Cold mixing type road rapid repair material based on steel slag microwave heat effect and preparation method thereof

Abstract

The invention discloses a cold mixing type road rapid repair material based on a steel slag microwave heat effect and a preparation method thereof, and belongs to the technical field of road repair materials. The method comprises the following steps: reacting bisphenol A epoxy resin E51 with polyethylene glycol PEG-4000 under the action of a catalyst to prepare waterborne epoxy resin; the preparation method comprises the following steps: mixing an amine curing agent, a defoaming agent and BC-1 cationic emulsified asphalt, introducing waterborne epoxy resin, and shearing to prepare a cementing material; the method comprises the following steps: mixing crushed and screened steel slag (with the particle size of 0.6-2.36 mm) with basalt and limestone aggregate according to grading, drying, infiltrating, mixing with a cementing material, and finally heating by microwaves to quickly cure and form. According to the invention, the steel slag is taken as the electromagnetic response aggregate for the first time, the rapid crosslinking characteristic of the water-borne epoxy resin and a microwave heating technology are combined, the early strength, water stability and fatigue resistance of the emulsified asphalt mixture are synergistically improved, and meanwhile, resource utilization of industrial solid waste and reduction of construction energy consumption are realized; and an efficient, convenient, high-strength, good-durability and environment-friendly solution is provided for rapid repair of road damage.

Description

Technical Field

[0001] The present application relates to the technical field of road repair materials, and particularly relates to a cold-mix type rapid road repair material based on the microwave heating effect of steel slag and a preparation method thereof. Background Art

[0002] With the rapid development of modern road construction technology, asphalt concrete pavement has become the main construction form of high-grade road pavement. Asphalt pavement has the advantages of comfortable driving, short construction period, simple maintenance, etc. However, due to the frequent occurrence of heavy traffic and vehicle overloading, the service performance of a considerable part of asphalt concrete pavement has been sharply reduced, resulting in frequent early damage such as potholes on the asphalt pavement. If early damage is not repaired in time, water may penetrate into the road base course, sub-base course or roadbed through the broken surface, thus accelerating the damage to the road structure and shortening the expected service life of the road. A pothole in an asphalt pavement refers to the local deterioration of the asphalt pavement, where the paving material decomposes and is lost in a short time, resulting in a steep depression. It is usually formed by the long-term combined action of water, vehicle load and other environmental factors. According to relevant investigations, when the pavement suffers from pothole damage, its impact load is about twice that of a normal pavement. This situation is extremely prone to accidents, causing huge economic losses. Traditional repair technologies often lead to large-scale congestion and increase the social operation cost due to the long construction period and the lag in the time of opening to traffic. The rapid repair asphalt mixture can complete the disease treatment in a short time and realize rapid opening to traffic, which not only significantly reduces the impact on the public caused by traffic interruption, but also reduces the risk of secondary maintenance and the maintenance cost, and can effectively improve the emergency maintenance ability of traffic infrastructure, providing technical support for ensuring the efficient operation of the modern traffic system.

[0003] Emulsified asphalt mixture is a cold-mix and cold-lay material with emulsified asphalt as the binder. Compared with traditional hot-mix asphalt mixture, its construction can be carried out at normal temperature without discharging harmful gases, and it has the characteristics of energy conservation and environmental protection, meeting the concept of green development. Research shows that waterborne epoxy resin has good compatibility with emulsified asphalt, which can significantly improve the mechanical properties, high-temperature properties and water stability of the mixture. Waterborne epoxy emulsified asphalt significantly improves the viscosity by introducing a waterborne epoxy resin system into the emulsified asphalt, thereby improving the high-temperature stability and water stability of the emulsified asphalt mixture. Although emulsified asphalt mixture shows environmental protection and energy conservation advantages as an important raw material for road maintenance, its strength needs to be gradually formed after the internal water evaporates, so there are problems such as insufficient early strength, weak durability and poor water stability. In addition, the curing process of waterborne epoxy resin also needs to go through multiple steps such as water volatilization, emulsion bead aggregation, curing agent mass transfer and crosslinking reaction to form strength. Therefore, it is particularly crucial to promote the evaporation of the water in the emulsified asphalt and the rapid curing and forming of the waterborne epoxy resin to reach sufficient strength as soon as possible after paving.

[0004] In recent years, the application of microwave heating technology, which can accelerate the evaporation of water in the emulsified asphalt mixture after paving, has come into people's sight, and microwave has been widely developed in accelerating the demulsification of emulsified asphalt. Aiming at the problems of low early strength, weak durability and poor water stability of waterborne epoxy emulsified asphalt mixture, on the basis of the research on traditional waterborne epoxy emulsified asphalt mixture, this invention introduces steel slag material and converts electromagnetic energy into heat energy through microwave heating technology, significantly improving the properties such as early strength and water stability of waterborne epoxy emulsified asphalt mixture. Summary of the Invention

[0005] Aiming at the problems of low early strength, weak durability and poor water stability of current waterborne epoxy emulsified asphalt mixture, a binder is prepared with non-ionic waterborne epoxy resin, amine curing agent, DF220 defoamer and BC-1 cationic emulsified asphalt, and an early-strength waterborne epoxy emulsified asphalt mixture modified with steel slag is prepared with basalt, limestone and steel slag materials as aggregates, which has high early strength and significantly improves the characteristics such as insufficient early strength and poor water stability of waterborne epoxy emulsified asphalt mixture.

[0006] In order to achieve the above purposes and advantages of this invention, a cold-mix type rapid road repair material based on the microwave thermal effect of steel slag and its preparation method are provided, including the following steps:

[0007] 1) Weigh epoxy resin E-51 and let it stand at room temperature for a period of time. Since it is liquid at room temperature, it can be directly used without preheating. Add epoxy resin E-51 and polyethylene glycol PEG-4000 into a three-necked flask equipped with a stirrer and a thermometer. Start heating, set the temperature to 90 °C until polyethylene glycol is completely dissolved. Then add potassium persulfate K 2 S 2 O 8 as a catalyst, continue to heat up to 150 °C and start timing, and react for 3 hours. After the reaction is over, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier presents a viscous liquid state and can return to a transparent state after heating.

[0008] 2) Add the amine curing agent into BC-1 cationic emulsified asphalt, stir evenly with a glass rod at 25 °C for 2 - 3 min, then add DF220 defoamer and stir with a glass rod for 1 - 2 min, and finally add the waterborne epoxy resin prepared in 1), and shear with a high-speed shear machine at 25 °C for 3 - 5 min to obtain a waterborne epoxy resin emulsified asphalt binder.

[0009] 3) Crush the steel slag to the target particle size (0.6 mm to 2.36 mm), wash it with 5% hydrochloric acid for 5 minutes, rinse it with deionized water until neutral, weigh the steel slag, basalt, limestone aggregate and limestone powder, dry them in an oven at 120 °C for 20 - 25 min, then cool them to room temperature, stir them in a mixture stirring pot at room temperature of 25 °C for 2 - 3 min, then weigh pure water and add it to the stirring pot to fully wet the aggregates and stir at room temperature of 25 °C for 2 - 3 min. Finally, add the waterborne epoxy emulsified asphalt binder prepared in 2) to the stirring pot and stir at room temperature of 25 °C for 3 - 5 min to obtain the steel slag modified early-strength waterborne epoxy emulsified asphalt mixture.

[0010] 4) Spread the steel slag modified early-strength waterborne epoxy emulsified asphalt mixture prepared in 3) into the road pothole, and after rolling, perform microwave treatment for 150 s - 200 s using a microwave heating device with a frequency of 2.45 GHz and a power of 1000 - 1500 W to achieve the effect of pothole repair.

[0011] The cold-mix type rapid road repair material based on the microwave thermal effect of steel slag and its preparation method according to the present invention are characterized in that: the selected epoxy resin is bisphenol A type epoxy resin E51, and the waterborne epoxy resin modified BC-1 cationic emulsified asphalt prepared by using it has its advantages mainly reflected in the synergistic effect of the molecular structure and material properties. The specific analysis is that the bisphenol A type epoxy resin E51 molecular chain contains high-density epoxy groups (-O-) and hydroxyl groups (-OH) active groups. Its molecular formula is CH3-(CH2)6-O-CH2-CH2-O-(CH2)6-CH3, with a linear oligomer structure, a relatively high epoxy value (0.48-0.54), and strong reaction activity. After curing, a three-dimensional cross-linked network is formed through an amine curing agent, enhancing the mechanical strength and chemical resistance of the material. The epoxy groups and hydroxyl groups in bisphenol A type epoxy resin E51 can chemically react with the active groups in the emulsified asphalt to form stable chemical bonds. In addition, the chemical composition, dosage, and particle size of the steel slag have a significant impact on the performance of the prepared mixture. After adding the steel slag component, the initial Marshall stability and 48-hour immersion Marshall stability of the asphalt mixture are improved to varying degrees compared with the asphalt mixture without steel slag. However, as the dosage of the steel slag increases, the mechanical effect of acting as an aggregate gradually decreases, resulting in a slight decrease in its Marshall stability. At the same time, the skeleton effects generated by steel slag with different particle sizes are different. When replacing 10% of the aggregate with steel slag with a lower particle size, although it can make the waterborne epoxy resin cure earlier and play a role after microwave heating, it still weakens the skeleton structure of the asphalt mixture compared with the initial ratio, and particles with larger or smaller particle sizes are likely to form an uneven heating effect in the mixture, reducing the overall heating rate and resulting in poor curing of the waterborne epoxy resin system and demulsification of the emulsified asphalt. The present invention controls the steel slag dosage at 10% and the particle size at 0.6 mm to 2.36 mm, which can effectively ensure the efficiency of the steel slag in converting electromagnetic energy into heat energy.

[0012] To optimize the above steps, the specific measures taken also include:

[0013] In step 1), the ratio of bisphenol A type epoxy resin E-51, polyethylene glycol PEG-4000, and potassium persulfate K 2 S 2 O 8 is n(E51):n(PEG-4000):n(K2S2O8) = 2.1:1:0.1.

[0014] In step 2), the solid content of the amine curing agent is 45-50%, the amine hydrogen equivalent is 220-280, the pH value is 9-10, the particle size is <2 μm, and it accounts for 3.5% of the mass of the overall waterborne epoxy emulsified asphalt binder. The self-made waterborne epoxy resin accounts for 8.75%-9.25% of the mass of the overall waterborne epoxy emulsified asphalt binder. BC-1 cationic emulsified asphalt accounts for 87.55%-90% of the mass of the overall waterborne epoxy emulsified asphalt binder. DF-220 is a mineral oil defoamer with 100% activity, non-silicone, excellent initial defoaming property and long-lasting foam suppression property, self-emulsifying in water, and does not contain alkylphenol ethoxylates, accounting for 0.2% of the mass of the overall waterborne epoxy emulsified asphalt binder.

[0015] In step 3), the chemical components of the steel slag such as Fe, Mg, Al, etc. should not be less than 80%, and the incorporation ratio is 10%-15% of the mass of the overall aggregate.

[0016] The beneficial effects of the present invention are as follows:

[0017] (1) Significantly improve the early mechanical properties of the mixture. A rigid skeleton is formed by the high hardness and porous structure of the steel slag aggregate, combined with the rapid cross-linking and curing of the waterborne epoxy resin. The early (7-day) compressive strength of the mixture can reach 12-18 MPa, which is 30%-50% higher than that of the traditional waterborne epoxy emulsified asphalt mixture (7-10 MPa), meeting the harsh requirements of heavy-duty traffic roads for early strength. At the same time, the flexural strength and toughness are enhanced. Experiments show that the 7-day flexural strength of the mixture is increased by 25%-40%, and the ultimate flexural tensile strain is increased by 15%-20%, significantly reducing the risk of early cracking after construction. After the steel slag is converted into electromagnetic energy, the waterborne epoxy resin system is rapidly cured, the construction efficiency is improved, and the curing period is shortened by 30%-40%. Its rapid curing characteristics make it suitable for construction in low-temperature environments, solving the problems of slow low-temperature curing and easy frost damage of traditional materials.

[0018] (2) The prepared steel slag modified early-strength waterborne epoxy emulsified asphalt mixture has excellent durability and stability. The porous structure of the steel slag adsorbs the light components in the asphalt, reducing the path of water intrusion. At the same time, the cured film of the epoxy resin forms a dense barrier. After the freeze-thaw cycle test (-18°C to 25°C for 10 cycles), the residual stability of the mixture is ≥85%, which is significantly improved compared with the unmodified mixture (≤70%). It effectively slows down asphalt aging and extends the service life of the road surface. The dynamic creep test (40°C, 0.7 MPa stress) shows that the fatigue life (10^5 cycles) of the modified mixture is 2-3 times higher than that of traditional materials, and it is suitable for high-traffic sections.

[0019] (3) It has the benefits of environmental protection and resource recycling. The steel slag content accounts for 10% of the total mass of the aggregates. Each ton of the mixture can consume 100 kg of steel slag, reducing the land occupation and heavy metal pollution caused by the stacking of steel slag (such as the leaching amounts of chromium and nickel are reduced by more than 50%). At the same time, the steel slag replaces part of the natural aggregates (such as basalt and limestone), reducing the ecological damage caused by the exploitation of natural stone. The utilization of steel slag can reduce the energy consumption in the production of the mixture. The steel slag aggregate does not require high-temperature calcination (natural aggregates require calcination at 1200 °C), and the CO 2 emission per ton of the mixture is reduced by about 50 kg. At the same time, the volatile organic compound (VOCs) emission of the waterborne epoxy emulsified asphalt system is < 50 mg / m 3 , far lower than that of the solvent-based epoxy asphalt (> 200 mg / m 3 ), improving the construction environment.

[0020] (4) It has excellent economic benefits and construction convenience. As an industrial waste residue, the procurement cost of steel slag is only 30% - 50% of that of natural aggregates, and the comprehensive cost of the mixture is reduced by 10% - 15%. The improvement of the early strength can shorten the road closure and maintenance time, reducing the indirect economic losses caused by traffic control. The good construction adaptability of the steel slag-modified early-strength waterborne epoxy emulsified asphalt mixture enables the mixture to be mixed at normal or low temperatures without special heating equipment, reducing the construction energy consumption, making it suitable for rapid repair scenarios such as thin layer overlay (2 - 5 cm) and pothole repair, and light traffic can be opened within 30 minutes. Specific embodiments

[0021] The present invention will be further described below in conjunction with the embodiments.

[0022] Example 1

[0023] A cold-mix type road rapid repair material based on the microwave thermal effect of steel slag and its preparation method include the following steps:

[0024] Weigh epoxy resin E-51 and let it stand at room temperature for a period of time. Since it is liquid at room temperature, it can be directly used without preheating. Add epoxy resin E-51 and polyethylene glycol PEG-4000 into a three-necked flask equipped with a stirrer and a thermometer. Start heating, set the temperature to 90 °C until the polyethylene glycol is completely dissolved. Then add potassium persulfate K 2 S 2 O 8As a catalyst, the ratio of bisphenol A epoxy resin E-51, polyethylene glycol PEG-4000 and potassium persulfate K2S2O8 is n(E51):n(PEG-4000):n(K2S2O8) = 2.1:1:0.1. Continue to heat up to 150 °C and start timing, and react for 3 hours. After the reaction, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier presents a viscous liquid state and can return to a transparent state after heating. Add the amine curing agent to the BC-1 cationic emulsified asphalt, stir evenly with a glass rod at 25 °C for 2-3 min, then add the defoaming agent DF220 and stir with a glass rod for 2 min. Finally, add the prepared waterborne epoxy resin and shear it with a high-speed shearer at 25 °C for 4 min to obtain the waterborne epoxy resin emulsified asphalt binder. Crush the steel slag to a particle size of 0.6 mm to 2.36 mm, wash it with 5% hydrochloric acid for 5 minutes, rinse it with deionized water until neutral, and weigh the steel slag, basalt, limestone aggregate and limestone powder. The mix proportion of basalt, limestone aggregate and limestone powder is shown in Table 1 below.

[0025] Table 1 Aggregate Mix Proportion

[0026] Sieve hole size (mm) 16.0 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 Upper limit of gradation 100 100 88 68 52 38 27 22 16 8 Lower limit of gradation 100 90 67 38 24 16 10 7 5 4 Median value of gradation 100 95 77.5 53 38 27 18.5 14.5 10.5 6

[0027] The steel slag accounts for 10% of the total aggregate mass, and then it is dried in an oven at 120 °C for 20-25 min, and then cooled to room temperature. Stir it with a mixture stirring pot at 25 °C for 2-3 min. Then weigh pure water and add it to the stirring pot to fully wet the aggregate and stir it at 25 °C for 2-3 min. Finally, add the prepared waterborne epoxy emulsified asphalt binder to the stirring pot and stir it at 25 °C for 3-5 min to obtain the steel slag modified early-strength waterborne epoxy emulsified asphalt mixture. Use a microwave heating device with 2.45 GHz and a power of 1000 to perform microwave treatment for 180 s to achieve the effect of pothole repair.

[0028] Comparative Example 1

[0029] A cold-mix type rapid road repair material based on the microwave thermal effect of steel slag and its preparation method include the following steps:

[0030] Weigh epoxy resin E-51 and let it stand at room temperature for a period of time. Since it is liquid at room temperature, it can be directly used without preheating. Add epoxy resin E-51 and polyethylene glycol PEG-4000 to a three-necked flask equipped with a stirrer and a thermometer. Start heating, set the temperature to 90 °C until the polyethylene glycol is completely dissolved. Then add potassium persulfate K 2 S 2 O 8As a catalyst, the ratio of bisphenol A epoxy resin E-51, polyethylene glycol PEG-4000 and potassium persulfate K2S2O8 is n(E51):n(PEG-4000):n(K2S2O8) = 2.1:1:0.1. Continue to heat up to 150 °C and start timing, and react for 3 hours. After the reaction, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier presents a viscous liquid state and can return to a transparent state after heating. Add the amine curing agent to the BC-1 cationic emulsified asphalt, stir evenly with a glass rod at 25 °C for 2-3 min, then add the defoaming agent DF220 and stir with a glass rod for 2 min, and finally add the prepared waterborne epoxy resin, and shear at 25 °C with a high-speed shearer for 4 min to obtain the waterborne epoxy resin emulsified asphalt binder. Crush the steel slag to a particle size of 2.36 mm - 9.5 mm, wash it with 5% hydrochloric acid for 5 minutes, rinse it with deionized water until neutral, and weigh the steel slag, basalt, limestone aggregate and limestone powder. The mix proportion of basalt, limestone aggregate and limestone powder is shown in Table 2 below.

[0031] Table 2 Aggregate Mix Proportion

[0032] Sieve hole size (mm) 16.0 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 Upper limit of gradation 100 100 88 68 52 38 27 22 16 8 Lower limit of gradation 100 90 67 38 24 16 10 7 5 4 Median value of gradation 100 95 77.5 53 38 27 18.5 14.5 10.5 6

[0033] The steel slag accounts for 10% of the total aggregate mass, and then it is dried in an oven at 120 °C for 20-25 min, and then cooled to room temperature. Stir at 25 °C room temperature for 2-3 min using a mixture stirring pot, then weigh pure water and add it to the stirring pot to fully wet the aggregate and stir at 25 °C room temperature for 2-3 min. Finally, add the prepared waterborne epoxy emulsified asphalt binder to the stirring pot and stir at 25 °C room temperature for 3-5 min to prepare the steel slag modified early-strength waterborne epoxy emulsified asphalt mixture. Use a microwave heating device with 2.45 GHz and a power of 1000 to perform microwave treatment for 180 s to achieve the effect of pothole repair.

[0034] Comparative Example 2

[0035] A cold-mix type rapid road repair material based on the microwave thermal effect of steel slag and its preparation method include the following steps:

[0036] Weigh epoxy resin E-51 and let it stand at room temperature for a period of time. Since it is liquid at room temperature, it can be used directly without preheating. Add epoxy resin E-51 and polyethylene glycol PEG-4000 to a three-necked flask equipped with a stirrer and a thermometer. Start heating, set the temperature to 90 °C until the polyethylene glycol is completely dissolved. Then add potassium persulfate K 2 S 2 O 8As a catalyst, the ratio of bisphenol A epoxy resin E-51, polyethylene glycol PEG-4000 and potassium persulfate K2S2O8 is n(E51):n(PEG-4000):n(K2S2O8) = 2.1:1:0.1. Continue to heat up to 150 °C and start timing, and react for 3 hours. After the reaction, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier presents a viscous liquid state and can return to a transparent state after heating. Add the amine curing agent to BC-1 cationic emulsified asphalt, stir evenly with a glass rod at 25 °C for 2 - 3 min, then add the defoaming agent DF220 and stir with a glass rod for 2 min. Finally, add the prepared waterborne epoxy resin and shear it with a high-speed shearer at 25 °C for 4 min to obtain the waterborne epoxy resin emulsified asphalt binder. Crush the steel slag to a particle size of 0.075 mm - 0.6 mm, wash it with 5% hydrochloric acid for 5 minutes, rinse it with deionized water until neutral, and weigh the steel slag, basalt, limestone aggregate and limestone powder. The mix proportion of basalt, limestone aggregate and limestone powder is shown in Table 3 below.

[0037] Table 3 Aggregate Mix Proportion

[0038] Sieve hole size (mm) 16.0 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 Upper limit of gradation 100 100 88 68 52 38 27 22 16 8 Lower limit of gradation 100 90 67 38 24 16 10 7 5 4 Median value of gradation 100 95 77.5 53 38 27 18.5 14.5 10.5 6

[0039] The steel slag accounts for 10% of the total aggregate mass, then dry it in an oven at 120 °C for 20 - 25 min, then cool it to room temperature and stir it with a mixture stirring pot at 25 °C for 2 - 3 min. Then weigh pure water and add it to the stirring pot to fully wet the aggregate and stir it at 25 °C for 2 - 3 min. Finally, add the prepared waterborne epoxy emulsified asphalt binder to the stirring pot and stir it at 25 °C for 3 - 5 min to prepare the steel slag modified early-strength waterborne epoxy emulsified asphalt mixture. Use a microwave heating device with 2.45 GHz and a power of 1000 for microwave treatment for 180 s to achieve the effect of pothole repair.

[0040] Comparative Example 3

[0041] A cold-mix type rapid road repair material based on the microwave thermal effect of steel slag and its preparation method include the following steps:

[0042] Weigh epoxy resin E-51 and let it stand at room temperature for a period of time. Since it is liquid at room temperature, it can be directly used without preheating. Add epoxy resin E-51 and polyethylene glycol PEG-4000 to a three-necked flask equipped with a stirrer and a thermometer. Start heating, set the temperature to 90 °C until the polyethylene glycol is completely dissolved. Then add potassium persulfate K 2 S 2 O 8As a catalyst, the ratio of bisphenol A epoxy resin E-51, polyethylene glycol PEG-4000 and potassium persulfate K2S2O8 is n(E51):n(PEG-4000):n(K2S2O8) = 2.1:1:0.1. Continue to heat up to 150 °C and start timing, and react for 3 hours. After the reaction, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier presents a viscous liquid state and can return to a transparent state after heating. Add the amine curing agent to the BC-1 cationic emulsified asphalt, stir evenly with a glass rod at 25 °C for 2-3 min, then add the defoamer DF220 and stir with a glass rod for 2 min. Finally, add the prepared waterborne epoxy resin and shear it with a high-speed shearer at 25 °C for 4 min to obtain the waterborne epoxy resin emulsified asphalt binder. Crush the steel slag to a particle size of 0.6 mm - 2.36 mm, wash it with 5% hydrochloric acid for 5 minutes, rinse it with deionized water until neutral, and weigh the steel slag, basalt, limestone aggregate and limestone powder. The mix proportion of basalt, limestone aggregate and limestone powder is shown in Table 4 below.

[0043] Table 4 Aggregate Mix Proportion

[0044]

[0045]

[0046] The steel slag accounts for 20% of the total aggregate mass, then dry it in an oven at 120 °C for 20 - 25 min, then cool it to room temperature and stir it with a mixture stirring pot at 25 °C for 2 - 3 min. Then weigh pure water and add it to the stirring pot to fully wet the aggregate and stir it at 25 °C for 2 - 3 min. Finally, add the prepared waterborne epoxy emulsified asphalt binder to the stirring pot and stir it at 25 °C for 3 - 5 min to obtain the steel slag modified early-strength waterborne epoxy emulsified asphalt mixture. Use a microwave heating device with 2.45 GHz and a power of 1000 to conduct microwave treatment for 180 s to achieve the effect of pothole repair.

[0047] Control Example 4

[0048] The traditional emulsified asphalt mixture is a commercially available product.

[0049] Control Example 5

[0050] The traditional waterborne epoxy emulsified asphalt mixture is a commercially available product.

[0051] Verification of Implementation Effect:

[0052] After the steel slag modified early-strength waterborne epoxy emulsified asphalt mixture prepared in Example 1 of the present invention is paved and formed, its early mechanical properties, water stability and durability are measured, and a comparative analysis is carried out with Comparative Examples 1-5 (including different steel slag particle sizes, dosages and traditional materials). Among them, the early mechanical properties are characterized by 7-day compressive strength (ASTM C39), 7-day flexural strength (ASTM C78) and ultimate flexural tensile strain (ASTM C1018); the water stability is evaluated by immersion Marshall stability (ASTM D6927) and freeze-thaw residual stability (AASHTO T283); the durability is determined by the dynamic creep test (EN 12697-25) to measure the fatigue life. The mixture gradation used in the experiment is the median value shown in Table 1, the binder is composed of waterborne epoxy resin (8.75%), BC-1 emulsified asphalt (87.55%), amine curing agent (3.5%) and defoaming agent (0.2%), the steel slag dosage is 10% of the total mass of the aggregate, the particle size range is 0.6-2.36 mm, and the microwave heating conditions are 2.45 GHz, power 1000 W and action time 180 s. In Comparative Examples 1-3, the steel slag particle size or dosage is adjusted respectively, and Comparative Examples 4-5 are traditional emulsified asphalt and waterborne epoxy emulsified asphalt mixtures. The test results are shown in the following table:

[0053] Table 5 Test Results

[0054]

[0055] It can be seen from the test results that the steel slag modified early-strength waterborne epoxy emulsified asphalt mixture prepared in Example 1 of the present invention is significantly superior to Comparative Examples 1-5 in terms of key indexes such as 7-day compressive strength (15.2 MPa), immersion Marshall stability (87.1%), and freeze-thaw residual stability (87.5%). Specifically, when the steel slag particle size is controlled at 0.6-2.36 mm and the dosage is 10%, the skeleton density and microwave thermal efficiency of the mixture reach the best synergistic effect. Compared with Comparative Example 1 (steel slag particle size 2.36-9.5 mm), the immersion Marshall stability (87.1%) of Example 1 is increased by 7.3%, and the freeze-thaw residual stability (87.5%) is increased by 10.6%. This is due to the continuous gradation structure formed after the optimization of the steel slag particle size and its high-efficient microwave absorbing ability (dielectric loss factor tanδ of Fe and Mg oxides = 0.62). Microwave heating (2.45 GHz, 1500 W, 180 s) rapidly raises the internal temperature of the mixture to 110 °C, accelerating the demulsification of the emulsified asphalt (moisture residue rate 0.6%) and the cross-linking of the waterborne epoxy resin (curing degree 95%), so as to maintain high stability under immersion conditions. In Comparative Example 2 (steel slag particle size 0.075-0.6 mm), due to the too high proportion of fine particles (8.2% passing rate of 0.075 mm sieve vs median value of gradation 6%), the skeleton density is damaged, the immersion Marshall stability (80.6%) is decreased by 7.5% compared with Example 1, and the microwave heating efficiency is low (heating rate 5 °C / s), and the dynamic creep fatigue life (7.2×10 4Secondly, it is only 47% of that in Example 1. From the perspective of the influence of the dosage, when 10% of natural aggregates are replaced by steel slag in Example 1, its angularity (angular coefficient 1.5) complements that of basalt (1.2) and limestone (1.0), and the Marshall stability (12.4 kN) is increased by 72% compared with the traditional emulsified asphalt mixture (Comparative Example 4, 7.2 kN). In Comparative Example 3 (steel slag dosage 20%), due to the extrusion of the basalt skeleton by excessive steel slag (the proportion of basalt decreased from 45% to 35%), the construction compaction degree is only 93% (97% in Example 1), and the free calcium oxide in the steel slag swells when encountering water to generate internal stress, resulting in the freeze-thaw residual stability (82.1%) decreasing by 6.2% compared with Example 1. From the analysis of the material modification mechanism, in Example 1, bisphenol A epoxy resin E51 (epoxy value 0.51) and amine curing agent (amine hydrogen equivalent 250) form a three-dimensional cross-linked network under microwave heating, and its flexural strength (3.6 MPa) and ultimate flexural tensile strain (1.42%) are increased by 38.5% and 20.3% respectively compared with the traditional waterborne epoxy emulsified asphalt mixture (Comparative Example 5, 2.6 MPa, 1.18%). In Comparative Example 5, due to the lack of heat generation by the steel slag absorbing waves, the epoxy resin relies on natural curing, the cross-linking density is low, and the residual water results in the freeze-thaw residual stability (68.9%) being much lower than that in Example 1. Further, the Fe(OH)3 microcrystalline layer generated by cleaning the steel slag surface with 5% hydrochloric acid enhances the chemical adhesion force with the asphalt, and the stability of 87.1% can still be maintained under the immersion condition, which is 23.0% higher than that in Comparative Example 4 (traditional emulsified asphalt, 70.8%), proving that the steel slag-epoxy synergy has a significant effect on water damage protection. Compared with Comparative Example 4 (traditional emulsified asphalt), the environmental protection and economic benefits of Example 1 are more prominent: 100 kg of steel slag is consumed per ton of the mixture, reducing CO 2 emissions by 50 kg, and the traffic can be opened 30 minutes after 180 s of microwave heating, with the efficiency increased by 12 times compared with the natural curing (6 hours) in Comparative Example 5, and the comprehensive cost reduced by 10% - 15%. In Comparative Examples 1 - 3, due to unbalanced gradation or improper dosage, there are significant defects in mechanical properties, durability and environmental protection, further highlighting the foresight of the "steel slag particle size - dosage - microwave" ternary synergy design in the present invention.

[0056] From the test results of the examples and comparative examples, the present invention realizes the comprehensive improvement of the early strength, water stability and construction efficiency of the mixture by controlling the steel slag particle size (0.6 - 2.36 mm) and dosage (10%), combined with the rapid cross-linking of waterborne epoxy resin and microwave heating technology. In Comparative Examples 1 - 5, due to gradation damage, low wave absorption efficiency or lack of modification, the necessity of refined utilization of steel slag and multi-technology synergy is verified.

Claims

1. A cold-mixed road rapid repair material based on the microwave thermal effect of steel slag and a preparation method thereof, characterized in that: The following steps are involved: 1) Weigh epoxy resin E-51 and let it stand at room temperature for a while. Since it is liquid at room temperature, it can be used directly without preheating. Add epoxy resin E-51 and polyethylene glycol PEG-4000 to a three-necked flask equipped with a stirrer and a thermometer. Start heating and set the temperature to 90°C until the polyethylene glycol is completely dissolved. Then add potassium persulfate K2S2O8 as a catalyst, continue to heat to 150°C and start timing, and react for 3 hours. After the reaction is completed, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier appears in a viscous liquid state, and it can return to a transparent state after heating. 2) Add the amine curing agent to the BC-1 cationic emulsified asphalt, stir evenly with a glass rod at 25°C for 2 to 3 minutes, then add the DF220 defoamer and stir with a glass rod for 1 to 2 minutes, finally add the water-based epoxy resin prepared in 1), and shear with a high-speed shearing machine at 25°C for 3 to 5 minutes to obtain a water-based epoxy resin emulsified asphalt binder. 3) The steel slag is crushed to a target particle size (0.6 mm to 2.36 mm), washed with 5% hydrochloric acid for 5 minutes, rinsed with deionized water until neutral, steel slag, basalt, limestone aggregate and limestone powder are weighed and dried in an oven at 120°C for 20 to 25 minutes, then cooled to room temperature and stirred in a mixture stirring pot at 25°C for 2 to 3 minutes, then purified water is weighed and added to the stirring pot to fully wet the aggregate and stirred at 25°C for 2 to 3 minutes, finally, the water-based epoxy emulsified asphalt binder prepared in 2) is added to the stirring pot, and stirred at 25°C for 3 to 5 minutes to obtain a steel slag modified early-strength water-based epoxy emulsified asphalt mixture. 4) The steel slag modified early-strength water-based epoxy emulsified asphalt mixture prepared in 3) is spread into the potholes of the road, and after rolling, it is subjected to microwave treatment for 150s to 200s using a 2.45GHz, 1000-1500W power microwave heating device to achieve the purpose of pothole repair.

2. The cold-mixed road rapid repair material based on the microwave thermal effect of steel slag and the preparation method thereof according to claim 1, characterized in that: In step 1), the ratio of bisphenol A epoxy resin E-51, polyethylene glycol PEG-4000 and potassium persulfate K2S2O8 is n(E51):n(PEG-4000):n(K2S2O8)=2.1:1:0.

1.

3. The cold-mixed road rapid repair material based on the microwave thermal effect of steel slag and the preparation method thereof according to claim 1, characterized in that: In step 2), the solid content of the amine curing agent is 45-50%, the amine hydrogen equivalent is 220-280, the pH value is 9-10, the particle size is <2μm, and it accounts for 3.5% of the total mass of the water-based epoxy emulsified asphalt binder. The homemade water-based epoxy resin accounts for 8.75%-9.25% of the total mass of the water-based epoxy emulsified asphalt binder. The BC-1 cationic emulsified asphalt accounts for 87.55%-90% of the total mass of the water-based epoxy emulsified asphalt binder. DF-220 is a mineral oil defoamer, 100% active, non-silicone, with excellent initial defoaming and long-lasting antifoaming properties, self-emulsifies in water, does not contain alkylphenol ethoxylates, and accounts for 0.2% of the total mass of the water-based epoxy emulsified asphalt binder.

4. The cold-mixed road rapid repair material based on the microwave thermal effect of steel slag and the preparation method thereof according to claim 1, characterized in that: In step 3), the chemical components of the steel slag in step 3, such as Fe, Mg, Al, etc., should not be less than 80%, and the proportion of the admixture is 10-15% of the total aggregate mass.

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