Concrete material based on industrial solid waste reclaimed material as well as preparation method and application of concrete material

Abstract

The invention belongs to the technical field of solid waste recycling and building materials, and particularly relates to a concrete material based on industrial solid waste reclaimed materials and a preparation method and application of the concrete material based on the industrial solid waste reclaimed materials. Comprising the following components in parts by weight: 40-50 parts of industrial solid waste micro powder, 10-20 parts of passivated coarse aggregate, 180-200 parts of sol-impregnated fine aggregate dispersion liquid, 30-40 parts of alkaline basic liquid, 5-10 parts of compound microorganism sustained-release capsules and 0.1-0.2 part of a polycarboxylate superplasticizer. According to the microbial activator, the crack repairing capacity of the solid waste-based concrete is remarkably improved, microcracks of aggregate are filled in cooperation with silica sol, the mechanical property is enhanced, the long-term strength and durability are improved, and a reliable technical scheme is provided for green building materials and intelligent infrastructures.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization and building materials, and specifically relates to a concrete material based on industrial solid waste recycled materials, and a preparation method and application thereof. Background Art

[0002] Concrete materials based on recycled industrial solid waste have attracted considerable attention in the areas of resource utilization and environmental protection. Currently, common recycled industrial solid waste materials include fly ash (FA), blast furnace slag (GGBS), steel slag (SS), silica fume (SF), red mud (RM), tailings (TM), and recycled aggregate from construction waste (RCA). However, their practical application still faces the following key drawbacks, which hinder their large-scale promotion and high-performance development. The main reasons are analyzed as follows: First, the industrial solid waste currently used in concrete materials (such as steel slag, fly ash, and waste concrete) is only simply crushed as recycled aggregate. The microcracks and pores inside the aggregate lead to low concrete density and higher water absorption than natural aggregate, which in turn leads to insufficient performance of the recycled aggregate and poor mechanics and durability of the concrete; old cement slurry or impurities are attached to the surface of the recycled aggregate, and the bonding strength with the cement matrix interface transition zone (ITZ) is low (≤2.0MPa), which easily becomes a crack expansion channel, resulting in weak interfacial bonding; the leaching concentration of heavy metals (Pb, Cr, Cd) in metallurgical solid waste (such as red mud and carbide slag) exceeds the limit, and there is a pollution risk if used directly. Secondly, existing concrete materials made from recycled industrial solid waste mostly rely on adding strong alkaline chemical stimulants (such as NaOH and KOH) to activate the activity of solid waste. Their effectiveness is limited and their side effects are significant. This is because strong alkaline solutions are highly corrosive to production equipment, and residual alkaline substances can easily trigger alkali-aggregate reactions, causing concrete expansion and cracking. Improving the cementitious activity alone cannot solve the comprehensive needs of microcrack self-repair, heavy metal solidification, etc. Due to insufficient stimulation efficiency, the solid waste substitution rate is limited, and the proportion of industrial solid waste replacing cement is usually less than 30%, making it difficult to achieve high-dosage resource utilization.

[0003] In addition, concrete lacks self-repairing ability. In order to improve its self-repairing ability, existing concrete mostly uses microcapsule encapsulated chemical repair agents (such as epoxy resin and silicate solution), but these repair agents are expensive and have poor compatibility with solid waste systems, low repair efficiency, and are environmentally unfriendly. Summary of the Invention

[0004] The purpose of the present invention is to provide a concrete material based on industrial solid waste recycled materials and its preparation method and application, so as to overcome the shortcomings of the prior art. The present invention provides a concrete material based on industrial solid waste recycled materials that takes into account high mechanical strength, self-repairing ability, environmental safety and industrial feasibility.

[0005] In order to achieve the above object, the technical solution of the present invention is: In a first aspect, the present invention provides a concrete material based on industrial solid waste recycled materials, which includes the following components by weight: 40-50 parts of industrial solid waste fine powder, 10-20 parts of passivated coarse aggregate, 180-200 parts of sol-impregnated fine aggregate dispersion, 30-40 parts of alkaline base liquid, 5-10 parts of composite microbial sustained-release capsules, and 0.1-0.2 parts of polycarboxylic acid water reducer.

[0006] In concrete materials based on recycled industrial solid waste, industrial solid waste fine powder replaces cement, providing gelling activity and filling the pores of passivated coarse aggregate. The stable phosphate mineral layer formed on the surface of the metallurgical solid waste in the passivated coarse aggregate can fix heavy metal ions, thereby reducing the concentration of heavy metals (Pb, Cr, Cd) leached from metallurgical solid waste (such as red mud and carbide slag) and the risk of heavy metal environmental pollution. The sol-impregnated fine aggregate dispersion is used to fill microcracks in the passivated coarse aggregate, improving interfacial bond strength and enhancing mechanical properties. The alkaline base fluid forms a dense gel through an alkali-induced reaction, reducing porosity, improving impermeability and corrosion resistance, and further reducing cement usage, thereby increasing the proportion of industrial solid waste replacing cement and achieving high-dosage resource utilization. Furthermore, it can adjust the pH to stabilize the environment of the composite microbial capsule. The composite microbial sustained-release capsules slowly release microorganisms, promoting the self-healing of CaCO3 at cracks, significantly improving the crack repair ability of solid waste-based concrete, and combined with silica sol to fill micro-cracks in aggregates, enhancing mechanical properties and improving long-term strength and durability. Polycarboxylate water reducers can achieve efficient dispersion of aggregates in concrete, thereby significantly improving the workability and mechanical properties of concrete. The concrete material based on industrial solid waste recycled materials of the present invention constructs a "chemical-physical-biological" multi-dimensional system through the synergistic effect of various components, which can take into account high mechanical strength, self-healing ability, environmental safety and industrial feasibility.

[0007] Alternatively, a concrete material based on recycled industrial solid waste may include the following components, by weight: 40-45 parts industrial solid waste fine powder, 10-15 parts passivated coarse aggregate, 180-190 parts sol-impregnated fine aggregate dispersion, 30-35 parts alkaline base fluid, 5-8 parts composite microbial sustained-release capsules, and 0.1-0.15 parts polycarboxylate superplasticizer. Concrete materials based on recycled industrial solid waste within this composition range exhibit enhanced mechanical strength, self-healing capabilities, environmental safety, and industrial feasibility.

[0008] Alternatively, a concrete material based on recycled industrial solid waste may include the following components, by weight: 40 parts industrial solid waste fine powder, 10 parts passivated coarse aggregate, 180 parts sol-impregnated fine aggregate dispersion, 30 parts alkaline base fluid, 5 parts composite microbial sustained-release capsules, and 0.1 part polycarboxylate superplasticizer. Concrete materials based on recycled industrial solid waste within this composition range exhibit optimal mechanical strength, self-healing capabilities, environmental safety, and industrial feasibility.

[0009] The polycarboxylate water reducer used can be methoxy polyethylene glycol ester polycarboxylate water reducer.

[0010] In some other embodiments, the industrial solid waste fine powder includes steel slag and fly ash, and the mass ratio of steel slag to fly ash is 3:(1-2); the particle size of the industrial solid waste fine powder is ≤100 μm; the industrial solid waste fine powder of this component uses steel slag and fly ash instead of cement, which can provide gelling activity and fill pores.

[0011] Alternatively, the passivated coarse aggregate is a metallurgical solid waste modified by phosphate soaking, with a particle size of 5-20 mm. The stable phosphate mineral layer formed on the surface of the metallurgical solid waste in the passivated coarse aggregate can fix heavy metal ions, thereby reducing the concentration of heavy metals (Pb, Cr, Cd) leached from metallurgical solid waste (such as red mud and carbide slag), and the risk of heavy metal environmental pollution caused by them.

[0012] In some other embodiments, the sol-impregnated fine aggregate dispersion comprises waste concrete, nano-silica sol, and a dispersant, wherein the mass ratio of the waste concrete to the nano-silica sol is 1:(3-4); The particle size of waste concrete is 1-5 mm; The solid content of the nano-silica sol is 10 wt%-15 wt%; The dispersant is one of Span-80, PEG 200, sodium polyacrylate, Tween-60, and Tween-80, with the added amount being 0.5%-1.0% of the mass of the nano-silica sol. The sol-impregnated fine aggregate dispersion is used to fill and passivate microcracks in the coarse aggregate, improving interfacial bonding strength and thus enhancing mechanical properties.

[0013] In some other embodiments, the composite microorganism sustained-release capsule comprises a core material and a wall material wrapped around the surface of the core material, and the particle size of the composite microorganism sustained-release capsule is 50-100 μm; The core material includes Bacillus pasteurianus spores, calcium lactate and yeast extract, and the mass ratio of Bacillus pasteurianus spores, calcium lactate and yeast extract is (3-4):1:1; The concentration of viable bacteria of Bacillus pasteurianus spores is >10 6 CFU / g; The wall material is sodium alginate.

[0014] Encapsulated composite microbial sustained-release capsules isolate the alkaline medium with a sodium alginate wall, ensuring that Bacillus pasteurianus spores remain dormant before the concrete hardens, only being activated by water after cracks appear. This prevents the early hydration heat of concrete from damaging the microbial activity during direct mixing, effectively protecting sensitive active components. When the concrete cracks, the capsules rupture due to mechanical stress, releasing the microorganisms and nutrients within to repair the cracks. This allows for relatively precise control of the timing of functional release, achieving an on-demand response. The sodium alginate wall separates the sol-impregnated fine aggregate dispersion from the Bacillus pasteurianus spores. The nanosilica sol in the sol-impregnated fine aggregate dispersion specializes in interface enhancement, while the encapsulated composite microorganisms independently perform repairs, achieving a "time-sharing and zone-sharing" synergistic approach. This avoids the functional offset that would occur with direct mixing. In addition, traditional liquid stimulants need to be strictly protected from light and stored at controlled temperature, while the dry composite microbial sustained-release capsules of the present invention can be stored at room temperature for ≥6 months, reducing transportation and storage costs; encapsulation technology solves the problems of activity loss, functional conflict and complex process caused by direct mixing of traditional stimulants through the "protection-controlled release-synergy" three-in-one design, providing key technical support for the industrial promotion of solid waste-based high-performance concrete.

[0015] In some other embodiments, the alkaline base liquid is composed of the following components by weight: 10-15% water glass, 20-25% alkaline residue, and the balance water; The modulus of water glass is 1.2-1.8; the alkali residue has a particle size of ≤45 μm. Alkali residue is an industrial byproduct containing active ingredients such as Ca(OH)₂ and CaCO₃. The alkaline base liquid made from water glass and alkali residue can stimulate the activity of solid waste micropowders while adjusting the pH to stabilize the microbial capsule environment. For example, alkali residue is an industrial byproduct obtained by precipitation of waste liquid generated during the ammonia-soda process to produce soda ash.

[0016] In a second aspect, the present invention provides a method for preparing a concrete material based on industrial solid waste recycled materials as described in the first aspect, comprising the following steps: (1) Dry-mixing industrial solid waste powder and passivated coarse aggregate to prepare a premix; (2) After mixing the sol-impregnated fine aggregate dispersion and the alkaline base liquid, the composite microbial sustained-release capsule is added and stirred to prepare a mixture; (3) The premix is ​​added to the mixture, and then a polycarboxylic acid water reducer is added. After pouring, curing is performed to obtain a concrete material based on industrial solid waste recycled materials.

[0017] This preparation method is simple to operate, and the components can be prefabricated in advance. By adjusting the mixing method of the components, the uniform dispersion of the components can be improved, thereby producing a concrete material based on industrial solid waste recycled materials that has high mechanical strength, self-repairing ability, environmental safety and industrial feasibility.

[0018] In some other embodiments, in step (1), the method for preparing industrial solid waste fine powder is as follows: steel slag and fly ash are mixed to prepare a mixture, and after removing iron impurities by magnetic separation, the mixture is crushed to obtain the fine powder; The mixing mass ratio of steel slag and fly ash is 3:(1-2), and the crushed particle size is ≤100μm.

[0019] Alternatively, the passivated coarse aggregate is prepared as follows: crushing the metallurgical solid waste, soaking it in a phosphate solution, discharging the material and drying it; The particle size of the crushed metallurgical solid waste is 5-20 mm, the concentration of the phosphate solution is 0.4-0.6 mol / L, and the soaking time is 20-24 hours.

[0020] In some other embodiments, in step (2), the preparation method of the sol-impregnated fine aggregate dispersion is as follows: Alternatively, the waste concrete is crushed and added to the nano-silica sol, and then a dispersant is added and ultrasonic treatment is performed; The mass ratio of waste concrete and nano-silica sol is 1:(3-4); The particle size of waste concrete is 1-5 mm; The solid content of the nano-silica sol is 10 wt%-15 wt%; The dispersant is one of Span-80, PEG 200, sodium polyacrylate, Tween-60 and Tween-80, and the amount of the dispersant added is 0.5%-1.0% of the mass of the nano-silica sol; The frequency of ultrasonic treatment was 35-45 kHz and the time was 20-40 min; Alternatively, the alkaline base liquid is prepared as follows: water glass and alkaline residue are added to heated water in sequence, and magnetic stirring is performed to obtain a suspension; The modulus of water glass is 1.2-1.8; the particle size of alkali residue is ≤45μm, and alkali residue is an industrial by-product containing active ingredients such as Ca(OH)2 and CaCO3; The temperature of the heated water is 30-35°C, the speed of the magnetic stirring is 450-550 rpm, the time is 30-35 minutes, and the pH of the suspension is 12.5-13; Alternatively, the composite microbial sustained-release capsule is prepared as follows: Bacillus pasteurianus spores, calcium lactate, and yeast extract are mixed to prepare a core material; the core material is added to a sodium alginate aqueous solution, and a CaCl2 solution is added to carry out a cross-linking reaction to obtain the capsule; The particle size of the composite microbial sustained-release capsule is 50-100 μm; The mass ratio of Bacillus pasteurianus spores, calcium lactate and yeast extract is (3-4):1:1; The concentration of viable bacteria of Bacillus pasteurianus spores is >10 6 CFU / g; The concentration of sodium alginate aqueous solution is 2-3 wt %, and the concentration of CaCl2 solution is 4-5 wt %; The temperature of the cross-linking reaction is 20-30°C, and the time of the cross-linking reaction is 25-30 min.

[0021] Alternatively, in step (2), the stirring speed is 100-200 rpm and the stirring time is 15-25 min; Alternatively, in step (3), the curing is performed in a CO2 gas with a concentration of 10-20% for 2-3 hours, followed by standard curing for 7 days.

[0022] In a third aspect, the present invention provides the use of the concrete material based on recycled industrial solid waste as described in the first aspect in solid waste resource utilization and building materials, preferably in concrete crack repair. This significantly enhances the crack repair ability of solid waste-based concrete, and, combined with silica sol to fill microcracks in aggregate, enhances mechanical properties, improving long-term strength and durability, providing a reliable technical solution for green building materials and intelligent infrastructure.

[0023] In a fourth aspect, the present invention provides a method for repairing concrete cracks. The method comprises placing the concrete material based on recycled industrial solid waste described in the first aspect into the concrete cracks, maintaining an ambient humidity of 80% or higher and a temperature of 25°C, and allowing the cracks to be repaired over a period of 7-28 days. This method significantly improves crack repair rate and strength.

[0024] Beneficial effects of the present invention: (1) The concrete material based on industrial solid waste recycled materials of the present invention optimizes and modifies components such as industrial solid waste micropowder, passivated coarse aggregate, sol-impregnated fine aggregate dispersion, alkaline base liquid and composite microbial slow-release capsules. Through the synergistic effect of each component, a "chemical-physical-biological" multi-dimensional system is constructed, which can take into account high mechanical strength, self-repairing ability, environmental safety and industrial feasibility. Among them, the composite microbial slow-release capsules significantly improve the crack repair ability of solid waste-based concrete, and with the silica sol filling the micro-cracks of the aggregate, enhance the mechanical properties, improve the long-term strength and durability, and provide a reliable technical solution for green building materials and intelligent infrastructure; (2) The encapsulation of the present invention isolates the alkaline medium through the sodium alginate wall material, ensuring that the spores remain dormant before the concrete hardens and are only activated by water after cracks appear; thereby avoiding the early hydration heat of the concrete during direct mixing that will destroy the activity of microorganisms and effectively protecting sensitive active components; the capsules rupture due to mechanical stress when the concrete cracks, releasing the internal microorganisms and nutrients to repair the cracks in a targeted manner, and can more accurately control the timing of function release to achieve on-demand response; the nano-silica added in the present invention has a high surface activity that may interfere with microbial metabolism, and direct mixing will lead to the cancellation of the functions of the two. The present invention creatively proposes encapsulation to isolate the two, with nanomaterials specializing in interface enhancement and microorganisms independently performing repairs to achieve "time-sharing and zone-sharing" synergy; traditional liquid stimulants must be strictly protected from light and stored at a controlled temperature, while the dry capsules of the present invention can be stored at room temperature for ≥6 months, reducing transportation and storage costs; the encapsulation technology of the present invention solves the problems of activity loss, functional conflict and complex process of direct mixing of traditional stimulants through the "protection-controlled release-synergy" trinity design, providing key technical support for the industrial promotion of solid waste-based high-performance concrete.

[0025] (3) The preparation method of the concrete material based on industrial solid waste recycled materials of the present invention is simple to operate, and the components can be prefabricated in advance. By adjusting the mixing method of the components, the uniform dispersion of the components can be improved, thereby obtaining a concrete material based on industrial solid waste recycled materials that takes into account high mechanical strength, self-repairing ability, environmental safety and industrial feasibility.

[0026] (4) The present invention applies concrete materials made from recycled industrial solid waste to solid waste resource utilization and building materials, especially in concrete crack repair. This significantly improves the crack repair capability of solid waste-based concrete, and by combining it with silica sol to fill micro-cracks in aggregates, it enhances mechanical properties, improves long-term strength and durability, and provides a reliable technical solution for green building materials and intelligent infrastructure.

[0027] (5) The present invention provides a method for repairing concrete cracks, which directly places concrete materials based on industrial solid waste recycled materials into concrete cracks. In an environment with a humidity of ≥80% and a temperature of 25°C, the repair time is 7-28 days, which can significantly improve the crack repair rate and strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 These are actual pictures before and after the crack repair in Example 1 of the present invention, where a is before repair and b is after repair. DETAILED DESCRIPTION

[0030] Those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Specific conditions are not specified in the examples, and the procedures are carried out according to conventional conditions or the conditions recommended by the manufacturer. Components used without manufacturer indication are all conventional products that can be obtained commercially. Among them, metallurgical solid waste is blast furnace slag from Jinan Iron and Steel Group, waste concrete is concrete from the abandoned construction waste landfill site in Xinglongshan, Jinan, Bacillus pasteurianus spores are purchased from the Shanghai Collection of Microorganisms Center, yeast extract is yeast powder YEAST EXTRACT produced by Oxoid, and alkali slag is an industrial by-product produced by Binhua Group after propylene oxide production. Polycarboxylic acid water reducer is methoxy polyethylene glycol ester polycarboxylic acid water reducer.

[0031] The current industrial solid waste recycled concrete technology has core problems such as "low performance, high risk, and single function", which restrict its large-scale promotion and high-performance development. The main reasons are analyzed as follows: (1) Insufficient performance of recycled aggregates leads to poor mechanics and durability of concrete. This is because the industrial solid waste (such as steel slag, fly ash, and waste concrete) currently used in concrete materials is simply crushed as recycled aggregate, which has the following problems: First, high porosity and water absorption. The microcracks and pores inside the aggregates lead to low concrete density. The water absorption rate is 30-50% higher than that of natural aggregates, which significantly reduces the compressive strength (usually ≤40MPa) and freeze-thaw resistance (mass loss >5% after 200 freeze-thaw cycles); second, weak interfacial bonding. Old cement paste or impurities are attached to the surface of the recycled aggregate, and the bonding strength with the cement matrix interface transition zone (ITZ) is low (≤2.0MPa), which easily becomes a crack expansion channel; third, heavy metal environmental risks. The leaching concentration of heavy metals (Pb, Cr, Cd) in metallurgical solid waste (such as red mud and calcium carbide slag) exceeds the limit, and there is a pollution risk if used directly.

[0032] (2) The traditional activator system has limited effectiveness and significant side effects. Existing concrete materials made from recycled industrial solid waste mostly rely on adding strong alkaline chemical activators (such as NaOH and KOH) to activate the activity of solid waste. However, they have the following disadvantages: First, they are highly corrosive and have an environmental burden. Strong alkaline solutions are highly corrosive to production equipment, and residual alkaline substances can easily trigger alkali-aggregate reactions, causing concrete expansion and cracking. Second, they have a single function, which only improves the gelling activity and cannot solve the comprehensive needs of microcrack self-repair and heavy metal solidification. Third, the solid waste substitution rate is limited. Due to insufficient activation efficiency, the proportion of industrial solid waste replacing cement is usually less than 30%, making it difficult to achieve high-dosage resource utilization.

[0033] (3) Self-repairing technology is expensive and has poor compatibility with solid waste systems. Existing self-repairing concrete mostly uses microcapsules to encapsulate chemical repair agents (such as epoxy resins and silicate solutions), but it has the following bottlenecks: First, the repair efficiency is low. After the release of the repair agent, it can only seal cracks with a width of ≤0.1mm, and the repair rate is <50%, which cannot meet engineering needs; second, it is environmentally unfriendly. The carbon emissions of the chemical repair agent production process are high, which is contrary to the green concept of solid waste concrete; third, the compatibility is poor. The interface between the repair agent and the solid waste aggregate is weak, and it is easy to peel off and fail during long-term service.

[0034] The present invention provides a systematic solution that takes into account high mechanical strength, self-repairing ability, environmental safety and industrial feasibility, as follows: An embodiment of the present invention provides a concrete material based on industrial solid waste recycled materials, which includes the following components, by weight: 40-50 parts of industrial solid waste fine powder, 10-20 parts of passivated coarse aggregate, 180-200 parts of sol-impregnated fine aggregate dispersion, 30-40 parts of alkaline base liquid, 5-10 parts of composite microbial sustained-release capsules, and 0.1-0.2 parts of polycarboxylate water reducer.

[0035] Some other embodiments of the present invention provide a method for preparing a concrete material based on industrial solid waste recycled materials, comprising the following steps: (1) Dry-mixing industrial solid waste powder and passivated coarse aggregate to prepare a premix; (2) After mixing the sol-impregnated fine aggregate dispersion and the alkaline base liquid, the composite microbial sustained-release capsule is added and stirred to prepare a mixture; (3) The premix is ​​added to the mixture, and then a polycarboxylic acid water reducer is added. After pouring, curing is performed to obtain a concrete material based on industrial solid waste recycled materials.

[0036] Some other embodiments of the present invention provide applications of concrete materials based on industrial solid waste recycled materials in solid waste resource utilization and building materials, preferably, applications in repairing concrete cracks.

[0037] Other embodiments of the present invention provide a method for repairing concrete cracks. This method involves placing a concrete material made from recycled industrial solid waste into the cracks. The cracks are maintained at an ambient humidity of 80% or higher and a temperature of 25°C for a period of 7-28 days. This method significantly improves crack repair rates and strength.

[0038] The technical solutions of the present invention are further described below through specific embodiments: Example 1 1. A concrete material based on industrial solid waste recycled materials, comprising the following components, calculated by weight, as shown in Table 1: 40 parts of industrial solid waste fine powder, 10 parts of passivated coarse aggregate, 180 parts of sol-impregnated fine aggregate dispersion, 30 parts of alkaline base liquid, 5 parts of composite microbial sustained-release capsules, and 0.1 parts of polycarboxylate water reducer; Among them, industrial solid waste micropowder includes steel slag and fly ash (the mass ratio of steel slag and fly ash is 3:1), and the particle size of industrial solid waste micropowder is ≤100μm; the preparation method of industrial solid waste micropowder is: mix steel slag and fly ash in a weight ratio of 3:1, remove iron impurities through magnetic separation equipment, and crush to ≤100μm through a crusher.

[0039] The passivated coarse aggregate is a metallurgical solid waste modified by phosphate immersion, and the particle size of the passivated coarse aggregate is 5-20 mm. The preparation method of the passivated coarse aggregate is: the metallurgical solid waste is crushed into particles with a size of 5-20 mm through multiple stages, immersed in a phosphate solution with a concentration of 0.5 mol / L for 20 hours, and dried after discharge.

[0040] The sol-impregnated fine aggregate dispersion comprises waste concrete, nano-silica sol, and a dispersant (Span-80). The mass ratio of waste concrete to nano-silica sol is 1:3, and the amount of dispersant added is 0.5% of the mass of the nano-silica sol. The particle size of the waste concrete is 3 mm; the solid content of the nano-silica sol is 10%. The sol-impregnated fine aggregate dispersion is prepared by: crushing the waste concrete into particles with a size of 3 mm through multi-stage crushing, adding the particles to a nano-silica sol with a solid content of 10% and a weight three times that of the waste concrete, and then adding 0.5% of the dispersant by weight of the nano-silica sol. The mixture is ultrasonically treated at 40 kHz for 30 minutes to obtain the dispersion.

[0041] The composite microbial sustained-release capsule comprises a core material and a wall material wrapped on the surface of the core material. The particle size of the composite microbial sustained-release capsule is 50-100 μm. The core material comprises Bacillus pasteurianus spores, calcium lactate and yeast extract. The mass ratio of Bacillus pasteurianus spores, calcium lactate and yeast extract is 3:1:1. The live bacteria concentration of Bacillus pasteurianus spores is 10 6 CFU / g; the wall material is a sodium alginate aqueous solution, and the concentration of the sodium alginate aqueous solution is 2wt%; the preparation method of the composite microbial sustained-release capsule comprises the following steps: (1) Preparation of core material: Bacillus pasteurianus spores (live bacteria concentration is 10 6 CFU / g) was mixed with calcium lactate and yeast extract at a mass ratio of 3:1:1 as a self-repair active substance; (2) Wall material coating: Sodium alginate aqueous solution (concentration of 2 wt%) was used as the wall material and CaCl2 solution (concentration of 4 wt%) was used as the cross-linking agent to prepare microcapsules with a particle size of 50-100 μm.

[0042] The alkaline base liquid is composed of the following components by weight: 10% water glass (modulus 1.2), 20% alkali residue, and the remainder deionized water. The alkaline base liquid is prepared by grinding the alkali residue to a particle size ≤45μm and sieving to remove impurities. Deionized water is heated to 30°C, and the water glass and alkali residue powder are added in sequence. The mixture is magnetically stirred at 500 rpm for 30 minutes until a uniform suspension is formed. The pH is then adjusted to 12.8.

[0043] 2. A method for preparing a concrete material based on industrial solid waste recycled materials, comprising the following steps: (1) Dry-mix industrial solid waste powder and passivated coarse aggregate to obtain a premix; (2) Mix the sol-impregnated fine aggregate dispersion and alkaline base liquid, stir evenly, add the composite microbial sustained-release capsule, and stir at a low speed of 100-200 rpm for 10-20 minutes to avoid mechanical damage; (3) Add the premix to the mixture of step (2), add polycarboxylate water reducer, and introduce 10% CO2 gas for curing for 2 hours during the initial setting stage after pouring. After standard curing for 7 days, place the mixture in an environment with a humidity of ≥80% for repair.

[0044] Example 2 A concrete material based on industrial solid waste recycled materials, including the following components in parts by weight as shown in Table 1: 40 parts of industrial solid waste powder, 20 parts of passivated coarse aggregate, 200 parts of sol-impregnated fine aggregate dispersion, 30 parts of alkaline base liquid, 10 parts of composite microbial sustained-release capsules, and 0.2 parts of polycarboxylate water reducer; Among them, industrial solid waste micropowder includes steel slag and fly ash (the mass ratio of steel slag and fly ash is 3:2), and the particle size of industrial solid waste micropowder is ≤100μm; the preparation method of industrial solid waste micropowder is: mix steel slag and fly ash in a weight ratio of 3:2, remove iron impurities through magnetic separation equipment, and crush to ≤100μm through a crusher.

[0045] The passivated coarse aggregate is a metallurgical solid waste modified by phosphate soaking, and the particle size of the passivated coarse aggregate is 5-20 mm. The preparation method of the passivated coarse aggregate is as follows: the metallurgical solid waste is crushed into particles of 5-20 mm through multiple stages, soaked in a phosphate solution with a concentration of 0.5 mol / L for 24 hours, and dried after discharge; The sol-impregnated fine aggregate dispersion comprises waste concrete, nano-silica sol and a dispersant, wherein the mass ratio of the waste concrete, the nano-silica sol and the dispersant is 1:4, the amount of the dispersant added is 1% of the mass of the nano-silica sol, and the particle size of the waste concrete is 3 mm; the solid content of the nano-silica sol is 10-15%, and the dispersant is Span-80. The preparation method of the sol-impregnated fine aggregate dispersion comprises the following steps: crushing the waste concrete into particles with a size of 3 mm through multi-stage crushing, adding the waste concrete to a nano-silica sol with a solid content of 12% and a weight four times that of the waste concrete, adding the dispersant in an amount of 1% by weight of the sol, and ultrasonically treating the waste concrete at 40 kHz for 30 minutes.

[0046] The composite microbial sustained-release capsule comprises a core material and a wall material wrapped on the surface of the core material. The particle size of the composite microbial sustained-release capsule is 50-100 μm. The core material comprises Bacillus pasteurianus spores, calcium lactate and yeast extract. The mass ratio of Bacillus pasteurianus spores, calcium lactate and yeast extract is 4:1:1. The live bacteria concentration of Bacillus pasteurianus spores is 10 6 CFU / g; the wall material is a sodium alginate aqueous solution, and the concentration of the sodium alginate aqueous solution is 3wt%; the preparation method of the composite microbial sustained-release capsule comprises the following steps: (1) Core material preparation: Bacillus pasteurianus spores were mixed with calcium lactate and yeast extract in a mass ratio of 4:1:1 as the self-repairing active substance; (2) Wall material coating: Sodium alginate aqueous solution was used as the wall material and 5 wt% CaCl2 solution was used as the cross-linking agent to prepare microcapsules with a particle size of 50-100 μm.

[0047] The alkaline base liquid is composed of the following components, in the stated weight percentages: 15% water glass (modulus 1.8), 25% alkali residue, and the remainder deionized water. The alkaline base liquid is prepared by grinding the alkali residue to a particle size ≤45μm and sieving to remove impurities. Deionized water is heated to 35°C, and the water glass and alkali residue powder are added in sequence. The mixture is magnetically stirred at 500 rpm for 35 minutes until a uniform suspension is formed. The pH is then adjusted to 13.

[0048] 2. A method for preparing a concrete material based on industrial solid waste recycled materials, comprising the following steps: (1) Dry-mix industrial solid waste fine powder and passivated coarse aggregate to obtain a premix; (2) Mix the sol-impregnated fine aggregate dispersion and alkaline base liquid, stir evenly, add the composite microbial sustained-release capsule, and stir at a low speed of 200 rpm for 20 minutes to avoid mechanical damage; (3) Add the premix to the mixture of step (2), add polycarboxylate water reducer, and introduce 20% CO2 gas for curing for 3 hours during the initial setting stage after pouring. After standard curing for 7 days, place the mixture in an environment with a humidity of ≥80% for repair.

[0049] Example 3 A concrete material based on industrial solid waste recycled materials, which is different from Example 1 in that the components are shown in Table 1 in parts by weight, and the preparation method is consistent with Example 1.

[0050] Example 4 A concrete material based on industrial solid waste recycled materials, which is different from Example 1 in that the components are shown in Table 1 in parts by weight, and the preparation method is consistent with Example 1.

[0051] Comparative Example 1 A concrete material based on industrial solid waste recycled materials, including the following components in parts by weight as shown in Table 1: 50 parts of industrial solid waste powder, 20 parts of passivated coarse aggregate, 200 parts of sol-impregnated fine aggregate dispersion, and 0.2 parts of polycarboxylate water reducer.

[0052] Among them, industrial solid waste micropowder includes steel slag and fly ash (the mass ratio of steel slag and fly ash is 3:1), and the particle size of industrial solid waste micropowder is ≤100μm; the preparation method of industrial solid waste micropowder is: mix steel slag and fly ash in a weight ratio of 3:1, remove iron impurities through magnetic separation equipment, and crush to ≤100μm through a crusher.

[0053] The passivated coarse aggregate is metallurgical solid waste modified by soaking in phosphate (sodium phosphate), and the particle size of the passivated coarse aggregate is 20 mm. The preparation method of the passivated coarse aggregate is as follows: the metallurgical solid waste is crushed into particles of 20 mm through multiple stages, soaked in a sodium phosphate solution with a concentration of 0.5 mol / L for 24 hours, and dried after discharge; The sol-impregnated fine aggregate dispersion comprises waste concrete, nano-silica sol and a dispersant, wherein the mass ratio of the waste concrete, the nano-silica sol and the dispersant is 1:4, the amount of the dispersant added is 1% of the mass of the nano-silica sol, and the particle size of the waste concrete is 0-5 mm; the solid content of the nano-silica sol is 15%, and the dispersant is Span-80. The preparation method of the sol-impregnated fine aggregate dispersion comprises the following steps: crushing the waste concrete into particles with a size of 0-5 mm through multi-stage crushing, adding the waste concrete to a nano-silica sol with a solid content of 15% and a weight of 4 times the waste concrete, adding the dispersant in an amount of 1% by weight of the sol, and ultrasonically treating the waste concrete at 40 kHz for 30 minutes.

[0054] 2. A method for preparing a concrete material based on industrial solid waste recycled materials, comprising the following steps: (1) Dry mix industrial solid waste powder and passivated coarse aggregate, add sol impregnation fine aggregate dispersion, and stir evenly; (2) Add polycarboxylic acid water reducer, and introduce 10% CO2 gas for 2 hours during the initial setting stage after pouring. After 7 days of standard curing, place the mixture in an environment with a humidity of ≥80% for repair.

[0055] Comparative Example 2 A concrete material based on industrial solid waste recycled materials, which is different from Example 1 in that the components are shown in Table 1 in parts by weight, and the preparation method is consistent with Example 1.

[0056] Comparative Example 3 A concrete material based on industrial solid waste recycled materials, which is different from Example 1 in that the components are shown in Table 1 in parts by weight, and the preparation method is consistent with Example 1.

[0057] Comparative Example 4 A concrete material based on industrial solid waste recycled materials, which is different from Example 1 in that the components are shown in Table 1 in parts by weight, and the preparation method is consistent with Example 1.

[0058] Comparative Example 5 A concrete material based on industrial solid waste recycled materials, which is different from Example 1 in that the components are shown in Table 1 in parts by weight, and the preparation method is consistent with Example 1.

[0059] Comparative Example 6 A concrete material based on industrial solid waste recycled materials, which is different from Example 1 in that the components are shown in Table 1 by weight, wherein the passivated coarse aggregate is not modified by phosphate soaking, and metallurgical solid waste is directly used. The preparation method is consistent with Example 1.

[0060] Comparative Example 7 A concrete material based on industrial solid waste recycled materials, which is different from Example 1 in that the components are shown in Table 1 by weight, wherein the alkaline base liquid is replaced by a strong alkaline chemical activator NaOH. The preparation method is consistent with that in Example 1.

[0061] Table 1 Composition of concrete materials based on industrial solid waste recycled materials

[0062] The following is a comparative example of the effects of microbial stimulants on concrete performance, including experimental design, testing standards, data comparison, and conclusion analysis, highlighting their technical advantages in crack repair rate and strength improvement: Performance testing: Specimen preparation: 100 μm × 100 μm × 100 μm cubic specimens were prepared according to GB / T 50081-2016. Curing conditions: Standard curing room (20 ± 2°C, humidity ≥ 95%) until the age of 28 days.

[0063] Crack repair rate test: (1) Artificial cracks (width 0.2 ± 0.05 mm, depth 10 mm) were pre-placed on the specimen surface; (2) the specimen was exposed to an environment with 80% humidity and a temperature of 25°C; (3) the crack width was observed over time using a microscope (ASTM C1582 standard). Evaluation criteria: Repair was considered complete when the crack width returned to ≤ 0.05 mm, and the repair rate was calculated. The crack repair rate test results are shown in Table 2. Table 2 Crack repair rate test results

[0064] As can be seen from Table 2, a comparative analysis of Examples 1 and 2 shows that the increase in the amount of polycarboxylate water-reducing agent will reduce the amount of water used, which results in a decrease in the early repair rate compared with Example 1; in Example 3, as the amount of industrial solid waste fine powder increases, the effective active cement component increases, and the early repair effect is slightly improved; compared with Example 4, the increase in the base liquid and the corresponding increase in the effective calcium carbonate component, the early repair effect is slightly improved.

[0065] In Comparative Example 1, no alkaline base liquid or composite microbial sustained-release capsules were added, and the early repair effect was 0, and the 28-day repair effect was also unsatisfactory. This is because the absence of alkaline base liquid makes it difficult to stimulate the formation of dense gel between aggregates, resulting in a larger porosity, reduced impermeability and corrosion resistance. The absence of composite microbial sustained-release capsules results in the lack of self-repairing ability of concrete, and it is also unable to cooperate with silica sol to fill the microcracks in the aggregate, resulting in poor mechanical properties, long-term strength and durability. In Comparative Example 2, only alkaline base liquid was added without composite microbial sustained-release capsules, and the effect was improved compared with Comparative Example 1, but without the long-term effect of composite microbial sustained-release capsules, the 28-day repair effect was still unsatisfactory. In Comparative Example 3, only composite microbial sustained-release capsules were added without alkaline base liquid, and similar to Comparative Example 2, the effect of the combined action of the two was not achieved; the amount of industrial solid waste micropowder added in Comparative Example 4 was smaller than that in Example 1, and the early repair effect was slightly lower than that in Example 1. The reason for this is that the cement effect of industrial solid waste micropowder was reduced.

[0066] In Comparative Example 5, excessive amounts of industrial solid waste powder, passivated coarse aggregate and composite microbial sustained-release capsules were added, while the water reducer was not increased accordingly, resulting in no reduction in water and insufficient density. Therefore, the repair effect was worse than that of the embodiment.

[0067] In Comparative Example 6, the passivated coarse aggregate is not modified by phosphate soaking, and metallurgical solid waste is directly used. The microcracks and pores inside the aggregate lead to low concrete density and higher water absorption than natural aggregate, which in turn leads to insufficient performance of the recycled aggregate and poor concrete mechanics and durability; old cement slurry or impurities are attached to the surface of the recycled aggregate, and the bonding strength in the transition zone between the recycled aggregate and the cement matrix is ​​low, which easily becomes a crack expansion channel, resulting in weak interfacial bonding; the leaching concentration of heavy metals (Pb, Cr, Cd) in metallurgical solid waste (such as red mud and carbide slag) exceeds the limit, and there is a pollution risk if used directly.

[0068] Comparative Example 7 uses a strong alkaline chemical stimulant such as NaOH to replace the alkaline base liquid, but its effectiveness is limited and its side effects are significant. This is because the strong alkaline solution is highly corrosive to the production equipment, and the residual alkaline substances can easily trigger an alkali-aggregate reaction, causing the concrete to expand and crack; it only improves the cementing activity, but cannot solve the comprehensive needs of microcrack self-repair, heavy metal solidification, etc.; due to insufficient stimulation efficiency, the solid waste substitution rate is limited, and the proportion of industrial solid waste replacing cement is usually less than 30%, making it difficult to achieve high-dosage resource utilization.

[0069] Compressive strength test: A universal testing machine was used to conduct 28-day and 365-day compressive strength tests. The test results are shown in Figure 3.

[0070] Table 3 Compressive strength test results

[0071] It can be seen from Table 3 that the compressive strength trend is basically the same as the crack repair rate test results in Table 2. This also explains to a certain extent that the higher the crack repair rate, the greater the compressive strength value, thus verifying its repair effect.

[0072] Through comparative examples, it was verified that microbial stimulants significantly improved the crack repair ability of solid waste-based concrete, and combined with silica sol to fill the micro-cracks of aggregates, enhanced mechanical properties, and improved long-term strength and durability, providing a reliable technical solution for green building materials and smart infrastructure.

[0073] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A concrete material based on industrial solid waste recycled materials, characterized in that: The preparation comprises the following components by weight: 40-50 parts of industrial solid waste fine powder, 10-20 parts of passivated coarse aggregate, 180-200 parts of sol-impregnated fine aggregate dispersion, 30-40 parts of alkaline base liquid, 5-10 parts of composite microbial sustained-release capsules, and 0.1-0.2 parts of polycarboxylic acid water reducer.

2. The concrete material based on industrial solid waste recycled materials according to claim 1, characterized in that: The industrial solid waste fine powder includes steel slag and fly ash, and the mass ratio of the steel slag to the fly ash is 3: (1-2); the particle size of the industrial solid waste fine powder is ≤100 μm; Alternatively, the passivated coarse aggregate is metallurgical solid waste modified by phosphate immersion, and the particle size of the passivated coarse aggregate is 5-20 mm.

3. The concrete material based on industrial solid waste recycled materials according to claim 1, characterized in that: The sol-impregnated fine aggregate dispersion comprises waste concrete, nano-silica sol and a dispersant, wherein the mass ratio of the waste concrete to the nano-silica sol is 1:(3-4); The particle size of the waste concrete is 1-5 mm; The solid content of the nano-silica sol is 10 wt%-15 wt%; The dispersant is one of Span-80, PEG 200, sodium polyacrylate, Tween-60 and Tween-80, and the added amount of the dispersant is 0.5%-1.0% of the mass of the nano-silica sol.

4. The concrete material based on industrial solid waste recycled materials according to claim 1, characterized in that: The composite microorganism sustained-release capsule comprises a core material and a wall material wrapped on the surface of the core material, and the particle size of the composite microorganism sustained-release capsule is 50-100 μm; The core material comprises Bacillus pasteurianus spores, calcium lactate and yeast extract, wherein the mass ratio of the Bacillus pasteurianus spores, calcium lactate and yeast extract is (3-4):1:1; The live bacteria concentration of the Bacillus pasteurianus spores is >10 6 CFU / g; The wall material is sodium alginate.

5. The concrete material based on industrial solid waste recycled materials according to claim 1, characterized in that: The alkaline base liquid is composed of the following components by weight percentage: 10-15% water glass, 20-25% alkaline residue, and the balance water; The modulus of the water glass is 1.2-1.8; the particle size of the alkali residue is ≤45 μm; the alkali residue is an industrial by-product containing active ingredients such as Ca(OH) 2 and CaCO 3 .

6. A method for preparing a concrete material based on industrial solid waste recycled materials according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Dry-mixing industrial solid waste powder and passivated coarse aggregate to prepare a premix; (2) After mixing the sol-impregnated fine aggregate dispersion and the alkaline base liquid, the composite microbial sustained-release capsule is added and stirred to prepare a mixture; (3) The premix is ​​added to the mixture, and then a polycarboxylic acid water reducer is added. After pouring, curing is performed to obtain a concrete material based on industrial solid waste recycled materials.

7. The method for preparing concrete material based on industrial solid waste recycled materials according to claim 6, characterized in that: In step (1), the preparation method of the industrial solid waste fine powder is as follows: steel slag and fly ash are mixed to prepare a mixture, iron impurities are removed by magnetic separation, and then crushed to obtain the mixture; The mixing mass ratio of the steel slag and fly ash is 3:(1-2), and the crushed particle size is ≤100 μm; Alternatively, the passivated coarse aggregate is prepared by crushing the metallurgical solid waste, soaking it in a phosphate solution, and drying it after discharging; The particle size of the crushed metallurgical solid waste is 5-20 mm, the concentration of the phosphate solution is 0.4-0.6 mol / L, and the soaking time is 20-24 hours.

8. The method for preparing concrete material based on industrial solid waste recycled materials according to claim 6, characterized in that: In step (2), the preparation method of the sol-impregnated fine aggregate dispersion is as follows: Alternatively, the waste concrete is crushed and added to the nano-silica sol, and then a dispersant is added and ultrasonic treatment is performed; The mass ratio of the waste concrete to the nano-silica sol is 1:(3-4); The particle size of the waste concrete is 1-5 mm; The solid content of the nano-silica sol is 10 wt%-15 wt%; The dispersant is one of Span-80, PEG 200, sodium polyacrylate, Tween-60 and Tween-80, and the amount of the dispersant added is 0.5%-1.0% of the mass of the nano-silica sol; The frequency of the ultrasonic treatment is 35-45kHz, and the time is 20-40 min; Alternatively, the alkaline base liquid is prepared by sequentially adding water glass and alkaline residue to heated water, and then magnetically stirring the mixture to obtain a suspension; The modulus of the water glass is 1.2-1.8; the particle size of the alkali residue is ≤45 μm, and the alkali residue is an industrial by-product containing active ingredients of Ca(OH)2 and CaCO3; The temperature of the heated water is 30-35°C, the speed of the magnetic stirring is 450-550 rpm, the time is 30-35 min, and the pH of the suspension is 12.5-13; Alternatively, the composite microbial sustained-release capsule is prepared by mixing Bacillus pasteurianus spores, calcium lactate, and yeast extract to prepare a core material; adding the core material to a sodium alginate aqueous solution, and then adding a CaCl2 solution to carry out a cross-linking reaction to obtain the composite microbial sustained-release capsule; The particle size of the composite microbial sustained-release capsule is 50-100 μm; The mass ratio of the Bacillus pasteurianus spores, calcium lactate and yeast extract is (3-4):1:1; The live bacteria concentration of the Bacillus pasteurianus spores is >10 6 CFU / g; The concentration of the sodium alginate aqueous solution is 2-3 wt %, and the concentration of the CaCl2 solution is 4-5 wt %; or, in step (2), the stirring speed is 100-200 rpm, and the time is 15-25 min; Alternatively, in step (3), the curing is performed in a CO2 gas with a concentration of 10-20% for 2-3 hours, followed by standard curing for 7 days.

9. Use of the concrete material based on industrial solid waste recycled materials according to any one of claims 1 to 5 in solid waste resource utilization and building materials, preferably, in concrete crack repair.

10. A method for repairing concrete cracks, characterized in that: The concrete material based on industrial solid waste recycled materials according to any one of claims 1 to 5 is placed in a concrete crack, the ambient humidity is ≥80%, the temperature is 25°C, and the repair time is 7-28 days.

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