A warm mix asphalt mixture and preparation method thereof

Abstract

The invention discloses a warm-mix asphalt mixture and a preparation method thereof. The asphalt mixture comprises, by weight, 5-7 parts of pretreated SBS asphalt, 25-30 parts of modified fine aggregate, 45-60 parts of modified coarse aggregate, 8-12 parts of filler, 1-2 parts of warm-mix agent, 2-4 parts of additive, and 0.02-0.05 parts of accelerator. The preparation method of the invention comprises the following steps: heating the pretreated SBS asphalt to 110-130°C, sequentially adding the warm-mix agent and the additive under stirring, stirring, shearing, adding the accelerator, and then adding the modified fine aggregate, the modified coarse aggregate, and the filler. The asphalt mixture of the invention has a low mixing temperature, and the aging resistance, structural strength, low-temperature performance, salt erosion resistance, and the like of the obtained asphalt mixture are significantly improved.

Description

Technical Field

[0001] The invention belongs to the field of polymer materials, relates to a preparation method of an asphalt material, and in particular to a warm mix asphalt mixture and a preparation method thereof. Background Art

[0002] Asphalt mixture is a general term for a mixture made by mixing mineral materials and asphalt binders. It is divided into continuous gradation and discontinuous gradation according to the material composition and structure. According to the different temperatures required for asphalt during mixing construction, it can be divided into cold mix asphalt mixture, warm mix asphalt mixture and hot mix asphalt mixture. SBS asphalt has excellent high-temperature rutting resistance, low-temperature cracking resistance, fatigue resistance and excellent elastic recovery ability, but the mixing temperature of SBS asphalt mixture is 175 ℃ ~ 185 ℃, which is a commonly used hot mix asphalt. During the mixing process, due to the high temperature, thermal aging will occur rapidly in a short time, which will have a great impact on the comprehensive performance of the asphalt mixture. In addition, the temperature of hot mix asphalt paving and compaction is usually not less than 140 ℃, which brings inconvenience to our practical application.

[0003] Therefore, in order to reduce the mixing temperature of SBS asphalt, lower the paving and compaction temperature, and simplify the operation, it is necessary to study the components and preparation methods of asphalt mixtures. Summary of the invention

[0004] The purpose of the present invention is to reduce the mixing temperature of SBS asphalt, reduce the paving and compacting temperature, and simplify the operation, and to study the components and preparation method of asphalt mixture.

[0005] The technical solution adopted by the present invention provides a warm-mix asphalt mixture, the key point being that, measured by weight, the above-mentioned asphalt mixture includes 5 to 7 parts of pretreated SBS asphalt, 25 to 30 parts of modified fine aggregate, 45 to 60 parts of modified coarse aggregate, 8 to 12 parts of filler, 1 to 2 parts of warm-mix agent, 2 to 4 parts of additives, and 0.02 to 0.05 parts of accelerator.

[0006] Specifically, the pretreatment process is to heat the SBS asphalt to a molten state, add butylene maleate and sulfur, and stir for 1 h to 3 h. The mass ratio of the SBS asphalt, butylene maleate and sulfur is 1:0.01-0.02:0.5-1.2.

[0007] Preferably, the raw materials of the above-mentioned modified coarse aggregate include any one or more combinations of basalt, granite, and diabase; the raw materials of the above-mentioned modified fine aggregate include any one or more combinations of natural sand, machine-made sand, and stone chips; the above-mentioned filler is slaked lime; and the above-mentioned accelerator is 2-(2,4-dinitrophenylthio)benzothiazole.

[0008] Specifically, the preparation method of the above-mentioned warm-mix agent is: add 5 parts of hydroxyethyl cellulose and 5 parts of artificial zeolite into water, heat to 80°C to 110°C, add 0.3 parts to 0.8 parts of lauric acid, continue stirring and heat to 100°C to 115°C, keep warm for 1 h to 2 h, filter and dry to obtain the warm-mix agent.

[0009] Preferably, the raw materials of the above-mentioned additives include 8 to 10 parts of rubber powder, 5 to 8 parts of acid-hydrolyzed starch, 0.2 to 0.4 parts of maleic anhydride, 0.05 to 0.1 parts of hydroquinone, 0.01 to 0.03 parts of ferrous sulfate, 0.5 to 1.0 parts of acrylic acid, 0.06 to 0.08 parts of hydrogen peroxide, 0.01 to 0.03 parts of vitamin C and 0.03 to 0.06 parts of mercaptopropionic acid, and 1 to 2 parts of 4-hydroxybutyl vinyl polyoxyethylene ether.

[0010] Furthermore, the preparation method of the above-mentioned additive is:

[0011] The rubber powder is dissolved in an organic solvent, mixed with acid-decomposed starch, and stirred at room temperature; maleic anhydride and hydroquinone are added, mixed, heated to 95°C to 105°C, and reacted for 2 h to 4 h to obtain a modified rubber powder mixture; ferrous sulfate and acrylic acid are added to 4-hydroxybutyl vinyl polyoxyethylene ether, hydrogen peroxide is added at room temperature, and after uniform stirring, the modified rubber powder mixture is added, vitamin C and mercaptopropionic acid are added, and the reaction is stirred for 1.5 h to 2.5 h; the pH value is adjusted to neutral, filtered, and dried to obtain the additive.

[0012] Furthermore, the modification process of the modified coarse aggregate and modified fine aggregate is to soak the coarse aggregate or fine aggregate in a Bian Ze reagent, ultrasonically treat it for 0.5 h to 1 h, take out the coarse aggregate or fine aggregate, add an aluminate coupling agent with a mass ratio of 0.05% to 0.5% of the coarse aggregate or fine aggregate, and dry mix it at 125 ℃ to 140 ℃ for 1 h to 2 h.

[0013] A method for preparing a warm-mix asphalt mixture is used to prepare the above-mentioned asphalt mixture. The key lies in: heating the pretreated SBS asphalt to 110°C to 130°C, adding a warm-mix agent and an additive in sequence under stirring, continuing stirring for 0.5 h to 1 h, and continuing to shear on a high-speed shearing machine for 1 h to 2 h after sufficient swelling, and then adding an accelerator under stirring, stirring for 0.5 h to 1 h while keeping warm, adding modified fine aggregate, modified coarse aggregate, and filler, and stirring for 0.5 h to 1 h.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention reduces the mixing temperature by adding a modified zeolite warm-mixing agent, and the warm-mixing agent used is a modified warm-mixing agent of artificial zeolite fiber particles. Zeolite has a large number of channels and holes distributed on the surface. The existence of the holes and channels enables the zeolite to absorb and retain moisture, and can be used as a warm-mixing agent to make asphalt foam continuously. The effect of artificial zeolite is not as good as that of natural zeolite, but the cost of natural zeolite is higher. The present invention puts artificial zeolite in a water-soluble cellulose solution, fills the holes of the zeolite with water-soluble cellulose, and then adds lauric acid to modify the cellulose to obtain insoluble cellulose particles, thereby expanding the channel capacity of the zeolite and improving the adsorption and water retention capacity of the artificial zeolite warm-mixing agent.

[0016] The present invention uses modified aggregates, and aluminate coupling agents do not need to use diluents during modification, and the modification can be completed by a dry mixing method, which is easy to operate. The inorganic-philic end and the organic-philic end of this type of coupling agent can react chemically with the surface of the inorganic filler and the organic end in the asphalt or form an entangled structure, which not only enhances the interfacial compatibility between the filler and the asphalt, but also improves the adhesion. The present invention pre-treats the SBS asphalt before use, and butyl maleate is added during the pre-treatment process, which improves the penetration and elastic recovery performance of the asphalt, and also improves the ductility and anti-aging performance. The accelerator used in the present invention is 2-(2,4-dinitrophenylthio)benzothiazole, which helps to improve the anti-aging ability and improve the strength of the mixture. In addition, it can also form a covalent bond with the hydroxyl or carboxyl group of the rubber powder, which not only enhances the surface activity of the rubber powder, but also improves its compatibility with the polymer matrix.

[0017] The present invention also adds a mixed macromolecular material of rubber powder and starch as an additive. The starch matrix is ​​a high molecular three-dimensional network structure. After grafting polyether macromonomers, acrylic acid monomers, and maleic anhydride monomers, the three-dimensional network structure is further expanded, which greatly improves the stability of asphalt, gives the material good mechanical properties, and enables the asphalt mixture to adapt to a variety of environments. The starch-based material can improve the cohesion of the matrix asphalt, as well as the cohesion of the asphalt to the aggregate and filler, and improves the structural strength and water damage resistance and salt erosion resistance of the asphalt mixture, which is manifested as a more stable and durable performance in a high-salinity environment. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] If no specific conditions are specified in the examples, the experiments can be carried out under conventional conditions. If no manufacturer is specified for the reagents or instruments used, they are conventional products that can be purchased commercially. The normal temperature in the examples is 18°C ​​to 35°C.

[0020] Embodiment 1 to Embodiment 4

[0021] Prepare the raw materials for asphalt mixture, including the following aspects:

[0022] Pretreatment of SBS asphalt: Heat SBS asphalt to a molten state, add butylene maleate and sulfur, and stir for 1 to 3 hours. The mass ratio of SBS asphalt, butylene maleate and sulfur is 1:0.01 to 0.02:0.5 to 1.2. A portion of the asphalt sample is retained in each example, namely asphalt samples 1 to 4.

[0023] The specific process parameters and material ratios are shown in Table 1.

[0024] Aggregate modification: Soak the coarse aggregate or fine aggregate in a Bian Ze reagent, ultrasonicate for 0.5 h to 1 h, take out the coarse aggregate or fine aggregate, add 0.05% to 0.5% of the aggregate mass of an aluminate coupling agent, and dry mix at 125 ℃ to 140 ℃ for 1 h to 2 h. A portion of the coarse aggregate sample is retained in each example, namely coarse aggregate samples 1 to 4.

[0025] The specific process parameters and material ratios are shown in Table 1.

[0026] Table 1: Process parameters related to SBS asphalt pretreatment and aggregate modification

[0027]

[0028] Preparation of warm mix agent: Add 5 parts of hydroxyethyl cellulose and 5 parts of artificial zeolite into water, heat to 80 ℃ ~ 110 ℃, add 0.3 parts ~ 0.8 parts of lauric acid, continue stirring and heat to 100 ℃ ~ 115 ℃, keep warm for 1 h ~ 2 h, filter and dry to obtain the warm mix agent.

[0029] The specific process parameters and material ratios are shown in Table 2.

[0030] Table 2: Preparation process parameters and material ratios of warm mix agent

[0031]

[0032] Preparation of additives:

[0033] S1. Dissolve 8-10 parts of rubber powder in an organic solvent, mix with 5-8 parts of acid-decomposed starch, and stir at room temperature;

[0034] S2, adding 0.2-0.4 parts of maleic anhydride and 0.05-0.1 parts of hydroquinone, mixing and heating to 95°C-105°C and reacting for 2-4 hours to obtain a modified rubber powder mixture;

[0035] S3. Add 0.01-0.03 parts of ferrous sulfate and 0.5-1.0 parts of acrylic acid to 1-2 parts of 4-hydroxybutyl vinyl polyoxyethylene ether, add 0.06-0.08 parts of hydrogen peroxide at room temperature, stir evenly, add the prepared modified rubber powder mixture, add 0.01-0.03 parts of vitamin C and 0.03-0.06 parts of mercaptopropionic acid, stir and react for 1.5 h to 2.5 h; adjust the pH value to neutral, filter, and dry to obtain the additive.

[0036] The specific process parameters and material ratios are shown in Table 3.

[0037] Table 3: Preparation process parameters and material ratios of additives

[0038]

[0039] Table 3: Preparation process parameters and material ratios of additives

[0040]

[0041] Embodiment 5 to Embodiment 10

[0042] The materials obtained in Examples 1 to 4 are used as raw materials to prepare warm mix asphalt mixtures. The steps are as follows. For specific process parameters and material ratios, see Table 4:

[0043] Heat 5 to 7 parts of pretreated SBS asphalt to 110 ℃ ~ 130 ℃, add 1 to 2 parts of warm mix agent and 2 to 4 parts of additives in sequence under stirring, continue stirring for 0.5 h ~ 1 h, wait for full swelling, continue shearing on the high-speed shearing machine for 1 h ~ 2 h, then add 0.02 to 0.05 parts of accelerator 2-(2,4-dinitrophenylthio)benzothiazole under stirring, keep stirring for 0.5 h ~ 1 h, add 25 to 30 parts of modified fine aggregate, 45 to 60 parts of modified coarse aggregate, and 8 to 12 parts of filler slaked lime, and stir for 0.5 h ~ 1 h.

[0044] The raw materials of the modified coarse aggregate include any one or more combinations of basalt, granite and diabase; the raw materials of the modified fine aggregate include any one or more combinations of natural sand, machine-made sand and stone chips.

[0045] According to Example 5 to Example 10, mixed material samples 1 to 6 were prepared respectively.

[0046] Table 4: Preparation process parameters and material ratios of warm mix asphalt mixture

[0047]

[0048] Table 4: Preparation process parameters and material ratios of warm mix asphalt mixture

[0049]

[0050] Comparative Example 1

[0051] The implementation method is the same as that of Example 5, except that no additive is added to prepare a mixed material control 1.

[0052] Comparative Example 2

[0053] The implementation method is the same as Example 5, except that the coarse aggregate added is not modified coarse aggregate, but raw materials of the same mass fraction, type and proportion, and the same specifications are directly used to prepare the mixture control 2.

[0054] Analysis and testing

[0055] 1. Take asphalt samples 1 to 4 and use untreated SBS asphalt as the reference material. According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTJ 052-2000), the test data are shown in Table 5.

[0056] Table 5: Asphalt sample test data

[0057]

[0058] From the results in Table 5, it can be seen that the penetration, ductility and elastic recovery properties of the pretreated asphalt are all improved. After aging, the ductility is tested again, and it is found that the ductility after pretreatment changes little, indicating that the pretreated asphalt has better low-temperature stability.

[0059] 2. Take coarse aggregate samples 1 to 4 and use unmodified coarse aggregate as the reference material. According to the Test Procedure for Aggregates in Highway Engineering (JTG E42-2005), the test data are shown in Table 6.

[0060] Table 6: Coarse aggregate test data

[0061]

[0062] From the results in Table 6, it can be seen that the modified coarse aggregate has better adhesion and can adapt to different climate zones. The water absorption rate of the modified coarse aggregate is reduced, and it is less likely to produce shrinkage cracks during use, which helps to improve the performance of cement stabilizing crushed stone and improve the durability of the mixture.

[0063] 3. Take mixture samples 1 to 6 and reference materials 1 and 2, and test them according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTJ 052-2000) and "Asphalt Pavement Design Specifications" (JTG D50-2004), respectively. The test data can be found in 7 and Table 8.

[0064] Table 7: Mixture dynamic stability and failure strain test results

[0065]

[0066] Table 8: Test results of residual stability and residual strength ratio of mixture

[0067]

[0068] As shown in Tables 7 and 8, the dynamic stability, failure strain performance, residual stability of the immersion Marshall test and residual strength ratio of the freeze-thaw splitting test of the asphalt mixture of the present invention are significantly improved under different climatic conditions, indicating that the asphalt mixture of the present invention is more resistant to high and low temperatures and its service life is improved in a variety of environments.

[0069] 4. Take mixture samples 1 to 6 and reference materials 1 and 2, and test the residual stability after immersion in 10% salt water for 48 h and 72 h in humid and arid environments. For specific test methods, refer to the immersion Marshall test recorded in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTJ 052-2000); test the residual strength ratio of the thaw splitting test after 3 and 9 salt-freeze cycles in humid and arid environments. For specific test methods, refer to the residual strength ratio of the freeze-thaw splitting test recorded in the "Asphalt Pavement Design Code" (JTGD50-2004). The test results are shown in Tables 9 and 10.

[0070] Table 9: Residual stability results of salt water Marshall test

[0071]

[0072] Table 10: Residual strength ratio results of salt freeze-thaw splitting test

[0073]

[0074] As shown in the results of Tables 9 and 10, the present invention also improves the salt and frost resistance of the asphalt mixture.

Claims

1. A warm mix asphalt mixture, characterized in that: In terms of weight, the asphalt mixture comprises 5 to 7 parts of pretreated SBS asphalt, 25 to 30 parts of modified fine aggregate, 45 to 60 parts of modified coarse aggregate, 8 to 12 parts of filler, 1 to 2 parts of warm mix agent, 2 to 4 parts of additives, and 0.02 to 0.05 parts of accelerator; The preparation method of the warm-mix agent is as follows: 5 parts of hydroxyethyl cellulose and 5 parts of artificial zeolite are added to water, heated to 80°C to 110°C, 0.3 parts to 0.8 parts of lauric acid are added, stirring is continued and the temperature is raised to 100°C to 115°C, after heat preservation reaction for 1 h to 2 h, filtering and drying to obtain the warm-mix agent; The raw materials of the additive include 8 to 10 parts of rubber powder, 5 to 8 parts of acid-decomposed starch, 0.2 to 0.4 parts of maleic anhydride, 0.05 to 0.1 parts of hydroquinone, 0.01 to 0.03 parts of ferrous sulfate, 0.5 to 1.0 parts of acrylic acid, 0.06 to 0.08 parts of hydrogen peroxide, 0.01 to 0.03 parts of vitamin C and 0.03 to 0.06 parts of mercaptopropionic acid, and 1 to 2 parts of 4-hydroxybutyl vinyl polyoxyethylene ether; The rubber powder is dissolved in an organic solvent, mixed with acid-decomposed starch, and stirred at room temperature; maleic anhydride and hydroquinone are added, mixed, heated to 95°C to 105°C, and reacted for 2 h to 4 h to obtain a modified rubber powder mixture; ferrous sulfate and acrylic acid are added to 4-hydroxybutyl vinyl polyoxyethylene ether, hydrogen peroxide is added at room temperature, and after uniform stirring, the modified rubber powder mixture is added, vitamin C and mercaptopropionic acid are added, and the reaction is stirred for 1.5 h to 2.5 h; the pH value is adjusted to neutral, filtered, and dried to obtain the additive; The modification process of the modified coarse aggregate and modified fine aggregate is to soak the coarse aggregate or fine aggregate in a Bian Ze reagent, perform ultrasonic treatment for 0.5 h to 1 h, take out the coarse aggregate or fine aggregate, add an aluminate coupling agent with a mass ratio of 0.05% to 0.5% of the coarse aggregate or fine aggregate, and dry mix at 125°C to 140°C for 1 h to 2 h.

2. A warm mix asphalt mixture according to claim 1, characterized in that: The pretreatment process is to heat SBS asphalt to a molten state, add butylene maleate and sulfur, and stir for 1 h to 3 h before completion. The mass ratio of SBS asphalt, butylene maleate and sulfur is 1:0.01-0.02:0.5-1.

2.

3. A warm mix asphalt mixture according to claim 1, characterized in that: The raw materials of the modified coarse aggregate include any one or more combinations of basalt, granite, and diabase; the raw materials of the modified fine aggregate include any one or more combinations of natural sand, machine-made sand, and stone chips; the filler is slaked lime; and the accelerator is 2-(2,4-dinitrophenylthio)benzothiazole.

4. A method for preparing a warm mix asphalt mixture, for preparing the asphalt mixture according to claim 1, characterized in that: Heat the pretreated SBS asphalt to 110 ℃ ~ 130 ℃, add warm mix agent and additives in sequence while stirring, continue stirring for 0.5 h ~ 1 h, wait for full swelling, continue shearing on the high-speed shearing machine for 1 h ~ 2 h, then add accelerator while stirring, keep stirring for 0.5 h ~ 1 h, add modified fine aggregate, modified coarse aggregate and filler, and stir for 0.5 h ~ 1 h.

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