Intelligent response type concrete admixture, preparation method and application thereof

Abstract

This invention belongs to the field of building materials technology, and relates to a smart responsive concrete admixture, its preparation method, and its application. The smart responsive concrete admixture includes a main chain and at least one smart responsive side chain and at least one nano-reinforcing side chain bonded to the main chain. The main chain includes polyether structural units and unsaturated carboxylic acid structural units. The smart responsive side chain includes block copolymer temperature-sensitive structural units and calcium ion strongly chelating structural units. Composite nanoparticles are bonded to the nano-reinforcing side chains. From the inside out, the composite nanoparticles consist of a silica core, a soluble calcium source layer, and a silane coupling agent layer. The smart responsive concrete admixture provided by this invention, by introducing smart responsive side chains and nano-reinforcing side chains onto the main chain, can decouple setting time from temperature control, thereby reducing the adiabatic temperature and maximum heat release rate while ensuring early strength.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to an intelligent responsive concrete admixture, its preparation method, and its application. Background Technology

[0002] With the rapid development of the construction industry, mass concrete is increasingly used in various projects such as large reservoir dams, nuclear power plant containment structures, and foundation slabs for super high-rise buildings. However, due to its large volume and high amount of cementitious materials, the temperature effect in ordinary concrete is amplified step by step. Excessive internal temperature rise and uneven heat dissipation can easily lead to temperature stress cracks, seriously affecting the structural safety and durability.

[0003] Traditional methods for suppressing hot cracking include using medium- and low-heat cement, pre-embedding cooling water pipes, pre-cooling raw materials, and segmented casting. These methods significantly increase construction difficulty and cost, limiting their application. In recent years, some scholars have proposed suppressing hot cracking by adding hydration heat control materials. These materials can reduce the second exothermic peak and cumulative heat release during cement hydration, or absorb some of the hydration heat to reduce the temperature gradient, thereby reducing the risk of shrinkage-induced cracking in concrete. They offer advantages such as simplicity, efficiency, and cost-effectiveness, and have gradually become a research hotspot both domestically and internationally.

[0004] Currently, hydration heat regulation materials typically include starch-based hydration heat inhibitors, retarding and reinforcing material composites, and phase change dopants. For example, CN110606922A discloses a polycarboxylate superplasticizer with hydration heat regulation. It uses carboxymethyl starch, which undergoes multiple pretreatment steps including pyrolysis, acid hydrolysis, and enzymatic hydrolysis, followed by esterification with unsaturated hydroxy ester monomers to prepare modified carboxymethyl starch monomers. These modified carboxymethyl starch monomers are then polymerized with polyether monomers and acrylic monomers to obtain the polycarboxylate superplasticizer with hydration heat regulation. This polycarboxylate superplasticizer can effectively reduce the hydration heat release rate of cement, but it reduces the early strength of concrete and significantly prolongs the concrete setting time. Furthermore, CN119191746A, CN117326818A, CN116425452A, and CN119430728A all disclose methods to achieve slow-release or temperature-triggered release by physically combining or encapsulating retarding / endothermic components with porous materials or phase change materials (such as paraffin). However, these technologies are essentially multi-component physical mixtures or simple core-shell structures, lacking chemical bonds between functional units, resulting in insufficient synergy, and making it difficult to avoid the negative impact of retarding components on early strength and setting time. For example, CN113716891A discloses the introduction of dextrin esterification products and composite nanomaterials as hydration heat regulation functional materials, followed by copolymerization with polycarboxylic acid additives to achieve hydration heat regulation. However, while this method can balance retarding and early strength effects, its regulation mechanism remains static and cannot respond to dynamic changes in temperature and ion concentration during hydration. Furthermore, compensation for early strength mainly relies on the added nanomaterials, resulting in insufficient synergy.

[0005] Therefore, developing a concrete admixture that can intelligently sense and respond to changes in the hydration environment, achieve adaptive regulation of the hydration heat release process, and at the same time not sacrifice or even enhance the early mechanical properties and long-term durability of concrete is the key to solving the crack resistance problem of large-volume concrete. Summary of the Invention

[0006] The primary objective of this invention is to provide a smart responsive concrete admixture that can dynamically adjust its dispersion, slow release, and nucleation effects according to changes in the internal temperature and calcium ion concentration of concrete. This enables intelligent peak reduction and delay of the hydration heat peak, while simultaneously promoting early strength development through a unique composite nanostructure. It also decouples setting time from temperature control, thereby reducing the adiabatic temperature and maximum heat release rate while ensuring early strength.

[0007] The second objective of this invention is to provide a method for preparing a smart responsive concrete admixture.

[0008] A third objective of this invention is to provide a smart responsive concrete admixture obtained by the above method.

[0009] A fourth objective of this invention is to provide the application of the above-mentioned intelligent responsive concrete admixture in the construction field.

[0010] The intelligent responsive concrete admixture provided by the present invention includes a main chain and at least one intelligent responsive side chain and at least one nano-reinforcing side chain bonded to the main chain. The main chain includes polyether structural units and unsaturated carboxylic acid structural units. The intelligent responsive side chain includes block copolymer temperature-sensitive structural units and calcium ion strong chelating structural units. Composite nanoparticles are bonded to the nano-reinforcing side chain. The composite nanoparticles, from the inside out, include a silica core, a soluble calcium source layer, and a silane coupling agent layer.

[0011] The preparation method of the intelligent responsive concrete admixture provided by the present invention includes a free radical copolymerization reaction of polyether monomer, unsaturated carboxylic acid, intelligent responsive macromonomer and nanocomposite macromonomer. The intelligent responsive macromonomer is an unsaturated monomer including temperature-sensitive structural units and calcium ion strongly chelating structural units. The nanocomposite macromonomer is an unsaturated monomer bonded with composite nanoparticles. The composite nanoparticles include, from the inside out, a silica core, a soluble calcium source layer and a silane coupling agent layer. The resulting free radical copolymerization product is the intelligent responsive concrete admixture.

[0012] The intelligent responsive concrete admixture provided by this invention overcomes the shortcomings of traditional hydration heat regulation materials that reduce temperature peaks at the cost of prolonged setting time (reducing early strength) by introducing intelligent responsive side chains and nano-reinforced side chains onto the main chain. This achieves decoupling of setting time and temperature control, reducing adiabatic temperature and maximum heat release rate while ensuring early strength. The reasons for this are speculated to be: firstly, the introduction of temperature-sensitive structural units on the intelligent responsive side chains overcomes the limitations of static addition in existing technologies. Through the "switching" effect of these temperature-sensitive structural units, dynamic sensing and precise suppression of the hydration heat release peak are achieved, resulting in excellent water-reducing performance in the early stages of temperature rise; secondly, the slow-release effect is automatically enhanced during the peak temperature stage, avoiding interference from traditional retarders during the hydration induction period and effectively reducing the peak; and thirdly, the effect weakens in the later stages without affecting long-term strength development. On the other hand, the smart-response side chains exhibit hydrophilic extension at low temperatures below the cement hydration peak, adsorbing onto the surface of cement particles and acting as a dispersant. When the internal temperature of the concrete rises to near or at the peak, the smart-response side chains undergo a dramatic phase transition shrinkage, exposing and enriching a large number of chelating groups in situ, thereby achieving the effect of controlling Ca. 2+ The "switching" strong chelation precisely and dynamically suppresses the exothermic peak during the accelerated hydration period. Furthermore, the composite nanoparticles with a "core-shell" structure introduced onto the nano-reinforced side chains function as both "nucleating agents" and "active component slow-release agents," not only promoting early strength enhancement but also releasing active SiO2 and Ca... 2+It can also participate in volcanic ash reaction and further hydration, providing a continuous source of strength growth and microstructure filling effect, achieving spatiotemporal synergy between crack resistance and enhancement. In summary, the intelligent responsive concrete admixture provided by this invention can dynamically regulate the heat release of hydration according to the temperature and ionic environment during the cement hydration process, and synergistically improve early strength and long-term durability. Detailed Implementation

[0013] The intelligent responsive concrete admixture provided by the present invention includes a main chain and at least one intelligent responsive side chain and at least one nano-reinforcing side chain bonded to the main chain. The main chain includes polyether structural units and unsaturated carboxylic acid structural units. The intelligent responsive side chain includes block copolymer temperature-sensitive structural units and calcium ion strong chelating structural units. Composite nanoparticles are bonded to the nano-reinforcing side chain. The composite nanoparticles, from the inside out, include a silica core, a soluble calcium source layer, and a silane coupling agent layer.

[0014] In the aforementioned intelligent responsive concrete admixture, preferably, based on the total weight of the intelligent responsive concrete admixture, the content of the main chain is 45%~65%, the content of the intelligent responsive side chain is 10%~20%, and the content of the nano-reinforcing side chain is 20%~40%. This allows for an optimal balance between dispersibility, temperature-sensitive response, and nano-reinforcement, achieving the goal of "intelligent temperature control without retarding setting and no decrease in early strength." Specifically, the content of the main chain can be 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, etc. The content of the intelligent responsive side chain can be 10%, 12%, 14%, 16%, 18%, 20%, etc. The content of the nano-reinforcing side chain can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, etc.

[0015] In the aforementioned intelligent responsive concrete admixture, the main chain comprises polyether structural units and unsaturated carboxylic acid structural units, which can provide steric hindrance and dispersing force. The preferred mass ratio of polyether structural units to unsaturated carboxylic acid structural units in the main chain is 100:(20~30), such as 100:20, 100:22, 100:24, 100:26, 100:28, 100:30, etc.

[0016] In the aforementioned intelligent responsive concrete admixture, the intelligent responsive side chain includes temperature-sensitive structural units and calcium ion-strong chelating structural units. These temperature-sensitive and calcium ion-strong chelating structural units are block copolymers, not random copolymers. This is because the principle of the intelligent responsive side chain is that the temperature-sensitive structural units collapse at a certain temperature due to their temperature sensitivity, thereby exposing the calcium ion-strong chelating structural units. If the temperature-sensitive and calcium ion-strong chelating structural units are randomly copolymerized, all chain segments respond simultaneously to temperature changes, and the entire polymer chain collapses simultaneously, encapsulating the calcium ion-strong chelating structural units internally, thus failing to achieve the intelligent responsive function. The intelligent responsive side chain hydrophilically extends and adsorbs onto the surface of cement particles at low temperatures below the cement hydration peak, acting as a dispersant. When the internal temperature of the concrete rises to near or at the peak temperature, the intelligent responsive side chain undergoes a violent phase transition and shrinks, exposing itself in situ and accumulating a large number of chelating groups, thus achieving the effect of chelating calcium ions. + The "switch-on" strong chelation precisely and dynamically suppresses the exothermic peak during the hydration acceleration period. The preferred mass ratio of the temperature-sensitive structural unit to the calcium ion strong chelating structural unit in the intelligent response side chain is 1:(0.1~0.5), such as 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, etc. The temperature-sensitive structural unit is derived from a temperature-sensitive monomer, i.e., a structural unit obtained by polymerizing a temperature-sensitive monomer. Examples of temperature-sensitive monomers include at least one of N-isopropylacrylamide, N-vinylcaprolactam, N-isopropylacrylamide, and / or copolymers of N-vinylcaprolactam and acrylic compounds. The calcium ion strong chelating structural unit is derived from a calcium ion strong chelating monomer, i.e., a structural unit obtained by polymerizing a calcium ion strong chelating monomer. The calcium ion strongly chelating monomer is preferably a phosphonate-containing monomer, specifically including at least one of methacryloyloxyethylphosphonate, diethyl vinylphosphonate, and 2-hydroxyethyl methacrylate phosphate. Furthermore, the smart-responsive side chain can be linked to the main chain via at least one of acetal, ketal, acylhydrazone, and ester bonds. In a preferred embodiment, the temperature-sensitive structural unit in the smart-responsive side chain is linked to the main chain, while the calcium ion strongly chelating structural unit is linked to the temperature-sensitive structural unit. Additionally, the number-average molecular weight of the smart-responsive side chain is preferably 6000-10000, such as 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, 10000, etc.

[0017] In the aforementioned intelligent responsive concrete admixture, the nano-reinforcing side chain comprises polyether macromonomer structural units, acrylic structural units, and composite nanoparticles. The preferred mass ratio of the polyether macromonomer structural units, acrylic structural units, and composite nanoparticles on the nano-reinforcing side chain is 100:(1~10):(1~10). Specifically, the preferred mass ratio of the polyether macromonomer structural units to the acrylic structural units on the nano-reinforcing side chain is 100:(1~10), such as 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, etc. The preferred mass ratio of the polyether macromonomer structural unit on the nano-reinforced side chain to the composite nanoparticles is 100:(1~10), such as 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, etc. The preferred particle size D90 of the silica core in the composite nanoparticles is 10nm~20nm, such as 10nm, 12nm, 14nm, 16nm, 18nm, 20nm, etc. The preferred coating amount of the soluble calcium source layer in the composite nanoparticles is 40%~60% of the mass of the silica core, such as 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, etc. The soluble calcium source layer can be selected from at least one of calcium carbonate layer, calcium acetate layer, and calcium gluconate layer. The soluble calcium source layer exhibits slow dissolution in cement paste environments with pH > 12. The coating amount of the silane coupling agent layer in the composite nanoparticles is preferably 5% to 15% of the silica core mass, such as 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc.

[0018] The preparation method of the intelligent responsive concrete admixture provided by the present invention includes a free radical copolymerization reaction of polyether monomer, unsaturated carboxylic acid, intelligent responsive macromonomer (SRM), and nanocomposite macromonomer (NPM). The intelligent responsive macromonomer is an unsaturated monomer comprising a temperature-sensitive structural unit of block copolymerization and a calcium ion strongly chelating structural unit. The nanocomposite macromonomer is an unsaturated monomer bonded with composite nanoparticles. The composite nanoparticles, from the inside out, comprise a silica core, a soluble calcium source layer, and a silane coupling agent layer. The resulting free radical copolymerization product is the intelligent responsive concrete admixture.

[0019] In the preparation process of the above-mentioned intelligent responsive concrete admixture, the intelligent responsive macromonomer can be prepared using various existing methods. Preferably, it is prepared by carrying out a chain transfer reaction between a temperature-sensitive monomer, a calcium ion strongly chelating monomer, and an unsaturated monomer in the presence of an initiator and a RAFT reagent. The preferred mass ratio of the temperature-sensitive monomer to the calcium ion strongly chelating monomer is 1:(0.1~0.5), such as 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, etc. The molar ratio of the unsaturated monomer to the temperature-sensitive monomer is preferably (0.001~0.01), such as 0.001:1, 0.002:1, 0.003:1, 0.004:1, 0.005:1, 0.006:1, 0.007:1, 0.008:1, 0.009:1, 0.01:1, etc. The temperature-sensitive monomer may include at least one of N-isopropylacrylamide, N-vinylcaprolactam, N-isopropylacrylamide, and / or copolymers of N-vinylcaprolactam with acrylic compounds. The calcium ion strongly chelating monomer is preferably a phosphonate-containing monomer, specifically including at least one of dimethyl methacryloyloxyethylphosphonate, diethyl vinylphosphonate, and 2-hydroxyethyl methacrylate phosphate. Specific examples of the RAFT reagent include at least one selected from 4-cyano-4-(thiobenzoylthio)pentanoic acid, 2-(dodecylthiothiocarbonylthio)-2-methylpropionic acid, and 3-(benzylthiothiocarbonylthio)propionic acid. The unsaturated monomer can be any reactive group containing polymerizable unsaturated double bonds and groups other than the unsaturated double bonds in the RAFT reagent. For example, if the RAFT reagent contains a carboxylic acid, the unsaturated monomer can contain unsaturated double bonds and hydroxyl groups. Furthermore, the initiator can be a peroxide initiator or an azo initiator. Examples of peroxide initiators include benzoyl peroxide (BPO), diisopropyl peroxide dicarbonate (IPP), and dicyclohexyl peroxide dicarbonate (DCP). Examples of azo initiators include azobisisobutyronitrile (AIBN) and azobisisoheptanenitrile (ABVN). The preferred conditions for the chain transfer reaction include a temperature of 60℃~80℃, such as 60℃, 62℃, 64℃, 66℃, 68℃, 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, etc.; and a time of 5h~10h, such as 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, etc.

[0020] In the preparation process of the above-mentioned intelligent responsive concrete admixture, the nanocomposite macromonomer can be prepared by various existing methods. Preferably, it is obtained by polymerizing composite nanoparticles with polyether macromonomers and acrylic monomers. In a preferred embodiment, the polymerization reaction method includes dissolving polyether macromonomers, composite nanoparticles, and an initiator in water, heating the resulting substrate to 50℃~70℃ (e.g., 50℃, 52℃, 55℃, 58℃, 60℃, 62℃, 65℃, 68℃, 70℃, etc.), and then adding acrylic monomers dropwise over a time controlled at 0.5h~2h (e.g., 0.5h, 0.8h, 1h, 1.2h, 1.5h, 1.8h, 2h, etc.). After the addition is complete, the reaction is continued at a constant temperature for 1h~5h (e.g., 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, etc.). The preferred mass ratio of the polyether macromonomer, acrylic monomer, and composite nanoparticles is 100:(1~10):(1~10). Specifically, the preferred mass ratio of the polyether macromonomer to the acrylic monomer is 100:(1~10), such as 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, etc. The preferred mass ratio of the polyether macromonomer to the composite nanoparticles is 100:(1~10), such as 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, etc. The polyether macromonomer is preferably selected from at least one of isobutylene alcohol polyoxyethylene ether, isopentenyl alcohol polyoxyethylene ether, ethylene glycol monovinyl polyethylene glycol ether, and 4-hydroxybutylvinyl polyoxyethylene ether. The acrylic monomer is preferably selected from at least one of acrylic acid, methacrylic acid, and maleic acid.

[0021] In the preparation process of the aforementioned intelligent responsive concrete admixture, the composite nanoparticles, from the inside out, comprise a silica core, a soluble calcium source layer, and a silane coupling agent layer (SiO2@Ca@polymerizable silane). The composite nanoparticles are grafted onto the main chain via a silane coupling agent. These nanoparticles use nano-silica (SiO2) as the core, are coated with a soluble calcium source as an intermediate shell, and the outermost layer is a silane coupling agent layer containing polymerizable double bonds. In the early stages of hydration, these composite nanoparticles provide nucleation sites and promote the growth of hydration products to enhance early strength. As hydration progresses, the shell gradually dissolves, replenishing the calcium content. 2+The released SiO2 promotes later-stage hydration and participates in the volcanic ash reaction, achieving spatiotemporal compensation for strength development and microstructure self-compactment. The composite nanoparticles can be prepared using various existing methods, such as a sol-gel method combined with co-precipitation. Specifically, silica sol is dispersed in water, and soluble calcium salts and soluble carbonates are simultaneously added dropwise to the resulting silica aqueous solution for precipitation, coating the silica surface with a soluble calcium source layer. Then, the silica coated with the resulting soluble calcium source layer undergoes a condensation reaction with an unsaturated double-bonded silane coupling agent in an alcohol solvent. The resulting unsaturated double-bonded nanoparticles are the composite nanoparticles. The silica sol can be prepared by hydrolyzing tetraethyl orthosilicate. The preferred method for the precipitation reaction includes adjusting the pH of the silica aqueous solution to 9-11 (e.g., 9, 9.2, 9.4, 9.6, 9.8, 10, 10.2, 10.4, 10.6, 10.8, 11, etc.), then simultaneously adding a soluble calcium salt solution and a soluble carbonate solution over a time controlled between 1.5h and 2.5h (e.g., 1.5h, 1.8h, 2h, 2.2h, 2.5h, etc.). After the addition is complete, the solution is allowed to mature for another 0.5h-2h (e.g., 0.5h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, etc.). The solid content of the silica sol is preferably 20%-40%, such as 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, etc. The particle size D90 of the silica sol is preferably 10nm~20nm, such as 10nm, 12nm, 14nm, 16nm, 18nm, 20nm, etc. The molar ratio of the soluble calcium salt to the soluble carbonate is preferably 1:(0.9~1.1), such as 1:0.9, 1:0.92, 1:0.94, 1:0.96, 1:0.98, 1:1, 1:1.02, 1:1.04, 1:1.06, 1:1.08, 1:1.1, etc. The amount of the soluble calcium salt and soluble carbonate is preferably such that the resulting calcium carbonate accounts for 40%~60% of the mass of silica, such as 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, etc. The soluble calcium salt is selected from at least one of calcium chloride, calcium nitrate, calcium formate, calcium acetate, calcium lactate, and calcium gluconate. The soluble carbonate is selected from at least one of sodium carbonate, potassium carbonate, and ammonium carbonate. The silane coupling agent is preferably γ-methacryloxypropyltrimethoxysilane and / or vinyltrimethoxysilane. The condensation reaction conditions preferably include a temperature of 70℃~90℃, such as 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, etc.; and a time of 3h~6h, such as 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, etc.

[0022] In the preparation process of the above-mentioned intelligent responsive concrete admixture, the free radical copolymerization method preferably includes dispersing polyether monomers, intelligent responsive macromonomers, nanocomposite macromonomers, oxidants, and reducing agents I in water, and simultaneously adding solutions A and B to the resulting base solution. Solution A is an aqueous solution of unsaturated carboxylic acids, and solution B is a mixed aqueous solution of reducing agent II and chain transfer agent. The oxidant can be at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, cumene hydroperoxide, benzoyl peroxide, and tert-butanol peroxide. The reducing agents I and II can be the same or different, and can each be independently selected from at least one of L-ascorbic acid, ferrous sulfate, azobisisopropylimidazoline hydrochloride, azobiscyclohexylformonitrile, sodium bisulfite, sodium sulfite, sodium metabisulfite, sodium formaldehyde sulfoxylate, sodium hypophosphite, sodium phosphite, and ferrous ammonium sulfate. The chain transfer agent is preferably a thiol-based chain transfer agent, more preferably at least one selected from mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, and mercaptopropanol. The amount of the oxidant is preferably 1% to 10% of the mass of the polyether monomer, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc. The total amount of reducing agent I and reducing agent II is preferably 1% to 5% of the mass of the polyether monomer, such as 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. The terms "I" and "II" are merely for distinguishing reducing agents introduced at different positions for ease of description and have no other special meaning. The amount of the chain transfer agent is preferably 1% to 5% of the mass of the polyether monomer, such as 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. The addition times of solutions A and B are preferably independently 30 min to 120 min, such as 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, etc. The conditions for the free radical copolymerization reaction preferably include an initial addition temperature of 15 to 40 °C, such as 15 °C, 18 °C, 20 °C, 22 °C, 25 °C, 28 °C, 30 °C, 32 °C, 35 °C, 38 °C, 40 °C, etc.; and a reaction time of 0.5 h to 5 h after the solutions are added, such as 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, etc. Furthermore, after the free radical copolymerization reaction is completed, the pH value of the resulting reaction solution is preferably adjusted to 6 to 7, such as 6, 6.2, 6.4, 6.6, 6.8, 7, etc.

[0023] The present invention also provides a smart responsive concrete admixture prepared by the above method.

[0024] The present invention also provides the application of the aforementioned intelligent responsive concrete admixture in the construction field.

[0025] The present invention will be described in detail below through examples and comparative examples.

[0026] Preparation Example 1-1: Preparation of Smart Response Macromonomer (SRM-1) In a reaction flask, 0.5 mmol of 4-cyano-4-(thiobenzoylthio)valerate (CPADB), 0.1 mmol of azobisisobutyronitrile (AIBN), 50 mmol of N-isopropylacrylamide (NIPAM), and 30 mL of 1,4-dioxane were added sequentially. The mixture was reacted at 70 °C for 6 h. After the reaction solution was cooled, it was precipitated in ethanol and dried under vacuum to obtain a PNIPAM prepolymer with dithioester and carboxyl groups retained at the ends.

[0027] The above-mentioned PNIPAM prepolymer (as a macromolecular RAFT reagent) was dissolved in 30 mL of 1,4-dioxane, and 10 mmol of dimethyl methacryloyloxyethylphosphonate (DEPEMA) and 0.05 mmol of azobisisobutyronitrile (AIBN) were added. After deoxygenation, the mixture was reacted at 70 °C for 8 h. The reaction solution was precipitated in excess ethanol, centrifuged, and vacuum dried to obtain the HOOC-PNIPAM-b-PDEPEMA block copolymer.

[0028] In a dry 100 mL three-necked flask, add 0.1 mol of hydroxyethyl methacrylate (HEMA), 0.1 mol of 2-ethyl-2-methyl-1,3-dioxolane-4-methanol, 0.95 g of p-toluenesulfonic acid, 10 mg of hydroquinone, and 50 mL of anhydrous toluene. Heat to 80 °C and reflux for 8 h. Meanwhile, remove the generated water using a Dean-Stark water separator to obtain a linker molecule (VKD) with double bonds and hydrolyzable ketal bonds, denoted as HEMA-ketal-OH.

[0029] 5 g of HOOC-PNIPAM-b-PPEMA was dissolved in 50 mL of anhydrous dichloromethane. 0.5 mmol of HEMA-ketal-OH, 0.75 mmol of dicyclohexylcarbodiimide (DCC), and 0.1 mmol of 4-dimethylaminopyridine (DMAP) were added. The mixture was stirred at room temperature for 24 h under nitrogen protection. After the reaction was complete, the dicyclohexylurea precipitate was removed by filtration. The filtrate was precipitated in excess anhydrous diethyl ether, centrifuged, and dried under vacuum at 40 °C for 24 h to obtain HEMA-ketal-OOC-PNIPAM-b-PDEPEMA (with polymerizable double bonds and breakable linker units at the ends).

[0030] HEMA-ketal-OOC-PNIPAM-b-PDEPEMA (10 g) was dissolved in 100 mL of 1,4-dioxane, and 50 mL of concentrated hydrochloric acid was added. The mixture was stirred at room temperature for 24 h, and then freeze-dried to obtain a white solid with polymerizable double bonds at the ends, which was the smart-responsive macromonomer, denoted as SRM-1. GPC analysis showed that the number-average molecular weight (Mn) of this smart-responsive macromonomer was 8000.

[0031] Preparation Example 1-2: Preparation of Smart Response Macromonomer (SRM-2) In a reaction flask, 0.5 mmol of 4-cyano-4-(thiobenzoylthio)valerate, 0.1 mmol of azobisisobutyronitrile, 50 mmol of N-vinylcaprolactam, and 30 mL of 1,4-dioxane were added sequentially. The mixture was reacted at 60 °C for 10 h. After the reaction solution was cooled, it was precipitated in ethanol and dried under vacuum to obtain a prepolymer with terminal dithioester groups and carboxyl groups.

[0032] The above-mentioned PNIPAM prepolymer (as a macromolecular RAFT reagent) was dissolved in 30 mL of 1,4-dioxane, and 25 mmol of diethyl vinylphosphonate and 0.05 mmol of azobisisobutyronitrile (AIBN) were added. After deoxygenation, the mixture was reacted at 70 °C for 8 h. The reaction solution was precipitated in excess ethanol, centrifuged, and vacuum dried to obtain the block copolymer.

[0033] The remaining steps are the same as in Preparation Example 1-1, yielding a smart-responsive macromonomer, denoted as SRM-2. GPC analysis showed that the number-average molecular weight (Mn) of this smart-responsive macromonomer was 9500.

[0034] Preparation Examples 1-3: Preparation of Smart Response Macromonomer (SRM-3) In a reaction flask, 0.5 mmol of 4-cyano-4-(thiobenzoylthio)valerate, 0.1 mmol of azobisisobutyronitrile, 50 mmol of N-isopropylacrylamide, and 30 mL of 1,4-dioxane were added sequentially. The mixture was reacted at 80 °C for 5 h. After the reaction solution was cooled, it was precipitated in ethanol and dried under vacuum to obtain a prepolymer with terminal dithioester groups and carboxyl groups.

[0035] The above-mentioned PNIPAM prepolymer (as a macromolecular RAFT reagent) was dissolved in 30 mL of 1,4-dioxane, and 5 mmol of 2-hydroxyethyl methacrylate phosphate and 0.05 mmol of azobisisobutyronitrile (AIBN) were added. After deoxygenation, the mixture was reacted at 70 °C for 8 h. The reaction solution was precipitated in excess ethanol, centrifuged, and vacuum dried to obtain the block copolymer.

[0036] The remaining steps are the same as in Preparation Example 1-1, yielding a smart-responsive macromonomer, denoted as SRM-3. GPC analysis showed that the number-average molecular weight (Mn) of this smart-responsive macromonomer was 6800.

[0037] Preparation Examples 1-4: Preparation of Reference Smart Response Macromonomer (DSRM-1) The smart-responsive macromonomer was prepared according to the method in Example 1-1, except that dimethyl methacryloyloxyethylphosphonate (DEPEMA) was replaced with the same molar amount of N-isopropylacrylamide (NIPAM). All other conditions were the same as in Example 1-1, yielding a reference smart-responsive macromonomer, denoted as DSRM-1. GPC analysis showed that the number-average molecular weight (Mn) of this reference smart-responsive macromonomer was 8200.

[0038] Preparation Examples 1-5: Preparation of Reference Smart Response Macromonomer (DSRM-2) The smart-responsive macromonomer was prepared according to the method in Example 1-1, except that N-isopropylacrylamide (NIPAM) was replaced with the same molar amount of dimethyl methacryloyloxyethylphosphonate (DEPEMA), while the other conditions were the same as in Example 1-1, resulting in a reference smart-responsive macromonomer, denoted as DSRM-2. The number-average molecular weight (Mn) of this reference smart-responsive macromonomer was determined by GPC to be 8500.

[0039] Preparation Example 2-1: Preparation of Nanocomposite Macromolecular Monomer (NPM-1) 100g of nano-SiO2 sol (30% solid content, 15nm particle size D90) was placed in a reaction flask, and 200g of deionized water was added. The mixture was heated to 60℃ with mechanical stirring. The pH of the resulting silica aqueous solution was adjusted to 10.5 using ammonia. Then, 1.0mol / L CaCl2 solution and 1.0mol / L Na2CO3 solution were simultaneously and slowly added dropwise to the system at a 1:1 volume ratio using a dual-channel constant flow pump. The dropping rate was controlled to complete the reaction within 2 hours. The theoretical coating amount is 50% CaCO3 by mass of SiO2. After the addition was complete, the mixture was allowed to mature for another hour. The resulting reaction product was then centrifuged, washed, and dried to obtain SiO2@Ca composite powder. SiO2@Ca composite powder was dispersed in 200g of ethanol, and 5g of silane coupling agent KH-570 (γ-methacryloyloxypropyltrimethoxysilane) was added. The mixture was refluxed at 80℃ for 4h. The resulting reaction product was then centrifuged, washed, and dried to obtain composite nanoparticles with double bonds, denoted as NPs-1. The coating amount of the silane coupling agent layer in the composite nanoparticles NPs-1 accounted for 12.5% ​​of the mass of SiO2.

[0040] 100g of isobutylene polyoxyethylene ether (TPEG, number-average molecular weight Mn of 2400), 5g of composite nanoparticles NPs-1, 200g of deionized water, and 2g of potassium persulfate (KPS) were added to a reaction vessel. The temperature was raised to 60℃, and a mixture of 5g of acrylic acid (AA) and 10g of water was slowly added dropwise over 1 hour. After the addition was complete, the reaction was maintained at this temperature for 2 hours and then cooled to obtain an aqueous solution of the nanocomposite macromolecular monomer, denoted as NPM-1, with a solid content of approximately 35%.

[0041] Preparation Example 2-2: Preparation of Nanocomposite Macromolecular Monomer (NPM-2) 100g of nano-SiO2 sol (40% solid content, 10nm particle size D90) was placed in a reaction flask, and 200g of deionized water was added. The mixture was heated to 60℃ with mechanical stirring. The pH of the resulting silica aqueous solution was adjusted to 10.5 using ammonia. Then, 1.0mol / L calcium nitrate solution and 1.0mol / L Na2CO3 solution were simultaneously and slowly added dropwise to the system at a 1:1 volume ratio using a dual-channel constant flow pump. The dropping rate was controlled to complete the reaction within 2 hours. The theoretical coating amount is 40% CaCO3 by mass of SiO2. After the addition was complete, the mixture was allowed to mature for another hour. The resulting reaction product was then centrifuged, washed, and dried to obtain SiO2@Ca composite powder. SiO2@Ca composite powder was dispersed in 200g of ethanol, and 5g of silane coupling agent KH-570 (γ-methacryloyloxypropyltrimethoxysilane) was added. The mixture was refluxed at 70℃ for 6h. The resulting reaction product was then centrifuged, washed, and dried to obtain composite nanoparticles with double bonds, denoted as NPs-2. The silane coupling agent layer in the composite nanoparticles NPs-1 accounted for 14.2% of the SiO2 mass.

[0042] 100g of isobutylene polyoxyethylene ether (TPEG, number-average molecular weight Mn of 2400), 1g of composite nanoparticles NPs-2, 200g of deionized water, and 2g of potassium persulfate (KPS) were added to a reaction vessel. The temperature was raised to 50℃, and a mixture of 10g of acrylic acid (AA) and 10g of water was slowly added dropwise over 2 hours. After the addition was complete, the reaction was maintained at this temperature for 1 hour, then cooled to obtain an aqueous solution of the nanocomposite macromolecular monomer, denoted as NPM-2, with a solid content of approximately 32%.

[0043] Preparation Example 2-3: Preparation of Nanocomposite Macromolecular Monomer (NPM-3) 100g of nano-SiO2 sol (20% solid content, 20nm particle size D90) was placed in a reaction flask, and 200g of deionized water was added. The mixture was heated to 60℃ with mechanical stirring. The resulting silica aqueous solution was adjusted to pH 10.5 using ammonia. Then, 1.0mol / L CaCl2 solution and 1.0mol / L Na2CO3 solution were simultaneously and slowly added dropwise to the system at a 1:1 volume ratio using a dual-channel constant flow pump. The dropwise addition rate was controlled to complete the reaction within 2 hours. The theoretical coating amount is 60% CaCO3 by mass of SiO2. After the addition was complete, the mixture was allowed to mature for another hour. The resulting reaction product was then centrifuged, washed, and dried to obtain SiO2@Ca composite powder. SiO2@Ca composite powder was dispersed in 200g of ethanol, and 5g of silane coupling agent KH-570 (γ-methacryloyloxypropyltrimethoxysilane) was added. The mixture was refluxed at 90℃ for 3h. The resulting reaction product was then centrifuged, washed, and dried to obtain composite nanoparticles with double bonds, denoted as NPs-3. The coating amount of the silane coupling agent layer in the composite nanoparticles NPs-3 accounted for 11.8% of the mass of SiO2.

[0044] 100g of isobutylene polyoxyethylene ether (TPEG, number-average molecular weight Mn of 2400), 10g of composite nanoparticles NPs-3, 200g of deionized water, and 2g of potassium persulfate (KPS) were added to a reaction vessel. The temperature was raised to 70℃, and a mixture of 1g of acrylic acid (AA) and 10g of water was slowly added dropwise over 2 hours. After the addition was complete, the reaction was maintained at this temperature for 5 hours and then cooled to obtain an aqueous solution of the nanocomposite macromolecular monomer, denoted as NPM-3, with a solid content of approximately 30%.

[0045] Preparation Example 2-4: Preparation of Reference Nanocomposite Macromolecular Monomer (DNPM-1) The nanocomposite macromonomer was prepared according to the method of Preparation Example 2-1, except that the composite nanoparticles NPs-1 were replaced with the same weight of silane coupling agent KH-570 (γ-methacryloyloxypropyltrimethoxysilane), and the other conditions were the same as in Preparation Example 2-1, to obtain an aqueous solution of the reference nanocomposite macromonomer, denoted as DNPM-1, with a solid content of about 35%.

[0046] Example 1: Smart Response Concrete Admixture In a four-necked flask, add 150g of ethylene glycol monovinyl polyethylene glycol ether (GPEG, number average molecular weight Mn of 3000), 50g of smart responsive macromonomer SRM-1, 100g of aqueous solution of nanocomposite macromonomer NPM-1, and 200g of deionized water. After stirring to dissolve, add 12g of hydrogen peroxide (H2O2, 7%) and 2g of ferrous sulfate (FeSO4·7H2O, 1%), controlling the initial temperature at approximately 20℃. Then, simultaneously add solutions A and B. Solution A is an aqueous solution obtained by dissolving 40g of acrylic acid in 60g of water, and solution B is an aqueous solution obtained by dissolving 0.5g of vitamin C (Vc) and 3g of mercaptopropionic acid (MPA) in 50g of water. The addition time for both solutions A and B is 1 hour. After the addition is complete, keep it warm and mature for 1 hour. Then, adjust the pH to 6.5 with 30% sodium hydroxide solution and add water until the total solids content is 40%, resulting in a light yellow viscous liquid, which is the intelligent responsive concrete admixture, denoted as PCE-SN1.

[0047] Example 2: Smart Response Concrete Admixture In a four-necked flask, add 140g of ethylene glycol monovinyl polyethylene glycol ether (GPEG, number average molecular weight Mn of 3000), 34g of smart responsive macromonomer SRM-2, 136g of aqueous solution of nanocomposite macromonomer NPM-2, and 200g of deionized water. After stirring to dissolve, add 12g of hydrogen peroxide (H2O2, 7%) and 2g of ferrous sulfate (FeSO4·7H2O, 1%), controlling the initial temperature at approximately 20℃. Then, simultaneously add solutions A and B. Solution A is an aqueous solution obtained by dissolving 30g of acrylic acid in 60g of water, and solution B is an aqueous solution obtained by dissolving 0.5g of vitamin C (Vc) and 3g of mercaptopropionic acid (MPA) in 50g of water. The addition time for both solutions A and B is 1 hour. After the addition is complete, keep it warm and mature for 1 hour. Then, adjust the pH to 6.5 with 30% sodium hydroxide solution and add water until the total solids content is 40%, resulting in a light yellow viscous liquid, which is the intelligent responsive concrete admixture, denoted as PCE-SN2.

[0048] Example 3: Smart Response Concrete Admixture In a four-necked flask, add 160g of ethylene glycol monovinyl polyethylene glycol ether (GPEG, number average molecular weight Mn of 3000), 68g of the smart responsive macromonomer SRM-3, 68g of the aqueous solution of the nanocomposite macromonomer NPM-3, and 200g of deionized water. After stirring to dissolve, add 12g of hydrogen peroxide (H2O2, 7%) and 2g of ferrous sulfate (FeSO4·7H2O, 1%), controlling the initial temperature at approximately 20℃. Then, simultaneously add solutions A and B. Solution A is an aqueous solution obtained by dissolving 44g of acrylic acid in 60g of water, and solution B is an aqueous solution obtained by dissolving 0.5g of vitamin C (Vc) and 3g of mercaptopropionic acid (MPA) in 50g of water. The addition time for both solutions A and B is 1 hour. After the addition is complete, keep it warm and mature for 1 hour. Then, adjust the pH to 6.5 with 30% sodium hydroxide solution and add water until the total solids content is 40%, resulting in a light yellow viscous liquid, which is the intelligent responsive concrete admixture, denoted as PCE-SN3.

[0049] Comparative Example 1 (without Smart Response Chain) The smart responsive concrete admixture was prepared according to the method of Example 1, except that the smart responsive macromonomer SRM-1 was replaced by parts by weight of isobutylene alcohol polyoxyethylene ether (TPEG, number average molecular weight Mn of 2400), and the other conditions were the same as in Example 1, to obtain the reference smart responsive concrete admixture, denoted as CP-1.

[0050] Comparative Example 2: Without nano-reinforced segments The intelligent responsive concrete admixture was prepared according to the method of Example 1, except that the aqueous solution of the nanocomposite macromolecular monomer NPM-1 was replaced with an aqueous solution of isobutylene alcohol polyoxyethylene ether with the same solid content. The number average molecular weight Mn of isobutylene alcohol polyoxyethylene ether was 2400. The other conditions were the same as in Example 1, and a reference intelligent responsive concrete admixture was obtained, which was denoted as CP-2.

[0051] Comparative Example 3: Physical Mixing Mix 150g of ethylene glycol monovinyl polyethylene glycol ether (GPEG, number average molecular weight Mn of 3000), 50g of smart responsive macromonomer SRM-1, 100g of aqueous solution of nanocomposite macromonomer NPM-1, and 200g of deionized water evenly. Then adjust the pH to 6.5 with 30% sodium hydroxide solution and add water until the total solid content is 40%, resulting in a light yellow viscous liquid, which is the reference smart responsive concrete admixture, denoted as CP-3.

[0052] Comparative Example 4: Traditional Core-Shell Inhibitors The core-shell inhibitor (glucose / activated carbon / paraffin) was prepared according to the method disclosed in Example 1 of CN116425452A, and the solid content was controlled at 40% to obtain a reference concrete admixture, denoted as CP-4.

[0053] Comparative Example 5: Commercially Available Products The commercially available slow-release concrete water-reducing agent with a solid content of 40% was selected and designated as CP-5.

[0054] Comparative Example 6 The smart responsive concrete admixture was prepared according to the method of Example 1, except that the smart responsive macromonomer SRM-1 was replaced by the same weight of the reference smart responsive macromonomer DSRM-1, and the other conditions were the same as in Example 1, to obtain the reference smart responsive concrete admixture, which was denoted as CP-6.

[0055] Comparative Example 7 The smart responsive concrete admixture was prepared according to the method of Example 1, except that the smart responsive macromonomer SRM-1 was replaced by the same weight of the reference smart responsive macromonomer DSRM-2, and the other conditions were the same as in Example 1, resulting in the reference smart responsive concrete admixture, denoted as CP-7.

[0056] Comparative Example 8 The intelligent responsive concrete admixture was prepared according to the method of Example 1, except that the aqueous solution of the nanocomposite macromolecular monomer NPM-1 was replaced with a reference nanocomposite macromolecular monomer DNPM-1 aqueous solution with the same solid content. The other conditions were the same as in Example 1, and a reference intelligent responsive concrete admixture was obtained, which was denoted as CP-8.

[0057] Test case (1) Concrete performance testing: Refer to GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" and GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The concrete mix proportion (C30) is as follows: cement: sand: stone: water = 360:818:1000:165 kg / m³. The admixture dosage is 0.2% (consolidated weight) of the binder. Workability, setting time, and compressive strength at various ages of the concrete were tested. The results are shown in Table 1.

[0058] (2) Heat of hydration test: Referring to GB / T 12959-2024 "Determination of heat of hydration of cement", a TAM Air isothermal micro calorimeter was used to test the heat release rate of hydration of cement paste (water-cement ratio 0.4) with 0.2% admixture (consolidation) at 20℃ and the cumulative heat release over 72 hours. The results are shown in Table 2.

[0059] Table 1: Concrete Performance Test Results

[0060] Table 2: Isothermal calorimetry results of cement paste (20°C, admixture 0.2%)

[0061] As shown in Table 1, the 1-day strength of the intelligent responsive concrete admixtures PCE-SN1, PCE-SN2, and PCE-SN3 provided by this invention is slightly lower than that of CP1 (which lacks a responsive chain segment, i.e., has a weak retarding effect), but significantly higher than that of CP2 to CP8. CP1 (without a responsive chain segment) has acceptable early strength but suffers from poor temperature control (high adiabatic peak temperature and high maximum heat release rate). This demonstrates that the dual enhancement mechanism of "nucleation + slow release" effectively compensates for the potential lag in strength development caused by intelligent retarding, and its 28-day strength is the highest, indicating that the long-term microstructure can be optimized. Furthermore, the intelligent responsive concrete admixtures provided by this invention exhibit good slump retention, with a high initial slump, and maintain a high slump even after 1 hour, meaning minimal slump loss. This is attributed to the stability of its molecular structure and the lubricating effect of the nanoparticles.

[0062] As can be seen from the results in Table 2, the intelligent responsive concrete admixtures provided by this invention can significantly reduce the adiabatic temperature peak and the maximum heat release rate. Among them, the adiabatic peak temperature of PCE-SN1, PCE-SN2, and PCE-SN3 can be controlled below 59.2℃, and the maximum heat release rate is reduced by 53.9%, 51.0%, and 49.2%, respectively. Their effects are significantly better than those of CP1~CP8, which proves the key dynamic role of the intelligent responsive side chain in suppressing the heat release peak. The temperature-sensitive unit, chelating group, and nanoparticles are all indispensable. The absence of any single component will lead to a significant decrease in the overall performance.

[0063] As can be seen from the above data, the intelligent responsive concrete admixture provided by this invention has successfully achieved the goal of not significantly delaying setting when strongly retarding and not synchronously reducing early strength when strongly controlling temperature. It has achieved the best balance in four aspects: maintaining workability, inhibiting heat of hydration, promoting early strength, and ensuring long-term strength. The fundamental reason for this is the design of the dynamic response mechanism and the spatiotemporal compensation nanostructure, rather than a simple combination or encapsulation of existing components.

[0064] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A smart responsive concrete admixture, characterized in that, The intelligent responsive concrete admixture includes a main chain and at least one intelligent responsive side chain and at least one nano-reinforcing side chain bonded to the main chain. The main chain includes polyether structural units and unsaturated carboxylic acid structural units. The intelligent responsive side chain includes block copolymer temperature-sensitive structural units and calcium ion strong chelating structural units. Composite nanoparticles are bonded to the nano-reinforcing side chain. The composite nanoparticles, from the inside out, include a silica core, a soluble calcium source layer, and a silane coupling agent layer.

2. The intelligent responsive concrete admixture according to claim 1, characterized in that, Based on the total weight of the intelligent responsive concrete admixture, the content of the main chain is 45%~65%, the content of the intelligent responsive side chain is 10%~20%, and the content of the nano-reinforced side chain is 20%~40%.

3. The intelligent responsive concrete admixture according to claim 1, characterized in that, The mass ratio of polyether structural units to unsaturated carboxylic acid structural units in the main chain is 100:(20~30).

4. The intelligent responsive concrete admixture according to claim 1, characterized in that, The mass ratio of temperature-sensitive structural units to calcium ion-chelating structural units in the intelligent response side chain is 1:(0.1~0.5). Preferably, the temperature-sensitive structural unit is derived from a temperature-sensitive monomer selected from at least one of N-isopropylacrylamide, N-vinylcaprolactam, N-isopropylacrylamide and / or copolymers of N-vinylcaprolactam and acrylic compounds; Preferably, the calcium ion strongly chelating structural unit is derived from a calcium ion strongly chelating monomer, which is a phosphonate ester monomer, preferably at least one selected from methacryloyloxyethylphosphonate, vinylphosphonate, and 2-hydroxyethyl methacrylate phosphate. Preferably, the smart response side chain is connected to the main chain via at least one of the following bonds: acetal bond, ketal bond, acylhydrazone bond, and ester bond; Preferably, the temperature-sensitive structural unit in the smart response side chain is bonded to the main chain, while the calcium ion strong chelating structural unit is bonded to the temperature-sensitive structural unit. Preferably, the number-average molecular weight of the smart response side chain is 6000~10000.

5. The intelligent responsive concrete admixture according to claim 1, characterized in that, The nano-reinforced side chain includes polyether macromonomer structural units, acrylic structural units, and composite nanoparticles. Preferably, the mass ratio of the polyether macromonomer structural unit, the acrylic structural unit and the composite nanoparticle on the nano-reinforced side chain is 100:(1~10):(1~10); Preferably, the particle size D90 of the silica core in the composite nanoparticles is 10nm~20nm; Preferably, the soluble calcium source layer in the composite nanoparticles is selected from at least one of calcium carbonate layer, calcium acetate layer, and calcium gluconate layer; Preferably, the soluble calcium source layer in the composite nanoparticles accounts for 40% to 60% of the mass of the silica core; Preferably, the coating amount of the silane coupling agent layer in the composite nanoparticles accounts for 5% to 15% of the mass of the silica core.

6. A method for preparing a smart responsive concrete admixture, characterized in that, The method involves a free radical copolymerization reaction of polyether monomers, unsaturated carboxylic acids, smart responsive macromonomers, and nanocomposite macromonomers. The smart responsive macromonomers are unsaturated monomers comprising temperature-sensitive structural units and calcium ion-chelating structural units. The nanocomposite macromonomers are unsaturated monomers bonded with composite nanoparticles. The composite nanoparticles, from the inside out, comprise a silica core, a soluble calcium source layer, and a silane coupling agent layer. The resulting free radical copolymerization product is a smart responsive concrete admixture.

7. The preparation method of the intelligent responsive concrete admixture according to claim 6, characterized in that, The intelligent responsive macromonomer is obtained by chain transfer reaction of a temperature-sensitive monomer with a calcium ion-chelating monomer and an unsaturated monomer in the presence of an initiator and a RAFT reagent; preferably, the mass ratio of the temperature-sensitive monomer to the calcium ion-chelating monomer is 1:(0.1~0.5); preferably, the temperature-sensitive monomer is selected from at least one of N-isopropylacrylamide, N-vinylcaprolactam, N-isopropylacrylamide and / or copolymers of N-vinylcaprolactam and acrylic compounds; preferably, the calcium ion-chelating monomer is a phosphonate monomer, preferably at least one of dimethyl methacryloyloxyethylphosphonate, diethyl vinylphosphonate and 2-hydroxyethyl methacrylate phosphate; preferably, the RAFT reagent is selected from at least one of 4-cyano-4-(thiobenzoylthio)valerate, 2-(dodecylthiothiocarbonylthio)-2-methylpropionic acid and 3-(benzylthiothiocarbonylthio)propionic acid; Preferably, the nanocomposite macromonomer is obtained by polymerizing composite nanoparticles with polyether macromonomers and acrylic monomers; preferably, the polymerization method includes dissolving the polyether macromonomer, composite nanoparticles and an initiator in water, heating the resulting substrate to 50°C~70°C and then adding the acrylic monomer dropwise, with the dropwise addition time controlled at 0.5h~2h, and continuing the reaction at the temperature for 1h~5h after the dropwise addition is completed; preferably, the mass ratio of the polyether macromonomer, acrylic monomer and composite nanoparticles is 100:(1~10):(1~10); preferably, the polyether macromonomer is selected from at least one of isobutylene polyoxyethylene ether, isopentenylene polyoxyethylene ether, ethylene glycol monovinyl polyethylene glycol ether and 4-hydroxybutylvinyl polyoxyethylene ether; preferably, the acrylic monomer is selected from at least one of acrylic acid, methacrylic acid and maleic acid.

8. The preparation method of the intelligent responsive concrete admixture according to claim 6, characterized in that, The composite nanoparticles are prepared by the following method: Silica sol is dispersed in water; soluble calcium salt and soluble carbonate are simultaneously added dropwise to the resulting silica aqueous solution to induce a precipitation reaction, thereby coating the silica surface with a soluble calcium source layer. Then, the silica coated with the soluble calcium source undergoes a condensation reaction with an unsaturated double-bonded silane coupling agent in an alcohol solvent. The resulting unsaturated double-bonded nanoparticles are the composite nanoparticles. Preferably, the precipitation reaction method includes adjusting the pH of the silica aqueous solution to 9-11, then simultaneously adding a soluble calcium salt solution and a soluble carbonate solution for 1.5-2.5 hours, followed by a aging process of 0.5-2 hours after addition. Preferably, the solid content of the silica sol is... The content of the soluble calcium salt and soluble carbonate is 20%~40%, and the particle size D90 is 10nm~20nm; preferably, the molar ratio of the soluble calcium salt and soluble carbonate is 1:(0.9~1.1); preferably, the amount of the soluble calcium salt and soluble carbonate is such that the obtained calcium carbonate accounts for 40%~60% of the mass of silicon dioxide; preferably, the soluble calcium salt is selected from at least one of calcium chloride, calcium nitrate, calcium formate, calcium acetate, calcium lactate and calcium gluconate; preferably, the soluble carbonate is selected from at least one of sodium carbonate, potassium carbonate and ammonium carbonate; preferably, the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane and / or vinyltrimethoxysilane; preferably, the condensation reaction conditions include a temperature of 70℃~90℃ and a time of 3h~6h; Preferably, the free radical copolymerization method includes dispersing polyether monomers, smart responsive macromonomers, nanocomposite macromonomers, oxidant and reducing agent I in water, and simultaneously adding solution A and solution B to the resulting base solution. Solution A is an aqueous solution of unsaturated carboxylic acid, and solution B is a mixed aqueous solution of reducing agent II and chain transfer agent. Preferably, the oxidant is selected from at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, cumene hydroperoxide, benzoyl peroxide, and tert-butanol peroxide. Preferably, reducing agent I and reducing agent II are each independently selected from L-ascorbic acid, ferrous sulfate, azobisisopropylimidazoline hydrochloride, azobiscyclohexylformonitrile, sodium bisulfite, sodium sulfite, sodium metabisulfite, and sodium formaldehyde sulfoxylate. At least one of sodium hypophosphite, sodium phosphite, and ferrous ammonium sulfate; preferably, the chain transfer agent is a thiol chain transfer agent, more preferably selected from at least one of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, and mercaptopropanol; preferably, the amount of the oxidant is 1% to 10% of the mass of the polyether monomer; preferably, the total amount of reducing agent I and reducing agent II is 1% to 5% of the mass of the polyether monomer; preferably, the amount of the chain transfer agent is 1% to 5% of the mass of the polyether monomer; preferably, the dropping time of solution A and solution B is independently 30 min to 120 min; preferably, the conditions for the free radical copolymerization reaction include an initial dropping temperature of 15 to 40°C and a reaction time of 0.5 h to 5 h after the solution is dropped.

9. The intelligent responsive concrete admixture prepared by the method according to any one of claims 6 to 8.

10. The application of the intelligent responsive concrete admixture according to any one of claims 1 to 5 and 9 in the construction field.

Images