Nanocomposite phase change antifreezing type water reducing agent and preparation thereof

Abstract

This invention discloses a nanocomposite phase change antifreeze water-reducing agent and its preparation method, comprising water and the following components in parts by weight: 5-8 parts polycarboxylate superplasticizer mother liquor, 6-10 parts ethylene glycol, 8-10 parts calcium formate, 2-4 parts sodium nitrite, 5-8 parts methanol, 2-5 parts sodium metasilicate, 1-2 parts sodium thiocyanate, 0.3-0.6 parts air-entraining agent, 6-8 parts modified nano titanium dioxide, and 8-10 parts ternary phase change material. This nanocomposite phase change antifreeze water-reducing agent is a composite functional admixture that introduces nanomaterials and phase change materials into traditional antifreeze water-reducing agents. It not only prevents concrete from freezing at low temperatures but also regulates the internal temperature changes of concrete through "phase change" characteristics, thereby improving the durability of concrete under freeze-thaw cycles.

Description

Technical Field

[0001] This invention relates to a water-reducing agent and its preparation, particularly a nanocomposite phase change antifreeze water-reducing agent and its preparation. Background Technology

[0002] In modern concrete construction, the application of water-reducing agents greatly improves the workability, fluidity, and compressive strength of concrete, reduces cement usage, lowers concrete costs, and reduces structural weight, significantly decreasing the release of heat of hydration. However, concrete construction and curing are often strictly limited by ambient temperature, especially in low-temperature or cold regions during winter. The cement hydration process is highly susceptible to environmental temperature changes. When the temperature drops to 0°C, the free water in the concrete begins to freeze, expanding in volume by about 9%. The resulting ice expansion stress can damage the initial setting cement paste structure, preventing the concrete from developing its strength properly and even causing permanent structural damage and durability degradation, leading to a decline in the quality of the concrete project.

[0003] To address the problem of concrete freezing damage in winter, existing technologies typically employ two main approaches. One is physical insulation measures, such as covering with insulation materials or using heated sheds; these methods are costly, complex, and energy-intensive. The other is adding antifreeze agents. Traditional antifreeze agents usually lower the freezing point of the system by incorporating inorganic salts or organic antifreeze agents, thus preventing the cement paste from expanding and damaging the structure when frozen. However, these antifreeze agents have significant drawbacks: First, the use of certain chloride-based antifreeze agents introduces chloride ions, which corrode steel reinforcement and lead to a decline in the quality of concrete projects. Second, as ambient temperatures continue to decrease, some organic antifreeze agents may crystallize or become ineffective, leaving concrete still at risk of crystallization. Furthermore, single-component antifreeze agents are often only effective within a specific temperature range, and their latent heat release capacity is limited in the face of drastically fluctuating frigid environments, making it difficult to maintain the dynamic balance of hydration heat within the concrete. Third, while lowering the freezing point of concrete, some antifreeze agents may cause concrete expansion, increase the dosage, or reduce the long-term durability of concrete, even leading to structural expansion and damage. Fourth, the preparation and use of traditional antifreeze agents may involve organic solvents or powdered particles, posing risks of volatility, scaling, or harm to the health of construction workers.

[0004] In recent years, researchers have attempted to introduce nanomaterials to improve the performance of antifreeze water-reducing agents. Nanomaterials, with their high specific surface area and unique surface activity and thermophysical properties, have proven to have potential advantages in antifreeze agents. The most common approach is to utilize phase change materials (PCMs) to regulate concrete temperature. As special materials with potential heat storage capabilities, PCMs can absorb or release a large amount of latent heat during phase change, thereby buffering the impact of environmental temperature changes on the hydration process of concrete. Introducing them into water-reducing agent systems can not only delay rapid changes in the internal temperature of concrete and enhance its antifreeze performance, but also improve the thermal equilibrium state of concrete by utilizing their thermal conductivity. However, pure PCMs suffer from drawbacks such as low thermal conductivity, easy leakage, and weak interfacial bonding with the cement matrix.

[0005] The project aims to develop a novel composite antifreeze water-reducing agent that combines high water reduction, active temperature regulation, and long-lasting antifreeze properties. By combining organic and inorganic antifreeze components with nanotechnology and phase change materials, and utilizing the high specific surface area and nucleation induction effect of nanoparticles, the phase change materials are modified to prepare a nanocomposite phase change antifreeze water-reducing agent. This technology can not only lower the freezing point through a dual physical and chemical action, but also utilize the heat storage and release characteristics of nanocomposite phase change materials to provide internal curing conditions for concrete hardening at sub-zero temperatures, thereby improving its longevity and durability.

[0006] The purpose of this invention is to provide a nanocomposite phase change antifreeze water-reducing agent and its preparation. This nanocomposite phase change antifreeze water-reducing agent is a composite functional admixture that incorporates nanomaterials and phase change materials, based on traditional antifreeze water-reducing agents. It not only prevents concrete from freezing at low temperatures but also regulates internal temperature changes in concrete through its "phase change" properties, thereby improving the durability of concrete under freeze-thaw cycles.

[0007] A nanocomposite phase change antifreeze water-reducing agent comprises water and the following components in parts by weight: 5-8 parts polycarboxylate water-reducing agent mother liquor, 6-10 parts ethylene glycol, 8-10 parts calcium formate, 2-4 parts sodium nitrite, 5-8 parts methanol, 2-5 parts sodium metasilicate, 1-2 parts sodium thiocyanate, 0.3-0.6 parts air-entraining agent, 6-8 parts modified nano titanium dioxide, and 8-10 parts ternary phase change material.

[0008] Preferably, in the aforementioned nanocomposite phase change antifreeze water-reducing agent, the polycarboxylate water-reducing agent mother liquor comprises polyether macromonomer, acrylic small monomer, acid anhydride, initiator, redox component, chain transfer agent, sodium hydroxide and water.

[0009] Preferably, in the aforementioned nanocomposite phase change antifreeze water-reducing agent, the polycarboxylate water-reducing agent mother liquor comprises, by weight, 340-380 parts of polyether macromonomer, 40-60 parts of acrylic small monomer, 10-20 parts of acid anhydride, 6.0-8.0 parts of initiator, 2.0-3.0 parts of redox component, 1.5-2.0 parts of chain transfer agent, and 500-600 parts of water.

[0010] Preferably, in the aforementioned nanocomposite phase change antifreeze water-reducing agent, the redox component is a combination of hydrogen peroxide and ferric sulfate heptahydrate or cobalt sulfate heptahydrate, and the mass ratio of hydrogen peroxide to ferric sulfate heptahydrate or cobalt sulfate heptahydrate is 5-8:1.

[0011] Preferably, in the aforementioned nanocomposite phase change antifreeze water-reducing agent, the ternary phase change material is a composition of tetradecane, lauryl alcohol, and decanoic acid, with a mass ratio of tetradecane: lauryl alcohol: decanoic acid = 6-7: 2-3: 1.

[0012] Preferably, in the aforementioned nanocomposite phase change antifreeze water-reducing agent, the air-entraining agent is a mixture of sodium dodecylbenzenesulfonate, oleanolic acid and sodium rosinate, with a mass ratio of sodium dodecylbenzenesulfonate: oleanolic acid: sodium rosinate = 5.0: 3.1: 1.9.

[0013] A method for preparing the aforementioned nanocomposite phase change antifreeze water-reducing agent includes the following steps: S1. Take 40 parts of water, add sodium metasilicate according to the mass ratio, stir until completely dissolved, then add polycarboxylate superplasticizer mother liquor, continue stirring until uniform, and obtain an aqueous solution; S2. Add ethylene glycol, methanol, calcium formate, sodium nitrite, sodium thiocyanate and ternary phase change material to another container, slowly heat to 70-90℃, and fully melt and mix to obtain an oil phase solution; S3. The aqueous solution is stirred at room temperature. While stirring, the oil phase solution is slowly dripped into the aqueous solution. The dripping is completed in 30±2 minutes. Stirring continues, and the modified nano-titanium dioxide is slowly added. After the liquid phase is stirred evenly, the air-entraining agent is added and fully mixed to obtain a nano-composite antifreeze water-reducing agent.

[0014] Preferably, in the aforementioned method for preparing the nanocomposite phase change antifreeze water-reducing agent, the preparation method of the polycarboxylate water-reducing agent mother liquor is as follows: Acrylic acid monomers, acid anhydrides, and a portion of water are mixed to prepare solution A; chain transfer agent, redox components, and a portion of water are thoroughly mixed to prepare solution B; initiator is dissolved in a portion of water to prepare solution C; sodium hydroxide is dissolved in water to prepare a 30% sodium hydroxide aqueous solution; the remaining water is added to a container, and the polyether macromonomer is added while stirring. After complete dissolution, solution B is slowly added, and after stirring evenly, solution A is added dropwise, controlling the addition of solution A to be completed in 60±2 minutes. After adding solution A for 10-20 minutes, solution C is added dropwise, controlling the addition of solution C to be completed in 70±2 minutes. The initial temperature of the dropwise addition is 17-23℃. After the dropwise addition is completed, the reaction is continuously stirred for 30-100 minutes. After the stirring reaction is completed, the sodium hydroxide aqueous solution is added to adjust the pH to 5-7, obtaining the polycarboxylate superplasticizer mother liquor.

[0015] Preferably, in the aforementioned method for preparing the nanocomposite phase change antifreeze water-reducing agent, the preparation method of the ternary phase change material is as follows: Weigh out tetradecane, lauryl alcohol, and decanoic acid; place the container in a constant temperature water bath at 70-80℃, add lauryl alcohol, and slowly add tetradecane while stirring. After the tetradecane dissolves, slowly add the prepared decanoic acid dropwise using a dropper. Continue stirring in the water bath until all substances melt to form a homogeneous transparent liquid; transfer the transparent liquid into an ultrasonic oscillator and vibrate for 15-20 minutes. While still hot, pour it into an aluminum crucible and cool and solidify at room temperature to obtain the ternary phase change material.

[0016] Preferably, in the aforementioned method for preparing the nanocomposite phase change antifreeze water-reducing agent, the method for preparing the modified nano titanium dioxide is as follows: Powdered nano-titanium dioxide is dried in an oven at 100-110℃ for 0.5-1.5 hours to remove surface water. It is then ground in a ball mill at 200-300 rpm with a ball-to-particle ratio of 3-7:1 for 20-40 minutes to depolymerize it. Following this, it is heat-treated at 300-400℃ for 1-5 hours under nitrogen protection. The treated nano-titanium dioxide is dispersed in anhydrous ethanol and ultrasonically treated for 10-30 minutes at a frequency of 20-40 kHz and a power of 300-500 W. Then, under stirring at 300-500 rpm, 5-10% (by weight of the nano-titanium dioxide) of a silane coupling agent solution is slowly added, and ultrasonic treatment continues for another 10-30 minutes. Finally, the treated nano-titanium dioxide is centrifuged at 7800-8200 pm for 5-15 minutes, and 0.1-0.3% (by weight of the nano-titanium dioxide) of hydroxypropyl methylcellulose is added and mixed thoroughly to obtain modified nano-titanium dioxide.

[0017] The "cutting-edge technology" of this water-reducing agent is mainly reflected in the following two aspects: 1. Nanocomposite technology: By introducing modified nano-titanium dioxide materials, which fill the spaces between cement particles, a "micro-aggregate effect" is achieved, significantly refining the pore structure of concrete and increasing its density. This not only enhances the early strength of concrete but also blocks water penetration channels, fundamentally reducing the likelihood of frost damage. While traditional air-entraining agents can alleviate frost heave, they sacrifice some strength. Nanocomposite water-reducing agents reduce the content of freezeable water by densifying the concrete structure, thereby mitigating the risk of freeze-thaw damage at its source. Simultaneously, the incorporation of nanomaterials significantly improves the impermeability and resistance to chloride ion attack of concrete, which is particularly important for bridges, tunnels, or marine concrete in cold regions.

[0018] 2. Phase change energy storage technology: This invention introduces a ternary phase change material (PCM) dispersed within a water-reducing agent system. When the ambient temperature decreases, the PCM releases a significant amount of latent heat, which slows the temperature drop of the concrete, ensuring the cement hydration reaction continues for a certain period and preventing structural damage caused by the freezing and expansion of internal water. Concrete has its lowest strength and is most susceptible to freezing before initial setting. The heat released by the PCM maintains a positive temperature environment within the concrete, ensuring normal early strength development.

[0019] Based on the above scheme and principle, the beneficial effects of the present invention are as follows: 1. The water-reducing agent of this invention is prepared from polycarboxylate superplasticizer mother liquor, modified nano-titanium dioxide, ternary phase change materials, and other auxiliary raw materials. The polycarboxylate superplasticizer mother liquor exhibits good compatibility with the modified nano-titanium dioxide and ternary phase change materials. The polar groups in its molecular structure can form hydrogen bonds with the surface of the modified nano-titanium dioxide, thereby enhancing the overall stability of the water-reducing agent. Simultaneously, its non-polar segments can interpenetrate with the organic components in the ternary phase change materials, promoting the uniform dispersion of the phase change materials. These characteristics make the polycarboxylate superplasticizer mother liquor an ideal base material for the water-reducing agent designed in this study. Its uniqueness lies in achieving a combination of high water reduction and excellent antifreeze performance through precise formulation design and innovative preparation methods. This combination is not merely a simple chemical additive, but rather improves the microscopic "skeleton" of concrete through nanotechnology and endows concrete with "temperature regulation" capabilities through the phase change materials. Although its cost may be higher than ordinary antifreeze agents, it is a highly valuable solution for projects in cold regions, with stringent durability requirements, or involving large-volume concrete construction. The nanocomposite antifreeze water-reducing agent of the present invention is not a single substance, but a "composite formula" with the synergistic effect of multiple components. The nanomaterials have extremely high specific surface area and pozzolanic activity, which can fill the micropores of concrete and accelerate cement hydration, thereby significantly improving the early strength of concrete, which is the key to resisting frost damage.

[0020] 2. The nanocomposite phase change antifreeze water-reducing agent of this invention also includes auxiliary raw materials such as sodium metasilicate, ethylene glycol, calcium formate, and sodium thiocyanate. Sodium metasilicate, as an inorganic salt-based early-strength agent, can accelerate the hydration reaction process of cement, thereby shortening the concrete setting time and improving early strength. Ethylene glycol, sodium thiocyanate, calcium formate, and sodium nitrite, as the main antifreeze additives, can lower the freezing point of the water-reducing agent solution and concrete under extreme low-temperature conditions. Even at sub-zero temperatures, it can ensure sufficient liquid water around cement particles for hydration reaction, preventing water from freezing and expanding, thus protecting the concrete structure. Furthermore, calcium formate not only has early-strength properties but also inhibits the migration of chloride ions in concrete through complexation, thereby reducing the risk of steel corrosion.

[0021] 3. This invention incorporates a composite air-entraining agent, sodium dodecylbenzenesulfonate, oleanolic acid, and sodium rosinate, during preparation. Compared to traditional single air-entraining agents, it possesses numerous advantages: (1) Multi-scale bubble control: Sodium dodecylbenzenesulfonate, as a powerful foaming agent, can quickly generate a large number of micro bubbles, while oleanolic acid and sodium rosinate work together to make the bubble size distribution more uniform, avoiding the problem of single bubbles being too large or too small.

[0022] (2) Dual stabilization mechanism: Sodium dodecylbenzenesulfonate reduces the surface tension to 40-60 mN / m, oleanolic acid forms a dense interface film through its pentacyclic triterpenoid structure, and sodium rosinate provides a hydrophobic protective layer. The three work together to significantly improve the stability of the bubble and reduce the gas content loss rate by more than 30%.

[0023] (3) Enhanced resistance to merging: The aglycone group (lipophilic) and monosaccharide group (hydrophilic) in oleanolic acid molecules form a natural barrier, effectively preventing the collision and merging of air bubbles, making the air bubbles in concrete more evenly distributed, improving the freeze-thaw resistance while greatly reducing strength loss.

[0024] The composite air-entraining agent introduces a large number of tiny, closed air bubbles through the synergistic effect of its three components. These air bubbles can act as "buffer valves" to absorb the expansion pressure generated when water freezes, preventing concrete from cracking.

[0025] Experiments have shown that the water-reducing agent of this invention, due to the use of highly active polycarboxylate superplasticizer mother liquor and the addition of modified nano-titanium dioxide to enhance dispersion, achieves a water reduction rate of over 30%, far exceeding the average level of traditional water-reducing agents. Secondly, regarding antifreeze capabilities, the introduction of modified nano-titanium dioxide and ternary phase change materials enables the water-reducing agent to maintain stable internal concrete temperatures in environments below -20°C, effectively preventing frost damage. Furthermore, this formula is non-toxic, harmless, alkali-free, and chlorine-free, and has no negative impact on concrete performance. These advantages not only demonstrate the innovation of the formula but also provide a more reliable solution for concrete construction in cold regions. Detailed Implementation

[0026] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0027] Embodiments of the present invention Example 1

[0028] The preparation method of polycarboxylate superplasticizer mother liquor is as follows: By weight, mix 50 parts acrylic acid monomer, 15 parts acid anhydride and 80 parts water to prepare solution A; mix 1.8 parts chain transfer agent, 2.5 parts redox component and 80 parts water thoroughly to prepare solution B; dissolve 7.0 parts initiator in 80 parts water to prepare solution C; and prepare a 30% sodium hydroxide aqueous solution by adding water. Add 310 parts of water to a container, add the polyether macromonomer while stirring, and after it is completely dissolved, slowly add solution B. After stirring evenly, start adding solution A dropwise, and control the addition of solution A to be completed within 60 minutes. After adding solution A dropwise for 15 minutes, start adding solution C dropwise, and control the addition of solution C to be completed within 70 minutes. The initial temperature of the dropwise addition is 20°C. After the dropwise addition is completed, continue stirring and reacting for 60 minutes. After the stirring reaction is completed, add the sodium hydroxide aqueous solution to adjust the pH to 6 to obtain the polycarboxylate superplasticizer mother liquor. The above-mentioned polyether macromonomer is vinyl polyethylene glycol ether; the acid anhydride is maleic anhydride; the initiator is azobisisobutyramidine hydrochloride; the chain transfer agent is mercaptopropionic acid; and the redox component is a mixture of hydrogen peroxide and ferric sulfate heptahydrate in a mass ratio of 6:1.

[0029] The preparation method of ternary phase change materials is as follows: Weigh out tetradecane, lauryl alcohol, and decanoic acid in a mass ratio of 6.5:2.5:1. Place the container in a 75°C constant temperature water bath, add lauryl alcohol, and slowly add tetradecane while stirring. After the tetradecane dissolves, slowly add the prepared decanoic acid dropwise using a dropper. Continue stirring in the water bath until all substances melt to form a homogeneous transparent liquid. Transfer the transparent liquid to an ultrasonic oscillator and vibrate for 18 minutes. While still hot, pour it into an aluminum crucible and cool and solidify at room temperature to obtain the ternary phase change material.

[0030] The preparation method of modified nano-titanium dioxide is as follows: Powdered nano-titanium dioxide was dried in an oven at 105℃ for 1 hour to remove surface water. It was then ground in a ball mill at 250 rpm with a ball-to-particle ratio of 5:1 for 30 minutes to depolymerize it. Following this, it was heat-treated at 350℃ for 3 hours under nitrogen protection. The treated nano-titanium dioxide was dispersed in anhydrous ethanol and ultrasonically treated for 20 minutes at a frequency of 30 kHz and a power of 400 W. Then, under stirring at 400 rpm, 8% (by weight) of a silane coupling agent solution (by mass of the nano-titanium dioxide) was slowly added, and ultrasonic treatment continued for another 20 minutes. Finally, the treated nano-titanium dioxide was centrifuged at 8000 pm for 10 minutes, and 0.2% (by mass of the nano-titanium dioxide) of hydroxypropyl methylcellulose was added and mixed thoroughly to obtain modified nano-titanium dioxide. Example 2

[0031] The preparation method of polycarboxylate superplasticizer mother liquor is as follows: By weight, 40 parts of acrylic acid monomer, 10 parts of acid anhydride and 50 parts of water are mixed to prepare solution A; 1.5 parts of chain transfer agent, 2.0 parts of redox component and 50 parts of water are thoroughly mixed to prepare solution B; 6.0 parts of initiator are dissolved in 50 parts to prepare solution C; sodium hydroxide is added to water to prepare a 30% sodium hydroxide aqueous solution. Add 350 parts of water to a container, add the polyether macromonomer while stirring, and after it is completely dissolved, slowly add solution B. After stirring evenly, start adding solution A dropwise, and control the addition of solution A to be completed in 58 minutes. After adding solution A dropwise for 10 minutes, start adding solution C dropwise, and control the addition of solution C to be completed in 68 minutes. The initial temperature of the dropwise addition is 17°C. After the dropwise addition is completed, continue stirring and reacting for 30 minutes. After the stirring reaction is completed, add the sodium hydroxide aqueous solution to adjust the pH to 5 to obtain the polycarboxylate superplasticizer mother liquor. The above-mentioned polyether macromonomer is vinyl polyethylene glycol ether; the acid anhydride is maleic anhydride; the initiator is azobisisobutyramidine hydrochloride; the chain transfer agent is mercaptopropionic acid; and the redox component is a mixture of hydrogen peroxide and ferric sulfate heptahydrate in a mass ratio of 5:1.

[0032] The preparation method of ternary phase change materials is as follows: Weigh out tetradecane, lauryl alcohol, and decanoic acid in a mass ratio of 6.0:3:1. Place the container in a 70°C constant temperature water bath, add lauryl alcohol, and slowly add tetradecane while stirring. After the tetradecane dissolves, slowly add the prepared decanoic acid dropwise using a dropper. Continue stirring in the water bath until all substances melt to form a homogeneous transparent liquid. Transfer the transparent liquid to an ultrasonic oscillator and vibrate for 15 minutes. While still hot, pour it into an aluminum crucible and cool and solidify at room temperature to obtain the ternary phase change material.

[0033] The preparation method of modified nano-titanium dioxide is as follows: Powdered nano-titanium dioxide was dried in a 100℃ oven for 1.5 hours to remove surface water. It was then ground in a ball mill at 200 rpm with a ball-to-particle ratio of 3:1 for 40 minutes to depolymerize it. Following this, it was heat-treated at 300℃ for 5 hours under nitrogen protection. The treated nano-titanium dioxide was dispersed in anhydrous ethanol and ultrasonically treated for 10 minutes at a frequency of 40 kHz and a power of 500 W. Then, under stirring at 300 rpm, 5% (by weight) of a silane coupling agent solution (by mass of the nano-titanium dioxide) was slowly added, and ultrasonic treatment continued for another 10 minutes. Finally, the treated nano-titanium dioxide was centrifuged at 7800 pm for 15 minutes, and 0.1% (by mass of the nano-titanium dioxide) of hydroxypropyl methylcellulose was added and mixed thoroughly to obtain modified nano-titanium dioxide. Example 3

[0034] The preparation method of polycarboxylate superplasticizer mother liquor is as follows: By weight, 60 parts of acrylic acid monomer, 20 parts of acid anhydride and 100 parts of water are mixed to prepare solution A; 2.0 parts of chain transfer agent, 3.0 parts of redox component and 100 parts of water are thoroughly mixed to prepare solution B; 8.0 parts of initiator are dissolved in 100 parts of water to prepare solution C; sodium hydroxide is added to water to prepare a 30% sodium hydroxide aqueous solution. Add 300 parts of water to a container, add the polyether macromonomer while stirring, and after it is completely dissolved, slowly add solution B. After stirring evenly, start adding solution A dropwise, and control the addition of solution A to be completed in 62 minutes. After adding solution A dropwise for 20 minutes, start adding solution C dropwise, and control the addition of solution C to be completed in 72 minutes. The initial temperature of the dropwise addition is 23°C. After the dropwise addition is completed, continue stirring and reacting for 100 minutes. After the stirring reaction is completed, add the sodium hydroxide aqueous solution to adjust the pH to 7 to obtain the polycarboxylate superplasticizer mother liquor. The above-mentioned polyether macromonomer is vinyl polyethylene glycol ether; the acid anhydride is phthalic anhydride; the initiator is azobisisobutyramidine hydrochloride; the chain transfer agent is mercaptopropionic acid; and the redox component is a mixture of hydrogen peroxide and cobalt sulfate heptahydrate in a mass ratio of 8:1.

[0035] The preparation method of ternary phase change materials is as follows: Weigh out tetradecane, lauryl alcohol, and decanoic acid in a mass ratio of 7.0:3.0:1. Place the container in an 80°C constant temperature water bath, add lauryl alcohol, and slowly add tetradecane while stirring. After the tetradecane dissolves, slowly add the prepared decanoic acid dropwise using a dropper. Continue stirring in the water bath until all substances melt to form a homogeneous transparent liquid. Transfer the transparent liquid to an ultrasonic oscillator and vibrate for 20 minutes. While still hot, pour it into an aluminum crucible and cool and solidify at room temperature to obtain the ternary phase change material.

[0036] The preparation method of modified nano-titanium dioxide is as follows: Powdered nano-titanium dioxide was dried in an oven at 110℃ for 0.5h to remove surface water. It was then ground for 20min using a ball mill at 300rpm and a ball-to-powder ratio of 7:1 to depolymerize it. Following this, it was heat-treated at 400℃ for 1h under nitrogen protection. The treated nano-titanium dioxide was dispersed in anhydrous ethanol and ultrasonically treated for 30min at a frequency of 20kHz and a power of 300W. Then, under stirring at 500rpm, 10% (by weight) of a silane coupling agent solution (by mass of the nano-titanium dioxide) was slowly added, and ultrasonic treatment continued for another 30min. Finally, the treated nano-titanium dioxide was centrifuged at 8200pm for 5min, and 0.3% (by mass of the nano-titanium dioxide) of hydroxypropyl methylcellulose was added and mixed thoroughly to obtain modified nano-titanium dioxide. Example 4

[0037] Preparation of nanocomposite phase change antifreeze water-reducing agent Raw material preparation: By weight, 7 parts of polycarboxylate superplasticizer mother liquor from Example 1; antifreeze components: 8 parts of ethylene glycol, 9 parts of calcium formate, 3 parts of sodium nitrite, 6 parts of methanol, 3 parts of sodium metasilicate, and 1.5 parts of sodium thiocyanate; functional components: 0.5 parts of air-entraining agent, obtained by mixing sodium dodecylbenzenesulfonate, oleanolic acid, and sodium rosinate in a mass ratio of 5.0:3.1:1.9; 7 parts of modified nano-titanium dioxide from Example 1; and 9 parts of ternary phase change material from Example 1; solvent: 40 parts of deionized water.

[0038] Preparation process: Take 40 parts of deionized water, add sodium metasilicate and stir to dissolve, add polycarboxylate superplasticizer mother liquor and stir evenly to obtain an aqueous phase; heat ethylene glycol, methanol, calcium formate, sodium nitrite, sodium thiocyanate and ternary phase change material to 80℃ to melt into an oil phase; under stirring, slowly add the oil phase to the aqueous phase over 30 minutes, slowly add modified nano titanium dioxide, and finally add air-entraining agent and stir evenly to obtain the finished product. Example 5

[0039] Preparation of nanocomposite phase change antifreeze water-reducing agent Raw material preparation: By weight, 5 parts of polycarboxylate superplasticizer mother liquor from Example 1; antifreeze components: 6 parts of ethylene glycol, 8 parts of calcium formate, 2 parts of sodium nitrite, 5 parts of methanol, 2 parts of sodium metasilicate, and 1 part of sodium thiocyanate; functional components: 0.3 parts of air-entraining agent, obtained by mixing sodium dodecylbenzenesulfonate, oleanolic acid, and sodium rosinate in a mass ratio of 5.0:3.1:1.9; 6 parts of modified nano-titanium dioxide from Example 1; and 8 parts of ternary phase change material from Example 1; solvent: 40 parts of deionized water.

[0040] Preparation process: Take 40 parts of deionized water, add sodium metasilicate and stir to dissolve, add polycarboxylate superplasticizer mother liquor and stir evenly to obtain an aqueous phase; heat ethylene glycol, methanol, calcium formate, sodium nitrite, sodium thiocyanate and ternary phase change material to 70℃ to melt into an oil phase; under stirring, slowly add the oil phase to the aqueous phase over 28 minutes, slowly add modified nano titanium dioxide, and finally add air-entraining agent and stir evenly to obtain the finished product. Example 6

[0041] Preparation of nanocomposite phase change antifreeze water-reducing agent Raw material preparation: By weight, 8 parts of polycarboxylate superplasticizer mother liquor from Example 1; antifreeze components: 10 parts of ethylene glycol, 10 parts of calcium formate, 4 parts of sodium nitrite, 8 parts of methanol, 5 parts of sodium metasilicate, and 2 parts of sodium thiocyanate; functional components: 0.6 parts of air-entraining agent, obtained by mixing sodium dodecylbenzenesulfonate, oleanolic acid, and sodium rosinate in a mass ratio of 5.0:3.1:1.9; 8 parts of modified nano-titanium dioxide from Example 1; and 10 parts of ternary phase change material from Example 1; solvent: 40 parts of deionized water.

[0042] Preparation process: Take 40 parts of deionized water, add sodium metasilicate and stir to dissolve, add polycarboxylate superplasticizer mother liquor and stir evenly to obtain an aqueous phase; heat ethylene glycol, methanol, calcium formate, sodium nitrite, sodium thiocyanate and ternary phase change material to 90℃ to melt into an oil phase; under stirring, slowly add the oil phase to the aqueous phase over 32 minutes, slowly add modified nano titanium dioxide, and finally add air-entraining agent and stir evenly to obtain the finished product.

[0043] Example 7: Concrete Performance Testing The nano-composite antifreeze water-reducing agent implemented in this invention was tested according to JC475-2004, and its concrete performance was tested at a temperature of -15℃. The experimental materials and formulations are as follows: Cement: P·O42.5 grade ordinary Portland cement; Aggregate: River sand, fineness modulus 2.8, crushed stone 5~20mm continuous gradation; Mix ratio: cement: sand: stone: water = 1:1.8:2.8:0.42; Admixtures: The nano-composite antifreeze water-reducing agent prepared in Example 4 of this invention, the commercially available ordinary water-reducing agent, and the commercially available antifreeze water-reducing agent are all added at a dosage of 2.5% of the total amount of cementitious materials.

[0044] The experimental results are shown in the table below: Table 1. Test results of admixture indicators at -15℃

[0045] As can be seen from the test data in Table 1, the water reduction rate of the nano-composite antifreeze water-reducing agent of this invention is as high as 36%, which is significantly higher than that of the comparative example. The product has good antifreeze effect, does not contain chloride ions or formaldehyde, and is almost free of alkali metal ions, making it very environmentally friendly. All test indicators meet the requirements of the first-class product of the building materials industry standard JC475-2004 "Concrete Antifreeze Agent" and also meet the requirements of the standard GB8076-2008 "Concrete Admixtures".

[0046] In terms of water reduction and enhancement: This is due to the "micro-aggregate effect" of modified nano titanium dioxide and the high dispersibility of water-reducing agent mother liquor, which makes the concrete more compact, develops its early strength rapidly, and can effectively resist low temperature freezing damage of -15℃.

[0047] Regarding antifreeze verification: In a -15℃ environment, Comparative Example 1, lacking antifreeze components, experienced rapid freezing of the concrete, resulting in almost zero strength. Comparative Example 2, while lowering the freezing point, lacked phase change energy storage, leading to insufficient internal temperature rise and low early strength. In Example 4, the ternary phase change material absorbed and stored heat under the action of cement hydration heat, releasing latent heat when the ambient temperature decreased, maintaining a positive temperature environment inside the concrete, ensuring the continuous progress of the hydration reaction, and thus maintaining later-stage strength.

[0048] Regarding freeze resistance and durability: The composite air-entraining agent introduced in Example 4 produces bubbles with small diameter, small spacing coefficient, and uniform distribution. As a "buffer valve," it effectively absorbs the expansion stress generated by freezing, making its freeze resistance level far exceed F300 and exhibiting excellent freeze resistance performance.

[0049] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A nanocomposite phase change deicing type water reducing agent, characterized by, It includes water and the following components in parts by weight: 5-8 parts polycarboxylate superplasticizer mother liquor, 6-10 parts ethylene glycol, 8-10 parts calcium formate, 2-4 parts sodium nitrite, 5-8 parts methanol, 2-5 parts sodium metasilicate, 1-2 parts sodium thiocyanate, 0.3-0.6 parts air-entraining agent, 6-8 parts modified nano titanium dioxide, and 8-10 parts ternary phase change material.

2. The nanocomposite phase change deicing type water reducing agent according to claim 1, characterized by: The polycarboxylate superplasticizer mother liquor comprises polyether macromonomers, acrylic acid monomers, acid anhydrides, initiators, redox components, chain transfer agents, sodium hydroxide, and water.

3. The nanocomposite phase change deicing type water reducing agent according to claim 1 or 2, characterized by: The polycarboxylate superplasticizer mother liquor, by weight, comprises 340-380 parts of polyether macromonomer, 40-60 parts of acrylic acid small monomer, 10-20 parts of acid anhydride, 6.0-8.0 parts of initiator, 2.0-3.0 parts of redox component, 1.5-2.0 parts of chain transfer agent, and 500-600 parts of water.

4. The nanocomposite phase change deicing type water reducing agent according to claim 3, characterized by: The redox component is a combination of hydrogen peroxide and ferric sulfate heptahydrate or cobalt sulfate heptahydrate, wherein the mass ratio of hydrogen peroxide to ferric sulfate heptahydrate or cobalt sulfate heptahydrate is 5-8:

1.

5. The nanocomposite phase change antifreeze water-reducing agent according to claim 1, characterized in that: The ternary phase change material is a composition of tetradecane, lauryl alcohol, and decanoic acid, with a mass ratio of tetradecane: lauryl alcohol: decanoic acid = 6-7: 2-3:

1.

6. The nanocomposite phase change antifreeze water-reducing agent according to claim 1, characterized in that: The air-entraining agent is a mixture of sodium dodecylbenzenesulfonate, oleanolic acid and sodium rosinate, with a mass ratio of sodium dodecylbenzenesulfonate:oleanolic acid:sodium rosinate = 5.0:3.1:1.

9.

7. A method for preparing a nanocomposite phase change antifreeze water-reducing agent according to any one of claims 1-6, characterized in that, The preparation steps are as follows: S1. Take 40 parts of water, add sodium metasilicate according to the mass ratio, stir until completely dissolved, then add polycarboxylate superplasticizer mother liquor, continue stirring until uniform, and obtain an aqueous solution; S2. Add ethylene glycol, methanol, calcium formate, sodium nitrite, sodium thiocyanate and ternary phase change material to another container, slowly heat to 70-90℃, and fully melt and mix to obtain an oil phase solution; S3. The aqueous solution is stirred at room temperature. While stirring, the oil phase solution is slowly dripped into the aqueous solution. The dripping is completed in 30±2 minutes. Stirring continues, and the modified nano-titanium dioxide is slowly added. After the liquid phase is stirred evenly, the air-entraining agent is added and fully mixed to obtain a nano-composite antifreeze water-reducing agent.

8. The preparation method of the nanocomposite phase change antifreeze water-reducing agent according to claim 7, characterized in that, The preparation method of the polycarboxylate superplasticizer mother liquor is as follows: Acrylic acid monomers, acid anhydrides, and a portion of water are mixed to prepare solution A; chain transfer agent, redox components, and a portion of water are thoroughly mixed to prepare solution B; initiator is dissolved in a portion of water to prepare solution C; sodium hydroxide is dissolved in water to prepare a 30% sodium hydroxide aqueous solution; the remaining water is added to a container, and the polyether macromonomer is added while stirring. After complete dissolution, solution B is slowly added, and after stirring evenly, solution A is added dropwise, controlling the addition of solution A to be completed in 60±2 minutes. After adding solution A for 10-20 minutes, solution C is added dropwise, controlling the addition of solution C to be completed in 70±2 minutes. The initial temperature of the dropwise addition is 17-23℃. After the dropwise addition is completed, the reaction is continuously stirred for 30-100 minutes. After the stirring reaction is completed, the sodium hydroxide aqueous solution is added to adjust the pH to 5-7, obtaining the polycarboxylate superplasticizer mother liquor.

9. The preparation method of the nanocomposite phase change antifreeze water-reducing agent according to claim 7, characterized in that, The preparation method of the ternary phase change material is as follows: Weigh out tetradecane, lauryl alcohol, and decanoic acid; place the container in a constant temperature water bath at 70-80℃, add lauryl alcohol, and slowly add tetradecane while stirring. After the tetradecane dissolves, slowly add the prepared decanoic acid dropwise using a dropper. Continue stirring in the water bath until all substances melt to form a homogeneous transparent liquid; transfer the transparent liquid into an ultrasonic oscillator and vibrate for 15-20 minutes. While still hot, pour it into an aluminum crucible and cool and solidify at room temperature to obtain the ternary phase change material.

10. The preparation method of the nanocomposite phase change antifreeze water-reducing agent according to claim 7, characterized in that, The preparation method of the modified nano-titanium dioxide is as follows: Powdered nano-titanium dioxide is dried in an oven at 100-110℃ for 0.5-1.5 hours to remove surface water. It is then ground in a ball mill at 200-300 rpm with a ball-to-particle ratio of 3-7:1 for 20-40 minutes to depolymerize it. Following this, it is heat-treated at 300-400℃ for 1-5 hours under nitrogen protection. The treated nano-titanium dioxide is dispersed in anhydrous ethanol and ultrasonically treated for 10-30 minutes at a frequency of 20-40 kHz and a power of 300-500 W. Then, under stirring at 300-500 rpm, 5-10% (by weight of the nano-titanium dioxide) of a silane coupling agent solution is slowly added, and ultrasonic treatment continues for another 10-30 minutes. Finally, the treated nano-titanium dioxide is centrifuged at 7800-8200 pm for 5-15 minutes, and 0.1-0.3% (by weight of the nano-titanium dioxide) of hydroxypropyl methylcellulose is added and mixed thoroughly to obtain modified nano-titanium dioxide.

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