are non-toxic and extremely inexpensive. Their mechanism of action is to further enhance the dispersion uniformity of phosphogypsum whiskers under the synergistic effect of plasticizers, reduce the possibility of agglomeration of phosphogypsum whiskers inside asphalt, and promote the formation of a cross-linked structure of phosphogypsum whiskers inside asphalt, thereby reinforcing the asphalt.

[0014] Based on the above technical solution, the stabilizer is one or a mixture of anhydrous calcium chloride and fatty alcohol polyoxyethylene ether. The stabilizer can enhance the storage stability of the modified asphalt and alleviate the segregation of the phosphogypsum whiskers inside the modified asphalt during storage or transportation. Therefore, the storage stability of the modified asphalt is enhanced by adding the stabilizer.

[0015] Based on the above technical solution, the matrix asphalt is one of No. 70 asphalt, No. 90 asphalt, No. 110 asphalt, or a mixture of two or more thereof.

[0016] The preparation method of the above-mentioned phosphogypsum whisker composite modified asphalt comprises the following steps:

[0017] Step 1, preparing premix A; weighing a certain mass of base asphalt, and then placing it in an oil bath pot at 157-167° C. for 25-35 minutes to obtain premix A;

[0018] Step 2, preparing mixture B; adding PSW, plasticizer, dispersant and stabilizer to premix A in sequence according to the formula, and adding in small amounts for multiple times, and then using a high-speed shearing machine to continuously shear the mixture at a speed of 4600-5200 rpm for 45-55 minutes to obtain mixture B;

[0019] Step three, preparing modified asphalt; placing mixture B in an oven at 150-170°C for development for 0.5-1.5h, and then manually stirring mixture B for 15-25min to expel the air mixed inside, thereby obtaining modified asphalt.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present invention provides a phosphogypsum whisker composite modified asphalt. Compared with the modified asphalt in the prior art, the various modified materials have better compatibility with the base asphalt, have excellent construction workability and storage stability, good permeability and excellent modification effect. Specifically, the PSW, as a base material of modified asphalt, has the advantages of high temperature resistance, high strength and good toughness, and can enhance the high temperature performance and structural stability of the base asphalt when uniformly dispersed in the asphalt; the plasticizer can promote the uniform dispersion of phosphogypsum whiskers in the asphalt, reduce the adverse effects of the phosphogypsum whiskers on the low temperature performance of the asphalt due to the characteristics of the powder material, and supplement some lightweight components absorbed by the phosphogypsum whiskers in the asphalt; the dispersant can further enhance the dispersion uniformity of the phosphogypsum whiskers under the synergistic effect of the plasticizer, reduce the possibility of agglomeration of the phosphogypsum whiskers in the asphalt, and promote the phosphogypsum whiskers to form a cross-linked structure in the asphalt, thereby reinforcing the asphalt; the stabilizer can enhance the storage stability of the modified asphalt, and the phosphogypsum whiskers are compatible with the asphalt through surface modification, but are very likely to be segregated during storage or transportation, so the storage stability of the modified asphalt is enhanced by adding a stabilizer; the base asphalt is the main material of the modified asphalt, and the incorporation and synergistic effect of multiple modified materials can further enhance its service performance, so that it can be better applied to asphalt pavement.

[0022] 2. At the same time, the present invention also provides a method for preparing the above-mentioned modified asphalt, which has a simple preparation process, convenient construction, and excellent practical performance. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is further described below in conjunction with the technical solution.

[0024] Example 1

[0025] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0026] PSW 13 parts, dioctyl phthalate 9 parts, alkylphenol polyoxyethylene ether 9 parts, anhydrous calcium chloride 0.4 parts, No. 70 asphalt 200 parts.

[0027] The above-mentioned preparation method applicable to the composite modified asphalt of phosphogypsum whiskers comprises the following steps:

[0028] Step 1, preparing premix A; weighing a certain mass of No. 70 asphalt into a beaker, and then placing it in an oil bath pot at 157° C. for 30 minutes to obtain premix A;

[0029] Step 2, preparing a mixture B; adding PSW, dioctyl phthalate, alkylphenol polyoxyethylene ether and anhydrous calcium chloride to the premix A in sequence according to the formula, and adding them in small amounts for multiple times, and then continuously shearing the mixture at a speed of 4900 rpm for 50 minutes using a high-speed shearing machine to obtain a mixture B;

[0030] Step three, preparing modified asphalt; placing mixture B in an oven at 150° C. for 1 hour, and then manually stirring mixture B for 20 minutes to expel the air mixed inside, thereby obtaining phosphogypsum whisker composite modified asphalt.

[0031] Example 2

[0032] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0033] PSW 9 parts, dioctyl adipate 10 parts, alkylphenol polyoxyethylene ether 4 parts, anhydrous calcium chloride 0.7 parts, No. 70 asphalt 225 parts.

[0034] The preparation method of the above-mentioned phosphogypsum whisker composite modified asphalt comprises the following steps:

[0035] Step 1, preparing premix A; weighing a certain mass of No. 70 asphalt into a beaker, and then placing it in an oil bath at 162° C. for 25 minutes to obtain premix A;

[0036] Step 2, preparing a mixture B; adding PSW, dioctyl adipate, alkylphenol polyoxyethylene ether and anhydrous calcium chloride to the premix A in order according to the formula, and adding them in small amounts for multiple times, and then using a high-speed shearing machine to continuously shear the mixture at a speed of 4600 rpm for 55 minutes to obtain a mixture B;

[0037] Step three, preparing modified asphalt; placing mixture B in an oven at 160° C. for 1 hour, and then manually stirring mixture B for 25 minutes to expel the air mixed inside, thereby obtaining phosphogypsum whisker composite modified asphalt.

[0038] Example 3

[0039] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0040] PSW 10 parts, dioctyl phthalate 2 parts, nonylphenol polyoxyethylene ether 10 parts, anhydrous calcium chloride 0.8 parts, No. 70 asphalt 250 parts.

[0041] The preparation method of the above-mentioned phosphogypsum whisker composite modified asphalt comprises the following steps:

[0042] Step 1, preparing premix A; weighing a certain mass of No. 70 asphalt into a beaker, and then placing it in an oil bath pot at 167° C. for 35 minutes to obtain premix A;

[0043] Step 2, preparing a mixture B; adding PSW, dioctyl phthalate, nonylphenol polyoxyethylene ether and anhydrous calcium chloride to the premix A in sequence according to the formula, and adding them in small amounts for multiple times, and then continuously shearing the mixture at a speed of 5200 rpm for 50 minutes using a high-speed shearing machine to obtain a mixture B;

[0044] Step three, preparing modified asphalt; placing mixture B in an oven at 160° C. for 1.5 hours, and then manually stirring mixture B for 25 minutes to expel the air mixed inside, thereby obtaining phosphogypsum whisker composite modified asphalt.

[0045] Example 4

[0046] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0047] PSW 8 parts, dioctyl phthalate 5 parts, alkylphenol polyoxyethylene ether 8 parts, fatty alcohol polyoxyethylene ether 0.1 parts, No. 90 asphalt 200 parts.

[0048] The preparation method of the above-mentioned phosphogypsum whisker composite modified asphalt comprises the following steps:

[0049] Step 1, preparing premix A; weighing a certain mass of No. 90 asphalt into a beaker, and then placing it in an oil bath at 162° C. for 35 minutes to obtain premix A;

[0050] Step 2, preparing a mixture B; adding PSW, dioctyl phthalate, alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether to the premix A in sequence according to the formula, and adding them in small amounts for multiple times, and then continuously shearing the mixture at a speed of 4900 rpm for 45 minutes using a high-speed shearing machine to obtain a mixture B;

[0051] Step three, preparing modified asphalt; placing mixture B in an oven at 150° C. for 1 hour, and then manually stirring mixture B for 25 minutes to expel the air mixed inside, thereby obtaining phosphogypsum whisker composite modified asphalt.

[0052] Example 5

[0053] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0054] PSW 6 parts, dioctyl adipate 7 parts, nonylphenol polyoxyethylene ether 6 parts, fatty alcohol polyoxyethylene ether 1 part, No. 90 asphalt 250 parts.

[0055] The preparation method of the above-mentioned phosphogypsum whisker composite modified asphalt comprises the following steps:

[0056] Step 1, preparing premix A; weighing a certain mass of No. 90 asphalt into a beaker, and then placing it in an oil bath at 162° C. for 30 minutes to obtain premix A;

[0057] Step 2, preparing a mixture B; adding PSW, dioctyl adipate, nonylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether to the premix A in sequence according to the formula, and adding in small amounts for multiple times, and then continuously shearing the mixture at a speed of 4600 rpm for 55 minutes using a high-speed shearing machine to obtain a mixture B;

[0058] Step three, preparing modified asphalt; placing mixture B in an oven at 170° C. for 1.5 hours, and then manually stirring mixture B for 25 minutes to expel the air mixed inside, thereby obtaining phosphogypsum whisker composite modified asphalt.

[0059] Example 6

[0060] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0061] PSW 11 parts, dioctyl adipate 8 parts, nonylphenol polyoxyethylene ether 1 part, anhydrous calcium chloride 0.2 parts, No. 90 asphalt 225 parts.

[0062] The method for preparing the composite modified asphalt of phosphogypsum whiskers comprises the following steps:

[0063] Step 1, preparing premix A; weighing a certain mass of No. 90 asphalt into a beaker, and then placing it in an oil bath pot at 167° C. for 25 minutes to obtain premix A;

[0064] Step 2, preparing a mixture B; adding PSW, dioctyl adipate, nonylphenol polyoxyethylene ether and anhydrous calcium chloride to the premix A in sequence according to the formula, and adding them in small amounts for multiple times, and then continuously shearing the mixture at a speed of 4600 rpm for 55 minutes using a high-speed shearing machine to obtain a mixture B;

[0065] Step three, preparing modified asphalt; placing mixture B in an oven at 160° C. for development for 0.5 h, and then manually stirring mixture B for 25 min to expel the air mixed inside, thereby obtaining phosphogypsum whisker composite modified asphalt.

[0066] Example 7

[0067] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0068] PSW 15 parts, dioctyl phthalate 6 parts, nonylphenol polyoxyethylene ether 7 parts, fatty alcohol polyoxyethylene ether 0.6 parts, No. 110 asphalt 200 parts.

[0069] The preparation method of the above-mentioned phosphogypsum whisker composite modified asphalt comprises the following steps:

[0070] Step 1, preparing premix A; weighing a certain mass of No. 110 asphalt into a beaker, and then placing it in an oil bath at 167° C. for 35 minutes to obtain premix A;

[0071] Step 2, preparing a mixture B; adding PSW, dioctyl phthalate, nonylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether to the premix A in sequence according to the formula, and adding in small amounts for multiple times, and then continuously shearing the mixture at a speed of 4900 rpm for 50 minutes using a high-speed shearing machine to obtain a mixture B;

[0072] Step three, preparing modified asphalt; placing mixture B in an oven at 170° C. for 1 hour, and then manually stirring mixture B for 25 minutes to expel the air mixed inside, thereby obtaining phosphogypsum whisker composite modified asphalt.

[0073] Example 8

[0074] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0075] PSW 14 parts, dioctyl phthalate 4 parts, alkylphenol polyoxyethylene ether 2 parts, fatty alcohol polyoxyethylene ether 0.9 parts, No. 110 asphalt 225 parts.

[0076] The preparation method of the above-mentioned phosphogypsum whisker composite modified asphalt comprises the following steps:

[0077] Step 1, preparing premix A; weighing a certain mass of No. 110 asphalt into a beaker, and then placing it in an oil bath pot at 157° C. for 35 minutes to obtain premix A;

[0078] Step 2, preparing a mixture B; adding PSW, dioctyl phthalate, alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether to the premix A in order according to the formula, and adding them in small amounts for multiple times, and then using a high-speed shearing machine to continuously shear the mixture at a speed of 5200 rpm for 55 minutes to obtain a mixture B;

[0079] Step three, preparing modified asphalt; placing mixture B in an oven at 150° C. for development for 0.5 h, and then manually stirring mixture B for 25 min to expel the air mixed inside, thereby obtaining phosphogypsum whisker composite modified asphalt.

[0080] Example 9

[0081] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0082] PSW 7 parts, dioctyl adipate 3 parts, alkylphenol polyoxyethylene ether 3 parts, anhydrous calcium chloride 0.5 parts, No. 110 asphalt 250 parts.

[0083] The above-mentioned preparation method applicable to the composite modified asphalt of phosphogypsum whiskers comprises the following steps:

[0084] Step 1, preparing premix A; weighing a certain mass of No. 110 asphalt into a beaker, and then placing it in an oil bath pot at 162° C. for 25 minutes to obtain premix A;

[0085] Step 2, preparing a mixture B; adding PSW, dioctyl adipate, alkylphenol polyoxyethylene ether and anhydrous calcium chloride to the premix A in order according to the formula, and adding them in small amounts for multiple times, and then continuously shearing the mixture at a speed of 4900 rpm for 55 minutes using a high-speed shearing machine to obtain a mixture B;

[0086] Step three, preparing modified asphalt; placing mixture B in an oven at 160° C. for 1.5 hours, and then manually stirring mixture B for 15 minutes to expel the air mixed inside, thereby obtaining phosphogypsum whisker composite modified asphalt.

[0087] Example 10

[0088] A phosphogypsum whisker composite modified asphalt, comprising the following components in weight fractions:

[0089] PSW 12 parts, dioctyl adipate 1 part, alkylphenol polyoxyethylene ether 5 parts, anhydrous calcium chloride 0.3 parts, No. 90 asphalt 250 parts.

[0090] The preparation method of the above-mentioned phosphogypsum whisker composite modified asphalt comprises the following steps:

[0091] Step 1, preparing premix A; weighing a certain mass of No. 90 asphalt into a beaker, and then placing it in an oil bath at 162° C. for 25 minutes to obtain premix A;

[0092] Step 2, preparing a mixture B; adding PSW, dioctyl adipate, alkylphenol polyoxyethylene ether and anhydrous calcium chloride to the premix A in sequence according to the formula, and adding them in small amounts for multiple times, and then continuously shearing the mixture at a speed of 4600 rpm for 45 minutes using a high-speed shearing machine to obtain a mixture B;

[0093] Step three, preparing modified asphalt; placing mixture B in an oven at 170° C. for 1 hour, and then manually stirring mixture B for 25 minutes to expel the air mixed inside, thereby obtaining phosphogypsum whisker composite modified asphalt.

[0094] Comparative Example 1

[0095] Compared with Example 1, Comparative Example 1 did not add a plasticizer, and the remaining components and preparation methods were the same;

[0096] Comparative Example 2

[0097] Comparative Example 2 Compared with Example 2, no dispersant was added, and the remaining components and preparation methods were the same;

[0098] Comparative Example 3

[0099] Compared with Example 3, Comparative Example 3 did not add a stabilizer, and the remaining components and preparation methods were the same.

[0100] Experimental results and performance analysis

[0101] According to the "Highway Engineering Asphalt and Asphalt Mixture Test Procedure" JTG E20-2011, the samples of Examples 1-10 and Comparative Examples 1-3 were subjected to needle penetration, softening point and ductility tests to test the effects of several modified materials on asphalt. In addition, in order to characterize the construction and storage stability of the modified asphalt, several asphalts were subjected to 135°C rotation viscosity test and segregation test to test their viscosity and segregation values. The test results are shown in Tables 1 and 2.

[0102] Table 1 Penetration, softening point and ductility test results of modified asphalt

[0103] sample Needle penetration / 0.1mm Softening point / ℃ 15℃ elongation / cm Example 1 72 49.1 49.5 Example 2 86 47.6 74.8 Example 3 62 47.8 57.2 Example 4 93 46.5 88.4 Example 5 118 45.4 77.6 Example 6 139 44.9 78.3 Example 7 99 46.3 88.4 Example 8 94 45.8 83.1 Example 9 112 44.7 99.8 Example 10 85 48.3 40.1 Comparative Example 1 55 48.5 32.9 Comparative Example 2 80 46.8 68.7 Comparative Example 3 61 47.6 55.3

[0104] A comparative analysis of the penetration of Examples 1-10 and Comparative Examples 1-3 revealed that: the penetration range of the prepared modified asphalt is 5.5-139 mm, and the penetration of Examples 1-3 of the present invention is relatively low, because not only No. 70 base asphalt with a smaller penetration grade is used, but also 9-13 parts of PSW are added. PSW, as a powder material with a fine particle size, increases the viscosity of asphalt after mixing with asphalt, thereby reducing the penetration of asphalt. Therefore, the two substances together make the penetration of the modified asphalt present a relatively low state; the penetration of Comparative Example 1 is the lowest, because no plasticizer is added compared with Example 1; the plasticizer can promote the uniform dispersion of phosphogypsum whiskers in the asphalt, reduce the adverse effects of phosphogypsum whiskers on the low-temperature performance of asphalt due to the powder material characteristics, and supplement some lightweight components absorbed by the phosphogypsum whiskers in the asphalt, so Comparative Example 1 lacking a plasticizer exhibits the lowest penetration. The penetrations of the remaining embodiments and comparative examples are all within a reasonable range, indicating that under the combined action of base asphalt, PSW, plasticizer, dispersant and stabilizer, the modified asphalt has a higher penetration, better fluidity and low-temperature crack resistance. On the premise of ensuring the effect of the modification, a sample with a relatively high penetration can be selected to improve the low-temperature performance of the modified asphalt.

[0105] A comparative analysis of the softening points of Examples 1-10 and Comparative Examples 1-3 shows that the softening point range of the prepared modified asphalt is 44.7-49.1°C. The softening point of Examples 7-9 of the present invention is relatively low. This is because they use No. 110 base asphalt with a higher penetration grade. Too high a penetration grade means that the softening degree of the base asphalt is also relatively high. Although Examples 7-9 incorporate a higher amount of PSW, the weight fraction of the base asphalt is much higher than that of other modified materials. Therefore, the modified asphalt exhibits a lower softening point, which also means that a higher penetration grade is difficult to have The high temperature performance of asphalt can be effectively guaranteed; the softening point of Comparative Example 2 is also significantly lower than that of Example 2, because no dispersant is added compared with Example 2; the dispersant can further enhance the dispersion uniformity of the phosphogypsum whiskers under the synergistic effect of the plasticizer, reduce the possibility of agglomeration of the phosphogypsum whiskers inside the asphalt, and promote the formation of a cross-linked structure of the phosphogypsum whiskers inside the asphalt, thereby reinforcing the asphalt. Therefore, the dispersion uniformity of the PSW inside the modified asphalt lacking a dispersant is difficult to be effectively guaranteed, and the structural stability of the modified asphalt is relatively weak. Therefore, Comparative Example 2 shows a lower softening point.

[0106] A comparative analysis of the ductility of Examples 1-10 and Comparative Examples 1-3 revealed that the ductility of the prepared modified asphalt ranges from 32.9 to 99.8 cm, and Examples 1-3 of the present invention have a lower ductility. This is because they not only use No. 70 base asphalt with a smaller penetration grade, but also add 9-13 parts of PSW. PSW, as a powdery material with a fine particle size, increases the viscosity of asphalt after mixing with asphalt, and easily causes stress concentration inside the asphalt. Therefore, the two substances together make the ductility of the modified asphalt present a lower state; in addition, Comparative Example 1 has the lowest ductility, because no plasticizer is added compared with Example 1; the plasticizer can promote the uniform dispersion of phosphogypsum whiskers in the asphalt, and supplement some of the lightweight components absorbed by the phosphogypsum whiskers in the asphalt. Therefore, Comparative Example 1 lacking a plasticizer exhibits the lowest ductility. In particular, although compared with Example 3, Comparative Example 3 lacks the addition of stabilizer, considering that the mechanism of action of the stabilizer is to enhance the storage stability of the modified asphalt and alleviate the segregation of the phosphogypsum whiskers inside the modified asphalt during storage or transportation, it will not have a significant impact on the basic physical properties of the modified asphalt. Therefore, compared with Example 3, the basic physical properties of Comparative Example 3 do not show significant differences.

[0107] Table 2 Test results of modified asphalt rotational viscosity and segregation value

[0108] sample Rotational viscosity / mPa·s Segregation value / ℃ Example 1 148 1.5 Example 2 167 0.5 Example 3 108 2.4 Example 4 93 0.6 Example 5 96 0.7 Example 6 120 0.4 Example 7 99 0.4 Example 8 151 1.1 Example 9 116 0.8 Example 10 125 1.8 Comparative Example 1 425 2.4 Comparative Example 2 231 1.6 Comparative Example 3 135 3.7

[0109] In order to characterize the construction and storage stability of the modified asphalt, the rotational viscosity and segregation value of the modified asphalt at 135°C were studied. A comparative analysis of the rotational viscosity and segregation values ​​of Examples 1-10 and Comparative Examples 1-3 showed that the rotational viscosity values ​​of Examples 1-10 and Comparative Examples 2-3 were significantly lower than 300 mPa·s. Although the rotational viscosity varied to a certain extent with the different ratios of the internal modification materials of the asphalt, the difference was not obvious. The rotational viscosity of Comparative Example 1 is significantly higher than that of other modified asphalts. This is because, compared with Example 1, Comparative Example 1 lacks plasticizers and contains a large amount of PSW. As a powdery material with a fine particle size, PSW will increase the viscosity of asphalt and absorb some light components inside the asphalt after mixing with asphalt, thereby causing the increase of the rotational viscosity of asphalt. The plasticizer can promote the uniform dispersion of phosphogypsum whiskers inside the asphalt and supplement some light components absorbed by the phosphogypsum whiskers inside the asphalt. Therefore, under the combined effect of these two factors, the rotational viscosity of Comparative Example 1 is significantly higher than that of other modified asphalts, which also means that the lack of plasticizer will lead to the attenuation of the construction and workability of the modified asphalt. In addition, Comparative Example 2 removes the dispersant on the basis of Example 2, and its rotational viscosity and segregation value show a certain increase. This is because the main function of the dispersant is to promote the uniform dispersion of PSW and reduce the stress concentration caused by its agglomeration. Therefore, the lack of dispersant leads to a decrease in the uniformity of the dispersion of PSW inside the asphalt, and the structural stability of the modified asphalt is reduced, which ultimately causes a decrease in construction and workability and storage stability. Compared with Example 3, no stabilizer was added to Comparative Example 3. It can be found that the rotational viscosity of Comparative Example 3 did not show a significant change, while the segregation value increased significantly. This is because the main function of the stabilizer is to improve the storage stability of the modified asphalt and reduce the possibility of its segregation, and its influence on construction and workability is relatively low. Therefore, Comparative Example 3 only shows a significant change in storage stability.

[0110] According to the performance test results of the above embodiments and comparative examples, the phosphogypsum whisker composite modified asphalt provided by the present invention has excellent construction workability and storage stability, good permeability and excellent modification effect. The modified asphalt has good high temperature performance and ductility, and exhibits excellent construction workability and storage stability. It can be seen that PSW, as the base material of modified asphalt, has the advantages of high temperature resistance, high strength and good toughness. When it is evenly dispersed in the asphalt, it can enhance the high temperature performance and structural stability of the base asphalt; plasticizers can promote the uniform dispersion of phosphogypsum whiskers in the asphalt, reduce the adverse effects of phosphogypsum whiskers on the low temperature performance of asphalt due to the characteristics of powder materials, and supplement some lightweight components absorbed by phosphogypsum whiskers in the asphalt; dispersants can further enhance the dispersion uniformity of phosphogypsum whiskers under the synergistic effect of plasticizers, reduce the possibility of agglomeration of phosphogypsum whiskers in the asphalt, and promote the formation of cross-linked structures of phosphogypsum whiskers in the asphalt, thereby reinforcing the asphalt; stabilizers can enhance the storage stability of modified asphalt and alleviate the segregation of phosphogypsum whiskers in the modified asphalt during storage or transportation; as the main material of modified asphalt, the incorporation and synergistic effect of multiple modified materials can further enhance its service performance, so that it can be better applied to asphalt pavement.

[0111] When designing the phosphogypsum whisker composite modified asphalt, combined with the changing trends of multiple service performances of the modified asphalt, it was found that the formula of the phosphogypsum whisker composite modified asphalt needs to include four ingredients: PSW, plasticizer, dispersant and stabilizer: PSW accounts for about 6-15 parts, plasticizer accounts for about 1-10 parts, dispersant accounts for about 1-10 parts and stabilizer accounts for about 0.1-1 part. The four materials can play a synergistic role to ensure that the modified asphalt has a good modification effect while having excellent construction and workability and storage stability.

Claims

1. A phosphogypsum whisker composite modified asphalt, characterized in that: The phosphogypsum whisker composite modified asphalt comprises the following components in weight fractions: PSW 6-15 parts, plasticizer 1-10 parts, dispersant 1-10 parts, stabilizer 0.1-1 parts and base asphalt 200-250 parts.

2. The phosphogypsum whisker composite modified asphalt according to claim 1, characterized in that: The PSW is surface-modified phosphogypsum whiskers, wherein the surface modification process is to dissolve 5% of a silane coupling agent into an aqueous solution with a mass ratio of anhydrous ethanol to water of 9:1 through an organic coating method, and then mix the aqueous solution with phosphogypsum in a mass ratio of 9:1 to form a suspension, and then use an ultrasonic vibrator to perform ultrasonic vibration modification on the suspension; the modification time is 60 minutes, and the modification temperature is 50°C; finally, the filtered modified solution is dried in an oven at 50°C for 24 hours, and then the dried solid is crushed by a ball mill and passed through a sieve with a diameter of 25μm, and the final material obtained is PSW.

3. The phosphogypsum whisker composite modified asphalt according to claim 1, characterized in that: The plasticizer is one of dioctyl phthalate and dioctyl adipate or a mixture of the two.

4. The phosphogypsum whisker composite modified asphalt according to claim 1, characterized in that: The dispersant is one of alkylphenol polyoxyethylene ether and nonylphenol polyoxyethylene ether, or a mixture of the two.

5. The phosphogypsum whisker composite modified asphalt according to claim 1, characterized in that: The stabilizer is one of anhydrous calcium chloride and fatty alcohol polyoxyethylene ether or a mixture of the two.

6. The phosphogypsum whisker composite modified asphalt according to claim 1, characterized in that: The matrix asphalt is one of No. 70 asphalt, No. 90 asphalt, and No. 110 asphalt, or a mixture of two or more thereof.

7. The method for preparing the phosphogypsum whisker composite modified asphalt according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1, preparing premix A; weighing a certain mass of base asphalt, and then placing it in an oil bath pot at 157-167° C. for 25-35 minutes to obtain premix A; Step 2, preparing mixture B; adding PSW, plasticizer, dispersant and stabilizer to premix A in sequence according to the formula, and adding in small amounts for multiple times, and then using a high-speed shearing machine to continuously shear the mixture at a speed of 4600-5200 rpm for 45-55 minutes to obtain mixture B; Step 3, preparing modified asphalt; Place mixture B in an oven at 150-170°C for 0.5-1.5 hours, and then manually stir mixture B for 15-25 minutes to expel the air mixed inside, and the modified asphalt can be obtained.