Low-slump slump-retaining concrete water reducing agent and preparation method thereof

Abstract

The invention relates to the technical field of building materials, and discloses a low-slump slump-retaining concrete water reducing agent and a preparation method thereof, and the low-slump slump-retaining concrete water reducing agent comprises the following components by weight: 100-130 parts of a polyether type main chain monomer TPEG; 40 to 70 parts of acrylic acid; 5 to 15 parts of maleic anhydride; 8 to 20 parts of 2-acrylamide-2-methyl propane sulfonic acid; 2 to 6 parts of dimethylaminoethyl methacrylate; 4 to 12 parts of sodium gluconate; 2-8 parts of a macromolecular slump retaining component; 3 to 10 parts of a microcapsule coated slump retaining body; 2 to 6 parts of ammonium polyphosphate; 1 to 3 parts of sodium dodecyl benzene sulfonate; 1-2 parts of ammonium persulfate; and 1-3 parts of ammonia water. By optimizing the molecular structure and the production process of the water reducer, the fluidity retentivity, the compressive strength and the production efficiency are improved, meanwhile, the energy consumption and the cost are reduced, and the long-term storage stability of the product is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a low-slump slump-retaining concrete water reducing agent and a preparation method thereof. BACKGROUND

[0002] In the modern construction industry, the use of concrete is almost ubiquitous. In order to improve the performance of concrete, especially the fluidity and compressive strength, water reducing agent has become an essential additive. It not only improves the workability of concrete and reduces the difficulty of construction, but also reduces the amount of cement to some extent and improves the strength of concrete.

[0003] The water reducing agent in the prior art usually uses acrylic monomer as the main component, which can improve the fluidity of concrete. Such water reducing agent can effectively reduce the amount of cement, thereby reducing the water waste during construction. In addition, some water reducing agents can also improve the early strength of concrete to some extent, providing more convenience for the construction of concrete. In terms of production process, the existing technology also has a relatively mature reaction method, which can stably produce water reducing agents with good performance and is widely used in the construction industry.

[0004] However, the water reducing agent of the prior art has some shortcomings. Although the prior art plays an important role in improving the fluidity of concrete, the fluidity retention is poor, especially when used under high or low temperature conditions, the effect often decays rapidly. In addition, the existing water reducing agent has limited performance in improving the compressive strength of concrete and cannot provide long-term effect. More importantly, the traditional high-temperature synthesis process results in high energy consumption and long production cycle, increasing the production cost. At the same time, some water reducing agents are prone to moisture absorption during storage, resulting in a decrease in performance, which causes difficulties in long-term storage and transportation. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application provides a low-slump slump-retaining concrete water reducing agent and a preparation method thereof, which solves the problems of poor fluidity retention, limited strength improvement and low production efficiency of the existing water reducing agent.

[0006] To achieve the above purpose, the present application realizes the following technical scheme: a low-slump slump-retaining concrete water reducing agent, the water reducing agent comprises the following components by weight: Polyether main chain monomer TPEG: 100-130 parts, the hydrophilic group in the TPEG molecular chain forms a hydrogen bond with the surface of the cement particles, reducing the electrostatic attraction between the cement particles, so that the cement particles can be better dispersed, thereby effectively reducing the viscosity of the concrete and improving the fluidity; Acrylic acid: 40-70 parts, the negative charge group of acrylic acid can form a charge shielding effect on the surface of cement particles, reducing the adhesion between particles, thereby improving the fluidity of concrete. It reacts with the surface of cement to form an organic coating, inhibiting the evaporation of water and maintaining the appropriate slump of concrete; Maleic anhydride: 5-15 parts, maleic anhydride reacts with the components on the surface of cement through its double bond, forming a stable polymer network structure, so that the water reducing agent can play a more lasting effect in concrete; 2-Acrylamide-2-methylpropane sulfonic acid: 8-20 parts, by generating a negative charge adsorption layer on the surface of cement, 2-acrylamide-2-methylpropane sulfonic acid can further reduce the adhesion between particles, reduce the separation and bleeding of concrete, thereby improving its crack resistance and fluidity; Dimethylaminoethyl methacrylate: 2-6 parts, the amino group in dimethylaminoethyl methacrylate can form hydrogen bonds or ion exchange on the surface of cement particles, enhancing the adsorption of water reducing agent on cement particles and optimizing the dispersibility of cement particles; Sodium gluconate: 4-12 parts, sodium gluconate adjusts the ion environment during cement hydration by interacting with cement particles, delays the setting time, and improves the fluidity and workability of concrete; Macromolecular slump retaining component: 2-8 parts, through crosslinking reaction of macromolecular chain, it can form an elastic structure in concrete, which can effectively maintain the fluidity of cement paste and reduce the loss of slump; Microcapsule coated slump retaining body: 3-10 parts, the core substance (such as water-soluble salt or other chemical substances) in the microcapsule coated slump retaining body gradually releases during the hardening process of concrete, playing a gradual release of water retention effect, effectively maintaining the slump; Ammonium polyphosphate: 2-6 parts, the addition of ammonium polyphosphate can delay the hydration heat release process, making the concrete more stable during construction, and the phosphate ion contained in it can combine with the calcium ion on the surface of cement particles to form a stable complex, thereby enhancing the durability of concrete; Sodium dodecyl benzene sulfonate: 1-3 parts, the hydrophobic group of sodium dodecyl benzene sulfonate can form an adsorption layer on the surface of cement particles, reducing the adhesion between cement particles, making the cement paste more easily flow, and improving the water reducing performance; Ammonium persulfate: 1-2 parts, the thermal decomposition product of ammonium persulfate can generate free radicals, which in turn initiate the polymerization reaction of monomers such as acrylic acid, increasing the molecular weight of the water reducing agent and enhancing its dispersing ability for cement particles; Ammonia: 1-3 parts, ammonia adjusts the pH value of the system through neutralization reaction, so that it can be maintained within a stable range, thereby promoting the smooth progress of polymerization reaction; Deionized water: 300-450 parts, as a polar solvent, it can effectively dissolve and disperse all organic and inorganic ingredients, help cement particles to be dispersed better, and thus improve the fluidity and slump retention of concrete.

[0007] Preferably, the preparation method of the polyether main chain monomer TPEG comprises: Polyoxyethylene-polyoxypropylene block polyether diol with a molecular weight of 2400-2600 and an addition amount of 100-130 parts is added to the reaction kettle, heated at 90-100°C, and dehydrated under reduced pressure for 1-2 hours. Polyoxyethylene-polyoxypropylene block polyether diol (polyether diol for short) is the precursor of TPEG, with a molecular weight range of 2400-2600, providing an appropriate molecular chain length, so that the obtained TPEG can exhibit good water-reducing and dispersing effect in concrete. Heating at 90-100°C and dehydrating under reduced pressure helps to remove water in polyether diol, making it more easily react with allyl glycidyl ether (AGGE) to ensure smooth reaction. By dehydration, the water content in polyether diol is reduced, which helps to improve the reaction rate and creates a dry environment for subsequent chemical reactions; After dehydration, 25-35 parts of allyl glycidyl ether and 0.5-1.3 parts of sodium hydroxide are added to the polyether diol, and the mixture is reacted at a temperature of 115-125°C for 4-6 hours, while the stirring speed is maintained at 300-500 rpm. Sodium hydroxide as a catalyst provides the necessary reaction conditions at a temperature of 115-125°C, so that the double bond in the AGGE molecule can crosslink with the polyether diol to form the desired block polymer TPEG. The allyl group of allyl glycidyl ether participates in the nucleophilic addition reaction, and sodium hydroxide as an alkaline catalyst promotes this reaction, forming a part of the polyether chain with an allyl group. This reaction lays the foundation for the core structure of the polyether main chain monomer TPEG. The stirring speed is controlled between 300-500 rpm, which helps to maintain the uniformity of the reaction and prevent local overheating or uneven reaction of the reaction system; After the reaction is completed, the mixture is cooled to below 80°C, and sodium hydroxide solution is added dropwise to adjust the pH to neutral to complete the neutralization. The addition of sodium hydroxide solution is to neutralize the acidic by-products that may be produced during the reaction, such as alcohols or amides, to ensure the stability of TPEG in subsequent processes; After removing the by-products and filtering the impurities under reduced pressure, the polyether main chain monomer TPEG with a hydroxyl value of 35-45 mgKOH / g and an unsaturation of 0.39-0.45 mmol / g is obtained as a colorless to light yellow transparent liquid. The reduced pressure operation can evaporate volatile by-products (such as water and alcohol) at low temperature by reducing the system pressure, thereby reducing impurities and by-products in the product. In this way, the purity of TPEG can be improved, and the final chemical structure (such as hydroxyl value and unsaturation) can be controlled.

[0008] Preferably, the preparation method of the macromolecular slump retaining component comprises: The molecular weight of the carboxymethyl cellulose sodium (CMCNa) is 1.0 x 10 5 -3.0 x 10 5 Da, and the addition amount is 2-8 parts. The carboxymethyl cellulose sodium (CMCNa) with a molecular weight of 1.0 x 10 5 -3.0 x 10 5 Da has good solubility and viscosity characteristics, and is suitable as a macromolecular slump retaining component. It is added to deionized water and stirred at a temperature of 40-60°C to ensure that the CMCNa is completely dissolved to form a high viscosity solution. As the temperature increases, the solubility of the CMCNa increases and the viscosity of the solution increases, which helps the subsequent reaction to proceed smoothly. By stirring in this temperature range, the CMCNa can be fully dissolved to achieve a uniform viscosity state, providing suitable slump retaining effect; Sodium gluconate is added to the above solution, and stirring is continued at the same temperature for 20-30 minutes to form a complex slow-release system by grafting and adsorbing the small molecule organic acid to the macromolecular backbone. The grafting reaction between the gluconate ions in the sodium gluconate and the carboxyl groups on the CMCNa molecules forms a stable complex structure. This complex structure not only increases the water solubility, but also provides the function of slowly releasing water in concrete, enhancing the slump retaining property of concrete; Ammonium polyphosphate is added to the mixture and stirring is continued for 10-20 minutes to form a phosphate chelation crosslinking point. The phosphate ions in the ammonium polyphosphate chelate with metal ions (such as calcium ions) in the cement slurry to form a crosslinked network structure. This crosslinked structure not only enhances the stability of the macromolecular slump retaining component, but also improves its dispersibility in cement, thereby maintaining the slump in concrete and preventing premature setting; The prepared composite solution is cooled to room temperature, the pH is adjusted to 6.5-7.0, and after filtration to remove insoluble substances, it is stored in a sealed container for later use. The pH value is adjusted to the neutral range (6.5-7.0) to ensure that the prepared composite solution will not be degraded due to over-acid or over-alkali conditions. Filtration to remove insoluble substances helps to remove particulate impurities, improve the transparency and purity of the liquid, and ensure product quality. Storage in a sealed container helps to avoid interference from moisture or other components in the air, maintaining the stability of the slump-retaining components.

[0009] Preferably, the preparation method of the microcapsule-coated slump-retaining body comprises: Sodium citrate is selected as the core material, and its mass fraction is 30-50% of the total mass of the microcapsule. It is dissolved in deionized water to form a uniform aqueous solution with a concentration of 5-15 wt%. When sodium citrate is used as the core material, it forms a stable solution with water, maintaining the uniformity of the aqueous solution through hydration effect, providing a uniform core material for the coating reaction. The stability of this solution is crucial for the formation of microcapsules, as it helps in the subsequent coating and stabilization process, ensuring the uniformity of the core of the microcapsule. Industrial-grade gelatin and polyethylene glycol are mixed in a mass ratio of 2:1-4:1, dissolved in deionized water, heated to 45-60°C, and stirred to form a uniform colloidal solution, which is used as the coating material. The ratio of gelatin and polyethylene glycol and the dissolution conditions allow them to form a stable colloidal solution, which has good coating properties. When this solution is mixed with the sodium citrate solution, the colloidal solution can form a uniform coating layer on the surface of the sodium citrate particles, initiating the formation of the initial microcapsule structure. The core material solution is slowly added to the colloidal solution, and emulsified at a stirring rate of 500-800 rpm for 15-30 minutes to form a preliminary embedded emulsion system. The emulsification reaction utilizes high stirring rate to uniformly coat the particles in the sodium citrate solution with the colloidal solution, gradually forming a microcapsule structure. The stirring rate and the rate of dropwise addition directly affect the uniformity of the capsule wall and the size of the capsule particle. High stirring rate promotes more uniform coating, while slow dropwise addition prevents particle aggregation or excessive reaction. At a system temperature of 40-55°C, 0.5-2% glutaraldehyde based on the mass of the wall material is added to the emulsion, and the reaction is allowed to proceed for 30-60 minutes to stabilize and form the capsule structure. Glutaraldehyde participates in the cross-linking reaction at this temperature range, reacting with the amino or hydroxyl groups in the gelatin and polyethylene glycol molecules through its aldehyde group to form cross-linking points. Cross-linking makes the wall material structure of the microcapsule more robust, improving the stability and resistance of the microcapsule, and preventing premature release of the coating material. The microcapsule emulsion is cooled to room temperature, and the particles are collected by centrifugation or low-pressure filtration, washed, and vacuum dried to obtain a light yellow microcapsule coated body with a particle size controlled in the range of 200-500 nanometers. The cooling process gradually solidifies the capsules in the emulsion, and the solvent and impurities are removed by centrifugation or low-pressure filtration to obtain pure microcapsule particles. By vacuum drying, the water is removed and the structural integrity of the microcapsules is maintained. The particle size of the microcapsules is controlled in the range of 200-500 nanometers, so that they can effectively and slowly release their wrapped ingredients in concrete, maintaining good slump retention effect.

[0010] The application also provides a preparation method of a low-slump slump-retaining concrete water reducing agent, comprising the following steps: S1, ingredient mixing: gradually adding the water reducing agent raw materials into deionized water, and sequentially performing dissolution, stirring, and homogenization to form a uniform mixed solution; S2, polymerization reaction: in a constant-temperature reaction kettle, adding the mixed solution into an initiator, controlling the reaction temperature and stirring rate, and allowing the monomers to fully react and polymerize to generate a target polymer; S3, post-treatment and drying: after the reaction is completed, performing cooling, filtration, and vacuum drying to obtain a powder water reducing agent product; S4, performance detection and packaging: performing physical property testing on the obtained water reducing agent through flowability and slump retention detection, and sealing and packaging the water reducing agent for storage after passing the test.

[0011] Preferably, the ingredient mixing comprises: The acrylic acid, maleic anhydride, 2-acrylamide-2-methylpropane sulfonic acid, and dimethylaminoethyl methacrylate are added into deionized water, and stirred for 30-60 minutes until completely dissolved. These monomers contain multiple hydrophilic groups and are easy to dissolve in deionized water and form a uniform solution. They can be fully hydrated during the dissolution process, avoiding the formation of uneven gels or particles. The bifunctional monomers such as acrylic acid and maleic anhydride will crosslink with each other in the subsequent polymerization reaction, forming a high-molecular network, thereby enhancing their performance as water reducing agents in concrete. Through sufficient stirring (30-60 minutes), it can be ensured that all ingredients are uniformly dispersed in water; Sodium dodecyl benzene sulfonate is added into the mixed solution, and stirred at 40-50°C for 20-30 minutes to form a uniform emulsion. Sodium dodecyl benzene sulfonate, as an anionic surfactant, can form an adsorption layer on the surface of the liquid, reduce the interfacial tension between the liquids, and promote the more uniform mixing of the water phase and the oil phase. By stirring at 40-50°C for 20-30 minutes, it can be ensured that the emulsifier fully plays a role, forming a stable emulsion, avoiding delamination or precipitation; The macromolecular slump retaining component solution and the microcapsule slump retaining body solution are added into the emulsion in sequence, and stirring is continuously carried out for 10-20 minutes to ensure uniform mixing. Under the action of stirring, the macromolecular slump retaining component and the microcapsule slump retaining body solution can be fully mixed with the components in the emulsion. In this process, the microcapsule coating technology of the slump retaining component ensures the slow release of the effective component in the concrete, and avoids the premature release of the slump retaining component. At the same time, the thickening effect of the macromolecular slump retaining component in the concrete can help to maintain the fluidity of the concrete and prolong the workability.

[0012] Preferably, the polymerization reaction comprises: Ammonium persulfate is added into the emulsion mixture as an initiator, and constant temperature reaction is carried out at 70-85°C. Ammonium persulfate decomposes at 70-85°C to generate free radicals (SO4·) as the initiation source of the polymerization reaction. These free radicals can initiate the polymerization reaction of monomers such as acrylic acid, maleic anhydride, and 2-acrylamide-2-methylpropanesulfonic acid to form long-chain polymers. The generation of free radicals enables the reaction to start quickly and continue, and temperature control within an appropriate range can avoid excessive reaction or the initiation of side reactions, ensuring the efficiency and high yield of the polymerization reaction; Ammonia is added dropwise to adjust the pH of the system to 7.0-8.5, and the reaction is carried out at a stirring rate of 300-500 rpm for 4-6 hours. The addition of ammonia is used to adjust the pH of the system to the range of 7.0-8.5, which helps to improve the efficiency of the reaction and ensure the stability of the polymerization product. The stirring rate is controlled between 300-500 rpm to ensure that the components in the system are fully mixed and the reaction proceeds uniformly. This process lasts for 4-6 hours to ensure that the polymerization reaction can be completed and the desired molecular weight and degree of polymerization are achieved.

[0013] Preferably, the post-treatment and drying comprise: After the reaction is completed, the product is cooled to room temperature to prevent polymer decomposition. High molecular weight polymers may be degraded due to thermal cracking or active chain segment movement in a high temperature environment, especially those containing amide, carboxylic acid or amine functional groups. By slowly cooling naturally or indirectly to room temperature, the polymer degradation process can be effectively inhibited, stabilizing its chemical structure and properties, and maintaining the high dispersibility and slump retaining ability of the final water reducing agent product; Vacuum filtration is used to remove insoluble substances and impurities to ensure the purity of the product. Vacuum filtration can quickly separate insoluble substances in a solid-liquid system at a lower pressure, avoiding mechanical shearing or polymer chain scission caused by high pressure on the product. During the filtration process, the polymer is in the form of a solution or a colloid passing through the filter membrane, while polymer particles or unreacted components are effectively intercepted, thereby improving the purity of the product and providing a clean basis for subsequent drying. High purity not only facilitates stable storage of the powder, but also improves the dispersibility and consistency of the concrete in construction; The water-reducing agent is dried in a vacuum dryer at 50-70℃ for 8-12 hours until the moisture content is below 5wt%, resulting in a powdered product. Vacuum drying reduces ambient pressure, allowing moisture to evaporate at a lower temperature, thus preventing performance loss in the heat-sensitive polymer due to high temperatures. Simultaneously, controlling the temperature range (50-70℃) effectively prevents the rupture or functional failure of slump-retaining components (such as microcapsules). The continuous drying process of 8-12 hours further stabilizes the polymer network structure, reduces residual moisture, improves product storage stability, and ensures good dispersibility and sustained-release properties in concrete systems.

[0014] Preferably, the performance testing and packaging includes: The slump retention test was used to assess the flowability retention performance of concrete water-reducing agents, and compressive strength tests were conducted to evaluate their strength development characteristics at different ages. The slump retention test reflects the slump retention effect of the water-reducing agent, detecting whether it effectively delays the setting and hardening process of concrete and maintains its construction fluidity for a longer period. The water-reducing agent improves the flowability of concrete by reducing the water-cement ratio and promotes strength development in later stages. The compressive strength test revealed the impact of the water-reducing agent on the cement hydration reaction. Infrared spectroscopy and nuclear magnetic resonance (NMR) were used to characterize and analyze the structure and chemical composition of water-reducing agents. Infrared spectroscopy utilizes the vibrational characteristics of molecules at different wavelengths to detect functional groups such as carboxylic acids, amides, and sulfonic acid groups in the water-reducing agent molecules, revealing their chemical structure and interactions. NMR, on the other hand, analyzes the internal structure of molecules, especially the linkage patterns and composition within polymer chains, by observing the NMR signals of hydrogen or carbon atoms. Combining these two techniques provides a comprehensive understanding of the molecular characteristics of water-reducing agents and offers a basis for further performance optimization. Powder products should be sealed in moisture-proof composite bags and stored in a cool, dry place, avoiding direct sunlight and high temperatures. Moisture, sunlight, and high temperatures can all lead to a decrease in the performance of water-reducing agents or a deterioration of the polymer structure. Moisture-proof composite bags effectively prevent moisture from entering and protect the powder from the effects of humidity; at the same time, a cool, dry storage environment can prevent chemical reactions caused by temperature fluctuations, thereby extending the shelf life of the water-reducing agent.

[0015] This invention provides a low-slump, slump-retaining concrete water-reducing agent and its preparation method. It has the following beneficial effects: 1. This invention employs a technical solution combining the polyether-type main-chain monomer TPEG with multifunctional acrylic monomers, achieving the technical effect of improving the flowability retention of water-reducing agents. Compared to the single acrylic monomer solution in existing technologies, this invention enhances the dispersibility of water-reducing agents by introducing multiple functional monomers, solving the problem of rapid flowability decay in traditional water-reducing agents.

[0016] 2. This invention employs a combination of microencapsulated slump-retaining agents and macromolecular slump-retaining components, achieving an enhanced strength improvement effect of water-reducing agents in concrete. Compared with existing technologies using single slump-retaining components, the combined structure of this invention effectively reduces friction between cement particles, enhances the compressive strength of concrete, and solves the problem of unstable compressive strength of existing water-reducing agents.

[0017] 3. This invention employs low-temperature reaction and high-efficiency polymerization technology in its production process, achieving the technical effects of shortening the production cycle and reducing energy consumption. Compared with the existing technology's high-temperature reaction and long-term synthesis scheme, this invention optimizes reaction conditions, ensuring the performance of the water-reducing agent while improving production efficiency, reducing energy waste, and solving the problems of high energy consumption and high cost in traditional processes.

[0018] 4. This invention improves the storage stability and long-term performance of water-reducing agents by adjusting their moisture content and particle size distribution. Compared with existing technologies that do not control particle size and moisture, this invention effectively avoids the problems of moisture absorption or uneven dispersion of water-reducing agents during storage, ensuring the long-term stability and application effectiveness of the product under different environmental conditions. Attached Figure Description

[0019] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see the appendix Figure 1 : Example 1: Raw materials and proportions: Polyether-type main chain monomer TPEG: 120 parts; Acrylic acid: 50 parts; Maleic anhydride: 10 parts; 2-Acrylamide-2-methylpropanesulfonic acid: 15 parts; Dimethylaminoethyl methacrylate: 5 parts; Sodium gluconate: 8 parts; Macromolecular slump-preserving component: 5 parts; Microcapsule-encapsulated collapsible body: 7 parts; Ammonium polyphosphate: 3 parts; Sodium dodecylbenzenesulfonate: 2 parts; Ammonium persulfate: 1.5 parts; Ammonia water: 2 parts; Deionized water: 350 parts.

[0022] Preparation process: 1. Add acrylic acid, maleic anhydride, 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate to deionized water and stir for 30 minutes until completely dissolved.

[0023] 2. Add sodium dodecylbenzenesulfonate and stir at 40°C for 30 minutes to form an emulsion.

[0024] 3. Add the macromolecular slump-retaining component and the microcapsule-encapsulated slump-retaining solution to the emulsion in sequence, and stir continuously for 15 minutes.

[0025] 4. Add ammonium persulfate initiator and react at a constant temperature of 75°C for 3 hours.

[0026] 5. Add ammonia water dropwise to adjust the pH to 7.5, and react for 4 hours at a stirring speed of 300 rpm.

[0027] 6. After the reaction is complete, cool the product to room temperature and remove insoluble substances by vacuum filtration.

[0028] 7. The water-reducing agent was obtained by drying it in a vacuum dryer at 60°C for 10 hours.

[0029] Example 2: Raw materials and proportions: Polyether-type main chain monomer TPEG: 110 parts; Acrylic acid: 60 parts; Maleic anhydride: 8 parts; 2-Acrylamide-2-methylpropanesulfonic acid: 12 parts; Dimethylaminoethyl methacrylate: 3 parts; Sodium gluconate: 6 parts; Macromolecular collapse-preserving component: 4 parts; Microcapsule-encapsulated collapsible preservative: 6 parts; Ammonium polyphosphate: 2 parts; Sodium dodecylbenzenesulfonate: 1.5 parts; Ammonium persulfate: 1 part; Ammonia solution: 1.8 parts; Deionized water: 375 parts.

[0030] Preparation process: 1. Add acrylic acid, maleic anhydride, 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate to deionized water and stir for 40 minutes to ensure complete dissolution.

[0031] 2. Add sodium dodecylbenzenesulfonate and stir at 50°C for 25 minutes to form a stable emulsion.

[0032] 3. Add the macromolecular slump-preserving component and the microcapsule-encapsulated slump-preserving agent in sequence, and stir for 20 minutes to ensure uniform mixing.

[0033] 4. Add ammonium persulfate to the emulsion and carry out the polymerization reaction at 80°C for 4 hours.

[0034] 5. Adjust the pH to 7.2 using ammonia water, react for 4 hours, and stir at 350 rpm.

[0035] 6. Cool to room temperature, reduce pressure and filter to remove impurities, and purify the product.

[0036] 7. Vacuum dry at 70℃ for 10 hours to obtain a low-moisture powdered water-reducing agent.

[0037] Example 3: Raw materials and proportions: Polyether-type main chain monomer TPEG: 125 parts; Acrylic acid: 65 parts; Maleic anhydride: 12 parts; 2-Acrylamide-2-methylpropanesulfonic acid: 18 parts; Dimethylaminoethyl methacrylate: 4 parts; Sodium gluconate: 10 parts; Macromolecular collapse-preserving component: 6 parts; Microcapsule-encapsulated collapsible body: 9 parts; Ammonium polyphosphate: 5 parts; Sodium dodecylbenzenesulfonate: 2.5 parts; Ammonium persulfate: 1.2 parts; Ammonia solution: 2.5 parts; Deionized water: 400 parts.

[0038] Preparation process: 1. Add acrylic acid, maleic anhydride, 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate to deionized water and stir for 50 minutes to ensure complete dissolution.

[0039] 2. Add sodium dodecylbenzenesulfonate to the mixture and stir at 45°C for 25 minutes to form an emulsion.

[0040] 3. Add the macromolecular slump-preserving component and the microcapsule-encapsulated slump-preserving agent, and stir continuously for 15 minutes to ensure uniformity.

[0041] 4. Add ammonium persulfate to the mixture to initiate the polymerization reaction, and react at 72°C for 4 hours.

[0042] 5. Adjust the pH to 7.3 with ammonia water and react at a stirring speed of 400 rpm for 5 hours.

[0043] 6. After cooling to room temperature, perform vacuum filtration to remove insoluble impurities.

[0044] 7. Vacuum drying at 60℃ for 10 hours yields a stable powder water-reducing agent.

[0045] Comparative Example 1: Compared with Example 1, the difference is that the microcapsule-encapsulated collapse-preserving body was removed, and all other aspects are the same.

[0046] Comparative Example 2: Compared with Example 1, the difference is that the amount of macromolecular collapse-preserving component was reduced to 3 parts, while the rest were the same.

[0047] Comparative Example 3: Compared with Example 1, the difference is that 1 part of ammonium persulfate was used, and the rest are the same.

[0048] Comparative Example 4: Compared with Example 1, the difference is that the amount of deionized water used is 400 parts, and all other aspects are the same.

[0049] Comparative Example 5: The difference from Example 2 is that ammonium polyphosphate was not used; otherwise, they are the same.

[0050] Comparative Example 6: Compared with Example 2, the difference is that the amount of ammonia water was increased to 3 parts, and the rest were the same.

[0051] Experiment 1: Experimental objective: To evaluate the combined effects of different water-reducing agents in the embodiments and comparative examples on the fluidity retention and compressive strength of concrete, with particular attention to the fluidity retention and strength improvement effects of concrete after the addition of different water-reducing agents.

[0052] Experimental materials and equipment: Water-reducing agent samples: Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4, 5, 6.

[0053] Concrete mix proportions: Water:cement ratio (W / C) is 0.45.

[0054] Cement: Standard grade 42.5 cement.

[0055] Aggregates: natural sand and crushed stone, conforming to conventional concrete aggregate standards.

[0056] Equipment: Slump tester; electronic balance; compression tester; thermometer (for ambient temperature measurement); concrete mixer.

[0057] Experimental steps: 1. Prepare concrete: Prepare cement, sand, gravel, and water according to the standard proportions, and add the corresponding proportions of water-reducing agent samples.

[0058] Use a concrete mixer to mix thoroughly, ensuring the water-reducing agent is completely dissolved and evenly distributed in the concrete.

[0059] 2. Liquidity maintenance test: The initial slump was determined using a slump test.

[0060] Concrete samples were placed in containers and their slump was recorded after 1 hour and 3 hours to assess their fluidity retention.

[0061] 3. Compressive strength test: Pour the concrete into a standard cubic mold (150×150×150mm) and vibrate it to shape.

[0062] After 7 and 28 days of curing, the compressive strength of the specimens was tested using a compressive strength testing machine.

[0063] Record the compressive strength of each sample.

[0064] 4. Data recording and analysis: Record the results of the fluidity test (slump value) and the data of compressive strength (7 days, 28 days).

[0065] The effects of different embodiments and comparative water-reducing agents were compared (experimental results are shown in Table 1).

[0066] Table 1: Test data on concrete fluidity and compressive strength From Table 1, we can obtain: First, the molecular structure of the water-reducing agent plays a crucial role in maintaining the fluidity of concrete. In the experiments, Examples 1, 2, and 3 exhibited high slump retention, especially after the addition of the polyether-type main-chain monomer TPEG and functional acrylic monomers. These components, through polar interactions and polymerization effects, effectively reduced the mutual attraction between cement particles, decreased the viscosity of the cement paste, and enhanced the fluidity of the concrete. Therefore, these water-reducing agents can effectively maintain fluidity for a longer period, avoiding increased construction difficulties caused by reduced concrete fluidity.

[0067] Secondly, the improvement in the compressive strength of concrete by water-reducing agents is mainly attributed to the stable film they form on the surface of cement particles, which reduces hydration between cement particles and improves their wettability. This process promotes the uniform dispersion of cement particles, thereby enhancing the density of the cement paste. Especially in Examples 3 and 5, the selected ammonium polyphosphate and macromolecular slump-retaining components not only effectively disperse cement particles but also further promote the chemical reaction between cement and water by adjusting the pH of the solution, thus increasing the compressive strength at 28 days. This indicates that the role of water-reducing agents in cement paste is to enhance its final strength by increasing the density of the cement paste and reducing its porosity.

[0068] Finally, the chemical stability and long-term storage properties of water-reducing agents are also important factors affecting concrete performance. Comparative results in the experiments showed that water-reducing agent samples with added microencapsulated slump retainers and certain high-efficiency polymers exhibited better stability during storage, which may be related to their intramolecular cross-linking structure and slow-release mechanism. These water-reducing agents maintain the fluidity of concrete by slowly releasing their active ingredients, and due to their low water absorption, they can effectively avoid the decline in water-reducing effect during long-term storage. Furthermore, water-reducing agents with higher stability are better able to adapt to different environmental conditions and maintain the expected performance of concrete. Therefore, in practical applications, these types of water-reducing agents have higher economic benefits and broader application prospects.

[0069] Experiment 2: Experimental objective: To evaluate the physical properties, chemical composition, and stability of different water-reducing agent samples, explore their changes during long-term storage and use, and ensure the reliability and stability of the selected water-reducing agent in long-term use.

[0070] Experimental materials and equipment: Water-reducing agent samples: Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4, 5, 6.

[0071] Test materials: Deionized water; Ethanol (used for cleaning); Standard particle size testing equipment.

[0072] Equipment: Electronic balance (for measuring moisture content and mass); microscope (for particle observation); infrared spectrometer (for FTIR testing); nuclear magnetic resonance spectrometer (for NMR testing); dryer (for moisture content testing); laser particle size analyzer (for particle size distribution determination).

[0073] Experimental steps: 1. Physical performance testing: Particle size analysis: The particle size distribution of the water-reducing agent sample was tested using a laser particle size analyzer. An appropriate amount of water-reducing agent powder was mixed with deionized water to ensure uniform dispersion before testing.

[0074] Bulk density measurement: Pour a known mass of water-reducing agent powder into a standard graduated cylinder, record its volume, and calculate the bulk density.

[0075] Moisture content determination: Take an appropriate amount of water-reducing agent sample, place it in a dryer, dry it at 60℃ for 24 hours, measure the mass change after drying, and calculate the moisture content.

[0076] 2. Chemical composition analysis: FTIR analysis: The water-reducing agent sample is placed in an FTIR device, its infrared spectrum is scanned, and the information of functional groups (such as carboxyl groups, ester groups, sulfonic acid groups, etc.) is analyzed to determine its chemical structure.

[0077] NMR analysis: Nuclear magnetic resonance (NMR) testing was used to further confirm the molecular structure and degree of cross-linking of the water-reducing agent, and to analyze the chain length of its polymer and the intermolecular interactions.

[0078] 3. Stability test: Storage stability: The water-reducing agent samples were stored in a constant temperature chamber at 25°C, and samples were taken periodically for physical and chemical tests. Tests were conducted every 30 days to observe changes in particle size, bulk density, and moisture content of the water-reducing agent.

[0079] Solubility test: The water-reducing agent sample was dissolved in deionized water, and its solubility and dissolution rate were observed to evaluate its solubility stability in water (the experimental results are shown in Table 2).

[0080] Table 2: Test data on physical properties and chemical stability of water-reducing agents From Table 2, we can obtain: First, the particle size and bulk density of water-reducing agents directly affect their dispersibility and flowability in concrete. In the experiments, smaller particles, such as those in Examples 1 and 3, exhibited better dispersibility, effectively reducing the mutual attraction between cement particles and enhancing flowability. This phenomenon indicates that water-reducing agents, by reducing particle size and optimizing packing structure, help improve the uniformity of cement paste, reduce water waste, and thus improve the workability and strength of concrete.

[0081] Secondly, the chemical stability of the water-reducing agent is crucial for its long-term performance. FTIR and NMR analyses revealed that the water-reducing agent in the examples possesses relatively stable functional groups, such as sulfonic acid and carboxyl groups. These functional groups contribute to the formation of a stable cement-water-reducing agent composite, reducing aggregation between cement particles. In particular, the cross-linking of the polymer chains ensures the water-reducing agent maintains strong stability during long-term storage. This indicates that the role of the water-reducing agent in concrete is not merely temporary; it continuously provides fluidity and enhances concrete strength through the stability of its chemical structure.

[0082] Finally, the water absorption characteristics of water-reducing agents directly affect their performance during storage and use. Examples 1 and 3 exhibited lower moisture content, indicating that their more compact molecular structure and lower water absorption capacity make them more stable during long-term storage. In contrast, the water-reducing agents in Comparative Examples 5 and 6 exhibited higher water absorption, which may lead to a decline in their performance during storage. The stability and low water absorption characteristics of the water-reducing agents indicate that they can maintain their effectiveness for a longer period under different environmental conditions, reducing performance degradation caused by environmental changes and thus ensuring the long-term quality of concrete.

[0083] Experiment 3: Experimental objective: To evaluate the cost-effectiveness and production efficiency of different water-reducing agent samples during the production process, and to help select a suitable water-reducing agent formulation that can reduce production costs and improve production efficiency while meeting performance requirements.

[0084] Experimental materials and equipment: Water-reducing agent samples: Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4, 5, 6.

[0085] raw material: TPEG, a polyether-type main-chain monomer; Acrylic monomers; Functional additives (such as maleic anhydride, 2-acrylamide-2-methylpropanesulfonic acid, etc.); Ammonium persulfate; Ammonium polyphosphate, etc.

[0086] Equipment: Reactor; constant temperature bath; stirrer; vacuum dryer; electronic balance; thermometer and hygrometer.

[0087] Experimental steps: 1. Production process flow: Prepare raw materials: Prepare the corresponding polyether main chain monomers, acrylic monomers and other auxiliary components according to the formulation of each water-reducing agent.

[0088] Reaction Synthesis: Add the prepared raw materials to the reactor in the specified proportions, heat and stir to ensure thorough mixing. Adjust the reaction temperature (60℃-75℃) in a constant temperature bath and continue stirring for 3-4 hours to complete the polymerization reaction.

[0089] Post-processing: After the reaction is complete, the product is cooled to room temperature and the moisture is removed using a vacuum dryer to obtain a dry water-reducing agent powder.

[0090] Production monitoring: During the production process, parameters such as the amount of raw materials added, reaction temperature, and stirring speed are checked regularly to ensure the stability and consistency of production.

[0091] 2. Production cost assessment: Raw material cost: Measure the amount of each component used in each water-reducing agent formulation and calculate the raw material cost of each component.

[0092] Energy cost: By recording the energy consumption of heating, stirring and other processes during the reaction, the energy cost of each batch of water-reducing agent is assessed.

[0093] Time cost: Calculate the impact of the production cycle on costs based on the time required for each production batch.

[0094] 3. Economic evaluation: Unit cost: Calculate the total production cost of each batch of water-reducing agent, and evaluate the production cost per ton of water-reducing agent by combining the total cost with the total output of the production batch.

[0095] Production efficiency: Calculate the production cycle of each water-reducing agent sample to evaluate the level of production efficiency.

[0096] Overall economic efficiency: Taking into account raw material costs, energy costs and production cycle, the economic efficiency of each water-reducing agent was evaluated, and a water-reducing agent formulation with high cost performance was selected (experimental results are shown in Table 3).

[0097] Table 3: Production Process and Economic Evaluation Data of Water-Reducing Agents From Table 3, we can obtain: First, the production process of water-reducing agents is closely related to their molecular structure and the chemical reactions of their functional groups. Shorter production cycles and lower energy consumption are generally associated with the molecular structural stability and reaction efficiency of the water-reducing agent. For example, the shorter production cycles and higher production efficiencies of Examples 2 and 3 indicate that the polymerization and crosslinking processes occur more efficiently and under milder reaction conditions during the synthesis of these water-reducing agents, thereby reducing energy consumption and shortening production time. This may be related to their relatively simple polymer structure and lower reaction activation energy, thus improving production efficiency.

[0098] Secondly, the raw material and production costs of water-reducing agents are directly related to their chemical composition and synthesis methods. In the experiments, Examples 2 and 3 showed lower unit costs, mainly due to the cost-effectiveness of the raw materials used in their formulations and the high efficiency of their synthesis processes, reducing reliance on expensive raw materials. By optimizing reaction conditions and rationally selecting polymer chain lengths and functional monomers, the production cost of the water-reducing agent was significantly reduced, reflecting effective molecular design and process optimization during synthesis. Compared to Comparative Examples 5 and 6, Examples 2 and 3 showed better economic efficiency, indicating better cost control in the synthesis of water-reducing agents.

[0099] Finally, the optimization of the water-reducing agent production process is not only reflected in the cost of raw materials and the production cycle, but also in the overall efficiency of the entire production process. Experimental results show that shorter production cycles and lower energy consumption can improve production efficiency. This indicates that the synthesis process of water-reducing agents further enhances the economics of the production process by improving reaction efficiency, reducing the generation of by-products, and eliminating unnecessary steps. This optimized production process can ensure the sustainability of water-reducing agents in large-scale production, reduce long-term production costs, and thus provide a more competitive solution for industrial applications.

[0100] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-slump, slump-retaining concrete water-reducing agent, characterized in that, The water-reducing agent comprises the following components in parts by weight: Polyether-type main chain monomer TPEG: 100-130 parts; Acrylic acid: 40-70 parts; Maleic anhydride: 5-15 parts; 2-Acrylamide-2-methylpropanesulfonic acid: 8-20 parts; Dimethylaminoethyl methacrylate: 2-6 parts; Sodium gluconate: 4-12 parts; Macromolecular slump-retaining components: 2-8 parts; Microcapsule-encapsulated collapsible body: 3-10 parts; Ammonium polyphosphate: 2-6 parts; Sodium dodecylbenzenesulfonate: 1-3 parts; Ammonium persulfate: 1-2 parts; Ammonia solution: 1-3 parts; Deionized water: 300-450 parts.

2. The low-slump, slump-retaining concrete water-reducing agent according to claim 1, characterized in that, The preparation method of the polyether-type main-chain monomer TPEG includes: Add 100-130 parts of polyoxyethylene-polyoxypropylene block polyether diol with a molecular weight of 2400-2600 to a reaction vessel, heat at 90-100℃, and dehydrate under reduced pressure for 1-2 hours. Add 25-35 parts of allyl glycidyl ether and 0.5-1.3 parts of sodium hydroxide to the dehydrated polyether glycol, and react at 115-125℃ for 4-6 hours, maintaining a stirring rate of 300-500 rpm during the reaction. After the reaction is complete, cool the mixture to below 80°C, and add sodium hydroxide solution dropwise to adjust the pH to neutral to complete the neutralization. After removing byproducts and filtering impurities under reduced pressure, a polyether-type main chain monomer TPEG with a hydroxyl value of 35-45 mgKOH / g and an unsaturation degree of 0.39-0.45 mmol / g is obtained, which is a colorless to light yellow transparent liquid.

3. The low-slump, slump-retaining concrete water-reducing agent according to claim 1, characterized in that, The preparation method of the macromolecular collapse-preserving component includes: With a molecular weight of 1.0 × 10 5 -3.0×10 5 Da, 2-8 parts of sodium carboxymethyl cellulose are added to deionized water and stirred at 40-60℃ for 30-60 minutes to obtain a uniform high-viscosity solution; Add sodium gluconate to the above solution and continue stirring for 20-30 minutes under the same temperature conditions to allow the small molecule organic acid to fully graft and adsorb onto the macromolecular skeleton to form a composite sustained-release system. Add ammonium polyphosphate to the mixture and continue stirring for 10-20 minutes to form phosphate chelate crosslinking points; The prepared composite solution was cooled to room temperature, the pH was adjusted to 6.5-7.0, and after filtering to remove insoluble matter, it was stored in a sealed container for later use.

4. The low-slump, slump-retaining concrete water-reducing agent according to claim 1, characterized in that, The preparation method of the microcapsule-encapsulated collapse-preserving body includes: Sodium citrate was selected as the core material, and its mass fraction was 30-50% of the total mass of the microcapsules. It was dissolved in deionized water to form a homogeneous aqueous solution with a concentration of 5-15 wt%, and then set aside. Industrial grade gelatin and polyethylene glycol are mixed in a mass ratio of 2:1-4:1, dissolved in deionized water, heated to 45-60℃, and stirred to form a uniform colloidal solution, which is used as a coating material. The core material solution is slowly added dropwise to the colloidal solution, and emulsified for 15-30 minutes at a stirring rate of 500-800 rpm to form a preliminary encapsulated emulsion system. While maintaining the system temperature at 40-55℃, add 0.5-2% glutaraldehyde (by weight of the wall material) to the emulsion and react for 30-60 minutes to stabilize and shape the capsule structure. The microcapsule emulsion was cooled to room temperature, and the particles were collected by centrifugation or low-pressure filtration. After washing, the particles were vacuum dried to obtain a light yellow microcapsule-encapsulated slump-resistant material with a particle size controlled at 200-500 nanometers.

5. A method for preparing a low-slump, slump-retaining concrete water-reducing agent, characterized in that, The preparation of a low-slump, slump-retaining concrete water-reducing agent according to any one of claims 1-4 includes the following steps: S1. Ingredients and Mixing: The water-reducing agent raw materials are gradually added to deionized water, and dissolved, stirred and homogenized in sequence to form a uniform mixture. S2. Polymerization reaction: In a constant temperature reactor, the mixture is added to the initiator, and the reaction temperature and stirring rate are controlled to allow the monomers to fully react and polymerize, generating the target polymer. S3. Post-processing and drying: After the reaction is completed, the product is cooled, filtered, and vacuum dried to obtain a powdered water-reducing agent product. S4. Performance Testing and Packaging: The obtained water-reducing agent is tested for physical properties through flowability and slump retention tests. After passing the tests, it is sealed and packaged for storage.

6. The method for preparing a low-slump, slump-retaining concrete water-reducing agent according to claim 5, characterized in that, The ingredients and mixing include: Add acrylic acid, maleic anhydride, 2-acrylamide-2-methylpropanesulfonic acid and dimethylaminoethyl methacrylate to deionized water and stir for 30-60 minutes until completely dissolved. Add sodium dodecylbenzenesulfonate to the mixture and stir at 40-50℃ for 20-30 minutes to form a uniform emulsion; Add the macromolecular slump-preserving component solution and the microcapsule slump-preserving component solution to the emulsion in sequence, and stir continuously for 10-20 minutes to ensure uniform mixing.

7. The preparation method of a low-slump, slump-retaining concrete water-reducing agent according to claim 5, characterized in that, The polymerization reaction includes: Ammonium persulfate was added to the emulsified mixture as an initiator, and the reaction was carried out at a constant temperature of 70-85℃. Adjust the pH of the system to 7.0-8.5 by adding ammonia dropwise, and react for 4-6 hours at a stirring speed of 300-500 rpm.

8. The preparation method of a low-slump, slump-retaining concrete water-reducing agent according to claim 5, characterized in that, The post-processing and drying include: After the reaction is complete, the product is cooled to room temperature to prevent polymer decomposition. Reduced pressure filtration is used to remove insoluble substances and impurities, ensuring the purity of the product. The product is dried in a vacuum dryer at 50-70℃ for 8-12 hours until the moisture content is less than 5wt%, thus obtaining a powdered water-reducing agent.

9. The preparation method of a low-slump, slump-retaining concrete water-reducing agent according to claim 5, characterized in that, The performance testing and packaging include: The fluidity retention performance of concrete water-reducing agents was tested by slump retention test, and compressive strength test was conducted to evaluate their strength development characteristics at different ages. The structure and chemical composition of the water-reducing agent were characterized and analyzed by infrared spectroscopy and nuclear magnetic resonance. Pack the powder product into a moisture-proof composite bag and store it in a cool, dry place, avoiding direct sunlight and high temperature environments.

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