A cold-mix thin-layer seal coat asphalt mixture and a preparation method thereof

Abstract

The application relates to the technical field of road maintenance materials, and discloses a cold-mixed thin-layer surface-coating asphalt mixture and a preparation method thereof; the preparation method comprises the following operation steps: step 1: emulsifiers and stabilizers are added into water at 60-70 DEG C, the pH is adjusted to 2-3, and heat preservation is carried out to obtain a soap solution; base asphalt is heated to 130-150 DEG C, and an anti-stripping agent is added and uniformly mixed; the mixture is respectively conveyed into an emulsifying device to be emulsified to obtain emulsified asphalt; the emulsified asphalt and water-based epoxy resin are uniformly mixed, and high-speed shearing is carried out for 5-7 minutes to obtain modified emulsified asphalt; and step 2: steel slag, a composite curing agent, an early strength agent and water are mixed for 50-60 seconds, cement is added and mixed for 40-60 seconds, and the modified emulsified asphalt, basalt and limestone are added and uniformly mixed in sequence to obtain the cold-mixed thin-layer surface-coating asphalt mixture.

Description

Technical Field

[0001] This invention relates to the field of road maintenance materials technology, specifically a cold-mix thin-layer overlay asphalt mixture and its preparation method. Background Technology

[0002] Thin-layer overlays are widely used in preventive and intermediate maintenance of asphalt pavements and are a relatively economical asphalt pavement repair technology. They can improve the waterproofing, skid resistance, and smoothness of the pavement. They are made by adding a thin layer of fine stone asphalt surface on the original asphalt pavement. They have advantages such as extending the service life of the pavement, being able to withstand heavy traffic and high shear stress, improving the smoothness of the pavement, and reducing traffic interruption time during construction.

[0003] Traditional hot-mix asphalt mixtures require high-temperature heating during construction, resulting in high energy consumption and some environmental pollution. Furthermore, construction is limited under certain special environmental conditions (such as low-temperature and humid areas). In contrast, cold-mix thin-layer overlay technology has advantages such as convenient construction, energy saving and environmental protection, and the ability to be stored and used at room temperature. It can overcome some of the shortcomings of hot-mix asphalt mixtures and is especially suitable for emergency road repairs and small-area maintenance.

[0004] In conclusion, the preparation of a cold-mix thin-layer overlay asphalt mixture is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a cold-mix thin-layer overlay asphalt mixture and its preparation method, so as to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a cold-mixed thin-layer overlay asphalt mixture includes the following steps:

[0008] Step 1: Add emulsifier and stabilizer to water at 60-70℃, adjust pH to 2-3, and keep warm to obtain soap solution; heat the base asphalt to 130-150℃, add anti-stripping agent, and mix evenly; separately feed it and soap solution into emulsification equipment for emulsification to obtain emulsified asphalt; mix emulsified asphalt and water-based epoxy resin evenly, and then shear at high speed for 5-7 minutes to obtain modified emulsified asphalt;

[0009] Step 2: Mix steel slag, composite curing agent, early strength agent and water for 50-60 seconds, then add cement and mix for 40-60 seconds. Then add modified emulsified asphalt, basalt and limestone in sequence and mix evenly to obtain cold-mix thin-layer overlay asphalt mixture.

[0010] In a more optimized form, the raw materials of the cold-mixed thin-layer overlay asphalt mixture include the following components: by mass parts, 15-20 parts steel slag, 1.2-1.5 parts composite curing agent, 0.1-0.4 parts early strength agent, 2-4 parts water, 1-1.5 parts cement, 6-10 parts modified emulsified asphalt, 60-70 parts basalt, and 6-8 parts limestone.

[0011] In a more optimized form, the early strength agent comprises calcium formate and triethanolamine in a mass ratio of (3-4):1.

[0012] A more optimized method for preparing the waterborne epoxy resin is as follows: (1) Polyethylene glycol glycidyl ether and E44 epoxy resin are added to anhydrous ethanol and mixed evenly. KH550 is added and reacted at 50-60°C for 5-6 hours. The temperature is raised to 80°C and stirring is continued for 2-3 hours to obtain modified epoxy resin; (2) Modified epoxy resin and emulsifier are mixed at high speed at 2000-5000 rpm. During the mixing process, deionized water is added dropwise until the phase inversion occurs to obtain waterborne epoxy resin.

[0013] In a more optimized form, the raw materials of the modified epoxy resin include the following components: by mass parts, 6-7 parts polyethylene glycol glycidyl ether, 2.5-3.2 parts E44 epoxy resin, 3-4 parts KH550, and 2-5 parts ethanol; the mass ratio of the modified epoxy resin to the curing agent is 1:(0.2-0.3).

[0014] In a more optimized form, the raw materials of the emulsified asphalt include the following components: by mass parts, 50-60 parts base asphalt, 30-38 parts soap solution, and 0.4-0.7 parts anti-stripping agent; the raw materials of the soap solution include the following components: by mass parts, 1.2-3 parts emulsifier, 0.4-0.5 parts stabilizer, and 80-90 parts water; the mass ratio of the emulsified asphalt to the waterborne epoxy resin is (4-7.5):1.

[0015] A more optimized method for preparing the composite curing agent is as follows: (1) 4-hydroxymethyl-5-methylimidazolium is added to 1,4-dioxane at 60-70°C and mixed evenly. Sodium chloride is added and the mixture is refluxed for 4 hours. The mixture is cooled to 0-4°C and allyl chloride is added and stirred for 30-40 minutes. The mixture is stirred at room temperature for 20-24 hours, purified, and dried to obtain vinylimidazolium curing agent; (2) vinylimidazolium curing agent is added to 1,4-dioxane and mixed evenly to obtain a mixture. Polyetheramine is heated to 70-80°C, and the mixture and triethylamine are added and mixed evenly. The mixture is stirred at 800-1000 r / min for 1-2 hours. The solvent is removed by vacuum distillation, washed, and dried to obtain the composite curing agent.

[0016] In a more optimized form, the raw materials of the vinylimidazolium curing agent include the following components: 4-5 parts of 4-hydroxymethyl-5-methylimidazolium, 2-3 parts of sodium chloride, 2.5-2.7 parts of allyl chloride, and 50-60 parts of 1,4-dioxane; the raw materials of the composite curing agent include the following components: by mass, 2-2.4 parts of polyetheramine, 1-1.2 parts of vinylimidazolium curing agent, and 0.01-0.02 parts of triethylamine; wherein the polyetheramine is a low molecular weight polyetheramine.

[0017] In a more optimized configuration, the emulsifier includes one or both of cationic and nonionic emulsifiers; the stabilizer includes one or more of polyvinyl alcohol, hydroxypropyl methylcellulose, and polyacrylamide; and the anti-stripping agent includes one or more of tall oil fatty acids, rosin acid, and stearic acid.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] In this scheme, steel slag, composite curing agent, early strength agent and water are mixed evenly, then cement is added and mixed, and then modified emulsified asphalt, basalt and limestone are added in sequence and mixed evenly to obtain cold-mixed thin-layer overlay asphalt mixture.

[0020] Emulsified asphalt can reduce the viscosity of the mixture, allowing the aggregates to mix evenly and thus improving fluidity; asphalt itself has elasticity and toughness, which can alleviate stress concentration between aggregates, reduce the risk of mixture cracking, and extend the service life of the pavement.

[0021] To improve the interfacial properties between emulsified asphalt and aggregates such as steel slag, water-based epoxy resin is introduced into the emulsified asphalt. Then, under the action of a curing agent, an interpenetrating network is formed, which improves the interfacial adhesion between the emulsified asphalt and the aggregates, thereby improving the mechanical properties of the pavement.

[0022] In this scheme, polyethylene glycol glycidyl ether, E44 epoxy resin, and KH550 are used to prepare a modified epoxy resin, which is then emulsified. E44 epoxy resin itself has a high crosslinking density, resulting in a brittle texture and insufficient toughness after curing. Polyethylene glycol glycidyl ether molecules contain flexible polyethylene glycol segments; introducing them into the E44 epoxy resin system allows for the formation of flexible segments within the epoxy resin's crosslinking network structure. Furthermore, the polyethylene glycol segments possess good hydrophilicity; during modification, the introduction of polyethylene glycol glycidyl ether adds hydrophilic groups to the epoxy resin molecular structure. During phase inversion, this improved hydrophilicity helps the epoxy resin disperse better in water, forming a stable emulsion system. KH550 (aminoalkylsilane) is used as a coupling agent; introducing it into the waterborne epoxy resin enhances the adhesion between the modified emulsified asphalt and steel slag.

[0023] However, if steel slag is not pretreated, the various metal oxides in it will undergo hydration reactions during roadside service, thus affecting the quality of the road surface. To solve this problem, the solution involves mixing early-strength agents and composite curing agents with steel slag, which can improve the surface properties of steel slag, thereby improving the mechanical properties and dynamic stability of the mixture.

[0024] Calcium formate, as an early-strength agent, accelerates the reaction of metal oxides in steel slag by releasing calcium ions, reducing the risk of later expansion. Triethanolamine, a metal ion in steel slag, forms a stable complex that coats the surface of the steel slag, inhibiting the hydration reaction. The combined use of these two agents can promote the hydration reaction of cement and steel slag, thereby improving the mechanical properties of the mixture. The composite curing agent is made by introducing imidazole groups into low molecular weight polyetheramine. In this scheme, steel slag is first uniformly mixed with the composite curing agent containing imidazole groups to improve the contact between the steel slag and the imidazole groups and enhance its surface energy. Then, modified asphalt and other aggregates are added to improve the mechanical properties of the pavement. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] In the following specific embodiments, "parts" refers to parts by weight. It should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: 4-hydroxymethyl-5-methylimidazolium (CAS number 29636-87-1); 1,4-dioxane (CAS number 123-91-1); allyl chloride (CAS number 107-05-1); polyetheramine (model D230), purchased from Zhejiang Huangma New Material Technology Co., Ltd.; octadecyltrimethylammonium chloride (cationic emulsifier) ​​(CAS number 112-03-8); and octylphenol polyoxyethylene ether (nonionic emulsifier) ​​(model...). OP-10 was purchased from Shandong Yonglida New Material Technology Co., Ltd.; polyvinyl alcohol (stabilizer) model 8805 was purchased from Sichuan Laitejuxin Pharmaceutical Excipients Co., Ltd.; rosin acid (anti-stripping agent) CAS number 514-10-3; triethanolamine CAS number 102-71-6; calcium formate CAS number 544-17-2; polyethylene glycol glycidyl ether (epoxy value 0.32, molecular weight 400) was purchased from Wuhan Rongcan Biotechnology Co., Ltd.; E44 epoxy resin was purchased from Langfang Xinglangyuan Anticorrosive Materials Co., Ltd.; KH550 (3-aminopropyltriethoxysilane) CAS number 919-30-2.

[0027] In the scheme, the preparation method of the composite curing agent is as follows: (1) Add 4 parts of 4-hydroxymethyl-5-methylimidazolium to 50 parts of 1,4-dioxane at 60℃ and mix evenly, add 2 parts of sodium chloride, reflux for 4 hours, cool to 0℃, add 2.5 parts of allyl chloride and stir for 30 minutes, stir at room temperature for 24 hours, evaporate the solvent, dilute with water, extract with dichloromethane 4 times, combine the organic phases, dry with anhydrous magnesium sulfate, filter, evaporate the solvent under vacuum to obtain vinylimidazolium curing agent; (2) Add 1 part of vinylimidazolium curing agent to 3 parts of 1,4-dioxane and mix evenly to obtain a mixture; heat 2.3 parts of polyetheramine to 70℃, add the mixture and 0.01 parts of triethylamine and mix evenly, stir at 800r / min for 1.5 hours, remove the solvent by vacuum distillation, wash, dry to obtain composite curing agent.

[0028] Example 1: A method for preparing a cold-mix thin-layer overlay asphalt mixture, comprising the following steps:

[0029] Step 1: (1) Add 6.2 parts of polyethylene glycol glycidyl ether and 2.5 parts of E44 epoxy resin to 3 parts of anhydrous ethanol and mix evenly. Add 3.5 parts of KH550 and react at 55°C for 6 hours. Then raise the temperature to 80°C and continue stirring for 2 hours to obtain modified epoxy resin. (2) Mix the modified epoxy resin with octylphenol polyoxyethylene ether at 4000 rpm. During the mixing process, add deionized water dropwise until the phase inversion occurs to obtain waterborne epoxy resin. The mass ratio of modified epoxy resin to octylphenol polyoxyethylene ether is 1:0.2.

[0030] (3) Add 1.5 parts of emulsifier (octadecyltrimethylammonium chloride and octylphenol polyoxyethylene ether in a mass ratio of 3:2) and 0.4 parts of stabilizer to 80 parts of water at 60°C, adjust the pH to 2, keep warm, and obtain soap solution; heat 60 parts of base asphalt to 140°C, add 0.5 parts of anti-stripping agent and mix evenly; send it and 38 parts of soap solution to emulsification equipment for emulsification to obtain emulsified asphalt; mix emulsified asphalt and waterborne epoxy resin evenly in a mass ratio of 7.5:1, and then shear at high speed for 6 minutes to obtain modified emulsified asphalt;

[0031] Step 2: Mix 15 parts steel slag, 1.2 parts composite curing agent, 0.1 parts early strength agent and 2 parts water for 60 seconds, then add 1.5 parts cement and mix for 40 seconds. Then add 6 parts modified emulsified asphalt, 60 parts basalt and 7 parts limestone in sequence and mix evenly to obtain cold-mix thin-layer overlay asphalt mixture.

[0032] Example 2: A method for preparing a cold-mix thin-layer overlay asphalt mixture, comprising the following steps:

[0033] Step 1: (1) Add 6.2 parts of polyethylene glycol glycidyl ether and 2.5 parts of E44 epoxy resin to 3 parts of anhydrous ethanol and mix evenly. Add 3.5 parts of KH550 and react at 55°C for 6 hours. Then raise the temperature to 80°C and continue stirring for 2 hours to obtain modified epoxy resin. (2) Mix the modified epoxy resin with octylphenol polyoxyethylene ether at 4000 rpm. During the mixing process, add deionized water dropwise until the phase inversion occurs to obtain waterborne epoxy resin. The mass ratio of modified epoxy resin to octylphenol polyoxyethylene ether is 1:0.2.

[0034] (3) Add 1.5 parts of emulsifier (octadecyltrimethylammonium chloride and octylphenol polyoxyethylene ether in a mass ratio of 3:2) and 0.4 parts of stabilizer to 80 parts of water at 60°C, adjust the pH to 2, keep warm, and obtain soap solution; heat 60 parts of base asphalt to 140°C, add 0.5 parts of anti-stripping agent and mix evenly; send it and 38 parts of soap solution to emulsification equipment for emulsification to obtain emulsified asphalt; mix emulsified asphalt and waterborne epoxy resin evenly in a mass ratio of 7.5:1, and then shear at high speed for 6 minutes to obtain modified emulsified asphalt;

[0035] Step 2: Mix 20 parts steel slag, 1.5 parts composite curing agent, 0.3 parts early strength agent and 2 parts water for 60 seconds, then add 1.5 parts cement and mix for 40 seconds. Then add 8 parts modified emulsified asphalt, 70 parts basalt and 6 parts limestone and mix evenly to obtain cold-mix thin-layer overlay asphalt mixture.

[0036] Example 3: A method for preparing a cold-mix thin-layer overlay asphalt mixture, comprising the following steps:

[0037] Step 1: (1) Add 6.2 parts of polyethylene glycol glycidyl ether and 2.5 parts of E44 epoxy resin to 3 parts of anhydrous ethanol and mix evenly. Add 3.5 parts of KH550 and react at 55°C for 6 hours. Then raise the temperature to 80°C and continue stirring for 2 hours to obtain modified epoxy resin. (2) Mix the modified epoxy resin with octylphenol polyoxyethylene ether at 4000 rpm. During the mixing process, add deionized water dropwise until the phase inversion occurs to obtain waterborne epoxy resin. The mass ratio of modified epoxy resin to octylphenol polyoxyethylene ether is 1:0.2.

[0038] (3) Add 1.5 parts of emulsifier (octadecyltrimethylammonium chloride and octylphenol polyoxyethylene ether in a mass ratio of 3:2) and 0.4 parts of stabilizer to 80 parts of water at 60°C, adjust the pH to 2, keep warm, and obtain soap solution; heat 60 parts of base asphalt to 140°C, add 0.5 parts of anti-stripping agent and mix evenly; send it and 38 parts of soap solution to emulsification equipment for emulsification to obtain emulsified asphalt; mix emulsified asphalt and waterborne epoxy resin evenly in a mass ratio of 7.5:1, and then shear at high speed for 6 minutes to obtain modified emulsified asphalt;

[0039] Step 2: Mix 20 parts steel slag, 1.3 parts composite curing agent, 0.1 parts early strength agent and 2 parts water for 60 seconds, then add 1.5 parts cement and mix for 40 seconds. Then add 8 parts modified emulsified asphalt, 70 parts basalt and 6 parts limestone and mix evenly to obtain cold-mix thin-layer overlay asphalt mixture.

[0040] Comparative Example 1 is based on Example 2, but introduces a single polyetheramine curing agent;

[0041] Step 1: (1) Add 6.2 parts of polyethylene glycol glycidyl ether and 2.5 parts of E44 epoxy resin to 3 parts of anhydrous ethanol and mix evenly. Add 3.5 parts of KH550 and react at 55°C for 6 hours. Then raise the temperature to 80°C and continue stirring for 2 hours to obtain modified epoxy resin. (2) Mix the modified epoxy resin with octylphenol polyoxyethylene ether at 4000 rpm. During the mixing process, add deionized water dropwise until the phase inversion occurs to obtain waterborne epoxy resin. The mass ratio of modified epoxy resin to octylphenol polyoxyethylene ether is 1:0.2.

[0042] (3) Add 1.5 parts of emulsifier (octadecyltrimethylammonium chloride and octylphenol polyoxyethylene ether in a mass ratio of 3:2) and 0.4 parts of stabilizer to 80 parts of water at 60°C, adjust the pH to 2, keep warm, and obtain soap solution; heat 60 parts of base asphalt to 140°C, add 0.5 parts of anti-stripping agent and mix evenly; send it and 38 parts of soap solution to emulsification equipment for emulsification to obtain emulsified asphalt; mix emulsified asphalt and waterborne epoxy resin evenly in a mass ratio of 7.5:1, and then shear at high speed for 6 minutes to obtain modified emulsified asphalt;

[0043] Step 2: Mix 20 parts steel slag, 1.5 parts polyetheramine D230 (curing agent), 0.3 parts early strength agent, and 2 parts water for 60 seconds, then add 1.5 parts cement and mix for 40 seconds. Then add 8 parts modified emulsified asphalt, 70 parts basalt, and 6 parts limestone in sequence and mix evenly to obtain cold-mix thin-layer overlay asphalt mixture.

[0044] Comparative Example 2 is based on Example 2, but without the introduction of KH550 into the modified epoxy resin;

[0045] Step 1: (1) Mix 6.2 parts of polyethylene glycol glycidyl ether, 2.5 parts of E44 epoxy resin and 1.5 parts of octylphenol polyoxyethylene ether at a high speed of 4000 rpm. During the mixing process, add deionized water dropwise until the phase inversion occurs to obtain waterborne epoxy resin.

[0046] (3) Add 1.5 parts of emulsifier (octadecyltrimethylammonium chloride and octylphenol polyoxyethylene ether in a mass ratio of 3:2) and 0.4 parts of stabilizer to 80 parts of water at 60°C, adjust the pH to 2, keep warm, and obtain soap solution; heat 60 parts of base asphalt to 140°C, add 0.5 parts of anti-stripping agent and mix evenly; send it and 38 parts of soap solution to emulsification equipment for emulsification to obtain emulsified asphalt; mix emulsified asphalt and waterborne epoxy resin evenly in a mass ratio of 7.5:1, and then shear at high speed for 6 minutes to obtain modified emulsified asphalt;

[0047] Step 2: Mix 20 parts steel slag, 1.5 parts composite curing agent, 0.3 parts early strength agent and 2 parts water for 60 seconds, then add 1.5 parts cement and mix for 40 seconds. Then add 8 parts modified emulsified asphalt, 70 parts basalt and 6 parts limestone and mix evenly to obtain cold-mix thin-layer overlay asphalt mixture.

[0048] Comparative Example 3 is based on Example 2, in which the raw materials of cold-mix thin-layer overlay asphalt mixture are directly mixed;

[0049] Step 1: (1) Add 6.2 parts of polyethylene glycol glycidyl ether and 2.5 parts of E44 epoxy resin to 3 parts of anhydrous ethanol and mix evenly. Add 3.5 parts of KH550 and react at 55°C for 6 hours. Then raise the temperature to 80°C and continue stirring for 2 hours to obtain modified epoxy resin. (2) Mix the modified epoxy resin with octylphenol polyoxyethylene ether at 4000 rpm. During the mixing process, add deionized water dropwise until the phase inversion occurs to obtain waterborne epoxy resin. The mass ratio of modified epoxy resin to octylphenol polyoxyethylene ether is 1:0.2.

[0050] (3) Add 1.5 parts of emulsifier (octadecyltrimethylammonium chloride and octylphenol polyoxyethylene ether in a mass ratio of 3:2) and 0.4 parts of stabilizer to 80 parts of water at 60°C, adjust the pH to 2, keep warm, and obtain soap solution; heat 60 parts of base asphalt to 140°C, add 0.5 parts of anti-stripping agent and mix evenly; send it and 38 parts of soap solution to emulsification equipment for emulsification to obtain emulsified asphalt; mix emulsified asphalt and waterborne epoxy resin evenly in a mass ratio of 7.5:1, and then shear at high speed for 6 minutes to obtain modified emulsified asphalt;

[0051] Step 2: Mix 20 parts steel slag, 1.5 parts composite curing agent, 0.3 parts early strength agent, 2 parts water, 1.5 parts cement, 8 parts modified emulsified asphalt, 70 parts basalt, and 6 parts limestone evenly to obtain cold-mix thin-layer overlay asphalt mixture.

[0052] Comparative Example 4 is based on Example 2, but introduces calcium formate as an early-strength agent alone;

[0053] Step 1: (1) Add 6.2 parts of polyethylene glycol glycidyl ether and 2.5 parts of E44 epoxy resin to 3 parts of anhydrous ethanol and mix evenly. Add 3.5 parts of KH550 and react at 55°C for 6 hours. Then raise the temperature to 80°C and continue stirring for 2 hours to obtain modified epoxy resin. (2) Mix the modified epoxy resin with octylphenol polyoxyethylene ether at 4000 rpm. During the mixing process, add deionized water dropwise until the phase inversion occurs to obtain waterborne epoxy resin. The mass ratio of modified epoxy resin to octylphenol polyoxyethylene ether is 1:0.2.

[0054] (3) Add 1.5 parts of emulsifier (octadecyltrimethylammonium chloride and octylphenol polyoxyethylene ether in a mass ratio of 3:2) and 0.4 parts of stabilizer to 80 parts of water at 60°C, adjust the pH to 2, keep warm, and obtain soap solution; heat 60 parts of base asphalt to 140°C, add 0.5 parts of anti-stripping agent and mix evenly; send it and 38 parts of soap solution to emulsification equipment for emulsification to obtain emulsified asphalt; mix emulsified asphalt and waterborne epoxy resin evenly in a mass ratio of 7.5:1, and then shear at high speed for 6 minutes to obtain modified emulsified asphalt;

[0055] Step 2: Mix 20 parts steel slag, 1.5 parts composite curing agent, 0.3 parts calcium formate (early strength agent), and 2 parts water for 60 seconds, then add 1.5 parts cement and mix for 40 seconds. Then add 8 parts modified emulsified asphalt, 70 parts basalt, and 6 parts limestone and mix evenly to obtain cold-mix thin-layer overlay asphalt mixture.

[0056] Testing: The cold-mix asphalt mixtures prepared in Examples 1-3 and Comparative Examples 1-4 were molded and cured according to the requirements of "Waterborne Epoxy Resin Emulsified Asphalt Mixture for Roads" (GB / T38990-2020) and "Technical Specification for Construction of Asphalt Pavement of Highway" (JTGF40-2004), and their dynamic stability, maximum flexural strain and indirect tensile strength after 7 days of curing were tested.

[0057] Table 1

[0058]

[0059]

[0060] Conclusions: Comparative Example 1, based on Example 2, introduced only polyetheramine curing agent, which reduced the correlation between the composite curing agent and steel slag, thus leading to a decrease in performance. Comparative Example 2, based on Example 2, did not introduce KH550 into the modified epoxy resin, resulting in a decrease in performance. This is because the introduction of KH550 can improve the interaction between the modified emulsified asphalt and aggregates, thereby improving performance. Comparative Example 3, based on Example 2, directly mixed the raw materials of the cold-mix thin-layer overlay asphalt mixture, thus leading to a decrease in the performance of Comparative Example 3. Comparative Example 4, based on Example 2, introduced only calcium formate early-strength agent, which reduced the surface energy of the steel slag, thus leading to a decrease in the performance of Comparative Example 4.

[0061] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a cold-mixed thin-layer overlay asphalt mixture, characterized in that: The following steps are included: Step 1: Add emulsifier and stabilizer to water at 60~70℃, adjust pH to 2~3, keep warm to obtain soap solution; heat the base asphalt to 130~150℃, add anti-stripping agent, and mix evenly; The emulsified asphalt and soap solution are separately fed into an emulsification device for emulsification to obtain emulsified asphalt; the emulsified asphalt and water-based epoxy resin are uniformly mixed and then subjected to high-speed shearing for 5-7 minutes to obtain modified emulsified asphalt. Step 2: Mix steel slag, composite curing agent, early strength agent and water for 50-60 seconds, then add cement and mix for 40-60 seconds. Then add modified emulsified asphalt, basalt and limestone in sequence and mix evenly to obtain cold-mix thin-layer overlay asphalt mixture. The preparation method of the composite curing agent is as follows: (1) 4-hydroxymethyl-5-methylimidazolium is added to 1,4-dioxane at 60~70℃ and mixed evenly. Sodium chloride is added and refluxed for 4 hours. The mixture is cooled to 0~4℃ and allyl chloride is added and stirred for 30~40 minutes. The mixture is stirred at room temperature for 20~24 hours, purified, and dried to obtain vinylimidazolium curing agent; (2) vinylimidazolium curing agent is added to 1,4-dioxane and mixed evenly to obtain a mixture. Polyetheramine is heated to 70~80℃ and the mixture and triethylamine are added and mixed evenly. The mixture is stirred at 800~1000r / min for 1~2 hours. The solvent is removed by vacuum distillation, washed, and dried to obtain the composite curing agent.

2. The method for preparing a cold-mixed thin-layer overlay asphalt mixture according to claim 1, characterized in that: The raw materials of the cold-mixed thin-layer overlay asphalt mixture include the following components by mass: 15-20 parts steel slag, 1.2-1.5 parts composite curing agent, 0.1-0.4 parts early strength agent, 2-4 parts water, 1-1.5 parts cement, 6-10 parts modified emulsified asphalt, 60-70 parts basalt, and 6-8 parts limestone.

3. The method for preparing a cold-mixed thin-layer overlay asphalt mixture according to claim 1, characterized in that: The early strength agent comprises calcium formate and triethanolamine in a mass ratio of (3~4):

1.

4. The method for preparing a cold-mixed thin-layer overlay asphalt mixture according to claim 1, characterized in that: The preparation method of the waterborne epoxy resin is as follows: (1) Polyethylene glycol glycidyl ether and E44 epoxy resin are added to anhydrous ethanol and mixed evenly. KH550 is added and reacted at 50~60℃ for 5~6 hours. The temperature is raised to 80℃ and stirring is continued for 2~3 hours to obtain modified epoxy resin; (2) Modified epoxy resin and emulsifier are mixed at high speed at 2000~5000 rpm. During the mixing process, deionized water is added dropwise until the phase inversion occurs to obtain waterborne epoxy resin.

5. The method for preparing a cold-mixed thin-layer overlay asphalt mixture according to claim 4, characterized in that: The modified epoxy resin raw materials include the following components: by mass parts, 6-7 parts polyethylene glycol glycidyl ether, 2.5-3.2 parts E44 epoxy resin, 3-4 parts KH550, and 2-5 parts ethanol; the mass ratio of the modified epoxy resin to the curing agent is 1:(0.2-0.3).

6. The method for preparing a cold-mixed thin-layer overlay asphalt mixture according to claim 1, characterized in that: The raw materials of the emulsified asphalt include the following components: by mass, 50-60 parts base asphalt, 30-38 parts soap solution, and 0.4-0.7 parts anti-stripping agent; the raw materials of the soap solution include the following components: by mass, 1.2-3 parts emulsifier, 0.4-0.5 parts stabilizer, and 80-90 parts water; the mass ratio of the emulsified asphalt to the waterborne epoxy resin is (4-7.5):

1.

7. The method for preparing a cold-mixed thin-layer overlay asphalt mixture according to claim 1, characterized in that: The raw materials of the vinylimidazolium curing agent include the following components: 4-5 parts 4-hydroxymethyl-5-methylimidazolium, 2-3 parts sodium chloride, 2.5-2.7 parts allyl chloride, and 50-60 parts 1,4-dioxane; the raw materials of the composite curing agent include the following components: by mass, 2-2.4 parts polyetheramine, 1-1.2 parts vinylimidazolium curing agent, and 0.01-0.02 parts triethylamine; the polyetheramine is a low molecular weight polyetheramine.

8. The method for preparing a cold-mixed thin-layer overlay asphalt mixture according to claim 1, characterized in that: The emulsifier includes one or both of cationic and nonionic emulsifiers; the stabilizer includes one or more of polyvinyl alcohol, hydroxypropyl methylcellulose, and polyacrylamide; and the anti-stripping agent includes one or more of tall oil fatty acids, rosin acid, and stearic acid.

9. A cold-mixed thin-layer overlay asphalt mixture is prepared according to any one of claims 1 to 8.

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