An admixture for fluid permeable concrete and its application

Abstract

This invention relates to an admixture for fluidized permeable concrete and its application. By weight percentage, it comprises: 10%-18% hydrothermal coupled recycled aggregate modifier; 20%-30% carbon dioxide responsive polycarboxylate superplasticizer; 15%-25% enzyme-mineral synergistic nanofiber reinforcing agent; 5%-10% phase change thermally conductive synergistic temperature-controlled microcapsules; and water. The hydrothermal coupled recycled aggregate modifier is obtained by modifying recycled aggregate powder with a silane coupling agent. This invention solves the technical problems of short construction windows, interface effect decay, low greening degree, delayed repair response, and limited temperature control range in existing technologies by introducing innovative mechanisms such as responsive release, multi-level interface strengthening, bio-based monomers, multiple triggers, and intelligent temperature regulation. It possesses significant inventiveness and is suitable for large-scale permeable paving projects such as urban roads and squares.

Description

Technical Field

[0001] This invention relates to the field of concrete admixture technology, specifically to an admixture for fluid permeable concrete and its application. Background Technology

[0002] Permeable concrete is a functional and ecological building material that enables rainwater infiltration and runoff reduction through its skeletal porous structure. It is one of the key materials for alleviating urban flooding and building sponge cities. In practical engineering applications, fluid permeable concrete not only needs to have good construction fluidity to meet the requirements of pumping and paving operations, but also needs to maintain a high permeability coefficient and sufficient mechanical strength to balance construction efficiency and service performance.

[0003] Currently, the conventional approach to improve the workability of permeable concrete is to compound polycarboxylate superplasticizers, retarders, and air-entraining agents into the admixture system. By using superplasticizers to improve slurry fluidity, retarders to regulate setting time, and air-entraining agents to introduce appropriate microbubbles, the uniformity and workability of the fresh mixture can be optimized to some extent. However, existing admixture systems still face several key technical challenges: First, improper selection of admixture components and dosages, especially blindly pursuing high water reduction rates to enhance fluidity, can easily lead to slurry segregation, causing the cement paste to separate from the aggregate. Excessive settling or aggregation of the segregated slurry can block the interconnected pores between the aggregates, significantly reducing the effective permeability coefficient of permeable concrete, or even completely eliminating its permeability.

[0004] Secondly, the interfacial transition zone (ITZ) between aggregate and cement paste is a weak point in the mechanical properties of permeable concrete. Existing admixture systems have limited effect on improving the interfacial structure. The hydration products in this region are loose and have high porosity, making it prone to becoming the starting point for crack initiation and propagation, thereby reducing the compressive strength, flexural strength, and durability of the material.

[0005] Third, current mainstream admixtures (such as polycarboxylate superplasticizers) rely on petrochemical-based raw materials, resulting in high energy consumption and carbon emissions during their production process. It is estimated that producing one ton of traditional polycarboxylate superplasticizer generates approximately 2.3 tons of CO2 equivalent in carbon emissions. Under the policy guidance of green, low-carbon, and "dual-carbon" goals, such high-carbon admixtures are unlikely to meet the requirements of sustainable development.

[0006] In conclusion, developing an environmentally friendly admixture that combines high fluidity, high permeability, high strength, and intelligent self-healing functions has become a key path to promote the upgrading of permeable concrete technology and achieve the low-impact development goals of sponge cities. Summary of the Invention

[0007] Therefore, it is necessary to provide an admixture for fluid permeable concrete and its application, in order to solve the problems existing in the prior art.

[0008] To achieve the above objectives, the present invention provides a technical solution: An admixture for fluid permeable concrete, comprising, by weight percentage: Hydrothermal coupling recycled aggregate modifier 10%-18%; Carbon dioxide responsive polycarboxylate superplasticizer 20%-30%; Enzyme-mineral synergistic nanofiber reinforcing agent 15%-25%; Phase change thermally conductive synergistic temperature control microcapsules 5%-10%; and water; The hydrothermal coupled recycled aggregate modifier is obtained by modifying recycled aggregate powder with a silane coupling agent.

[0009] Preferably, the coupling agent comprises at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and bis-(γ-triethoxysilylpropyl)tetrasulfide.

[0010] Preferably, the raw materials for preparing the carbon dioxide-responsive polycarboxylate superplasticizer, by weight, include: 160-180 parts of the aqueous two-phase system; 180-200 parts of low molecular weight methoxy polyether macromonomer; 30-35 parts of unsaturated acid monomer; 35-40 parts of carbon dioxide responsive monomer; 3-5 parts of initiator; and water.

[0011] More specifically, the low molecular weight methoxy polyether macromonomers have molecular weights of 1000, 1200, or 1400.

[0012] Preferably, the aqueous two-phase system is an aqueous solution of polyethylene glycol and ammonium sulfate.

[0013] Preferably, the raw materials for preparing the enzyme-mineral synergistic nanofiber reinforcing agent, by weight, include: 120-150 parts of lignin sulfonate; 1-5 parts laccase; 5-8 parts of nano-calcium carbonate; Potassium sorbate 0.5-0.8 parts and water.

[0014] The preparation process of the enzyme-mineral synergistic nanofiber reinforcing agent, wherein the lignin sulfonate is: the enzyme activity of the laccase is one of: 8000U / g, 10000U / g, or 15000U / g.

[0015] The particle size of the nano-calcium carbonate is one of the following: 20-50 nm, 100-500 nm, or 500-1000 nm.

[0016] Preferably, the lignin sulfonate includes at least one of sodium lignin sulfonate, calcium lignin sulfonate, sulfonated bamboo pulp lignin, or alkali lignin.

[0017] Preferably, the raw materials for preparing the phase change thermally conductive synergistic temperature control microcapsules, by weight, include: 60-80 parts of alkane compounds; 3-5 parts of nonionic emulsifier; 1-2 parts of nano-copper particles; 0.5-1.0 parts of graphene oxide; 0.5-1.0 parts of carbon nanotubes; 1-2 parts of hydrazine hydrate; and water.

[0018] Preferably, the alkane compound includes at least one selected from n-tetradecane, n-dodecane, n-hexadecane, or n-octadecane.

[0019] The nonionic emulsifier is one of Span-80, Tween-80, alkyl polysaccharide (APG), or AEO-9.

[0020] The present invention also provides an application of an admixture for fluid permeable concrete in concrete.

[0021] Furthermore, a method for preparing high-performance fluid permeable concrete is provided, comprising the following steps: S100. Preparation of hydrothermal coupled recycled aggregate modifier: S110: Recycled aggregate is impregnated or sprayed with a compound emulsion of acrylate and epoxy resin, which can form a polymer film containing functional groups such as hydroxyl, carboxyl, and ester groups on its surface.

[0022] S120: The treated recycled aggregate powder is placed in a hydrothermal reactor, and a silicate solution with a mass concentration of 10% is added. The mass-volume ratio of the recycled aggregate powder to the silicate solution is 1:5. The hydrothermal reaction is carried out at 120℃ and 0.2 MPa for 2 hours to generate a calcium silicate hydrate (CSH) gel layer. The silicate solution is one of sodium silicate solution, water glass solution, or sodium metasilicate solution.

[0023] S130: The hydrothermally reacted aggregate powder and silane coupling agent were mixed at a mass ratio of (5-8):1, and anhydrous ethanol was added as a dispersion medium. The mixture was stirred at 150 rpm for 2 hours in a 60°C water bath. Finally, the product was placed in a vacuum drying oven and dried at 80°C for 12 hours. After drying, it was ground to a particle size of <50 μm using a planetary ball mill, sealed, and stored to obtain the hydrothermally coupled recycled aggregate modifier.

[0024] S200. Preparation of carbon dioxide responsive polycarboxylate superplasticizer as follows: S210: Dissolve polyethylene glycol and ammonium sulfate in water to prepare an aqueous two-phase solution, and preheat it in a constant temperature water bath at 50-65℃; The mass ratio of polyethylene glycol to ammonium sulfate is 2:3; The polyethylene glycol mentioned is one of polyethylene glycol 8000, polyethylene glycol 6000, and polyethylene glycol 4000.

[0025] S220: Add low molecular weight methoxy polyether macromonomer, unsaturated acid monomer, carbon dioxide responsive monomer and initiator, and stir at 180-220 rpm for 2-3 hours. The unsaturated acid monomer includes acrylic acid; The low molecular weight methoxy polyether macromonomer is one of MPEG-1000, MPEG-1200, or MPEG-1400.

[0026] The initiator includes ammonium persulfate; The carbon dioxide responsive monomer is one of N,N-dimethylaminoethyl acrylate, dimethylaminopropylmethacrylamide, dimethylaminoethyl methacrylate, and N,N-bis(3-methacryloyloxypropyl)ethylenediamine.

[0027] S230: After the reaction is completed, the system is naturally cooled to room temperature and the system is divided into two phases: the upper layer is the polycarboxylate superplasticizer product and the lower layer is the inorganic salt phase. The upper product is separated by a separatory funnel, washed three times with deionized water and then vacuum dried to obtain a carbon dioxide responsive polycarboxylate superplasticizer.

[0028] S300. Preparation of enzyme-mineral synergistic nanofiber reinforcing agent: The enzyme-mineral synergistic nanofiber reinforcing agent is prepared by sulfonated lignin, laccase, and nano-calcium carbonate. The specific steps are as follows: S310: Dissolve lignin sulfonate in water to prepare a 15% (w / w) solution, adjust the pH to 5.5 with dilute hydrochloric acid, and preheat in a 35°C constant temperature water bath for 30 minutes. S320: Add laccase and stir at 200 rpm for 30 minutes; S330: Add 5% by mass of nano-calcium carbonate and continue the reaction for 15 minutes to promote the densification of the fiber network by utilizing the nucleation effect of nano-calcium carbonate. S340: Added as a preservative, stirred evenly and cooled to room temperature to obtain the enzyme-mineral synergistic nanofiber reinforcing agent.

[0029] The preservative is potassium sorbate with a mass fraction of 0.5%.

[0030] S400. Preparation of phase change thermally conductive and temperature-controlled microcapsules: The phase change thermally conductive and temperature-controlled microcapsules are jointly prepared from alkane compounds, nonionic emulsifiers, copper nanoparticles, graphene oxide and carbon nanotubes, and hydrazine hydrate. The specific preparation process is as follows: S410: Mix alkane compounds, nonionic emulsifiers and nano copper particles (particle size 50-100 nm), add to water, and emulsify at high speed of 10000 rpm for 10 minutes to obtain an oil-in-water emulsion. S420: Add graphene oxide (concentration 0.5 mg / mL) and carbon nanotubes (concentration 0.3 mg / mL) at 1% of the oil phase mass, adjust the pH to 9, add a crosslinking agent at 1% by mass, stir and react at 60°C for 2 hours to form a graphene-carbon nanotube composite coating layer. The crosslinking agent is one of glyoxal, glutaraldehyde, or genipin.

[0031] S430: Add 2% hydrazine hydrate by mass, reduce for 1 hour, filter and collect the microcapsules, wash with deionized water until neutral, and vacuum dry at 60°C to obtain the phase change thermally conductive synergistic temperature control microcapsules.

[0032] S500. Preparation of carbon dioxide-responsive polycarboxylate superplasticizer: Mix coarse aggregate with fine aggregate, add the additives prepared in steps S100, S200, S300 and S400 above, and dry mix for 1 minute; Add cement and water, controlling the water-cement ratio at 0.35-0.40, and mix wet for 2 minutes; If it is necessary to adjust the fluidity, carbon dioxide can be introduced into the mixture to adjust the performance of the water-reducing agent; After casting, it is cured for 28 days under standard conditions of 20℃ and 95% relative humidity.

[0033] The beneficial effects of this invention are: 1. The CSH gel layer prepared by the hydrothermal coupling modification technology of this invention can form a chemical bond with cement paste, further improving the interfacial bonding strength, while improving the pore structure of recycled aggregate and reducing water absorption. Simultaneously, laccase catalyzes the in-situ oxidative polymerization of lignin derivatives during the concrete mixing stage, forming a three-dimensional nanoscale fiber network. This network binds to the cement paste interface through hydrogen bonds and hydrophobic interactions, significantly improving the viscoelasticity and anti-segregation ability of the paste, enhancing aggregate encapsulation, and reducing segregation.

[0034] 2. By introducing carbon dioxide-responsive monomers into the two-phase synthesis system for ternary copolymerization, dynamic control of the water-reducing agent's performance is achieved. The fluidity of the slurry can be adjusted by introducing carbon dioxide according to construction needs. The response mechanism is more direct, and the construction operability is stronger. This solves the problem that traditional water-reducing agents have fixed performance and are difficult to adapt to complex construction environments.

[0035] 3. In the phase change-thermal conductivity synergistic regulation system, the thermal conductivity of microcapsules can be significantly improved by the composite coating layer of carbon nanotubes and graphene, and the copper nanoparticles can enhance its thermal conductivity, making the heat storage and release rate of microcapsules faster and the temperature control effect more significant.

[0036] 4. This invention solves the technical problems existing in the prior art, such as short construction window, interface effect decay, low degree of greening, delayed repair response and limited temperature control range, by introducing innovative mechanisms such as responsive release, multi-level interface enhancement, bio-based monomers, multiple triggers and intelligent temperature regulation. It has significant creativity and is suitable for large-scale permeable pavement projects such as urban roads and squares. Detailed Implementation

[0037] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0038] In the embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0039] Example 1

[0040] S100. Preparation of hydrothermal coupled recycled aggregate modifier: S110: Recycled aggregates are impregnated or sprayed using a compound emulsion of acrylate and epoxy resin with a mass-to-volume ratio of 1:2.

[0041] S120: The treated recycled aggregate powder is placed in a hydrothermal reactor, and a sodium metasilicate solution with a mass concentration of 10% is added. The mass-volume ratio of the recycled aggregate powder to the sodium metasilicate solution is 1:5. The hydrothermal reaction is carried out at 120℃ and 0.2 MPa for 2 hours to generate a calcium silicate hydrate (CSH) gel layer. S130: The hydrothermally reacted aggregate powder was mixed with the silane coupling agent γ-glycidoxypropyltrimethoxysilane at a mass ratio of 6:1. Anhydrous ethanol was added as a dispersion medium, and the mixture was stirred at 150 rpm for 2 hours in a 60°C water bath. Finally, the product was placed in a vacuum drying oven and dried at 80°C for 12 hours. After drying, it was ground to a particle size of <50 μm using a planetary ball mill, sealed, and stored to obtain the hydrothermally coupled recycled aggregate modifier.

[0042] S200. Preparation of carbon dioxide responsive polycarboxylate superplasticizer: S210: Dissolve polyethylene glycol 4000 and ammonium sulfate in water to prepare an aqueous two-phase solution, preheat it in a constant temperature water bath at 55℃ to obtain an aqueous two-phase system solution; wherein, the mass ratio of polyethylene glycol 4000 and ammonium sulfate is 2:3. S220: By weight, add 200 parts MPEG-1000, 32 parts acrylic acid, 38 parts N,N-bis(3-methacryloyloxypropyl)ethylenediamine and 4 parts ammonium persulfate initiator to 180 parts aqueous phase and stir at 200 rpm for 2 hours. S230: After the reaction is completed, the system is naturally cooled to room temperature and the system is divided into two phases: the upper layer is the polycarboxylate superplasticizer product and the lower layer is the inorganic salt phase. The upper product is separated by a separatory funnel, washed three times with deionized water and then vacuum dried to obtain a carbon dioxide responsive polycarboxylate superplasticizer.

[0043] S300. Preparation of enzyme-mineral synergistic nanofiber reinforcing agent: The enzyme-mineral synergistic nanofiber reinforcing agent is prepared by sulfonated lignin, laccase, and nano-calcium carbonate. The specific steps are as follows: S310: Dissolve 130 parts by weight of sodium lignosulfonate in water to prepare a 15% solution. Adjust the pH to 5.5 with dilute hydrochloric acid and preheat in a 35°C constant temperature water bath for 30 minutes. S320: Add 2 parts of 10000U / g laccase and stir at 200rpm for 30 minutes; S330: Add 5 parts of 20-50 nm nano calcium carbonate with a mass fraction of 5%, and continue the reaction for 15 minutes to promote the densification of the fiber network by utilizing the crystal nucleation effect of nano calcium carbonate. S340: Add 0.5 parts of potassium sorbate (0.5% by mass) as a preservative, stir evenly, and cool to room temperature to obtain the enzyme-mineral synergistic nanofiber reinforcing agent.

[0044] S400. Preparation of phase change thermally conductive and temperature-controlled microcapsules: The phase change thermally conductive and temperature-controlled microcapsules are jointly prepared from alkane compounds, nonionic emulsifiers, copper nanoparticles, graphene oxide and carbon nanotubes, and hydrazine hydrate. The specific preparation process is as follows: S410: By weight, 70 parts of n-hexadecane, 4 parts of nonionic emulsifier Tween-80 and 1 part of nano copper particles (particle size 50-100 nm) are mixed, added to water, and emulsified at high speed of 10000 rpm for 10 minutes to obtain an oil-in-water emulsion. S420: Add 0.5 parts of graphene oxide (concentration 0.5 mg / mL) and 0.8 parts of carbon nanotubes (concentration 0.3 mg / mL) at 1% of the oil phase mass, adjust the pH to 9, add 1% of the crosslinking agent glyoxal, stir and react at 60°C for 2 hours to form a graphene-carbon nanotube composite coating layer. S430: Add 1 part of 2% hydrazine hydrate, reduce for 1 hour, filter and collect the microcapsules, wash with deionized water until neutral, and vacuum dry at 60°C to obtain the phase change thermally conductive synergistic temperature control microcapsules.

[0045] S500. Preparation of carbon dioxide-responsive polycarboxylate admixtures: The additives prepared in steps S100, S200, S300 and S400 are mixed to obtain a carbon dioxide responsive polycarboxylate additive with a solid content of 40%.

[0046] The specific ratio is as follows: 15% hydrothermal coupled recycled aggregate modifier; 25% CO2-responsive polycarboxylate superplasticizer; Enzyme-mineral synergistic nanofiber reinforcing agent 20%; Phase change thermally conductive synergistic temperature control microcapsules 5%; and water.

[0047] Example 2

[0048] S100. Preparation of hydrothermal coupled recycled aggregate modifier: S110: Recycled aggregates are impregnated or sprayed using a compound emulsion of acrylate and epoxy resin with a mass-to-volume ratio of 1:2.

[0049] S120: The treated recycled aggregate powder is placed in a hydrothermal reactor, and a sodium metasilicate solution with a mass concentration of 10% is added. The mass-volume ratio of the recycled aggregate powder to the sodium silicate solution is 1:5. The hydrothermal reaction is carried out at 120℃ and 0.2 MPa for 2 hours to generate a calcium silicate hydrate (CSH) gel layer. S130: The hydrothermally reacted aggregate powder was mixed with the silane coupling agent N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane at a mass ratio of 5:1. Anhydrous ethanol was added as a dispersion medium, and the mixture was stirred at 150 rpm for 2 hours in a 60°C water bath. Finally, the product was placed in a vacuum drying oven and dried at 80°C for 12 hours. After drying, it was ground to a particle size of <50 μm using a planetary ball mill, sealed, and stored to obtain the hydrothermally coupled recycled aggregate modifier.

[0050] S200. Preparation of carbon dioxide responsive polycarboxylate superplasticizer: S210: Dissolve polyethylene glycol 8000 and ammonium sulfate in water to prepare an aqueous two-phase solution, preheat in a constant temperature water bath at 55℃ to obtain an aqueous two-phase system solution; wherein, the mass ratio of polyethylene glycol 8000 and ammonium sulfate is 2:3; S220: By weight, add 180 parts MPEG-1000, 35 parts acrylic acid, 36 parts dimethylaminoethyl methacrylate and 5 parts ammonium persulfate initiator to 160 parts aqueous phase and stir at 200 rpm for 3 hours. S230: After the reaction is completed, the system is naturally cooled to room temperature and the system is divided into two phases: the upper layer is the polycarboxylate superplasticizer product and the lower layer is the inorganic salt phase. The upper product is separated by a separatory funnel, washed three times with deionized water and then vacuum dried to obtain a carbon dioxide responsive polycarboxylate superplasticizer.

[0051] S300. Preparation of enzyme-mineral synergistic nanofiber reinforcing agent: The enzyme-mineral synergistic nanofiber reinforcing agent is prepared by sulfonated lignin, laccase, and nano-calcium carbonate. The specific steps are as follows: S310: Dissolve 130 parts by weight of sodium lignosulfonate in water to prepare a 15% solution. Adjust the pH to 5.5 with dilute hydrochloric acid and preheat in a 35°C constant temperature water bath for 30 minutes. S320: Add 1 part of 15000U / g laccase and stir at 200rpm for 30 minutes; S330: Add 5 parts of 100-500 nm nano calcium carbonate with a mass fraction of 5%, and continue the reaction for 15 minutes to promote the densification of the fiber network by utilizing the nucleation effect of nano calcium carbonate. S340: Add 0.6 parts of potassium sorbate (0.5% by mass) as a preservative, stir evenly, and cool to room temperature to obtain the enzyme-mineral synergistic nanofiber reinforcing agent.

[0052] S400. Preparation of phase change thermally conductive and temperature-controlled microcapsules: The phase change thermally conductive and temperature-controlled microcapsules are jointly prepared from alkane compounds, nonionic emulsifiers, copper nanoparticles, graphene oxide and carbon nanotubes, and hydrazine hydrate. The specific preparation process is as follows: S410: By weight, mix 80 parts of n-hexadecane, 5 parts of nonionic emulsifier Span-80 and 1 part of nano copper particles (particle size 50-100 nm), add to water, and emulsify at high speed of 10000 rpm for 10 minutes to obtain an oil-in-water emulsion. S420: Add 0.5 parts of graphene oxide (concentration 0.5 mg / mL) and 0.8 parts of carbon nanotubes (concentration 0.3 mg / mL) at 1% of the oil phase mass, adjust the pH to 9, add 1% of the crosslinking agent glutaraldehyde, stir and react at 60°C for 2 hours to form a graphene-carbon nanotube composite coating layer. S430: Add 1 part of 2% hydrazine hydrate, reduce for 1 hour, filter and collect the microcapsules, wash with deionized water until neutral, and vacuum dry at 60°C to obtain the phase change thermally conductive synergistic temperature control microcapsules.

[0053] S500. Preparation of carbon dioxide-responsive polycarboxylate admixtures: The additives prepared in steps S100, S200, S300 and S400 are mixed to obtain a carbon dioxide responsive polycarboxylate additive with a solid content of 40%.

[0054] The specific ratio is as follows: 10% hydrothermal coupled recycled aggregate modifier; 30% carbon dioxide responsive polycarboxylate superplasticizer; Enzyme-mineral synergistic nanofiber reinforcing agent 15%; Phase change thermally conductive synergistic temperature control microcapsules 10%; and water.

[0055] Example 3

[0056] S100. Preparation of hydrothermal coupled recycled aggregate modifier: S110: Recycled aggregates are impregnated or sprayed using a compound emulsion of acrylate and epoxy resin with a mass-to-volume ratio of 1:2.

[0057] S120: The treated recycled aggregate powder is placed in a hydrothermal reactor, and a sodium metasilicate solution with a mass concentration of 10% is added. The mass-volume ratio of the recycled aggregate powder to the sodium metasilicate solution is 1:5. The hydrothermal reaction is carried out at 120℃ and 0.2 MPa for 2 hours to generate a calcium silicate hydrate (CSH) gel layer. S130: The hydrothermally reacted aggregate powder was mixed with the silane coupling agent γ-aminopropyltriethoxysilane at a mass ratio of 8:1. Anhydrous ethanol was added as a dispersion medium, and the mixture was stirred at 150 rpm for 2 hours in a 60°C water bath. Finally, the product was placed in a vacuum drying oven and dried at 80°C for 12 hours. After drying, it was ground with a planetary ball mill to a particle size of <50 μm, sealed, and stored to obtain the hydrothermally coupled recycled aggregate modifier.

[0058] S200. Preparation of carbon dioxide responsive polycarboxylate superplasticizer: S210: Dissolve polyethylene glycol 6000 and ammonium sulfate in water to prepare an aqueous two-phase solution, and preheat it in a constant temperature water bath at 55℃ to obtain an aqueous two-phase system solution; wherein, the mass ratio of polyethylene glycol 4000 and ammonium sulfate is 2:3. S220: By weight, add 200 parts MPEG-1200, 30 parts acrylic acid, 40 parts N,N-dimethylaminoethyl acrylate and 3 parts ammonium persulfate initiator to 180 parts aqueous phase and stir at 200 rpm for 2.5 hours. S230: After the reaction is completed, the system is naturally cooled to room temperature and the system is divided into two phases: the upper layer is the polycarboxylate superplasticizer product and the lower layer is the inorganic salt phase. The upper product is separated by a separatory funnel, washed three times with deionized water and then vacuum dried to obtain a carbon dioxide responsive polycarboxylate superplasticizer.

[0059] S300. Preparation of enzyme-mineral synergistic nanofiber reinforcing agent: The enzyme-mineral synergistic nanofiber reinforcing agent is prepared by sulfonated lignin, laccase, and nano-calcium carbonate. The specific steps are as follows: S310: Dissolve 130 parts by weight of sodium lignosulfonate in water to prepare a 15% solution. Adjust the pH to 5.5 with dilute hydrochloric acid and preheat in a 35°C constant temperature water bath for 30 minutes. S320: Add 3 parts of 8000U / g laccase and stir at 200rpm for 30 minutes; S330: Add 8 parts of 5% by mass of 500-1000 nm nano calcium carbonate and continue the reaction for 15 minutes to promote the densification of the fiber network by utilizing the nucleation effect of nano calcium carbonate. S340: Add 0.6 parts of potassium sorbate (0.5% by mass) as a preservative, stir evenly, and cool to room temperature to obtain the enzyme-mineral synergistic nanofiber reinforcing agent.

[0060] S400. Preparation of phase change thermally conductive and temperature-controlled microcapsules: The phase change thermally conductive and temperature-controlled microcapsules are jointly prepared from alkane compounds, nonionic emulsifiers, copper nanoparticles, graphene oxide and carbon nanotubes, and hydrazine hydrate. The specific preparation process is as follows: S410: By weight, 60 parts of n-hexadecane, 5 parts of nonionic emulsifier AEO-9 and 1 part of nano copper particles (particle size 50-100 nm) are mixed, added to water, and emulsified at high speed of 10000 rpm for 10 minutes to obtain an oil-in-water emulsion. S420: Add 0.5 parts of graphene oxide (concentration 0.5 mg / mL) and 0.8 parts of carbon nanotubes (concentration 0.3 mg / mL) at 1% of the oil phase mass, adjust the pH to 9, add 1% of the crosslinking agent glyoxal, stir and react at 60°C for 2 hours to form a graphene-carbon nanotube composite coating layer. S430: Add 1 part of 2% hydrazine hydrate, reduce for 1 hour, filter and collect the microcapsules, wash with deionized water until neutral, and vacuum dry at 60°C to obtain the phase change thermally conductive synergistic temperature control microcapsules.

[0061] S500. Preparation of carbon dioxide-responsive polycarboxylate admixtures: The additives prepared in steps S100, S200, S300 and S400 are mixed to obtain a carbon dioxide responsive polycarboxylate additive with a solid content of 40%.

[0062] The specific ratio is as follows: 18% hydrothermal coupled recycled aggregate modifier; Carbon dioxide responsive polycarboxylate superplasticizer 22%; Enzyme-mineral synergistic nanofiber reinforcing agent 18%; Phase change thermally conductive synergistic temperature control microcapsules 7%; and water.

[0063] Comparative Example 1 The other steps are the same as in Example 1, except that no hydrothermal coupled recycled aggregate modifier is added when preparing the admixture for fluid permeable concrete.

[0064] Comparative Example 2 The other steps are the same as in Example 1, except that carbon dioxide-responsive polycarboxylate superplasticizer is not added when preparing the admixture for fluid permeable concrete.

[0065] Comparative Example 3 The other steps are the same as in Example 1, except that no enzyme-mineral synergistic nanofiber reinforcing agent is added when preparing the admixture for fluid permeable concrete.

[0066] Comparative Example 4 The other steps are the same as in Example 1, except that phase change thermally conductive synergistic temperature control microcapsules are not added when preparing admixtures for fluid permeable concrete.

[0067] Comparative Example 5 The other steps are the same as in Example 1, except that carbon dioxide is not introduced during the concrete experiment.

[0068] Performance testing The concrete workability of the admixtures obtained in the above examples and comparative examples was tested in accordance with the test methods for concrete mixture performance in GB / T 8076-2008 "Concrete Admixtures".

[0069] Mix coarse aggregate (sand) with fine aggregate (large stones and small stones), add the additives prepared in the above examples and comparative examples, and dry mix for 1 minute.

[0070] Add cement, fly ash and water, control the water-cement ratio at 0.40, and wet mix for 2 minutes; If it is necessary to adjust the fluidity, carbon dioxide can be introduced into the mixture to adjust the performance of the water-reducing agent; After casting, it is cured for 28 days under standard conditions of 20℃ and 95% relative humidity.

[0071] The specific concrete mix design is shown in Table 1, and the test results of cement and concrete performance are shown in Table 2. Table 1 Concrete Mix Proportions

[0072] Table 2 Concrete Performance Tests

[0073] As shown in Table 2, Example 1 exhibits the most outstanding core performance, with all indicators surpassing the benchmark concrete prepared using ordinary polycarboxylate admixtures. Its slump reaches 220 mm, spread 560 mm, slump time 7.8 s, and 7-day / 28-day compressive strengths reach 68.5 MPa and 79.8 MPa, respectively. Compared to comparative examples lacking any component (such as Comparative Example 2, which has almost no fluidity), the concrete prepared in Example 1 achieves a balance between high fluidity and excellent cohesiveness, demonstrating the necessity and synergistic effect of multiple components, far exceeding the performance benchmark of ordinary pumped concrete.

[0074] Among them, the hydrothermal coupling modifier optimized the transition zone of the recycled aggregate interface, the nanofiber reinforcing agent constructed a three-dimensional support network inside the slurry, and the temperature-controlled microcapsule reduced the generation of internal microcracks by smoothing the heat release of hydration. In the end, they jointly achieved a significant improvement in the density and mechanical strength of concrete.

[0075] The carbon dioxide-responsive polycarboxylic acid admixture of this invention addresses the problems of performance degradation during construction through a combination of a hydrothermal coupling modifier to enhance the interface, a carbon dioxide-responsive water-reducing agent to dynamically regulate flowability, an enzyme-mineral nanofiber reinforcing agent to improve viscoelasticity, and a phase change thermally conductive microcapsule for precise temperature control.

[0076] It should be noted that the specific parameters or reagents in the above embodiments are specific or preferred embodiments under the concept of the present invention, and not limitations thereof; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

Claims

1. An admixture for fluidized permeable concrete, characterized in that, By weight percentage, it includes: Hydrothermal coupling recycled aggregate modifier 10%-18%; Carbon dioxide responsive polycarboxylate superplasticizer 20%-30%; Enzyme-mineral synergistic nanofiber reinforcing agent 15%-25%; Phase change thermally conductive synergistic temperature control microcapsules 5%-10%; and water; The hydrothermal coupled recycled aggregate modifier is obtained by modifying recycled aggregate powder with a silane coupling agent.

2. The admixture for permeable flowable concrete according to claim 1, characterized in that, The coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and bis-(γ-triethoxysilylpropyl)tetrasulfide.

3. The admixture for permeable concrete according to claim 1, characterized in that, The raw materials for preparing the carbon dioxide responsive polycarboxylate superplasticizer, by weight, include: 160-180 parts of the aqueous two-phase system; 180-200 parts of low molecular weight methoxy polyether macromonomer; 30-35 parts of unsaturated acid monomer; 35-40 parts of carbon dioxide responsive monomer; 3-5 parts of initiator; and water.

4. The admixture for fluidized permeable concrete according to claim 3, characterized in that, The aqueous two-phase system is an aqueous solution of polyethylene glycol and ammonium sulfate.

5. The admixture for fluidized permeable concrete according to claim 1, characterized in that, The raw materials for preparing the enzyme-mineral synergistic nanofiber reinforcing agent, by weight, include: 120-150 parts of lignin sulfonate; 1-5 parts laccase; 5-8 parts of nano-calcium carbonate; water.

6. The admixture for fluidized permeable concrete according to claim 5, characterized in that, The raw materials for preparing the enzyme-mineral synergistic nanofiber reinforcing agent also include 0.5-0.8 parts of preservative.

7. The admixture for fluidized permeable concrete according to claim 5, characterized in that, The lignin sulfonate includes at least one of sodium lignin sulfonate, calcium lignin sulfonate, sulfonated bamboo pulp lignin, or alkali lignin.

8. The admixture for permeable concrete according to claim 1, characterized in that, The raw materials for preparing the phase change thermally conductive synergistic temperature control microcapsules, by weight, include: 60-80 parts of alkane compounds; 3-5 parts of nonionic emulsifier; 1-2 parts of nano-copper particles; 0.5-1.0 parts of graphene oxide; 0.5-1.0 parts of carbon nanotubes; 1-2 parts of hydrazine hydrate; and water.

9. The admixture for fluidized permeable concrete according to claim 8, characterized in that, The alkane compound includes at least one of n-tetradecane, n-dodecane, n-hexadecane, or n-octadecane.

10. The application of an admixture for fluid permeable concrete as described in any one of claims 1 to 9 in concrete.

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