Modified household garbage incineration slag based self-curing pavement base material and preparation method thereof

Abstract

This invention discloses a self-curing road base material based on modified municipal solid waste incinerator slag and its preparation method, belonging to the field of road base material preparation technology. It addresses the technical problem that the water retention, crack resistance, and durability of existing road base materials need further improvement. Specifically, it includes the following steps: dry-mixing cement, aggregate, and hydrophilic modified slag aggregate evenly in a mixer, adding mixing water, and mixing evenly to obtain a mixture. This invention uses pretreated municipal solid waste incinerator slag as functional aggregate, introducing a hydrophilic functional layer composed of dopamine copolymer, self-healing modified silica sol, and sodium polyacrylate into its pores to synergistically enhance the aggregate-cement interface properties, thereby improving the water retention, crack resistance, and durability of the base material.

Description

Technical Field

[0001] This invention relates to the field of road base material preparation technology, specifically to a self-curing road base material based on modified municipal solid waste incinerator slag and its preparation method. Background Technology

[0002] Road base course materials are mainly composed of cement-stabilized crushed stone, recycled aggregate stabilized materials, and various types of cementitious stabilized soil. Performance evaluation increasingly emphasizes the synergy of strength, volume stability, and durability. In engineering practice, in order to meet the requirements of rapid construction and long-term service, the early strength of base course materials can be guaranteed by optimizing gradation, cementing system, and curing conditions. However, under the action of dryness, temperature difference, and repeated loading, the drying shrinkage and thermal shrinkage caused by water loss in the base course can still easily induce micro-cracks, which in turn form through cracks and reflective crack channels, weakening the overall crack resistance and water stability. At the same time, defects in pore connectivity and interface transition zone accelerate the development of water seepage, freeze-thaw, salt corrosion, and fatigue damage, resulting in problems such as difficulty in controlling shrinkage cracking, rapid durability decline, and high maintenance dependence. Therefore, improving water retention, inhibiting cracking, and enhancing long-term durability have become important development directions for base course materials.

[0003] Currently, the industry selects low-heat or mineral admixture systems to optimize hydration products and pore structure, adds fibers to achieve crack bridging and toughness improvement, uses shrinkage compensation / expansion agents, shrinkage reducing agents or air-entraining agents to reduce drying shrinkage sensitivity, adds polymers such as emulsions, SBR, and EVA to modify and improve adhesion and impermeability, uses water-repellent agents to reduce water absorption and capillary penetration, and improves internal moisture content and workability through methods such as pre-wetting recycled aggregates and adding lightweight aggregates / water-absorbing resins.

[0004] However, mineral admixtures and expansion / shrinkage reduction systems often depend on curing conditions and hydration processes, making it difficult to continuously provide an effective water source and interface stability in dry substrate environments. Furthermore, excessive amounts may lead to slow strength growth or fluctuations in volume stability. Fibers primarily inhibit crack propagation rather than reducing microcrack initiation at the source, resulting in decreased bridging efficiency when interfacial bonding is insufficient. While internal addition of lightweight aggregates / water-absorbing resins can provide internal curing, it often faces problems such as poor controllability of water release, insufficient interface matching with the matrix, and inadequate pore connectivity and durability synergy. Summary of the Invention

[0005] The purpose of this invention is to provide a self-curing road base material based on modified municipal solid waste incinerator slag and its preparation method, in order to solve the technical problem that the water retention, crack resistance and durability of existing road base materials need to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing a self-curing road base material based on modified municipal solid waste incinerator slag, comprising the following steps: S1. Place sodium polyacrylate and deionized water in a reaction vessel and stir. Add self-healing modified silica sol and dopamine copolymer. Stir at room temperature for 20-40 minutes. Add sodium hydroxide aqueous solution to adjust the pH to 8-9. Let stand for 15-20 minutes to degas and obtain composite modified solution. S2. The pretreated municipal solid waste incinerator slag is immersed in the composite modification liquid at an impregnation ratio of 30-35:1, vacuum impregnated for 0.5-1h, and then cured at low temperature to obtain hydrophilic modified slag aggregate. S3. Dry mix cement, aggregate and hydrophilic modified slag aggregate in a mixer until uniform, add mixing water and mix evenly to obtain a mixture; S4. Inject the mixture into the mold, vibrate and compact it to obtain the molded body; S5. Curing the road base material yields the road base material.

[0007] Furthermore, in step S1, the ratio of sodium polyacrylate, deionized water, self-healing modified silica sol, and dopamine copolymer is 10-12g:800-1000mL:40-60g:25-30g, and the concentration of sodium hydroxide aqueous solution is 0.5-1.0mol / L.

[0008] Further, in step S2, the preparation method of the hydrophilic modified slag aggregate is as follows: pretreated municipal solid waste incineration slag is impregnated in a composite modification liquid at an impregnation ratio of 30-35:1, and vacuum impregnated for 0.5-1h under a negative pressure of -0.08MPa to -0.1MPa. The product is then taken out and placed in an oven at 50-60℃ for pre-drying for 1-2h. The oven temperature is then raised to 80-90℃ for pre-curing for 1-2h to obtain the hydrophilic modified slag aggregate.

[0009] Furthermore, in step S3, the ratio of cement, aggregate, hydrophilic modified slag aggregate, and mixing water is 95-100g:340-350g:240-250g:35-40mL. The cement is silicate cement, and the aggregate consists of coarse aggregate and fine aggregate in a mass ratio of 60-75:25-40. The coarse aggregate is one or more of crushed stone, pebbles, and recycled coarse aggregate with a particle size of 5-30mm. The fine aggregate is one or more of natural sand, manufactured sand, and recycled fine aggregate with a particle size of 0.1-4.75mm. The mixing water is one or more of tap water, groundwater, and deionized water.

[0010] Furthermore, in step S4, the injection method into the mold is one or both of single injection and layered injection, and the vibration compaction method is one or more of vibration table vibration, insertion vibration and surface vibration.

[0011] Furthermore, in step S5, the maintenance of the road base material is one or more of the following: natural maintenance, wet maintenance, standard maintenance, and steam maintenance.

[0012] Furthermore, the self-healing modified silica sol is prepared by the following steps: A1. Place silica sol, ethanol and deionized water in a reaction vessel and stir. Add acetic acid aqueous solution to adjust the pH to 4.2-4.8. Stir at room temperature for 5-10 min. Add 3-aminopropyltriethoxysilane solution dropwise and stir at room temperature for 1-2 h. Post-treatment yields amino-modified silica sol. A2. Place 4-carboxyphenylboronic acid, MES buffer, N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride in a reaction vessel and stir at room temperature for 20-30 min to obtain a carboxyl-activated solution. A3. Place the amino-modified silica sol and MES buffer in a reaction vessel and stir. Add carboxyl activating solution and stir at room temperature for 14-16 hours. Post-treatment yields self-healing modified silica sol.

[0013] Further, in step A1, the ratio of silica sol, ethanol, deionized water, and 3-aminopropyltriethoxysilane solution is 15-20g:10-15mL:10-12mL:8-10mL, the 3-aminopropyltriethoxysilane solution is a 10-20wt% 3-aminopropyltriethoxysilane ethanol solution, and the concentration of the acetic acid aqueous solution is 3-5wt%. The post-processing steps include: after the reaction is completed, adding the sol product to the upper chamber of a 30kDa ultrafiltration tube, centrifuging at 3000-5000g until the volume is reduced to one-third of the original volume, adding deionized water to the original volume, repeating the centrifugation and replenishment process 3-5 times, and finally adding deionized water until the solid content is 5-10wt%, to obtain amino-modified silica sol.

[0014] Furthermore, in step A2, the ratio of 4-carboxyphenylboronic acid, MES buffer, N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 1-2g:100-120mL:1.0-1.5g:1.0-1.5g, the concentration of MES buffer is 0.05-0.10mol / L, and the pH is 5.5-6.0.

[0015] Further, in step A3, the ratio of the amino-modified silica sol, MES buffer, and carboxyl activation solution is 8-10g:5-7mL:5-8mL, the concentration of the MES buffer is 0.05-0.10mol / L, and the pH is 5.5-6.0. The post-processing steps include: after the reaction is completed, adding 0.1-0.2g of ethanolamine to the reaction solution to terminate the reaction, adding the sol product to the upper chamber of a 30kDa ultrafiltration tube, centrifuging at 3000-5000g until the volume is reduced to one-third of the original volume, adding deionized water to the original volume, repeating the centrifugation and replenishment process 3-5 times, and finally adding deionized water until the solid content is 5-10wt%, to obtain the self-healing modified silica sol.

[0016] Furthermore, the dopamine copolymer is prepared by the following steps: B1. Place dopamine hydrochloride and N,N-dimethylformamide in a reaction vessel and stir. Heat the vessel to 0-5°C in an ice bath. Add triethylamine and react in an ice bath for 10-15 min. Add 2-methacrylic anhydride dropwise and react at room temperature for 8-12 h. Post-treatment yields the dopamine copolymer precursor. B2. The dopamine copolymer precursor, methacryloyloxyethyltrimethylammonium chloride, 3-(methacryloyloxy)propyltrimethoxysilane and methanol were placed in a reaction vessel under nitrogen atmosphere and stirred. Azobisisobutyronitrile was added, the reaction vessel was heated to 60-70℃ and kept at this temperature for 6-10 hours. The dopamine copolymer was then obtained after post-treatment.

[0017] Further, in step B1, the ratio of dopamine hydrochloride, N,N-dimethylformamide, triethylamine, and 2-methacrylic anhydride is 10-12g:180-200mL:10-12g:8-10g. The post-processing steps include: after the reaction is completed, filtration is performed, the filtrate is poured into 10 times the volume of ethanol to precipitate, filtration is performed, the filter cake is washed with ether 2-4 times, transferred to an oven at 50-60℃, and dried to constant weight to obtain the dopamine copolymer precursor.

[0018] Further, in step B2, the ratio of the dopamine copolymer precursor, methacryloyloxyethyltrimethylammonium chloride, 3-(methacryloyloxy)propyltrimethoxysilane, methanol, and azobisisobutyronitrile is 10-12g:8-10g:2-4g:200-250mL:0.08-0.10g. The post-processing step includes: after the reaction is completed, wait for the reaction vessel to cool to room temperature, slowly pour the reaction solution into 600-800mL of anhydrous diethyl ether to precipitate, filter, rinse the filter cake with anhydrous diethyl ether 2-4 times, transfer it to an oven, and dry for 6-8 hours to obtain the dopamine copolymer.

[0019] Furthermore, the pretreated municipal solid waste incinerator slag is prepared by the following steps: C1. The slag from municipal solid waste incineration furnaces is subjected to magnetic separation, air separation, and crushing and screening to obtain crude slag aggregate. C2. The coarse slag aggregate is evenly spread in the refractory tray of a tubular furnace under inert gas protection and treated at high temperature to obtain pretreated municipal solid waste incineration slag.

[0020] Furthermore, in step C1, the content of silicon dioxide in the municipal solid waste incineration slag is 35-40%, calcium oxide is 15-20%, aluminum oxide is 5-15%, and iron oxide is 5-12%. The preparation method of the crude slag aggregate is as follows: the municipal solid waste incineration slag is fed into a magnetic separation device for magnetic separation treatment to remove ferromagnetic metal impurities contained in the slag. Light impurities and incompletely burned combustibles in the slag are separated by air separation. The slag after air separation treatment is fed into a crushing device for crushing treatment. After screening, crude slag aggregate with a particle size of 3-10mm is obtained.

[0021] Furthermore, in step C2, the method for preparing pretreated municipal solid waste incinerator slag is as follows: the coarse slag aggregate is evenly spread in the refractory tray of a tubular furnace under inert gas protection, the temperature is raised to 700-800℃ at a rate of 5-10℃ / min, the temperature is maintained for 1-2 hours, and after cooling to room temperature, pretreated municipal solid waste incinerator slag is obtained. The inert gas is one or more of nitrogen, argon or helium.

[0022] The present invention also proposes a self-curing road base material based on modified municipal solid waste incinerator slag, which is prepared by the above-mentioned preparation method of the self-curing road base material based on modified municipal solid waste incinerator slag.

[0023] The present invention has the following beneficial effects: 1. The dopamine structural units retained in the dopamine copolymer molecules of this invention have properties similar to mussel adhesive proteins, containing abundant catechol and amino groups. These groups can form strong interfacial bonds with slag aggregates, cement hydration products, and silanol groups on the surface of silica sol through hydrogen bonds, coordination bonds, and π-π interactions. This improves the bond strength between the modified slag aggregates and the cement matrix, improves the structure of the interfacial transition zone, and reduces interfacial defects. At the same time, the quaternary ammonium salt groups and hydrophilic polymeric segments introduced into the dopamine copolymer enhance the hydrophilicity and water adsorption and retention capacity of the system, which helps to inhibit water migration during mixing and early curing stages, providing a stable water source for continuous cement hydration, improving the water retention performance and early volume stability of the base material. Furthermore, the dopamine copolymer and self-healing modified silica sol work synergistically in a weakly alkaline environment. Through the construction of dynamic non-covalent bonds and organic-inorganic composite networks, the material has a certain structural reconstruction capability when microcracks or interfacial damage occurs, improving the durability and service reliability of the pavement base material.

[0024] 2. The self-healing modified silica sol of the present invention uses silica sol as an inorganic framework. After introducing amino and phenylboronic acid groups on the surface, it maintains good aqueous dispersibility and significantly improves the chemical reactivity of the particle surface. In the composite modified liquid, the silica sol can undergo condensation reaction with hydroxyl groups in slag aggregate and cement hydration products through silanol groups, forming a continuous and stable inorganic-organic composite network on the aggregate surface and interface transition zone. This improves the interfacial bonding state between the modified slag aggregate and the cement matrix, reduces interfacial porosity and weak interfacial defects. Secondly, the silica sol particles are small in size and have a large specific surface area, which can fill the pores of slag and the micro-voids in the cement system, promote the densification of the slurry, and improve the impermeability and crack resistance of the road base material. Furthermore, the reversible dynamic bonds introduced by the phenylboronic acid groups endow the silica sol system with a certain structural reconstruction capability. When the material generates micro-cracks or interfacial damage during service, it can undergo dynamic reorganization under the action of moisture and ion environment, which helps to close cracks and restore interfacial performance.

[0025] 3. This invention also significantly removes ferromagnetic metals, lightweight impurities, and unburned combustibles from the slag through magnetic separation, airflow separation, and crushing and screening, resulting in a purer aggregate composition and more uniform particle size distribution. This effectively reduces the adverse effects of impurities on cement hydration and interfacial bonding. Secondly, high-temperature roasting promotes the complete decomposition or oxidation of residual organic matter in the slag, while simultaneously driving the transformation of unstable phases into stable crystalline phases. This reduces the risk of subsequent volume expansion, uneven chemical reactions, or durability degradation, and improves the long-term stability of the base material. Thirdly, the pretreated slag has a more open and stable internal pore structure, which is conducive to the full vacuum impregnation and fixation of the composite modification liquid. This provides a good carrier for the formation of the subsequent hydrophilic modification layer, enhancing its water storage and interfacial effects. During cement mixing and hardening, the pretreated slag can form a relatively stable interfacial structure with the hydration products, playing both the role of aggregate support and participating in the construction of the overall dense structure. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The sodium polyacrylate used in this invention was purchased from Shuangcheng Chemical Products Factory in Renqiu City, model number 0687, with a density of 0.80 g / cm³. 3 ; The silicate cement used in this invention was purchased from Shijiazhuang Yandong Mineral Products Co., Ltd., with grade 207-35, purity of 90%, and density of 2.6 g / cm³. 3 The brand is Yandong Mining; The silica sol used in this invention was purchased from Hangzhou Zheming New Materials Co., Ltd., with an effective ingredient content of 30%, a semi-transparent liquid appearance, and a particle size of 10nm.

[0028] Example 1 This embodiment provides a method for preparing pretreated municipal solid waste incinerator slag, including the following steps: Step I: Preparation of crude slag aggregate The slag from municipal solid waste incineration is fed into a magnetic separator to remove ferromagnetic metal impurities. Lightweight impurities and unburned combustibles are separated from the slag by air separation. The air-separated slag is then fed into a jaw crusher for crushing and screening to obtain coarse slag aggregate with a particle size of 3-5 mm.

[0029] Step II: Preparation of pretreated municipal solid waste incinerator slag The coarse slag aggregate is evenly spread in the refractory tray of a tube furnace under nitrogen protection, heated to 700°C at a rate of 5°C / min, and kept at that temperature for 1 hour. After cooling to room temperature, pretreated municipal solid waste incineration slag is obtained.

[0030] Metal impurities, light debris, and unburned combustibles in the slag are removed by magnetic separation and air separation. After crushing and screening, slag aggregate with uniform particle size is obtained. Then, it is roasted under inert gas and high temperature to decompose or oxidize the residual organic matter and promote the transformation of unstable phases, so as to obtain pretreated municipal solid waste incineration slag with stable composition and structure.

[0031] Example 2 This embodiment provides a method for preparing pretreated municipal solid waste incinerator slag, including the following steps: Step I: Preparation of crude slag aggregate The slag from municipal solid waste incineration is fed into a magnetic separator to remove ferromagnetic metal impurities. Lightweight impurities and unburned combustibles are separated from the slag by air separation. The air-separated slag is then fed into a jaw crusher for crushing and screening to obtain coarse slag aggregate with a particle size of 5-7.5 mm.

[0032] Step II: Preparation of pretreated municipal solid waste incinerator slag The coarse slag aggregate was evenly spread in the refractory tray of a tube furnace under nitrogen protection, heated to 750°C at a rate of 7°C / min, and kept at that temperature for 1.5 hours. After cooling to room temperature, pretreated municipal solid waste incineration slag was obtained.

[0033] Example 3 This embodiment provides a method for preparing pretreated municipal solid waste incinerator slag, including the following steps: Step I: Preparation of crude slag aggregate The slag from municipal solid waste incineration is fed into a magnetic separator to remove ferromagnetic metal impurities. Lightweight impurities and unburned combustibles are separated from the slag by air separation. The air-separated slag is then fed into a jaw crusher for crushing and screening to obtain coarse slag aggregate with a particle size of 7.5-10mm.

[0034] Step II: Preparation of pretreated municipal solid waste incinerator slag The coarse slag aggregate is evenly spread in the refractory tray of a tube furnace under nitrogen protection, heated to 800°C at a rate of 10°C / min, and kept at that temperature for 2 hours. After cooling to room temperature, pretreated municipal solid waste incineration slag is obtained.

[0035] Example 4 This embodiment provides a method for preparing a dopamine copolymer, including the following steps: Step ①: Preparation of dopamine copolymer precursor Weigh 100g of dopamine hydrochloride and 1800mL of N,N-dimethylformamide and place them in a reaction vessel. Stir and heat to 0°C in an ice bath. Add 100g of triethylamine and react in an ice bath for 10min. Add 80g of 2-methacrylic anhydride dropwise and react at room temperature for 8h. After the reaction is complete, filter the mixture and pour the filtrate into 10 times its volume of ethanol to precipitate. Filter the mixture and wash the filter cake twice with ether. Transfer the cake to an oven at 50°C and dry to constant weight to obtain the dopamine copolymer precursor.

[0036] Step ②: Preparation of dopamine copolymer Weigh out 100g of dopamine copolymer precursor, 80g of methacryloyloxyethyltrimethylammonium chloride, 20g of 3-(methacryloyloxy)propyltrimethoxysilane, and 1800mL of methanol and place them in a reaction vessel under nitrogen atmosphere and stir. Add 0.8g of azobisisobutyronitrile, heat the reaction vessel to 60℃, and keep it at this temperature for 6h. After the reaction is complete, wait for the reaction vessel to cool to room temperature, slowly pour the reaction solution into 6000mL of anhydrous diethyl ether to precipitate, filter, rinse the filter cake twice with anhydrous diethyl ether, transfer it to an oven and dry for 6h to obtain dopamine copolymer.

[0037] Under low-temperature alkaline conditions, the phenolic hydroxyl and amino groups in dopamine hydrochloride are activated and undergo an acylation reaction with 2-methacrylic anhydride, introducing a free radical polymerizable methacryloyl group into the molecular structure to obtain a dopamine copolymer precursor. Subsequently, under nitrogen protection, using azobisisobutyronitrile as an initiator, the precursor undergoes a free radical copolymerization reaction with methacryloyloxyethyltrimethylammonium chloride and 3-(methacryloyloxy)propyltrimethoxysilane to generate a dopamine copolymer containing dopamine structural units, quaternary ammonium salt groups and silane functional groups.

[0038] Introducing methacryloyl groups into dopamine molecules gives them polymerizability. Furthermore, through free radical copolymerization, quaternary ammonium salt groups and silane functional groups are synergistically grafted into the dopamine backbone to achieve the integration of functional units and structural fixation, resulting in dopamine copolymers.

[0039] Example 5 This embodiment provides a method for preparing a dopamine copolymer, including the following steps: Step ①: Preparation of dopamine copolymer precursor Weigh 110g of dopamine hydrochloride and 1900mL of N,N-dimethylformamide and place them in a reaction vessel. Stir and heat in an ice bath to 3°C. Add 110g of triethylamine and react in an ice bath for 13 minutes. Add 90g of 2-methacrylic anhydride dropwise and react at room temperature for 10 hours. After the reaction is complete, filter the solution and pour the filtrate into 10 times its volume of ethanol to precipitate. Filter the solution and wash the filter cake three times with ether. Transfer the cake to an oven at 55°C and dry it to constant weight to obtain the dopamine copolymer precursor.

[0040] Step ②: Preparation of dopamine copolymer Weigh out 110g of dopamine copolymer precursor, 90g of methacryloyloxyethyltrimethylammonium chloride, 30g of 3-(methacryloyloxy)propyltrimethoxysilane, and 1900mL of methanol and place them in a reaction vessel under nitrogen atmosphere and stir. Add 0.9g of azobisisobutyronitrile, heat the reaction vessel to 65℃, and keep it at this temperature for 8h. After the reaction is complete, wait for the reaction vessel to cool to room temperature, and slowly pour the reaction solution into 7000mL of anhydrous diethyl ether to precipitate. Filter the solution, rinse the filter cake with anhydrous diethyl ether 3 times, transfer it to an oven and dry for 7h to obtain dopamine copolymer.

[0041] Example 6 This embodiment provides a method for preparing a dopamine copolymer, including the following steps: Step ①: Preparation of dopamine copolymer precursor Weigh 120g of dopamine hydrochloride and 2000mL of N,N-dimethylformamide and place them in a reaction vessel. Stir and heat to 5°C in an ice bath. Add 120g of triethylamine and react in an ice bath for 15min. Add 100g of 2-methacrylic anhydride dropwise and react at room temperature for 12h. After the reaction is complete, filter the solution and pour the filtrate into 10 times its volume of ethanol to precipitate. Filter the solution and wash the filter cake 4 times with ether. Transfer the cake to an oven at 60°C and dry to constant weight to obtain the dopamine copolymer precursor.

[0042] Step ②: Preparation of dopamine copolymer Weigh 120g of dopamine copolymer precursor, 100g of methacryloyloxyethyltrimethylammonium chloride, 40g of 3-(methacryloyloxy)propyltrimethoxysilane, and 2000mL of methanol and place them in a reaction vessel under nitrogen atmosphere and stir. Add 1g of azobisisobutyronitrile, heat the reaction vessel to 70℃, and keep it at this temperature for 10h. After the reaction is complete, wait for the reaction vessel to cool to room temperature, slowly pour the reaction solution into 8000mL of anhydrous diethyl ether to precipitate, filter, rinse the filter cake with anhydrous diethyl ether 4 times, transfer it to an oven and dry for 8h to obtain dopamine copolymer.

[0043] Example 7 This embodiment provides a method for preparing a self-healing modified silica sol, including the following steps: Step 1: Preparation of amino-modified silica sol Weigh out 150g of silica sol, 100mL of ethanol and 100mL of deionized water and place them in a reaction vessel. Stir and add 3wt% acetic acid aqueous solution to adjust the pH to 4.2. Stir at room temperature for 5min. Add 80mL of 10wt% 3-aminopropyltriethoxysilane ethanol solution and stir at room temperature for 1h. After the reaction is complete, add the sol product to the upper chamber of a 30kDa ultrafiltration tube and centrifuge at 3000g until the volume is reduced to one-third of the original volume. Add deionized water to the original volume. Repeat the centrifugation and replenishment process 3 times. Finally, add deionized water to the solid content until it is 5wt% to obtain amino-modified silica sol.

[0044] Step 2: Preparation of carboxyl activation solution Weigh out 10g of 4-carboxyphenylboronic acid, 1000mL of 0.05mol / L MES buffer, 10g of N-hydroxysuccinimide and 10g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and place them in a reaction vessel. Stir at room temperature for 20min to obtain a carboxyl-activated solution.

[0045] Step 3: Preparation of self-healing modified silica sol Weigh 80g of amino-modified silica sol and 50mL of 0.05mol / L MES buffer and place them in a reaction vessel. Stir and add 50mL of carboxyl activation solution. Stir at room temperature for 14h. After the reaction is complete, add 1g of ethanolamine to the reaction solution to terminate the reaction. Add the sol product to the upper chamber of a 30kDa ultrafiltration tube and centrifuge at 3000g until the volume is reduced to one-third of the original volume. Add deionized water to the original volume. Repeat the centrifugation and replenishment process 3 times. Finally, add deionized water to the solid content until it is 5wt% to obtain self-healing modified silica sol.

[0046] Under weakly acidic conditions, the silanol groups on the surface of the silica sol undergo a hydrolysis-condensation reaction with 3-aminopropyltriethoxysilane, covalently introducing amino organosilicon segments into the silica sol surface to form an amino-modified silica sol. Subsequently, in the MES buffer system, the carboxyl groups of 4-carboxyphenylboronic acid are activated by N-hydroxysuccinimide / 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride to generate an active ester. This active ester further undergoes an amidation reaction with the amino groups on the surface of the amino-modified silica sol, while retaining the phenylboronic acid groups, to obtain a self-healing modified silica sol.

[0047] A stable amino functional layer is introduced on the surface of silica sol through silane coupling reaction, which enhances the reactivity of the particle surface and the dispersibility in the aqueous phase, and provides controllable reaction sites for subsequent covalent bonding. Furthermore, the carboxyl group in the 4-carboxyphenylboronic acid molecule is converted into a highly reactive intermediate by the N-hydroxysuccinimide / 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride system, so that the phenylboronic acid structure can participate in the subsequent coupling reaction efficiently under mild conditions. Through the amidation reaction of amino and activated carboxyl groups, the phenylboronic acid group is anchored on the surface of silica sol, introducing reversible dynamic bonding units, so that the sol system has structural reconstruction and self-healing characteristics, while maintaining colloidal stability.

[0048] Example 8 This embodiment provides a method for preparing a self-healing modified silica sol, including the following steps: Step 1: Preparation of amino-modified silica sol Weigh 175g of silica sol, 125mL of ethanol, and 110mL of deionized water and place them in a reaction vessel. Stir, add 4wt% acetic acid aqueous solution to adjust the pH to 4.6, stir at room temperature for 7min, add 90mL of 15wt% 3-aminopropyltriethoxysilane ethanol solution, stir at room temperature for 1.5h. After the reaction is complete, add the sol product to the upper chamber of a 30kDa ultrafiltration tube and centrifuge at 4000g until the volume is reduced to one-third of the original volume. Add deionized water to the original volume and repeat the centrifugation and replenishment process 4 times. Finally, add deionized water until the solid content is 7.5wt% to obtain amino-modified silica sol.

[0049] Step 2: Preparation of carboxyl activation solution Weigh out 15g of 4-carboxyphenylboronic acid, 1100mL of 0.075mol / L MES buffer, 12.5g of N-hydroxysuccinimide and 12.5g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and place them in a reaction vessel. Stir at room temperature for 25min to obtain a carboxyl-activated solution.

[0050] Step 3: Preparation of self-healing modified silica sol Weigh 90g of amino-modified silica sol and 60mL of 0.075mol / L MES buffer and place them in a reaction vessel. Stir and add 65mL of carboxyl activation solution. Stir at room temperature for 15h. After the reaction is complete, add 1.5g of ethanolamine to the reaction solution to terminate the reaction. Add the sol product to the upper chamber of a 30kDa ultrafiltration tube and centrifuge at 4000g until the volume is reduced to one-third of the original volume. Add deionized water to the original volume. Repeat the centrifugation and replenishment process 4 times. Finally, add deionized water to the solid content until it is 7.5wt%, and obtain the self-healing modified silica sol.

[0051] Example 9 This embodiment provides a method for preparing a self-healing modified silica sol, including the following steps: Step 1: Preparation of amino-modified silica sol Weigh 200g of silica sol, 150mL of ethanol and 120mL of deionized water and place them in a reaction vessel and stir. Add 5wt% acetic acid aqueous solution to adjust the pH to 4.8 and stir at room temperature for 10min. Add 100mL of 20wt% 3-aminopropyltriethoxysilane ethanol solution and stir at room temperature for 2h. After the reaction is complete, add the sol product to the upper chamber of a 30kDa ultrafiltration tube and centrifuge at 5000g until the volume is reduced to one-third of the original volume. Add deionized water to the original volume and repeat the centrifugation and replenishment process 5 times. Finally, add deionized water to the solid content to obtain amino-modified silica sol.

[0052] Step 2: Preparation of carboxyl activation solution Weigh out 20g of 4-carboxyphenylboronic acid, 1200mL of 0.10mol / L MES buffer, 15g of N-hydroxysuccinimide and 15g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and place them in a reaction vessel. Stir at room temperature for 30min to obtain a carboxyl-activated solution.

[0053] Step 3: Preparation of self-healing modified silica sol Weigh 100g of amino-modified silica sol and 70mL of 0.10mol / L MES buffer and place them in a reaction vessel. Stir and add 80mL of carboxyl activation solution. Stir at room temperature for 16h. After the reaction is complete, add 2g of ethanolamine to the reaction solution to terminate the reaction. Add the sol product to the upper chamber of a 30kDa ultrafiltration tube and centrifuge at 5000g until the volume is reduced to one-third of the original volume. Add deionized water to the original volume. Repeat the centrifugation and replenishment process 5 times. Finally, add deionized water to the solid content until it is 10wt% to obtain the self-healing modified silica sol.

[0054] Example 10 This embodiment provides a method for preparing a self-curing road base material based on modified municipal solid waste incinerator slag, including the following steps: Step 1: Preparation of composite modified liquid Weigh out 100g of sodium polyacrylate and 8000mL of deionized water and place them in a reaction vessel and stir. Add 400g of the self-healing modified silica sol prepared in Example 7 and 250g of the dopamine copolymer prepared in Example 4. Stir at room temperature for 20min. Add 0.5mol / L sodium hydroxide aqueous solution to adjust the pH to 8. Let stand for 15min to remove bubbles and obtain the composite modified solution.

[0055] Step 2: Preparation of hydrophilic modified slag aggregate The pretreated municipal solid waste incinerator slag prepared in Example 1 was impregnated in a composite modification liquid at an impregnation ratio of 30:1. Under a negative pressure of -0.08 MPa, it was vacuum impregnated for 0.5 h. The product was then removed and placed in an oven at 50 °C for pre-drying for 1 h. The oven temperature was then raised to 80 °C for pre-curing for 1 h to obtain hydrophilic modified slag aggregate.

[0056] Step 3: Prepare the mixture Mix 5-10mm crushed stone and 0.1-1.0mm natural sand at a mass ratio of 60:25 until homogeneous to obtain aggregate; Weigh out 950g of silicate cement, 3400g of aggregate and 2400g of hydrophilic modified slag aggregate, dry mix them evenly in a mixer, add 350mL of tap water, mix evenly to obtain the mixture.

[0057] Step 4: Preparing the molded body The mixture is injected into the mold at once and compacted by vibration table to obtain the molded body.

[0058] Step 5: Preparation of road base materials After demolding, the molded body is cured under standard conditions of 18°C ​​and 95% relative humidity. By covering it with a film and replenishing moisture regularly, the road base material is obtained.

[0059] In the aqueous system, sodium polyacrylate forms a stable dispersion network through carboxylate segments. Self-healing modified silica sol and dopamine copolymer synergistically construct a composite modified liquid under weakly alkaline conditions through hydrogen bonding, electrostatic interaction, and silanol-organic group interaction. After vacuum impregnation, the composite modified liquid penetrates into the pores of pretreated municipal solid waste incinerator slag and undergoes physical solidification and local condensation reaction during heating, forming a continuous hydrophilic functional layer on the aggregate surface. Subsequently, in the cement system, the modified slag aggregate, natural aggregate, and cement particles achieve interfacial bonding through hydration products, silanol condensation, and polymer segment entanglement. After vibration compaction and wet curing, the cement hydration reaction continues and a dense structure is constructed, ultimately resulting in a stable road base material.

[0060] By constructing a stable aqueous dispersion system and introducing silanol, dynamic bonds, and dopamine adhesion units, interfacial interactions are promoted under a weakly alkaline environment to form a stable composite modified liquid system. Further, through vacuum impregnation and heat treatment, the composite modified liquid enters the pores of the slag and forms a continuous hydrophilic layer on the surface. During the cement mixing process, the modified slag and the cementitious system are synergistically combined. Vibration compaction is used to improve the aggregate packing density and interfacial contact. Finally, wet curing promotes the continuous hydration reaction and forms a dense and stable road base material.

[0061] Example 11 This embodiment provides a method for preparing a self-curing road base material based on modified municipal solid waste incinerator slag, including the following steps: Step 1: Preparation of composite modified liquid Weigh out 110g of sodium polyacrylate and 9000mL of deionized water and place them in a reaction vessel and stir. Add 500g of the self-healing modified silica sol prepared in Example 8 and 275g of the dopamine copolymer prepared in Example 5. Stir at room temperature for 30min. Add 0.75mol / L sodium hydroxide aqueous solution to adjust the pH to 8.5. Let stand for 17min to remove bubbles and obtain the composite modified solution.

[0062] Step 2: Preparation of hydrophilic modified slag aggregate The pretreated municipal solid waste incinerator slag prepared in Example 2 was impregnated in a composite modification liquid at an impregnation ratio of 32:1. Under a negative pressure of -0.09 MPa, it was vacuum impregnated for 1 hour. The product was then removed and placed in an oven at 55°C for pre-drying for 1.5 hours. The oven temperature was then raised to 85°C for pre-curing for 1.5 hours to obtain hydrophilic modified slag aggregate.

[0063] Step 3: Prepare the mixture Mix 10-20mm crushed stone and 1-2.5mm natural sand at a mass ratio of 67.5:32.5 until homogeneous to obtain aggregate; Weigh out 975g of silicate cement, 3450g of aggregate and 2450g of hydrophilic modified slag aggregate, dry mix them evenly in a mixer, add 375mL of tap water, mix evenly to obtain the mixture.

[0064] Step 4: Preparing the molded body The mixture is injected into the mold at once and compacted by vibration table to obtain the molded body.

[0065] Step 5: Preparation of road base materials After demolding, the molded body is cured under standard conditions of 20℃ and 96.5% relative humidity. By covering it with a film and replenishing moisture regularly, the road base material is obtained.

[0066] Example 12 This embodiment provides a method for preparing a self-curing road base material based on modified municipal solid waste incinerator slag, including the following steps: Step 1: Preparation of composite modified liquid Weigh out 120g of sodium polyacrylate and 10000mL of deionized water and place them in a reaction vessel and stir. Add 600g of the self-healing modified silica sol prepared in Example 9 and 300g of the dopamine copolymer prepared in Example 6. Stir at room temperature for 40min. Add 1.0mol / L sodium hydroxide aqueous solution to adjust the pH to 9. Let stand for 20min to remove bubbles and obtain the composite modified solution.

[0067] Step 2: Preparation of hydrophilic modified slag aggregate The pretreated municipal solid waste incinerator slag prepared in Example 3 was impregnated in a composite modification liquid at an impregnation ratio of 35:1. Under a negative pressure of -0.1 MPa, it was vacuum impregnated for 1 hour. The product was then removed and placed in an oven at 60°C for pre-drying for 2 hours. The oven temperature was then raised to 90°C for pre-curing for 2 hours to obtain hydrophilic modified slag aggregate.

[0068] Step 3: Prepare the mixture Mix 20-30mm crushed stone and 2.5-4.75mm natural sand at a mass ratio of 75:40 until homogeneous to obtain aggregate; Weigh out 1000g of silicate cement, 3500g of aggregate and 2500g of hydrophilic modified slag aggregate, dry mix them evenly in a mixer, add 400mL of tap water, mix evenly to obtain a mixture.

[0069] Step 4: Preparing the molded body The mixture is injected into the mold at once and compacted by vibration table to obtain the molded body.

[0070] Step 5: Preparation of road base materials After demolding, the molded body is cured under standard conditions of 22°C and 98% relative humidity. By covering it with a film and replenishing moisture regularly, the road base material is obtained.

[0071] Comparative Example 1 The difference between this comparative example and Example 12 is that the dopamine copolymer was omitted when preparing the composite modified liquid in step one.

[0072] Comparative Example 2 The difference between this comparative example and Example 12 is that, in step one, when preparing the composite modified liquid, an equal amount of amino-modified silica sol is used to replace the self-healing modified silica sol.

[0073] Comparative Example 3 The difference between this comparative example and Example 12 is that, in step three, when preparing the mixture, the hydrophilic modified slag aggregate is replaced with an equal amount of pretreated municipal solid waste incinerator slag.

[0074] Performance testing: The contact shrinkage rate, total crack area per unit area (crack resistance), compressive fatigue deformation performance and water seepage height of the road base material samples prepared in Examples 10-12 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 50082-2024 "Standard for Test Methods of Long-term Performance and Durability of Concrete". The water retention rate of the mixtures prepared in Examples 10-12 and Comparative Examples 1-3 was tested in accordance with the standard JGJ / T 70-2009 "Standard for Test Methods of Basic Performance of Building Mortar". The specific data are shown in Table 1.

[0075] Table 1 - Performance Test Data for Each Sample Data Analysis: A comparative analysis of the data in Table 1 shows that the shrinkage rate of the road base material prepared by this invention is 3.26 × 10⁻⁶. -4 The total crack area per unit area is 5.7 mm. 2 ·m -2 The cumulative deformation rate of the compressive fatigue was 0.19%, the water penetration height was 6.0 mm, and the water retention rate of the mixture was 94.8%. All data were better than the comparative example. Therefore, this invention uses pretreated municipal solid waste incinerator slag as functional aggregate. Unfavorable phases are eliminated through high-temperature stabilization treatment. A composite modified liquid composed of dopamine copolymer, self-healing modified silica sol, and sodium polyacrylate is introduced into its pores to form a continuous hydrophilic functional layer. By utilizing the adhesion of dopamine, the dynamic bonding of self-healing silica sol, and the water storage effect of slag pores, the aggregate-cement interface is synergistically enhanced, effectively improving the water retention, crack resistance, and durability of the base material, and promoting the high-value utilization of solid waste resources.

[0076] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a self-curing road base material based on modified municipal solid waste incinerator slag, characterized in that, Includes the following steps: S1. Place sodium polyacrylate and deionized water in a reaction vessel and stir. Add self-healing modified silica sol and dopamine copolymer. Stir at room temperature for 20-40 minutes. Add sodium hydroxide aqueous solution to adjust the pH to 8-9. Let stand for 15-20 minutes to degas and obtain composite modified solution. S2. The pretreated municipal solid waste incinerator slag is immersed in the composite modification liquid at an impregnation ratio of 30-35:1, vacuum impregnated for 0.5-1h, and then thermally cured to obtain hydrophilic modified slag aggregate. S3. Dry mix cement, aggregate and hydrophilic modified slag aggregate in a mixer until uniform, add mixing water and mix evenly to obtain a mixture; S4. Inject the mixture into the mold, vibrate and compact it to obtain the molded body; S5. Curing the road base material to obtain the road base material; The self-healing modified silica sol is prepared by the following steps: A1. Place silica sol, ethanol and deionized water in a reaction vessel and stir. Add acetic acid aqueous solution to adjust the pH to 4.2-4.

8. Stir at room temperature for 5-10 min. Add 3-aminopropyltriethoxysilane solution dropwise and stir at room temperature for 1-2 h. Post-treatment yields amino-modified silica sol. A2. Place 4-carboxyphenylboronic acid, MES buffer, N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride in a reaction vessel and stir at room temperature for 20-30 min to obtain a carboxyl-activated solution. A3. Place the amino-modified silica sol and MES buffer in a reaction vessel and stir. Add carboxyl activation solution and stir at room temperature for 14-16 hours. Post-treatment yields self-healing modified silica sol. The dopamine copolymer was prepared by the following steps: B1. Place dopamine hydrochloride and N,N-dimethylformamide in a reaction vessel and stir. Heat the vessel to 0-5°C in an ice bath. Add triethylamine and react in an ice bath for 10-15 min. Add 2-methacrylic anhydride dropwise and react at room temperature for 8-12 h. Post-treatment yields the dopamine copolymer precursor. B2. The dopamine copolymer precursor, methacryloyloxyethyltrimethylammonium chloride, 3-(methacryloyloxy)propyltrimethoxysilane and methanol were placed in a reaction vessel under nitrogen atmosphere and stirred. Azobisisobutyronitrile was added, the reaction vessel was heated to 60-70℃ and kept at this temperature for 6-10 hours. The dopamine copolymer was then obtained after post-treatment.

2. The method for preparing self-curing road base material based on modified municipal solid waste incinerator slag according to claim 1, characterized in that, In step S1, the ratio of sodium polyacrylate, deionized water, self-healing modified silica sol and dopamine copolymer is 10-12g:800-1000mL:40-60g:25-30g, and the concentration of sodium hydroxide aqueous solution is 0.5-1.0mol / L.

3. The method for preparing a self-curing road base material based on modified municipal solid waste incinerator slag according to claim 1, characterized in that, In step A1, the ratio of silica sol, ethanol, deionized water and 3-aminopropyltriethoxysilane solution is 15-20g:10-15mL:10-12mL:8-10mL, the 3-aminopropyltriethoxysilane solution is a 10-20wt% 3-aminopropyltriethoxysilane ethanol solution, and the concentration of the acetic acid aqueous solution is 3-5wt%.

4. The method for preparing a self-curing road base material based on modified municipal solid waste incinerator slag according to claim 1, characterized in that, In step A2, the ratio of 4-carboxyphenylboronic acid, MES buffer, N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 1-2g:100-120mL:1.0-1.5g:1.0-1.5g, the concentration of MES buffer is 0.05-0.10mol / L, and the pH is 5.5-6.

0.

5. The method for preparing a self-curing road base material based on modified municipal solid waste incinerator slag according to claim 1, characterized in that, In step A3, the ratio of the amount of amino-modified silica sol, MES buffer, and carboxyl activation solution is 8-10g:5-7mL:5-8mL, the concentration of MES buffer is 0.05-0.10mol / L, and the pH is 5.5-6.

0.

6. The method for preparing a self-curing road base material based on modified municipal solid waste incinerator slag according to claim 1, characterized in that, In step B1, the ratio of the dopamine copolymer precursor, methacryloyloxyethyltrimethylammonium chloride, 3-(methacryloyloxy)propyltrimethoxysilane, methanol, and azobisisobutyronitrile is 10-12g:8-10g:2-4g:200-250mL:0.08-0.10g; in step B2, the weight ratio of the dopamine copolymer precursor, methacryloyloxyethyltrimethylammonium chloride, 3-(methacryloyloxy)propyltrimethoxysilane, methanol, and azobisisobutyronitrile is 10-12:8-10:2-4:0.08-0.

10.

7. The method for preparing a self-curing road base material based on modified municipal solid waste incinerator slag according to claim 1, characterized in that, The pretreated municipal solid waste incinerator slag is prepared by the following steps: C1. The slag from municipal solid waste incineration furnaces is subjected to magnetic separation, air separation, and crushing and screening to obtain crude slag aggregate. C2. The coarse slag aggregate is evenly spread in the refractory tray of a tubular furnace under inert gas protection and treated at high temperature to obtain pretreated municipal solid waste incineration slag.

8. A self-curing road base material based on modified municipal solid waste incinerator slag, characterized in that, The self-curing road base material based on modified municipal solid waste incinerator slag is prepared using the preparation method for self-curing road base material based on modified municipal solid waste incinerator slag as described in any one of claims 1-7.

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