A cold-mixed rapid road repairing material based on steel slag microwave heat effect and a preparation method thereof

Abstract

The application discloses a kind of cold-mixed type road rapid repair material based on steel slag microwave heat effect and preparation method thereof, belong to road repair material technical field.The method includes the following steps: bisphenol A type epoxy resin E51 is reacted with polyethylene glycol PEG-4000 under the action of catalyst to prepare water-based epoxy resin;Amine curing agent, defoaming agent and BC-1 cationic emulsified asphalt are mixed and then introduced into water-based epoxy resin, and adhesive is prepared by shearing;Crushed and sieved steel slag (particle size 0.6-2.36mm) is mixed with basalt and limestone aggregate according to gradation, and after drying and infiltration, it is mixed with the adhesive, and finally it is rapidly cured and formed by microwave heating.The application first proposes to use steel slag as electromagnetic responsive aggregate, combined with the rapid crosslinking characteristics of water-based epoxy resin and microwave heating technology, to synergistically improve the early strength, water stability and fatigue resistance of emulsified asphalt mixture, while realizing the resource utilization of industrial solid waste and reducing construction energy consumption, providing an efficient, convenient, high-strength, durable and environmentally friendly solution for road damage rapid repair.

Description

Technical Field

[0001] This application relates to the field of road repair materials technology, specifically to a cold-mixed rapid road repair material based on the microwave thermal effect of steel slag and its preparation method. Background Technology

[0002] With the rapid development of modern road construction technology, asphalt concrete pavement has become the main construction form for high-grade roads. Asphalt pavement has advantages such as driving comfort, short construction period, and simple maintenance. However, due to frequent heavy traffic and vehicle overloading, the performance of a considerable portion of asphalt concrete pavement has been drastically reduced, leading to frequent early damage such as potholes. If early damage is not repaired in time, moisture may seep into the pavement base, subbase, or subgrade through the broken surface, thereby accelerating damage to the road structure and shortening the expected service life of the road. Potholes in asphalt pavement refer to localized deterioration of the asphalt pavement, in which the paving material decomposes and is lost in a short period of time, resulting in steep depressions. It is usually formed by the long-term combined effects of water, vehicle loads, and other environmental factors. According to relevant surveys, the impact load on a road surface when potholes occur is about twice that of a normal road surface. This situation is extremely prone to accidents, causing huge economic losses. Traditional repair techniques, due to their long construction period and delayed traffic opening time, often lead to widespread congestion and increase social operating costs. Rapid repair asphalt mixtures can complete the treatment of defects in a short time and enable rapid reopening of traffic. This not only significantly reduces the impact of traffic interruptions on the public, but also reduces the risk and maintenance cost of secondary repairs. It can effectively improve the emergency maintenance capabilities of transportation infrastructure and provide technical support for ensuring the efficient operation of modern transportation systems.

[0003] Emulsified asphalt mixture is a cold-mix, cold-paveable material using emulsified asphalt as the binder. Compared to traditional hot-mix asphalt mixtures, its construction can be carried out at room temperature, without emitting harmful gases, and it features energy conservation and environmental protection, aligning with the concept of green development. Studies have shown that waterborne epoxy resin has good compatibility with emulsified asphalt, significantly improving the mechanical properties, high-temperature performance, and water stability of the mixture. Waterborne epoxy emulsified asphalt significantly increases viscosity by introducing a waterborne epoxy resin system into emulsified asphalt, thereby improving the high-temperature and water stability of the emulsified asphalt mixture. Although emulsified asphalt mixtures demonstrate environmental and energy-saving advantages as an important raw material for road maintenance, their strength depends on the gradual evaporation of internal moisture, resulting in insufficient early strength, weak durability, and poor water stability. Furthermore, the curing process of waterborne epoxy resin involves multiple steps, including moisture evaporation, emulsion bead aggregation, curing agent mass transfer, and cross-linking reaction, to achieve strength. Therefore, after paving, it is crucial to promote the rapid evaporation of moisture from the emulsified asphalt and the rapid curing of the waterborne epoxy resin to achieve sufficient strength.

[0004] In recent years, the application of microwave heating technology to accelerate the evaporation of moisture in paved emulsified asphalt mixtures has attracted attention, and microwaves have been widely developed in accelerating the demulsification of emulsified asphalt. Addressing the problems of low early strength, weak durability, and poor water stability in water-based epoxy emulsified asphalt mixtures, this invention, based on traditional research on water-based epoxy emulsified asphalt mixtures, introduces steel slag material and uses microwave heating technology to convert electromagnetic energy into thermal energy, significantly improving the early strength and water stability of water-based epoxy emulsified asphalt mixtures. Summary of the Invention

[0005] This invention addresses the problems of low early strength, weak durability, and poor water stability in current waterborne epoxy emulsified asphalt mixtures. It prepares a binder using nonionic waterborne epoxy resin, amine curing agent, DF220 defoamer, and BC-1 cationic emulsified asphalt, and uses basalt, limestone, and steel slag as aggregates to prepare a steel slag-modified early-strength waterborne epoxy emulsified asphalt mixture. This mixture exhibits high early strength and significantly improves the shortcomings of insufficient early strength and poor water stability inherent in current waterborne epoxy emulsified asphalt mixtures.

[0006] To achieve the above-mentioned objectives and advantages of the present invention, a cold-mixed rapid road repair material based on the microwave thermal effect of steel slag and its preparation method are provided, comprising the following steps:

[0007] 1) Weigh out 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 thermometer. Start heating, setting the temperature to 90℃, until the polyethylene glycol is completely dissolved. Then add potassium persulfate (K2S2O8) as a catalyst, continue heating to 150℃ and start timing, reacting for 3 hours. After the reaction is complete, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier becomes a viscous liquid, which can be restored to a transparent state upon heating.

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

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

[0010] 4) The steel slag modified early-strength waterborne epoxy emulsified asphalt mixture prepared in 3) is spread into the road potholes and compacted. Then, it is microwaved for 150s to 200s using a 2.45GHz microwave heating device with a power of 1000 to 1500W to achieve the effect of pothole repair.

[0011] The present invention relates to a cold-mix road rapid repair material based on the microwave thermal effect of steel slag and its preparation method. The key feature is that the selected epoxy resin is bisphenol A epoxy resin E51, which is used to prepare waterborne epoxy resin to modify BC-1 cationic emulsified asphalt. Its advantages mainly lie in the synergistic effect of molecular structure and material properties. Specifically, the bisphenol A epoxy resin E51 molecular chain contains a high density of epoxy (-O-) and hydroxyl (-OH) active groups. Its molecular formula is CH3-(CH2)6-O-CH2-CH2-O-(CH2)6-CH3, exhibiting a linear oligomer structure, a high epoxy value (0.48-0.54), and strong reactivity. After curing, a three-dimensional cross-linked network is formed through an amine curing agent, enhancing the material's mechanical strength and chemical resistance. The epoxy and hydroxyl groups in the bisphenol A epoxy resin E51 can chemically react with the active groups in the emulsified asphalt to form stable chemical bonds. Furthermore, the chemical composition, dosage, and particle size of steel slag have a significant impact on the performance of the prepared mixture. After incorporating steel slag, the initial Marshall stability and 48-hour immersion Marshall stability of the asphalt mixture are improved to varying degrees compared to the asphalt mixture without steel slag. However, as the dosage of steel slag increases, its mechanical effect as aggregate gradually decreases, leading to a slight decrease in its Marshall stability. Simultaneously, steel slag with different particle sizes produces different skeletal effects. When replacing 10% of the aggregate with steel slag of smaller particle size, it significantly affects the original gradation ratio. Although microwave heating allows the waterborne epoxy resin to cure earlier and function, it still weakens the skeletal structure of the asphalt mixture compared to the initial ratio. Larger or smaller particles tend to create uneven heating effects in the mixture, reducing the overall heating rate and resulting in poor curing of the waterborne epoxy resin system and poor demulsification of the emulsified asphalt. This invention controls the steel slag content to 10% and the particle size to 0.6mm to 2.36mm, which can effectively ensure the efficiency of the steel slag in converting electromagnetic energy into thermal energy.

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

[0013] 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.

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

[0015] In step 3), the chemical composition of steel slag, including Fe, Mg, Al, etc., should not be less than 80%, and the proportion of its admixture should be 10% to 15% of the total aggregate mass.

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

[0017] (1) Significantly improves the early mechanical properties of the mixture. The high hardness and porous structure of the steel slag aggregate form a rigid skeleton, which, combined with the rapid cross-linking and curing of waterborne epoxy resin, allows the early (7-day) compressive strength of the mixture to reach 12-18 MPa, an increase of 30%-50% compared to traditional waterborne epoxy emulsified asphalt mixtures (7-10 MPa), meeting the stringent early strength requirements of heavy-duty traffic pavements. Simultaneously, flexural strength and toughness are enhanced. Experiments show that the 7-day flexural strength of the mixture increases by 25%-40%, and the ultimate tensile strain increases by 15%-20%, significantly reducing the risk of early cracking after construction. The conversion of electromagnetic energy from steel slag enables rapid curing of the waterborne epoxy resin system, improving construction efficiency and shortening the curing cycle by 30%-40%. The rapid curing characteristic makes it suitable for construction in low-temperature environments, solving the problems of slow low-temperature curing and susceptibility to frost damage associated with traditional materials.

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

[0019] (3) It offers environmental and resource recycling benefits. Steel slag accounts for 10% of the total aggregate mass, and each ton of mixture can absorb 100 kg of steel slag, reducing land occupation and heavy metal pollution caused by steel slag stockpiling (e.g., reducing chromium and nickel leaching by more than 50%). Simultaneously, steel slag replaces some natural aggregates (such as basalt and limestone), reducing the ecological damage caused by natural stone mining. The utilization of steel slag reduces energy consumption in mixture production, as steel slag aggregate does not require high-temperature calcination (natural aggregate requires calcination at 1200℃), reducing CO2 emissions by approximately 50 kg per ton of mixture. Furthermore, the volatile organic compound (VOC) emissions of the water-based epoxy emulsified asphalt system are <50 mg / m³. 3 It is far lower than that of solvent-based epoxy asphalt (>200mg / m³). 3 ), to improve the construction environment.

[0020] (4) Excellent economic benefits and ease of construction: As an industrial waste, steel slag has a procurement cost of only 30%-50% of that of natural aggregates, reducing the overall cost of the mixture by 10%-15%. Early strength enhancement can shorten road closure maintenance time and reduce indirect economic losses caused by traffic control. The good construction adaptability of steel slag modified early strength waterborne epoxy emulsified asphalt mixture allows the mixture to be mixed at normal or low temperature without the need for special heating equipment, reducing construction energy consumption and making it suitable for rapid repair scenarios such as thin overlay (2-5cm) and pothole repair, allowing light traffic to be opened within 30 minutes. Detailed Implementation

[0021] The present invention will be further described below with reference to the embodiments.

[0022] Example 1

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

[0024] Weigh out 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 thermometer. Start heating, setting the temperature to 90℃, until the polyethylene glycol is completely dissolved. Then add potassium persulfate K2S2O8 as 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 heating to 150℃ and start timing, reacting for 3 hours. After the reaction is complete, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier becomes a viscous liquid, which can be restored to a transparent state upon heating. An amine curing agent was added to BC-1 cationic emulsified asphalt and stirred with a glass rod for 2-3 minutes at 25°C. Then, defoamer DF220 was added and stirred with a glass rod for 2 minutes. Finally, the prepared waterborne epoxy resin was added, and the mixture was sheared with a high-speed shearing machine at 25°C for 4 minutes to obtain waterborne epoxy resin emulsified asphalt binder. Steel slag was crushed to a particle size of 0.6 mm-2.36 mm, washed with 5% hydrochloric acid for 5 minutes, and rinsed with deionized water until neutral. Steel slag, basalt, limestone aggregate, and limestone powder were weighed. The proportions of basalt, limestone aggregate, and limestone powder are shown in Table 1 below.

[0025] Table 1 Aggregate mix proportions

[0026] Sieve aperture 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 grade 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 of gradation 100 95 77.5 53 38 27 18.5 14.5 10.5 6

[0027] Steel slag accounts for 10% of the total aggregate mass. It is then dried in an oven at 120℃ for 20–25 minutes, cooled to room temperature, and stirred in a mixing pot at 25℃ for 2–3 minutes. Pure water is then added to the mixing pot to fully wet the aggregate, and the mixture is stirred at 25℃ for 2–3 minutes. Finally, the prepared water-based epoxy emulsified asphalt binder is added to the mixing pot, and the mixture is stirred at 25℃ for 3–5 minutes to obtain a steel slag-modified early-strength water-based epoxy emulsified asphalt mixture. This mixture is then microwaved for 180 seconds using a 2.45GHz, 1000W microwave heating device to achieve pothole repair.

[0028] Comparative Example 1

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

[0030] Weigh out 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 thermometer. Start heating, setting the temperature to 90℃, until the polyethylene glycol is completely dissolved. Then add potassium persulfate K2S2O8 as 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 heating to 150℃ and start timing, reacting for 3 hours. After the reaction is complete, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier becomes a viscous liquid, which can be restored to a transparent state upon heating. An amine curing agent was added to BC-1 cationic emulsified asphalt and stirred with a glass rod for 2-3 minutes at 25°C. Then, defoamer DF220 was added and stirred with a glass rod for 2 minutes. Finally, the prepared waterborne epoxy resin was added, and the mixture was sheared with a high-speed shearing machine at 25°C for 4 minutes to obtain waterborne epoxy resin emulsified asphalt binder. Steel slag was crushed to a particle size of 2.36 mm to 9.5 mm, washed with 5% hydrochloric acid for 5 minutes, and rinsed with deionized water until neutral. Steel slag, basalt, limestone aggregate, and limestone powder were weighed. The proportions of basalt, limestone aggregate, and limestone powder are shown in Table 2 below.

[0031] Table 2 Aggregate mix proportions

[0032] Sieve aperture 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 grade 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 of gradation 100 95 77.5 53 38 27 18.5 14.5 10.5 6

[0033] Steel slag accounts for 10% of the total aggregate mass. It is then dried in an oven at 120℃ for 20–25 minutes, cooled to room temperature, and stirred in a mixing pot at 25℃ for 2–3 minutes. Pure water is then added to the mixing pot to fully wet the aggregate, and the mixture is stirred at 25℃ for 2–3 minutes. Finally, the prepared water-based epoxy emulsified asphalt binder is added to the mixing pot, and the mixture is stirred at 25℃ for 3–5 minutes to obtain a steel slag-modified early-strength water-based epoxy emulsified asphalt mixture. This mixture is then microwaved for 180 seconds using a 2.45GHz, 1000W microwave heating device to achieve pothole repair.

[0034] Comparative Example 2

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

[0036] Weigh out 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 thermometer. Start heating, setting the temperature to 90℃, until the polyethylene glycol is completely dissolved. Then add potassium persulfate K2S2O8 as 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 heating to 150℃ and start timing, reacting for 3 hours. After the reaction is complete, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier becomes a viscous liquid, which can be restored to a transparent state upon heating. An amine curing agent was added to BC-1 cationic emulsified asphalt and stirred with a glass rod for 2-3 minutes at 25°C. Then, defoamer DF220 was added and stirred with a glass rod for 2 minutes. Finally, the prepared waterborne epoxy resin was added, and the mixture was sheared with a high-speed shearing machine at 25°C for 4 minutes to obtain waterborne epoxy resin emulsified asphalt binder. Steel slag was crushed to a particle size of 0.075 mm-0.6 mm, washed with 5% hydrochloric acid for 5 minutes, and rinsed with deionized water until neutral. Steel slag, basalt, limestone aggregate, and limestone powder were weighed. The proportions of basalt, limestone aggregate, and limestone powder are shown in Table 3 below.

[0037] Table 3 Aggregate mix proportions

[0038] Sieve aperture 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 grade 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 of gradation 100 95 77.5 53 38 27 18.5 14.5 10.5 6

[0039] Steel slag accounts for 10% of the total aggregate mass. It is then dried in an oven at 120℃ for 20–25 minutes, cooled to room temperature, and stirred in a mixing pot at 25℃ for 2–3 minutes. Pure water is then added to the mixing pot to fully wet the aggregate, and the mixture is stirred at 25℃ for 2–3 minutes. Finally, the prepared water-based epoxy emulsified asphalt binder is added to the mixing pot, and the mixture is stirred at 25℃ for 3–5 minutes to obtain a steel slag-modified early-strength water-based epoxy emulsified asphalt mixture. This mixture is then microwaved for 180 seconds using a 2.45GHz, 1000W microwave heating device to achieve pothole repair.

[0040] Comparative Example 3

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

[0042] Weigh out 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 thermometer. Start heating, setting the temperature to 90℃, until the polyethylene glycol is completely dissolved. Then add potassium persulfate K2S2O8 as 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 heating to 150℃ and start timing, reacting for 3 hours. After the reaction is complete, a clear yellow liquid is obtained, which is the emulsifier. After cooling to room temperature, the emulsifier becomes a viscous liquid, which can be restored to a transparent state upon heating. An amine curing agent was added to BC-1 cationic emulsified asphalt and stirred with a glass rod for 2-3 minutes at 25°C. Then, defoamer DF220 was added and stirred with a glass rod for 2 minutes. Finally, the prepared waterborne epoxy resin was added, and the mixture was sheared with a high-speed shearing machine at 25°C for 4 minutes to obtain waterborne epoxy resin emulsified asphalt binder. Steel slag was crushed to a particle size of 0.6mm-2.36mm, washed with 5% hydrochloric acid for 5 minutes, and rinsed with deionized water until neutral. The steel slag, basalt, limestone aggregate, and limestone powder were weighed. The proportions of basalt, limestone aggregate, and limestone powder are shown in Table 4 below.

[0043] Table 4 Aggregate Mix Proportion

[0044]

[0045]

[0046] Steel slag accounts for 20% of the total aggregate mass. It is then dried in an oven at 120℃ for 20–25 minutes, cooled to room temperature, and stirred in a mixing pot at 25℃ for 2–3 minutes. Next, pure water is weighed and added to the mixing pot to fully wet the aggregate, and the mixture is stirred at 25℃ for 2–3 minutes. Finally, the prepared water-based epoxy emulsified asphalt binder is added to the mixing pot, and the mixture is stirred at 25℃ for 3–5 minutes to obtain a steel slag-modified early-strength water-based epoxy emulsified asphalt mixture. This mixture is then microwaved for 180 seconds using a 2.45GHz, 1000W microwave heating device to achieve pothole repair.

[0047] Comparative Example 4

[0048] Traditional emulsified asphalt mixtures are commercially available products.

[0049] Comparative Example 5

[0050] Traditional water-based epoxy emulsified asphalt mixtures are commercially available products.

[0051] Implementation effect verification:

[0052] The steel slag-modified early-strength waterborne epoxy emulsified asphalt mixture prepared in Example 1 of this invention was laid and molded. Its early mechanical properties, water stability, and durability were measured and compared with those of Comparative Examples 1-5 (including different steel slag particle sizes, admixtures, and traditional materials). Early mechanical properties were characterized by 7-day compressive strength (ASTM C39), 7-day flexural strength (ASTM C78), and ultimate tensile strain (ASTM C1018). Water stability was evaluated using immersion Marshall stability (ASTM D6927) and freeze-thaw residual stability (AASHTO T283). Durability was determined by dynamic creep testing (EN 12697-25) to measure fatigue life. The mixture gradation used in the experiment was the median value shown in Table 1. The binder consisted of waterborne epoxy resin (8.75%), BC-1 emulsified asphalt (87.55%), amine curing agent (3.5%), and defoamer (0.2%). The steel slag content was 10% of the total aggregate mass, with a particle size range of 0.6–2.36 mm. The microwave heating conditions were 2.45 GHz, 1000 W power, and 180 s reaction time. Comparative Examples 1-3 had their steel slag particle size or content adjusted, while Comparative Examples 4-5 were traditional emulsified asphalt and waterborne epoxy emulsified asphalt mixtures. The test results are shown in the table below:

[0053] Table 5 Test Results

[0054]

[0055] The test results show that the steel slag-modified early-strength waterborne epoxy emulsified asphalt mixture prepared in Example 1 of this invention significantly outperforms Comparative Examples 1-5 in key indicators such as 7-day compressive strength (15.2 MPa), water immersion Marshall stability (87.1%), and freeze-thaw residual stability (87.5%). Specifically, when the steel slag particle size is controlled between 0.6 and 2.36 mm and the admixture is 10%, the aggregate skeleton density and microwave thermal efficiency achieve the best synergistic effect. Compared with Comparative Example 1 (steel slag particle size 2.36–9.5 mm), the water 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 attributed to the continuous gradation structure formed after the steel slag particle size optimization and its efficient microwave absorption capability (Fe and Mg oxide dielectric loss factor tanδ = 0.62). Microwave heating (2.45 GHz, 1500 W, 180 s) rapidly raised the internal temperature of the mixture to 110 °C, accelerating the demulsification of emulsified asphalt (moisture residue 0.6%) and crosslinking of waterborne epoxy resin (curing degree 95%), thus maintaining high stability even under immersion conditions. In contrast, Comparative Example 2 (steel slag particle size 0.075–0.6 mm) had an excessively high proportion of fine particles (0.075 mm sieve passing rate 8.2% vs. median gradation 6%), which compromised the skeleton's density. Its immersion Marshall stability (80.6%) decreased by 7.5% compared to Example 1, and its microwave heating efficiency was low (heating rate 5 °C / s), resulting in a lower dynamic creep fatigue life (7.2 × 10⁻⁶). 4The percentage of steel slag in Example 1 was only 47% of that in Example 1. Regarding the impact of admixture dosage, in Example 1, when steel slag replaced 10% of natural aggregate, its angularity (angularity coefficient 1.5) complemented that of basalt (1.2) and limestone (1.0), resulting in a 72% increase in Marshall stability (12.4 kN) compared to the traditional emulsified asphalt mixture (Comparative Example 4, 7.2 kN). However, in Comparative Example 3 (20% steel slag), excessive steel slag compressed the basalt skeleton (reducing the basalt percentage from 45% to 35%), resulting in a compaction degree of only 93% (compared to 97% in Example 1). Furthermore, the free calcium oxide in the steel slag swelled upon contact with water, generating internal stress, leading to a 6.2% decrease in freeze-thaw residual stability (82.1%) compared to Example 1. Analysis of the material modification mechanism shows that in Example 1, the bisphenol A type epoxy resin E51 (epoxy value 0.51) and the amine curing agent (amine hydrogen equivalent 250) formed a three-dimensional cross-linked network under microwave heating. Its flexural strength (3.6 MPa) and ultimate tensile strain (1.42%) were increased by 38.5% and 20.3% respectively compared to the traditional waterborne epoxy emulsified asphalt mixture (Comparative Example 5, 2.6 MPa, 1.18%). In contrast, Comparative Example 5, lacking the heat generated by steel slag microwave absorption, relied on natural curing of the epoxy resin, resulting in a lower cross-linking density and residual moisture, leading to a freeze-thaw residual stability (68.9%) far lower than that of Example 1. Furthermore, the Fe(OH)3 microcrystalline layer generated by cleaning the steel slag surface with 5% hydrochloric acid enhanced the chemical adhesion to the asphalt, maintaining a stability of 87.1% even under immersion conditions, a 23.0% increase compared to Comparative Example 4 (traditional emulsified asphalt, 70.8%), demonstrating the significant effect of the steel slag-epoxy synergistic effect on water damage protection. Compared with Comparative Example 4 (traditional emulsified asphalt), Example 1 demonstrates significantly greater environmental and economic benefits: each ton of mixture absorbs 100 kg of steel slag, reducing CO2 emissions by 50 kg, and traffic can be opened after 30 minutes of microwave heating for 180 seconds, representing a 12-fold increase in efficiency compared to the natural curing (6 hours) of Comparative Example 5, with a 10%–15% reduction in overall cost. Comparative Examples 1–3, due to gradation imbalance or improper dosage, exhibit significant defects in mechanical properties, durability, and environmental friendliness, further highlighting the forward-looking nature of the "steel slag particle size-dosage-microwave" ternary synergistic design in this invention.

[0056] Based on the test results of the examples and comparative examples, this invention, by controlling the particle size (0.6–2.36 mm) and dosage (10%) of steel slag, combined with rapid crosslinking of waterborne epoxy resin and microwave heating technology, achieves a comprehensive improvement in the early strength, water stability, and construction efficiency of the mixture. Comparative examples 1-5, however, suffer from gradation damage, low microwave absorption efficiency, or lack of modification, verifying the necessity of refined utilization of steel slag and multi-technology synergy.

Claims

1. A method for preparing a cold-mixed rapid road repair material based on the microwave thermal effect of steel slag, characterized in that, Includes the following steps: (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 used directly without preheating. Add epoxy resin E-51 and polyethylene glycol PEG-4000 to a three-necked flask equipped with a stirrer and 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 heating to 150°C and start timing. 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 is in a viscous liquid state. It can be restored to a transparent state after heating. (2) Add amine curing agent to BC-1 cationic emulsified asphalt and stir evenly with a glass rod for 2-3 minutes at 25°C. Then add DF220 defoamer and stir with a glass rod for 1-2 minutes. Finally add the waterborne epoxy resin prepared in (1) and shear with a high-speed shearing machine at 25°C for 3-5 minutes to obtain waterborne epoxy resin emulsified asphalt binder. (3) Crush the steel slag to the target particle size of 0.6mm to 2.36mm, 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 mineral powder, dry them in an oven at 120℃ for 20 to 25 minutes, then cool them to room temperature and stir them at room temperature at 25℃ for 2 to 3 minutes. Then weigh pure water and add it to the mixing pot to fully wet the aggregate and stir it at room temperature at 25℃ for 2 to 3 minutes. Finally, add the water-based epoxy emulsified asphalt binder prepared in step (2) to the mixing pot and stir it at room temperature at 25℃ for 3 to 5 minutes to obtain the steel slag modified early strength water-based epoxy emulsified asphalt mixture. (4) The steel slag modified early strength waterborne epoxy emulsified asphalt mixture prepared in step (3) is spread into the road potholes and compacted. Then, it is microwaved for 150s to 200s using a microwave heating device with a power of 1000 to 1500W at 2.45GHz to achieve the effect of pothole repair.

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

4. The preparation method of a cold-mixed rapid road repair material based on the microwave thermal effect of steel slag according to claim 1, characterized in that: In step (3), the chemical composition of steel slag, including Fe, Mg, and Al, should not be less than 80%.

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