High-strength concrete material and preparation method thereof

Abstract

The invention relates to the field of building material preparation, in particular to a high-strength concrete material and a preparation method thereof.According to the high-strength concrete material, through the synergistic effect of core-shell type temperature-sensitive resin particles, a pH response type expanding agent and industrial solid waste composite micro powder, multi-environment self-adaptive crack resistance and mechanical property breakthrough are achieved. The core component is prepared from 180 to 240 parts of cement, industrial solid waste composite micro powder (30 to 50 parts of fly ash-based nano SiO2 and 50 to 70 parts of steel slag micro powder), 10 to 15 parts of core-shell resin particles and 8 to 12 parts of pH response type expanding agent. According to the preparation process, multi-section intelligent stirring (ultra-high-speed shearing and dispersing of the nanometer material) and dynamic maintenance of the internet of things are adopted, the hydration process is precisely regulated and controlled, and the finally prepared material has excellent compressive strength and anti-cracking performance. The method is suitable for severe scenes such as ocean engineering and plateau buildings, and has wide application prospects.

Description

Technical Field

[0001] The present invention relates to the field of building material preparation, and in particular to a high-strength concrete material and a preparation method thereof. Background Art

[0002] As the world's most widely used man-made material, increasing the strength of concrete has always been one of the core goals in the engineering field. Traditional high-strength concrete mainly relies on increasing cement dosage or adding steel fibers. However, high cement dosage leads to excessive hydration heat and increased risk of shrinkage cracking, while steel fibers are prone to rust and are expensive. In addition, problems such as uneven dispersion of nanomaterials and insufficient hydration synergy between expansive agents and cementitious materials in existing technologies have limited further improvements in concrete strength. How to reduce cement dosage while achieving synergistic enhancement of strength and durability through material compounding and process optimization is a technical problem that needs to be solved urgently.

[0003] Therefore, according to the above-mentioned related technologies, there is an urgent need to develop a high-strength concrete material and a preparation method thereof. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to propose a high-strength concrete material and a preparation method thereof, which significantly improves the density and interfacial bonding strength of concrete through the multi-phase synergistic effect of nano-composite resin, mineral micropowder and expansion agent, while inhibiting shrinkage cracking.

[0005] Based on the above objectives, the present invention provides a high-strength concrete material and a preparation method thereof.

[0006] A high-strength concrete material comprises the following raw materials in parts by weight: 180-240 parts of cement, 100-120 parts of industrial solid waste composite powder, 5-8 parts of silicon dioxide, 750-850 parts of aggregate A, 1000-1100 parts of aggregate B, 8-12 parts of a water reducer, 20-30 parts of an additive, and 120-150 parts of water;

[0007] The additives include the following raw materials in parts by mass: 10-15 parts of resin particles, 8-12 parts of expander, and 2-3 parts of emulsifier.

[0008] Preferably, the industrial solid waste composite powder comprises the following raw materials in parts by mass: 30-50 parts of fly ash-based nano-SiO2, 50-70 parts of steel slag powder, and 20 parts of slag powder.

[0009] Preferably, the fly ash-based nano-SiO2 is prepared by an alkali dissolution-acid precipitation process, with a particle size of ≤50 nm. Amorphous SiO2 (content ≥50%) in fly ash is dissolved under strong alkaline conditions to form sodium silicate (Na2SiO3). By controlling the pH value and crystallization kinetics of the acid precipitation process, silicate ions (SiO32-) are directionally grown into nano-scale particles (particle size ≤50 nm). The reaction equation is as follows:

[0010] Alkali dissolution stage: SiO2+2NaOH→Na2SiO3+H2O

[0011] Acid precipitation stage: Na2SiO3+2HCl→H2SiO3↓+2NaCl

[0012] Condensation reaction: nH2SiO3→(SiO2·H2O) n

[0013] The fly ash-based nano-SiO2 preparation process is as follows:

[0014] 1. Fly ash pretreatment: Select fly ash with SiO2 content ≥55%, loss on ignition ≤5%, grind in a ball mill for 2h (speed 800rpm), pass through a 325 mesh sieve (particle size ≤45μm) to increase the reaction contact area, remove iron impurities by magnetic separation (magnetic field strength 1500Gs) to avoid metal ion contamination, add 10% sodium carbonate solution (solid-liquid ratio 1:5), stir in a 60℃ water bath for 30min to remove Ca adsorbed on the fly ash surface. 2+ Mg 2+ Isocations.

[0015] 2. Alkali dissolution reaction: Reagent ratio: fly ash: NaOH: water = 1:0.8:8 (weight ratio), NaOH concentration is controlled at 3-4 mol / L, pretreated fly ash and NaOH solution are added to the autoclave, sealed and heated to 95±2°C, stirring speed is maintained at 300 rpm, reaction time is 4 hours, after the reaction is completed, hot filtration (filter cloth pore size ≤1 μm) is completed to obtain a clear sodium silicate solution (modulus M = 2.0-2.5), the filter residue (mainly Al2O3 and undissolved impurities) can be recovered for preparation of zeolite.

[0016] 3. Acid precipitation of nano-SiO2: 3mol / L hydrochloric acid (or CO2 gas) is used as the acid precipitation agent, CO2 gas is preferred (low-carbon process), the introduction rate is controlled at 500mL / min, the initial pH is 12-13, the acid solution is slowly added and stirred (rotation speed 800rpm), when the pH drops to 9-10, amorphous silica nuclei (particle size ≤ 10nm) are formed; continue to adjust to pH = 7-8, control the silica nucleus growth rate (Ostwald ripening), the final particle size is ≤ 50nm (laser particle size analyzer real-time monitoring), 0.5-1% polyethylene glycol (PEG-6000) or sodium hexametaphosphate is added during the acid precipitation process to inhibit particle agglomeration through steric hindrance effect, and the mass ratio of dispersant to SiO2 is 1:20.

[0017] 4. Washing and drying: transfer the acid precipitation to a centrifuge (speed 10000rpm, centrifugation time 15min), and wash with deionized water 3 times until the conductivity of the washing liquid is ≤10μS / cm (to remove Na + 、Cl - The washed wet powder was dispersed in an ethanol-water mixture (volume ratio of 1:1) at a solid-liquid ratio of 1:10, and ultrasonically treated (power 400 W, frequency 40 kHz) for 30 min to form a stable nanosol (particle size distribution D50 ≤ 30 nm, polydispersity index PDI ≤ 0.2). Spray drying: inlet air temperature 180°C, atomization pressure 0.8 MPa, the obtained powder particle size ≤ 50 nm, and good dispersibility; vacuum freeze drying: pre-freezing temperature -40°C, vacuum degree ≤ 10 Pa, drying time 24 h (nano-SiO2 agglomeration rate < 5%).

[0018] Through a two-stage acid precipitation process, which involves pH regulation in stages (12→10→8), crystal nuclei are first formed and then growth is controlled. Compared to the traditional one-step acid precipitation method (directly adjusting to pH = 7), particle size uniformity is improved by 60% (TEM observation shows a particle size distribution of ±10nm). CO2 mineralization synergy: When CO2 is used instead of hydrochloric acid for acid precipitation, the introduction of CO2 into the sodium silicate solution can produce a composite product of nano-SiO2 and calcium carbonate (CaCO3). CaCO3 acts as a dispersant to further inhibit SiO2 agglomeration (composite particle size ≤40nm) while simultaneously achieving carbon sequestration (approximately 0.3kg of CO2 is fixed per kilogram of fly ash). Approximately 300kg of nano-SiO2 can be produced per ton of fly ash, while also reducing the land occupied by fly ash storage and environmental pollution. While achieving low carbon and energy conservation, the prepared nano-SiO2 has a pozzolan activity index of 115%, higher than commercially available nano-SiO2 (activity index 105%). This can reduce cement usage by 10-15% while increasing concrete strength by 15-20%.

[0019] Preferably, the silicon dioxide is nano-silicon dioxide, and the particle size of the nano-silicon dioxide is 20-30 nm.

[0020] Preferably, the aggregate A is river sand, the fineness modulus of the river sand is 2.3-2.8, and the aggregate B is crushed stone, the particle size of the crushed stone is 5-25 mm.

[0021] Preferably, the resin particles are core-shell type resin particles, the core of the core-shell type resin particles is prepared from acrylic acid, sodium hydroxide, acrylamide and thermosensitive polymer, and the shell of the core-shell type resin particles is a nano-SiO2-carbon nanotube composite layer.

[0022] Preferably, the expander is prepared from magnesium oxide, calcium sulfoaluminate and pH-responsive microcapsules.

[0023] Preferably, the preparation process of the pH-responsive microcapsules is as follows:

[0024] Preparation of core material emulsion: Lithium carbonate, lithium stearate, and nano-SiO2 were mixed in appropriate proportions, Span-80 (10% of the total mass of the core material) was added, and the mixture was stirred in a 60°C oil bath for 30 minutes until uniformly dispersed. Liquid paraffin was slowly added (core material: paraffin = 1:2), and emulsified using a high-speed homogenizer (12000 rpm) for 10 minutes to form an oil phase emulsion (O phase) with a particle size of 50-100 μm.

[0025] Preparation of the aqueous phase solution: Dissolve acrylic acid (AA concentration 5%), N,N-methylenebisacrylamide (MBA concentration 0.5%), and potassium persulfate (KPS concentration 0.1%) in deionized water and adjust the pH to 3.5 (hydrochloric acid solution) to form an aqueous phase W. Slowly pour the W phase into the O phase emulsion while stirring at 200 rpm to form an O / W emulsion (the oil phase encapsulates the core material, and the aqueous phase contains the polymerizable monomers).

[0026] Interfacial polymerization reaction: The temperature was raised to 50°C, where KPS decomposed to generate free radicals, which initiated polymerization of AA and MBA at the oil-water interface to form a polyacrylic acid-methylenebisacrylamide cross-linked network capsule wall. After stirring at 300 rpm for 2 h, NaOH solution was added to adjust the system pH to 7.0 to terminate the polymerization.

[0027] Microcapsule separation and modification: The emulsion was transferred to a centrifuge (5000 rpm, 10 min), the supernatant was discarded, and the mixture was washed three times with an ethanol-water mixture (volume ratio of 1:1) to remove unreacted monomers. Silane coupling agent KH570 (2% of the mass of the microcapsules) was added and stirred at 60°C for 1 h to hydrophobically modify the capsule wall surface to prevent premature water absorption and swelling in an alkaline environment.

[0028] Particle size screening and drying: Microcapsules with a particle size range of 50-100 μm were collected through 200 mesh (75 μm) and 100 mesh (150 μm) standard sieves (screening efficiency ≥ 90%) and vacuum freeze-dried (-40°C, vacuum ≤ 10 Pa, drying time 24 hours) to avoid high temperature destruction of pH-responsive groups. The resulting microcapsules had a moisture content of <1%.

[0029] The core material (lithium-based anti-sulfate agent) is composed of: lithium carbonate (Li2CO3, purity ≥99%) 60%, lithium stearate 20%, nano-silicon dioxide 10%, dispersant (Span-80) 10%. The function of the core material is: Li + With SO4 2- The combination generates stable lithium aluminate, which inhibits the transformation of lithium aluminate into gypsum; lithium stearate improves the hydrophobicity of the core material, preventing it from dissolving prematurely in the alkaline environment of concrete; nano-SiO2 enhances the adhesion between the core material and the capsule wall.

[0030] The main monomer of the capsule wall material (pH-responsive polymer) is 50% acrylic acid (AA, pH-sensitive group -COOH), the cross-linking monomer is 5% N,N-methylenebisacrylamide (MBA, cross-linking agent), the initiator is 1% potassium persulfate (KPS), and the co-solvent is an ethanol-water mixture (volume ratio 3:7). In an acidic environment (pH < 7), the ionization degree of -COOH decreases, the polymer chain curls up and shrinks, causing the capsule wall to rupture; in an alkaline environment (pH ≥ 12), -COOH is fully ionized to -COO-, and the polymer chain stretches to form a stable capsule wall.

[0031] The pH-responsive microcapsules feature a dual-response synergistic mechanism: the capsule wall exhibits both pH-sensitive rupture and hydrophobic stability. Silane modification enhances alkali resistance, resolving the failure of traditional pH-responsive materials in highly alkaline environments. They also optimize the core material for sustained release: lithium stearate and nano-SiO2 form a composite core material that slows the diffusion rate of lithium ions within the microcapsule, achieving sustained corrosion resistance in saline environments (effective protection period ≥ 5 years).

[0032] Preferably, the emulsifier is obtained by mixing Span-80 and Tween-80 in a mass ratio of 1:0.8-1.2.

[0033] Preferably, the preparation process of the resin particles is as follows:

[0034] Step A1. Prepolymer Preparation: Add acrylic acid and sodium hydroxide to a beaker, slowly add deionized water dropwise, and stir until completely dissolved (pH adjusted to 6.5-7.0). Add acrylamide and PNIPAM and continue stirring for 30 minutes until a transparent solution is formed.

[0035] Step A2. Cross-linking polymerization: The transparent solution was transferred to a three-necked flask and deoxygenated by nitrogen gas for 15 min. The temperature was raised to 70±2°C, and potassium persulfate and N,N-methylenebisacrylamide were added. The mixture was stirred at 200 rpm for 2 h to form a milky white gel-like core.

[0036] Step A3. Granulation and preliminary drying: The gel was crushed into particles with a particle size of ≤2 mm, dried in a vacuum drying oven at 60°C to a moisture content of <5%, and passed through a 100-mesh sieve to obtain a core material;

[0037] Step A4. Preparation of nanodispersion: Nano-SiO2 and carbon nanotubes were added to an ethanol-water mixture and ultrasonically treated (power 300 W, frequency 40 kHz) for 45 min until no obvious agglomerates were formed (laser particle size analyzer D50 ≤ 100 nm) to obtain a dispersion;

[0038] Step A5. Coupling agent modification: KH570 was added to the dispersion, and the mixture was heated to 50°C and stirred for 1 hour to graft silane groups onto the surface of the nanoparticles (characteristic peak detected by infrared spectroscopy at 2850-2950 cm -1 verify);

[0039] Step A6. Spray coating molding: The core material is placed in a fluidized bed coating machine (inlet air temperature 120°C, atomization pressure 0.3 MPa), and the nano-mixture is evenly sprayed. Stirring is continued during the coating process (rotation speed 150 rpm) until the shell thickness reaches 50-100 nm (scanning electron microscopy observation). Finally, the coated particles are cured in a 100°C oven for 2 h to allow the silane coupling agent to fully react with the hydroxyl groups on the core surface to form a covalently bonded core-shell structure to obtain resin particles.

[0040] Preferably, the mass ratio of the acrylic acid, sodium hydroxide, acrylamide, PNIPAM, N,N-methylenebisacrylamide, potassium persulfate, deionized water, nano-SiO2, carbon nanotubes, KH570, and ethanol-water mixture is 20-22:8-10:3-4:2-2.5:0.05-0.08:0.2-0.4:50-52:10-12:0.8-1:1-1.5:100-110.

[0041] The resulting resin particles exhibit a thermosensitive, water-absorbing synergistic mechanism: the introduction of PNIPAM imparts the intelligent properties of rapid water release at low temperatures (to activate the early strength agent) and slow water release at high temperatures (to prevent excessive expansion), distinguishing them from the passive water release of traditional superabsorbent resins. The multifunctional design of the nanocomposite shell provides mechanical reinforcement: nano-SiO2 fills the shell pores, while carbon nanotubes form a "bridging-conductive" dual network, boosting the particle compressive strength to over 50 MPa (compared to approximately 20 MPa for traditional resin particles). Furthermore, it enhances interfacial bonding: the -Si-OC- chemical bond formed by the silane coupling agent increases the bond strength between the resin and cement hydration products by 40% (bond strength ≥1.2 MPa measured by pull-out tests).

[0042] A method for preparing a high-strength concrete material comprises the following steps:

[0043] Step S1. Nanodispersion: Mix the emulsifier, nano-silica and 20% water, and stir at 1800-2000 rpm for 5 minutes to form a nanodispersion mother solution;

[0044] Step S2. Gel activation: Cement, industrial solid waste composite powder and expansion agent were added to the nano-dispersed mother liquor and put into a mixer, stirred at 200-300 rpm for 3 minutes, 50% water was added, and stirred at 500-600 rpm for 8 minutes to form a slurry;

[0045] Step S3. Compounding: Aggregate A, Aggregate B, resin particles, remaining deionized water, and water reducer are added to the mortar, stirred at 1800-2000 rpm for 12 minutes, and placed in a curing chamber after forming. The temperature is maintained at 23-27°C and the humidity is ≥95% for the first three days, and the temperature is maintained at 18-22°C and the humidity is ≥85% for the fourth to twenty-eighth days to obtain a high-strength concrete material.

[0046] Beneficial effects of the present invention:

[0047] The present invention provides a high-strength concrete material and a preparation method thereof. Through the synergistic effect of multiple components and intelligent process design, the present invention achieves significant improvements in concrete strength, durability, environmental protection, and intelligent response capabilities. Specific beneficial effects are as follows:

[0048] 1. Synergistic improvement of high strength and high durability:

[0049] 1. Breakthrough in Mechanical Properties: Nanocomposite reinforcement: The high volcanic ash activity (activity index 115%) of fly ash-based nano-SiO2 (particle size ≤ 50nm) promotes the formation of CSH gel, and carbon nanotubes (elastic modulus 1TPa) bridge micro-cracks, making the 28-day compressive strength of concrete reach 88-95MPa, a 10-20% increase over traditional C80 concrete. Cementitious material optimization: f-CaO and MgO in steel slag powder provide micro-expansion to compensate for contraction, and Fe 3 + Ion catalyzed hydration generates AFm phase, which increases the early strength (3-day compressive strength) by more than 20% (compared with the traditional process from 38MPa to 52MPa).

[0050] 2. Significantly enhanced resistance to sulfate erosion: pH-responsive repair mechanism: When pH < 7, the microcapsules rupture to release Li+ and SO4 2- Stable ettringite is generated, which inhibits the formation of gypsum (ettringite content increases by 18%, and gypsum peak intensity decreases by 90%). After immersion in 5% NaCl solution for 28 days, the chloride ion permeability coefficient is as low as 1.2×10 -12 m 2 / s (anti-seepage grade P12).

[0051] 2. Intelligent response and self-adjustment function:

[0052] 1. Thermosensitive and adaptive anti-cracking: The core-shell resin particles use PNIPAM thermosensitive polymer to achieve "low-temperature rapid water release (water release rate ≥90% in 24 hours at 5°C) and high-temperature slow water release (≤50% at 30°C)", matching the cement hydration requirements, making the error between the hydration exothermic peak and the expansion agent reaction peak ≤±0.5h, reducing the shrinkage rate by 58%, and reducing the number of cracks to 3-4 / m 2 (Traditional technology 12-15 lines / m 2 ).

[0053] 2. Intelligent crack monitoring and early warning: A carbon nanotube conductive network (resistivity ≤ 100Ω·cm) monitors crack initiation in real time. When the microcrack width is ≥ 0.05mm, the resistivity change rate is ≥ 10%, realizing the "monitoring-early warning" function and breaking through the traditional passive crack resistance mode of concrete.

[0054] 3. High value and low carbonization of industrial solid waste:

[0055] 1. The utilization rate of solid waste has been greatly improved: the content of industrial solid waste such as fly ash-based nano-SiO2 and steel slag powder has reached more than 40% (traditional process is less than 20%). Each ton of concrete consumes 300kg of fly ash, reducing CO2 emissions by 120kg. At the same time, the added value of solid waste has increased from 300 yuan / ton to 8,000 yuan / ton, realizing resource recycling.

[0056] 2. Low-carbon preparation process: CO2 acid precipitation is used instead of hydrochloric acid process. Each kilogram of fly ash fixes about 0.3kg of CO2, while reducing the use of industrial hydrochloric acid by 300kg / ton of SiO2 and reducing energy consumption by 30%, which is in line with the "dual carbon" strategy.

[0057] 4. Construction technology optimization and engineering adaptability:

[0058] 1. Multi-stage mixing for uniform dispersion: Ultra-high-speed shear mixing (2000-2000rpm) ensures that the dispersion of nanomaterials (nano-SiO2, carbon nanotubes) is ≥95% (the dispersion of traditional processes is <70%), avoiding uneven strength caused by agglomeration. At the same time, staged mixing protects the integrity of coarse aggregate (the breakage rate of crushed stone with a particle size of 5-25mm is <5%).

[0059] 2. Intelligent maintenance and precise control: The maintenance chamber dynamically controls temperature and humidity (temperature ±2°C, humidity ±3%). High temperature and high humidity (25°C, humidity ≥95%) in the first three days accelerate the hydration of the expansion agent (the hydration rate of magnesium oxide increases from 78% to 92%). Cooling and moisturizing in the later period promote continuous strength development, adapting to harsh environments such as plateaus and oceans.

[0060] 5. Economic Benefits and Application Expansion: Cost Reduction: Industrial solid waste replaces high-priced nanomaterials, reducing overall costs by 25-30% (compared to traditional C80 concrete from 580 yuan / m 3 Reduced to 395 yuan / m 3 Expanded application scenarios: Suitable for extreme environments such as cross-sea bridges, nuclear power plants, and saline-alkali land buildings. Through intelligent response and self-repair capabilities (micro-crack self-repair width ≤ 0.2mm), the service life of the structure can be extended to more than 50 years, reducing maintenance costs by 40%.

[0061] In summary, the present invention has broken through the performance bottleneck of traditional concrete through the three-dimensional innovation of "intelligent response + nano-synergy + solid waste recycling", combining technological advancement, environmental friendliness and engineering economy, and has significant social value and market competitiveness. DETAILED DESCRIPTION

[0062] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0063] Example 1: A method for preparing a high-strength concrete material, comprising the following steps:

[0064] S1. Fly ash pretreatment: Fly ash with SiO2 content ≥55% and loss on ignition ≤5% was selected and ground in a ball mill for 2 h (speed 800 rpm), passed through a 325 mesh sieve (particle size ≤45 μm) to increase the reaction contact area, and magnetic separation was used to remove iron impurities (magnetic field strength 1500 Gs) to avoid metal ion contamination. 10% sodium carbonate solution (solid-to-liquid ratio 1:5) was added and stirred in a 60°C water bath for 30 min to remove Ca2+ adsorbed on the fly ash surface. 2+ Mg 2+ isocation;

[0065] S2. Alkali dissolution reaction: Reagent ratio: fly ash: NaOH: water = 1:0.8:8 (weight ratio), NaOH concentration was controlled at 3 mol / L, the pretreated fly ash and NaOH solution were added to the autoclave, sealed and heated to 95 ° C, maintained at a stirring speed of 300 rpm, the reaction time was 4h, and after the reaction was completed, hot filtration (filter cloth pore size ≤ 1 μm) to obtain a clear sodium silicate solution (modulus M = 2.0-2.5);

[0066] S3. Acid precipitation of nano-SiO2: 3 mol / L hydrochloric acid (or CO2 gas) is used as the acid precipitation agent, preferably CO2 gas (low carbon process), the introduction rate is controlled at 500 mL / min, the initial pH = 12-13, the acid solution is slowly added and stirred (speed 800 rpm), when the pH drops to 9-10, amorphous silica nuclei (particle size ≤ 10 nm) are formed; continue to adjust to pH = 7-8, control the silica nucleus growth rate (Ostwald ripening), the final particle size ≤ 50 nm (laser particle size analyzer real-time monitoring), add 0.5-1% polyethylene glycol (PEG-6000) or sodium hexametaphosphate during the acid precipitation process, inhibit particle agglomeration by steric hindrance effect, the mass ratio of dispersant to SiO2 is 1:20;

[0067] S4. Washing and drying: The acid precipitate was transferred to a centrifuge (speed 10000 rpm, centrifugation time 15 min), and washed with deionized water three times until the conductivity of the washing solution was ≤10μS / cm (to remove Na + 、Cl - The washed wet powder was dispersed in an ethanol-water mixture (volume ratio of 1:1) at a solid-liquid ratio of 1:10, and ultrasonically treated (power 400W, frequency 40kHz) for 30min to form a stable nanosol (particle size distribution D50≤30nm, polydispersity index PDI≤0.2). The powder was spray-dried at an air inlet temperature of 180°C and an atomizing pressure of 0.8MPa to obtain a powder with a particle size of ≤50nm and good dispersibility. The powder was then vacuum-freeze-dried at a pre-freezing temperature of 40°C, a vacuum degree of ≤10Pa, and a drying time of 24h (nano-SiO2 agglomeration rate <5%) to obtain fly ash-based nano-SiO2.

[0068] S5. 30 parts of fly ash-based nano-SiO2, 50 parts of steel slag powder, 20 parts of slag powder were mixed to obtain industrial solid waste composite powder;

[0069] S6. Preparation of prepolymer: 20 parts of acrylic acid and 8 parts of sodium hydroxide were added to a beaker, 50 parts of deionized water were slowly added dropwise, and stirred until completely dissolved (pH adjusted to 6.5-7.0), 3 parts of acrylamide and 2 parts of PNIPAM were added, and stirring was continued for 30 minutes until a transparent solution was formed;

[0070] S7. Cross-linking polymerization: The clear solution was transferred to a three-necked flask and deoxygenated with nitrogen for 15 min. The temperature was raised to 70°C, and 0.2 parts of potassium persulfate and 0.05 parts of N,N-methylenebisacrylamide were added. The mixture was stirred at 200 rpm for 2 h to form a milky white gel-like core.

[0071] S8. Granulation and preliminary drying: The gel was crushed into particles with a particle size of ≤2 mm, dried in a vacuum drying oven at 60°C to a moisture content of <5%, and passed through a 100-mesh sieve to obtain the core material;

[0072] S9. Preparation of nanodispersion: 10 parts of nano-SiO2 and 0.8 parts of carbon nanotubes were added to 100 parts of an ethanol-water mixture and ultrasonicated (power 300 W, frequency 40 kHz) for 45 min until no obvious agglomerates were formed (laser particle size analyzer D50 ≤ 100 nm) to obtain a dispersion;

[0073] S10. Coupling agent modification: Add 1 part of KH570 to the dispersion, heat to 50°C and stir for 1 hour to graft silane groups on the surface of the nanoparticles (infrared spectrum detection characteristic peak 2850-2950cm -1 verify);

[0074] S11. Spray coating: The core material was placed in a fluidized bed coating machine (inlet air temperature 120°C, atomization pressure 0.3 MPa) and the nano-mixture was evenly sprayed. Stirring was continued during the coating process (rotation speed 150 rpm) until the shell thickness reached 50-100 nm (scanning electron microscopy observation). Finally, the coated particles were cured in a 100°C oven for 2 h to allow the silane coupling agent to fully react with the hydroxyl groups on the core surface to form a covalently bonded core-shell structure, resulting in resin particles.

[0075] S12. Preparation of core material emulsion: Lithium carbonate, lithium stearate, and nano-SiO2 were mixed in appropriate proportions, Span-80 (10% of the total core material mass) was added, and the mixture was stirred in a 60°C oil bath for 30 min until uniformly dispersed. Liquid paraffin was slowly added (core material: paraffin = 1:2), and emulsified using a high-speed homogenizer (12000 rpm) for 10 min to form an oil phase emulsion (phase O) with a particle size of 50-100 μm.

[0076] S13. Prepare the aqueous solution: Dissolve acrylic acid (AA concentration 5%), N,N-methylenebisacrylamide (MBA concentration 0.5%), and potassium persulfate (KPS concentration 0.1%) in deionized water and adjust the pH to 3.5 (hydrochloric acid solution) to form an aqueous phase (W). Slowly pour the W phase into the O phase emulsion while stirring at 200 rpm to form an O / W emulsion (the oil phase encapsulates the core material and the aqueous phase contains the polymerizable monomers).

[0077] S14. Interfacial polymerization: The temperature was raised to 50°C. KPS decomposed to generate free radicals, which initiated polymerization of AA and MBA at the oil-water interface, forming a cross-linked polyacrylic acid-methylenebisacrylamide network capsule wall. After stirring at 300 rpm for 2 h, NaOH solution was added to adjust the pH to 7.0 to terminate the polymerization.

[0078] S15. Microcapsule Isolation and Modification: The emulsion was transferred to a centrifuge (5000 rpm, 10 min). The supernatant was discarded and the mixture was washed three times with an ethanol-water mixture (1:1 by volume) to remove unreacted monomers. Silane coupling agent KH570 (2% by mass of the microcapsules) was added and stirred at 60°C for 1 h to hydrophobically modify the capsule wall surface to prevent premature water absorption and swelling in an alkaline environment.

[0079] S16. Particle size screening and drying: Microcapsules with a particle size range of 50-100 μm were collected through 200 mesh (75 μm) and 100 mesh (150 μm) standard sieves (screening efficiency ≥ 90%), and vacuum freeze-dried (-40°C, vacuum degree ≤ 10 Pa, drying time 24 h) to avoid high temperature destruction of pH-responsive groups. The resulting microcapsules had a moisture content of <1%, and pH-responsive microcapsules were obtained. The core material (lithium-based anti-sulfate agent) was composed of: lithium carbonate (Li2CO3, purity ≥ 99%) 60%, lithium stearate 20%, nano-silica 10%, and dispersant (Span-80) 10%. The function of the core material is: Li + With SO4 2- The combination generates stable lithium aluminate, inhibiting the conversion of ettringite to gypsum; lithium stearate improves the hydrophobicity of the core material and prevents premature dissolution in the alkaline environment of concrete; nano-SiO2 enhances the adhesion between the core material and the capsule wall, while the main monomer of the capsule wall material (pH-responsive polymer) is 50% acrylic acid (AA, pH-sensitive group -COOH), the cross-linking monomer is 5% N,N-methylenebisacrylamide (MBA, cross-linking agent), the initiator is 1% potassium persulfate (KPS), and the co-solvent is an ethanol-water mixture (volume ratio 3:7). In an acidic environment (pH < 7), the ionization degree of -COOH decreases, the polymer chain curls and shrinks, causing the capsule wall to rupture; in an alkaline environment (pH ≥ 12), -COOH is fully ionized to -COO-, and the polymer chain stretches to form a stable capsule wall;

[0080] S17. Mixing magnesium oxide, calcium sulfoaluminate, and pH-responsive microcapsules in a ratio of 60%:30%:10% to obtain a swelling agent;

[0081] S18. Span-80 and Tween-80 were mixed in a mass ratio of 1:0.8 to obtain an emulsifier;

[0082] S19. Nanodispersion: Mix 2 parts of emulsifier, 5 parts of nanosilica with a particle size of 20-30 nm, and 20% deionized water and stir at 1800 rpm for 5 minutes to form a nanodispersion mother liquor;

[0083] S20 gel activation: 180 parts of cement, 100 parts of industrial solid waste composite powder and 8 parts of expansion agent were added to the nano-dispersed mother liquor into a mixer and stirred at 200 rpm for 3 min. 50% deionized water was added and stirred at 500 rpm for 8 min to form a slurry;

[0084] Step S3. Compounding: Add 750 parts of river sand with a fineness modulus of 2.3-2.8, 1000 parts of crushed stone with a particle size of 5-25 mm, 10 parts of resin particles, the remaining deionized water, and 8 parts of water reducer to the mortar, stir at 1800 rpm for 12 minutes, and move into a curing chamber after forming. Maintain the temperature at 23-27°C and humidity ≥95% for the first three days, and the temperature at 18-22°C and humidity ≥85% from the 4th to the 28th day to obtain a high-strength concrete material.

[0085] Example 2: A method for preparing a high-strength concrete material, comprising the following steps:

[0086] S1. Fly ash pretreatment: Fly ash with SiO2 content ≥55% and loss on ignition ≤5% was selected and ground in a ball mill for 2 h (speed 800 rpm), passed through a 325 mesh sieve (particle size ≤45 μm) to increase the reaction contact area, and magnetic separation was used to remove iron impurities (magnetic field strength 1500 Gs) to avoid metal ion contamination. 10% sodium carbonate solution (solid-to-liquid ratio 1:5) was added and stirred in a 60°C water bath for 30 min to remove Ca2+ adsorbed on the fly ash surface. 2+ Mg 2+ isocation;

[0087] S2. Alkali dissolution reaction: Reagent ratio: fly ash: NaOH: water = 1:0.8:8 (weight ratio), NaOH concentration was controlled at 3.5 mol / L, the pretreated fly ash and NaOH solution were added to the autoclave, sealed and heated to 96 ° C, maintained at a stirring speed of 300 rpm, the reaction time was 4h, and after the reaction was completed, hot filtration (filter cloth pore size ≤ 1 μm) to obtain a clear sodium silicate solution (modulus M = 2.0-2.5);

[0088] S3. Acid precipitation of nano-SiO2: 3 mol / L hydrochloric acid (or CO2 gas) is used as the acid precipitation agent, preferably CO2 gas (low carbon process), the introduction rate is controlled at 500 mL / min, the initial pH = 12-13, the acid solution is slowly added and stirred (speed 800 rpm), when the pH drops to 9-10, amorphous silica nuclei (particle size ≤ 10 nm) are formed; continue to adjust to pH = 7-8, control the silica nucleus growth rate (Ostwald ripening), the final particle size ≤ 50 nm (laser particle size analyzer real-time monitoring), add 0.5-1% polyethylene glycol (PEG-6000) or sodium hexametaphosphate during the acid precipitation process, inhibit particle agglomeration by steric hindrance effect, the mass ratio of dispersant to SiO2 is 1:20;

[0089] S4. Washing and drying: The acid precipitate was transferred to a centrifuge (speed 10000 rpm, centrifugation time 15 min), and washed with deionized water three times until the conductivity of the washing solution was ≤10μS / cm (to remove Na + 、Cl - The washed wet powder was dispersed in an ethanol-water mixture (volume ratio of 1:1) at a solid-liquid ratio of 1:10, and ultrasonically treated (power 400W, frequency 40kHz) for 30min to form a stable nanosol (particle size distribution D50≤30nm, polydispersity index PDI≤0.2). The powder was spray-dried at an air inlet temperature of 180°C and an atomizing pressure of 0.8MPa to obtain a powder with a particle size of ≤50nm and good dispersibility. The powder was then vacuum-freeze-dried at a pre-freezing temperature of 40°C, a vacuum degree of ≤10Pa, and a drying time of 24h (nano-SiO2 agglomeration rate <5%) to obtain fly ash-based nano-SiO2.

[0090] S5. 40 parts of fly ash-based nano-SiO2, 60 parts of steel slag powder, 20 parts of slag powder were mixed to obtain industrial solid waste composite powder;

[0091] S6. Preparation of prepolymer: 21 parts of acrylic acid and 9 parts of sodium hydroxide were added to a beaker, 51 parts of deionized water were slowly added dropwise, and stirred until completely dissolved (pH adjusted to 6.5-7.0), 3.5 parts of acrylamide and 2.2 parts of PNIPAM were added, and stirring was continued for 30 minutes to form a transparent solution;

[0092] S7. Cross-linking polymerization: The clear solution was transferred to a three-necked flask and deoxygenated by nitrogen flow for 15 min. The temperature was raised to 68°C, and 0.3 parts of potassium persulfate and 0.06 parts of N,N-methylenebisacrylamide were added. The mixture was stirred at 200 rpm for 2 h to form a milky white gel-like core.

[0093] S8. Granulation and preliminary drying: The gel was crushed into particles with a particle size of ≤2 mm, dried in a vacuum drying oven at 60°C to a moisture content of <5%, and passed through a 100-mesh sieve to obtain the core material;

[0094] S9. Preparation of nanodispersion: 11 parts of nano-SiO2 and 0.9 parts of carbon nanotubes were added to 105 parts of an ethanol-water mixture and ultrasonicated (power 300 W, frequency 40 kHz) for 45 min until no obvious agglomerates were formed (laser particle size analyzer D50 ≤ 100 nm) to obtain a dispersion;

[0095] S10. Coupling agent modification: 1.2 parts of KH570 were added to the dispersion, and the temperature was raised to 50°C and stirred for 1 hour to graft silane groups on the surface of the nanoparticles (the characteristic peak of the infrared spectrum was 2850-2950 cm -1 verify);

[0096] S11. Spray coating: The core material was placed in a fluidized bed coating machine (inlet air temperature 120°C, atomization pressure 0.3 MPa) and the nano-mixture was evenly sprayed. Stirring was continued during the coating process (rotation speed 150 rpm) until the shell thickness reached 50-100 nm (scanning electron microscopy observation). Finally, the coated particles were cured in a 100°C oven for 2 h to allow the silane coupling agent to fully react with the hydroxyl groups on the core surface to form a covalently bonded core-shell structure, resulting in resin particles.

[0097] S12. Preparation of core material emulsion: Lithium carbonate, lithium stearate, and nano-SiO2 were mixed in appropriate proportions, Span-80 (10% of the total core material mass) was added, and the mixture was stirred in a 60°C oil bath for 30 min until uniformly dispersed. Liquid paraffin was slowly added (core material: paraffin = 1:2), and emulsified using a high-speed homogenizer (12000 rpm) for 10 min to form an oil phase emulsion (phase O) with a particle size of 50-100 μm.

[0098] S13. Prepare the aqueous solution: Dissolve acrylic acid (AA concentration 5%), N,N-methylenebisacrylamide (MBA concentration 0.5%), and potassium persulfate (KPS concentration 0.1%) in deionized water and adjust the pH to 3.5 (hydrochloric acid solution) to form an aqueous phase (W). Slowly pour the W phase into the O phase emulsion while stirring at 200 rpm to form an O / W emulsion (the oil phase encapsulates the core material and the aqueous phase contains the polymerizable monomers).

[0099] S14. Interfacial polymerization: The temperature was raised to 50°C. KPS decomposed to generate free radicals, which initiated polymerization of AA and MBA at the oil-water interface, forming a cross-linked polyacrylic acid-methylenebisacrylamide network capsule wall. After stirring at 300 rpm for 2 h, NaOH solution was added to adjust the pH to 7.0 to terminate the polymerization.

[0100] S15. Microcapsule Isolation and Modification: The emulsion was transferred to a centrifuge (5000 rpm, 10 min). The supernatant was discarded and the mixture was washed three times with an ethanol-water mixture (1:1 by volume) to remove unreacted monomers. Silane coupling agent KH570 (2% by mass of the microcapsules) was added and stirred at 60°C for 1 h to hydrophobically modify the capsule wall surface to prevent premature water absorption and swelling in an alkaline environment.

[0101] S16. Particle size screening and drying: Microcapsules with a particle size range of 50-100 μm were collected through 200 mesh (75 μm) and 100 mesh (150 μm) standard sieves (screening efficiency ≥ 90%), and vacuum freeze-dried (-40°C, vacuum degree ≤ 10 Pa, drying time 24 h) to avoid high temperature destruction of pH-responsive groups. The resulting microcapsules had a moisture content of <1%, and pH-responsive microcapsules were obtained. The core material (lithium-based anti-sulfate agent) was composed of: lithium carbonate (Li2CO3, purity ≥ 99%) 60%, lithium stearate 20%, nano-silica 10%, and dispersant (Span-80) 10%. The function of the core material is: Li + With SO4 2- The combination generates stable lithium aluminate, inhibiting the conversion of ettringite to gypsum; lithium stearate improves the hydrophobicity of the core material and prevents premature dissolution in the alkaline environment of concrete; nano-SiO2 enhances the adhesion between the core material and the capsule wall, while the main monomer of the capsule wall material (pH-responsive polymer) is 50% acrylic acid (AA, pH-sensitive group -COOH), the cross-linking monomer is 5% N,N-methylenebisacrylamide (MBA, cross-linking agent), the initiator is 1% potassium persulfate (KPS), and the co-solvent is an ethanol-water mixture (volume ratio 3:7). In an acidic environment (pH < 7), the ionization degree of -COOH decreases, the polymer chain curls and shrinks, causing the capsule wall to rupture; in an alkaline environment (pH ≥ 12), -COOH is fully ionized to -COO-, and the polymer chain stretches to form a stable capsule wall;

[0102] S17. Magnesium oxide, calcium sulfoaluminate, and pH-responsive microcapsules were mixed in a ratio of 60%:30%:10% to obtain a swelling agent;

[0103] S18. Span-80 and Tween-80 were mixed in a mass ratio of 1:0.8-1.2 to obtain an emulsifier;

[0104] S19. Nanodispersion: 2.5 parts of emulsifier, 6 parts of nano-silica with a particle size of 20-30 nm and 20% deionized water were mixed and stirred at 1900 rpm for 5 minutes to form a nanodispersion mother liquor;

[0105] S20 gel activation: 210 parts of cement, 110 parts of industrial solid waste composite powder and 10 parts of expansion agent were added to the nano-dispersed mother liquor into a mixer and stirred at 250 rpm for 3 min. 50% deionized water was added and stirred at 550 rpm for 8 min to form a slurry;

[0106] Step S3. Compounding: Add 800 parts of river sand with a fineness modulus of 2.3-2.8, 1050 parts of crushed stone with a particle size of 5-25 mm, 12 parts of resin particles, the remaining deionized water, and 10 parts of a water reducer to the mortar, stir at 1900 rpm for 12 minutes, and move into a curing chamber after forming. Maintain the temperature at 23-27°C and the humidity at least 95% for the first three days, and the temperature at 18-22°C and the humidity at least 85% from the 4th to the 28th day to obtain a high-strength concrete material.

[0107] Example 3: A method for preparing a high-strength concrete material, comprising the following steps:

[0108] S1. Fly ash pretreatment: Fly ash with SiO2 content ≥55% and loss on ignition ≤5% was selected and ground in a ball mill for 2 h (speed 800 rpm), passed through a 325 mesh sieve (particle size ≤45 μm) to increase the reaction contact area, and magnetic separation was used to remove iron impurities (magnetic field strength 1500 Gs) to avoid metal ion contamination. 10% sodium carbonate solution (solid-to-liquid ratio 1:5) was added and stirred in a 60°C water bath for 30 min to remove Ca2+ adsorbed on the fly ash surface. 2+ Mg 2+ isocation;

[0109] S2. Alkali dissolution reaction: Reagent ratio: fly ash: NaOH: water = 1:0.8:8 (weight ratio), NaOH concentration was controlled at 3-4 mol / L, the pretreated fly ash and NaOH solution were added to the autoclave, sealed and heated to 95-97 ° C, maintained at a stirring speed of 300 rpm, the reaction time was 4h, and after the reaction was completed, hot filtration (filter cloth pore size ≤ 1 μm) to obtain a clear sodium silicate solution (modulus M = 2.0-2.5);

[0110] S3. Acid precipitation of nano-SiO2: 3 mol / L hydrochloric acid (or CO2 gas) is used as the acid precipitation agent, preferably CO2 gas (low carbon process), the introduction rate is controlled at 500 mL / min, the initial pH = 12-13, the acid solution is slowly added and stirred (speed 800 rpm), when the pH drops to 9-10, amorphous silica nuclei (particle size ≤ 10 nm) are formed; continue to adjust to pH = 7-8, control the silica nucleus growth rate (Ostwald ripening), the final particle size ≤ 50 nm (laser particle size analyzer real-time monitoring), add 0.5-1% polyethylene glycol (PEG-6000) or sodium hexametaphosphate during the acid precipitation process, inhibit particle agglomeration by steric hindrance effect, the mass ratio of dispersant to SiO2 is 1:20;

[0111] S4. Washing and drying: The acid precipitate was transferred to a centrifuge (speed 10000 rpm, centrifugation time 15 min), and washed with deionized water three times until the conductivity of the washing solution was ≤10μS / cm (to remove Na + 、Cl - The washed wet powder was dispersed in an ethanol-water mixture (volume ratio of 1:1) at a solid-liquid ratio of 1:10, and ultrasonically treated (power 400W, frequency 40kHz) for 30min to form a stable nanosol (particle size distribution D50≤30nm, polydispersity index PDI≤0.2). The powder was spray-dried at an air inlet temperature of 180°C and an atomizing pressure of 0.8MPa to obtain a powder with a particle size of ≤50nm and good dispersibility. The powder was then vacuum-freeze-dried at a pre-freezing temperature of 40°C, a vacuum degree of ≤10Pa, and a drying time of 24h (nano-SiO2 agglomeration rate <5%) to obtain fly ash-based nano-SiO2.

[0112] S5 50 parts of fly ash-based nano-SiO2, 70 parts of steel slag powder, 20 parts of slag powder were mixed to obtain industrial solid waste composite powder;

[0113] S6. Preparation of prepolymer: 22 parts of acrylic acid and 10 parts of sodium hydroxide were added to a beaker, 52 parts of deionized water were slowly added dropwise, and stirred until completely dissolved (pH adjusted to 6.5-7.0), 4 parts of acrylamide and 2.5 parts of PNIPAM were added, and stirring was continued for 30 minutes until a transparent solution was formed;

[0114] S7. Cross-linking polymerization: The clear solution was transferred to a three-necked flask and deoxygenated with nitrogen for 15 min. The temperature was raised to 72°C, and 0.4 parts of potassium persulfate and 0.08 parts of N,N-methylenebisacrylamide were added. The mixture was stirred at 200 rpm for 2 h to form a milky white gel-like core.

[0115] S8. Granulation and preliminary drying: The gel was crushed into particles with a particle size of ≤2 mm, dried in a vacuum drying oven at 60°C to a moisture content of <5%, and passed through a 100-mesh sieve to obtain the core material;

[0116] S9. Preparation of nanodispersion: 12 parts of nano-SiO2 and 1 part of carbon nanotubes were added to 110 parts of an ethanol-water mixture and ultrasonicated (power 300 W, frequency 40 kHz) for 45 min until no obvious agglomerates were formed (laser particle size analyzer D50 ≤ 100 nm) to obtain a dispersion;

[0117] S10. Coupling agent modification: 1.5 parts of KH570 were added to the dispersion, and the temperature was raised to 50°C and stirred for 1 hour to graft silane groups on the surface of the nanoparticles (the characteristic peak of the infrared spectrum was 2850-2950 cm -1 verify);

[0118] S11. Spray coating: The core material was placed in a fluidized bed coating machine (inlet air temperature 120°C, atomization pressure 0.3 MPa) and the nano-mixture was evenly sprayed. Stirring was continued during the coating process (rotation speed 150 rpm) until the shell thickness reached 50-100 nm (scanning electron microscopy observation). Finally, the coated particles were cured in a 100°C oven for 2 h to allow the silane coupling agent to fully react with the hydroxyl groups on the core surface to form a covalently bonded core-shell structure, resulting in resin particles.

[0119] S12. Preparation of core material emulsion: Lithium carbonate, lithium stearate, and nano-SiO2 were mixed in appropriate proportions, Span-80 (10% of the total core material mass) was added, and the mixture was stirred in a 60°C oil bath for 30 min until uniformly dispersed. Liquid paraffin was slowly added (core material: paraffin = 1:2), and emulsified using a high-speed homogenizer (12000 rpm) for 10 min to form an oil phase emulsion (phase O) with a particle size of 50-100 μm.

[0120] S13. Prepare the aqueous solution: Dissolve acrylic acid (AA concentration 5%), N,N-methylenebisacrylamide (MBA concentration 0.5%), and potassium persulfate (KPS concentration 0.1%) in deionized water and adjust the pH to 3.5 (hydrochloric acid solution) to form an aqueous phase (W). Slowly pour the W phase into the O phase emulsion while stirring at 200 rpm to form an O / W emulsion (the oil phase encapsulates the core material and the aqueous phase contains the polymerizable monomers).

[0121] S14. Interfacial polymerization: The temperature was raised to 50°C. KPS decomposed to generate free radicals, which initiated polymerization of AA and MBA at the oil-water interface, forming a cross-linked polyacrylic acid-methylenebisacrylamide network capsule wall. After stirring at 300 rpm for 2 h, NaOH solution was added to adjust the pH to 7.0 to terminate the polymerization.

[0122] S15. Microcapsule Isolation and Modification: The emulsion was transferred to a centrifuge (5000 rpm, 10 min). The supernatant was discarded and the mixture was washed three times with an ethanol-water mixture (1:1 by volume) to remove unreacted monomers. Silane coupling agent KH570 (2% by mass of the microcapsules) was added and stirred at 60°C for 1 h to hydrophobically modify the capsule wall surface to prevent premature water absorption and swelling in an alkaline environment.

[0123] S16. Particle size screening and drying: Microcapsules with a particle size range of 50-100 μm were collected through 200 mesh (75 μm) and 100 mesh (150 μm) standard sieves (screening efficiency ≥ 90%), and vacuum freeze-dried (-40°C, vacuum degree ≤ 10 Pa, drying time 24 h) to avoid high temperature destruction of pH-responsive groups. The resulting microcapsules had a moisture content of <1%, and pH-responsive microcapsules were obtained. The core material (lithium-based anti-sulfate agent) was composed of: lithium carbonate (Li2CO3, purity ≥ 99%) 60%, lithium stearate 20%, nano-silica 10%, and dispersant (Span-80) 10%. The function of the core material is: Li + With SO4 2- The combination generates stable lithium aluminate, inhibiting the conversion of ettringite to gypsum; lithium stearate improves the hydrophobicity of the core material and prevents premature dissolution in the alkaline environment of concrete; nano-SiO2 enhances the adhesion between the core material and the capsule wall, while the main monomer of the capsule wall material (pH-responsive polymer) is 50% acrylic acid (AA, pH-sensitive group -COOH), the cross-linking monomer is 5% N,N-methylenebisacrylamide (MBA, cross-linking agent), the initiator is 1% potassium persulfate (KPS), and the co-solvent is an ethanol-water mixture (volume ratio 3:7). In an acidic environment (pH < 7), the ionization degree of -COOH decreases, the polymer chain curls and shrinks, causing the capsule wall to rupture; in an alkaline environment (pH ≥ 12), -COOH is fully ionized to -COO-, and the polymer chain stretches to form a stable capsule wall;

[0124] S17. Magnesium oxide, calcium sulfoaluminate, and pH-responsive microcapsules were mixed in a ratio of 60%:30%:10% to obtain a swelling agent;

[0125] S18. Span-80 and Tween-80 were mixed in a mass ratio of 1:0.8-1.2 to obtain an emulsifier;

[0126] S19 Nanodispersion: 3 parts of emulsifier, 8 parts of nano-silica with a particle size of 20-30 nm and 20% deionized water were mixed and stirred at 2000 rpm for 5 minutes to form a nanodispersion mother liquor;

[0127] S20 gel activation: 240 parts of cement, 120 parts of industrial solid waste composite powder and 12 parts of expansion agent were added to the nano-dispersed mother liquor into a mixer and stirred at 300 rpm for 3 min. 50% deionized water was added and stirred at 600 rpm for 8 min to form a slurry;

[0128] Step S3. Compounding: Add 850 parts of river sand with a fineness modulus of 2.3-2.8, 1100 parts of crushed stone with a particle size of 5-25 mm, 15 parts of resin particles, the remaining deionized water, and 12 parts of a water reducer to the mortar, stir at 2000 rpm for 12 minutes, and move into a curing chamber after forming. Maintain the temperature at 23-27°C and the humidity at least 95% for the first three days, and the temperature at 18-22°C and the humidity at least 85% from the 4th to the 28th day to obtain a high-strength concrete material.

[0129] Comparative Example 1: Core-shell-free resin particles (replacement of traditional super absorbent resin):

[0130] The differences between this comparative example and Example 1 are as follows:

[0131] The core-shell resin particles are replaced by traditional super absorbent resin (non-core-shell structure, without temperature-sensitive polymer and carbon nanotubes), and the other components and processes remain unchanged.

[0132] Specific parameters: Resin particles: 10-15 parts of ordinary polyacrylic acid super absorbent resin (particle size 100-200 mesh, water absorption rate 600 times)

[0133] Preparation process: Omit steps S6-S11 (no nano-SiO2-carbon nanotube coating).

[0134] Comparative Example 2: Non-pH responsive microcapsules (traditional expansion agent replacement):

[0135] The differences between this comparative example and Example 1 are as follows:

[0136] The expander contains only 60% magnesium oxide and 40% calcium sulfoaluminate, and the pH-responsive microcapsules are removed, while the other components and processes remain unchanged.

[0137] Specific parameters: Expansion agent: magnesium oxide 60%, calcium sulfoaluminate 40% (without lithium-based anti-sulfate component).

[0138] Comparative Example 3: Low solid waste content (traditional cementitious material):

[0139] The differences between this comparative example and Example 1 are as follows:

[0140] The industrial solid waste composite micropowder contains only 120 parts of slag micropowder, and the fly ash-based nano-SiO2 and steel slag micropowder are removed, while the other components and processes remain unchanged.

[0141] Specific parameters: Cementitious materials: 300-380 parts of cement, 120 parts of slag powder (no fly ash-based nano-SiO2, steel slag powder).

[0142] Performance testing:

[0143] Compressive strength test (GB / T50081-2019): Specimen preparation: 150mm×150mm×150mm cubic specimen, standard curing for 28 days, equipment: electro-hydraulic servo pressure testing machine (accuracy ±1%).

[0144] Crack resistance test (flat plate method, GB / T26800-2011): Specimen size: 600mm × 600mm × 63mm flat plate, curing environment: temperature 20±2°C, humidity 60±5%, wind speed 5±0.5m / s, test the number of cracks and crack area within 72h.

[0145] Sulfate corrosion resistance test (GB / T50082-2009): Method: Soak in 5% Na2SO4 solution for 28 days and calculate the strength loss rate.

[0146] Shrinkage test (GB / T50082-2009): Specimen size: 100mm×100mm×515mm prism, test 28-day drying shrinkage.

[0147] The results are shown in Table 1 below:

[0148] Table 1

[0149]

[0150] Data Analysis:

[0151] As can be seen from Table 1, the concrete material prepared by the present invention has higher compressive strength, better crack resistance, higher resistance to sulfate erosion and lower shrinkage. This is due to 1. The effect of core-shell resin particles: Comparative Example 1 vs Example 1: The compressive strength decreased by 18.3%, indicating that the core-shell structured nano-SiO2-carbon nanotube composite layer significantly contributes to the strength through mechanical reinforcement and interface bonding improvement (carbon nanotubes bridge microcracks, nano-SiO2 fills pores). The number of cracks increased by 290% and the shrinkage increased by 132%, indicating that traditional superabsorbent resins lack temperature-sensitive regulation capabilities and cannot dynamically match hydration requirements, resulting in aggravated early shrinkage cracking. 2. The effect of pH-responsive microcapsules, Comparative Example 2 vs Example 1: The sulfate erosion strength loss rate increased by 4.8 times, proving that the Li released by the pH-responsive microcapsules + It effectively inhibits the formation of gypsum, while traditional expansion agents cannot cope with sulfate attack in acidic environments. The number of cracks increased by 206%, indicating that the lack of Li +The anti-sulfate effect causes additional shrinkage cracks inside the concrete due to erosion. 3. The effect of industrial solid waste composite micropowder: Comparative Example 3 vs Example 1: The compressive strength decreased by 22.1%, reflecting the contribution of the volcanic ash effect of fly ash-based nano-SiO2 (activity index 115%) and the micro-expansion compensation of steel slag micropowder to the strength. The shrinkage rate increased by 178%, indicating that the micro-expansion components (f-CaO, MgO) of industrial solid waste are crucial to inhibiting self-shrinkage, and low solid waste dosage leads to uncontrolled shrinkage. 4. Verification of synergistic effect: Example 1 achieves a comprehensive improvement in strength, crack resistance and durability through the triple synergy of core-shell resin dynamic water release + pH response anti-corrosion + solid waste micro-expansion, compared with the comparative example of single technology improvement, which confirms the necessity of multi-component collaborative design.

[0152] in conclusion:

[0153] Core-shell resin particles are the core of intelligent anti-cracking, and achieve "anti-cracking + monitoring" integration through temperature-sensitive water release and conductive monitoring;

[0154] pH-responsive microcapsules are key to resisting sulfate attack, solving the problem of traditional expanders failing in acidic environments;

[0155] Industrial solid waste composite micropowder is the basis of low carbon and high strength, and improves performance through the release of active components and micro-expansion effect.

[0156] The comparative data fully demonstrate that the core technical features of the present invention (core-shell structure, pH response, and high value conversion of solid waste) are significantly creative and technologically progressive.

[0157] Through the synergistic effect of multiple components and intelligent process design, the present invention achieves significant improvements in concrete strength, durability, environmental protection, and intelligent response capabilities. The specific beneficial effects are as follows:

[0158] 1. Synergistic improvement of high strength and high durability:

[0159] 3. Breakthrough in Mechanical Properties: Nanocomposite reinforcement: The high volcanic ash activity (activity index 115%) of fly ash-based nano-SiO2 (particle size ≤ 50nm) promotes the formation of CSH gel, and carbon nanotubes (elastic modulus 1TPa) bridge micro-cracks, making the 28-day compressive strength of concrete reach 88-95MPa, a 10-20% increase over traditional C80 concrete. Cementitious material optimization: f-CaO and MgO in steel slag powder provide micro-expansion to compensate for contraction, and Fe 3 + Ion catalyzed hydration generates AFm phase, which increases the early strength (3-day compressive strength) by more than 20% (compared with the traditional process from 38MPa to 52MPa).

[0160] 4. Significantly enhanced resistance to sulfate erosion: pH-responsive repair mechanism: When pH < 7, the microcapsules rupture to release Li+ and SO42- Stable ettringite is generated, which inhibits the formation of gypsum (ettringite content increases by 18%, and gypsum peak intensity decreases by 90%). After immersion in 5% NaCl solution for 28 days, the chloride ion permeability coefficient is as low as 1.2×10 -12 m 2 / s (anti-seepage grade P12).

[0161] 2. Intelligent response and self-adjustment function:

[0162] 3. Thermosensitive and adaptive anti-cracking: The core-shell resin particles use PNIPAM thermosensitive polymer to achieve "low-temperature rapid water release (water release rate ≥90% in 24 hours at 5°C) and high-temperature slow water release (≤50% at 30°C)", matching the cement hydration requirements, making the error between the hydration exothermic peak and the expansion agent reaction peak ≤±0.5h, reducing the shrinkage rate by 58%, and reducing the number of cracks to 3-4 / m 2 (Traditional technology 12-15 lines / m 2 ).

[0163] 4. Intelligent crack monitoring and early warning: A carbon nanotube conductive network (resistivity ≤ 100Ω·cm) monitors crack initiation in real time. When the microcrack width is ≥ 0.05mm, the resistivity change rate is ≥ 10%, realizing a "monitoring-early warning" function, breaking through the traditional passive crack resistance mode of concrete.

[0164] 3. High value and low carbonization of industrial solid waste:

[0165] 3. The utilization rate of solid waste has been greatly improved: the content of industrial solid waste such as fly ash-based nano-SiO2 and steel slag powder has reached more than 40% (traditional process is less than 20%), and each ton of concrete consumes 300kg of fly ash, reducing CO2 emissions by 120kg. At the same time, the added value of solid waste has increased from 300 yuan / ton to 8,000 yuan / ton, realizing resource recycling.

[0166] 4. Low-carbon preparation process: CO2 acid precipitation is used instead of hydrochloric acid process. Each kilogram of fly ash fixes about 0.3kg of CO2, while reducing the use of industrial hydrochloric acid by 300kg / ton of SiO2 and reducing energy consumption by 30%, which is in line with the "dual carbon" strategy.

[0167] 4. Construction technology optimization and engineering adaptability:

[0168] 3. Multi-stage stirring for uniform dispersion: Ultra-high-speed shear stirring (2000-2000rpm) ensures that the dispersion of nanomaterials (nano-SiO2, carbon nanotubes) is ≥95% (the dispersion of traditional processes is <70%), avoiding uneven strength caused by agglomeration. At the same time, staged stirring protects the integrity of coarse aggregate (the breakage rate of crushed stone with a particle size of 5-25mm is <5%).

[0169] 4. Intelligent maintenance and precise control: The maintenance chamber dynamically controls temperature and humidity (temperature ±2°C, humidity ±3%). High temperature and high humidity (25°C, humidity ≥95%) in the first three days accelerate the hydration of the expansion agent (the hydration rate of magnesium oxide increases from 78% to 92%). In the later period, cooling and moisturizing promote continuous strength development, adapting to harsh environments such as plateaus and oceans.

[0170] 5. Economic Benefits and Application Expansion: Cost Reduction: Industrial solid waste replaces high-priced nanomaterials, reducing overall costs by 25-30% (compared to traditional C80 concrete from 580 yuan / m 3 Reduced to 395 yuan / m 3 ). Application scenario expansion: It is suitable for extreme environments such as cross-sea bridges, nuclear power plants, and saline-alkali land buildings. Through intelligent response and self-repair capabilities (micro-crack self-repair width ≤ 0.2mm), the service life of the structure is extended to more than 50 years, and maintenance costs are reduced by 40%. In summary, the present invention has broken through the performance bottleneck of traditional concrete through the three-dimensional innovation of "intelligent response + nano-synergy + solid waste recycling", and has both technological advancement, environmental friendliness and engineering economy, and has significant social value and market competitiveness.

[0171] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0172] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-strength concrete material, characterized in that: The raw materials include the following parts by weight: 180-240 parts of cement, 100-120 parts of industrial solid waste composite powder, 5-8 parts of silicon dioxide, 750-850 parts of aggregate A, 1000-1100 parts of aggregate B, 8-12 parts of water reducer, 20-30 parts of additives, and 120-150 parts of water; The additives include the following raw materials in parts by mass: 10-15 parts of resin particles, 8-12 parts of expander, and 2-3 parts of emulsifier.

2. The high-strength concrete material according to claim 1, characterized in that: The industrial solid waste composite micropowder comprises the following raw materials in parts by weight: 30-50 parts of fly ash-based nano-SiO2, 50-70 parts of steel slag micropowder, and 20 parts of slag micropowder.

3. The high-strength concrete material according to claim 2, characterized in that: The fly ash-based nano-SiO2 is prepared through an alkali dissolution-acid precipitation process, and has a particle size of ≤50nm.

4. The high-strength concrete material according to claim 1, characterized in that: The silicon dioxide is nano silicon dioxide, and the particle size of the nano silicon dioxide is 20-30 nm.

5. The high-strength concrete material according to claim 1, characterized in that: The aggregate A is river sand, and the fineness modulus of the river sand is 2.3-2.

8. The aggregate B is crushed stone, and the particle size of the crushed stone is 5-25 mm.

6. The high-strength concrete material according to claim 1, characterized in that: The resin particles are core-shell type resin particles, the core of which is prepared from acrylic acid, sodium hydroxide, acrylamide and thermosensitive polymer, and the shell of which is a nano-SiO2-carbon nanotube composite layer.

7. The high-strength concrete material according to claim 1, characterized in that: The expansion agent is prepared from magnesium oxide, calcium sulfoaluminate and pH-responsive microcapsules.

8. The high-strength concrete material according to claim 1, characterized in that: The emulsifier is obtained by mixing Span-80 and Tween-80 in a mass ratio of 1:0.8-1.

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9. The high-strength concrete material according to claim 1, characterized in that: The preparation process of the resin particles is as follows: Step A1. Preparation of prepolymer: A transparent solution was prepared using acrylic acid, sodium hydroxide, deionized water, acrylamide and PNIPAM; Step A2. Cross-linking polymerization reaction: Potassium persulfate and N,N-methylenebisacrylamide are added to the transparent solution to react to obtain a gel-like core; Step A3. Granulation and preliminary drying: The gel-like core is crushed into particles with a particle size of ≤2 mm, dried and passed through a 100-mesh sieve to obtain a core material; Step A4. Preparation of nanodispersion: reacting nano-SiO2, carbon nanotubes and an ethanol-water mixture to obtain a dispersion; Step A5. Coupling agent modification: adding KH570 to the dispersion to react to obtain a nanomixture; Step A6. Spray coating molding: The core material is put into a fluidized bed coating machine, the nano-mixed liquid is evenly sprayed, and finally the resin particles are obtained through curing.

10. A method for preparing a high-strength concrete material, characterized in that: The following steps are involved: Step S1. Nanodispersion: Mix the emulsifier, nano-silica and 20% water, and stir at 1800-2000 rpm for 5 minutes to form a nanodispersion mother solution; Step S2. Gel activation: Cement, industrial solid waste composite powder and expansion agent were added to the nano-dispersed mother liquor and put into a mixer, stirred at 200-300 rpm for 3 minutes, 50% water was added, and stirred at 500-600 rpm for 8 minutes to form a slurry; Step S3. Compounding: Aggregate A, Aggregate B, resin particles, remaining deionized water, and water reducer are added to the mortar, stirred at 1800-2000 rpm for 12 minutes, and placed in a curing chamber after forming. The temperature is maintained at 23-27°C and the humidity is ≥95% for the first three days, and the temperature is maintained at 18-22°C and the humidity is ≥85% for the fourth to twenty-eighth days to obtain a high-strength concrete material.

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