Impermeable freeze-thaw-resistant concrete material and preparation method thereof

Abstract

The invention discloses an impervious freeze-thaw-resistant concrete material and a preparation method thereof, belongs to the technical field of concrete processing, and aims to solve the technical problem that the impervious performance and freeze-thaw resistance of a concrete material in the prior art need to be further improved. The phase-change concrete is prepared from the following raw materials in parts by weight: 80 to 100 parts of cement, 150 to 200 parts of aggregate, 5 to 15 parts of modified polyurethane emulsion, 3 to 10 parts of epoxy resin, 1 to 5 parts of modified phase-change capsules and 45 to 55 parts of auxiliary materials. According to the invention, silicon modified polyurethane emulsion is prepared, n-tetradecane is taken as a core material, melamine resin is taken as a wall material, modification is carried out through a silane coupling agent to obtain a modified phase change capsule, and the two modified materials are added into a concrete material to promote curing of epoxy resin, so that the impermeability and freeze-thaw resistance of the concrete material are improved, and the service life of the concrete material is prolonged. The mechanical property is also improved.

Description

Technical Field

[0001] This invention relates to the field of concrete processing technology, specifically to a waterproof and freeze-thaw resistant concrete material and its preparation method. Background Technology

[0002] As one of the most widely used building materials, concrete has attracted much attention for its durability in cold, humid or freeze-thaw environments, especially its impermeability and freeze-thaw resistance. Traditional concrete still has a large number of interconnected pores after the cement matrix hardens, which makes it easy to absorb water and suffer frost heave damage in low-temperature environments.

[0003] To address this issue, the industry often employs materials such as air-entraining agents, water-repellent agents, nanomaterials, polymer emulsions, and mineral admixtures to improve the density and water repellency of concrete, reduce its water absorption and capillary action, thereby enhancing its impermeability and freeze-thaw resistance.

[0004] In addition, some studies have attempted to regulate the pore structure and thermal response properties of concrete by incorporating functional additives such as rubber particles, cellulose, carbon nanotubes, and microcapsule materials, in order to improve its durability.

[0005] In the existing technology, the commonly used materials and modification methods still have certain shortcomings. In order to improve the freeze-thaw resistance and impermeability of concrete materials, polymer emulsions and microcapsule materials are often added during the preparation process. Although this method can reduce water absorption by capillaries, the poor interfacial bonding between these reinforcing materials and the cement matrix leads to a decrease in the structural mechanical properties of concrete materials. Furthermore, the added microcapsule materials are difficult to disperse and tend to agglomerate during the addition process, making it difficult to achieve the expected reinforcing effect.

[0006] Furthermore, most traditional methods only improve a single property and lack synergistic optimization in terms of impermeability and freeze resistance. Especially when facing frequent freeze-thaw cycles or microcrack development, they cannot effectively alleviate internal stress concentration and the formation of permeation channels. Therefore, a solution is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a concrete material that is impermeable and freeze-thaw resistant, and its preparation method, in order to solve the technical problem that the impermeability and freeze-thaw resistance of concrete materials in the prior art need to be further improved.

[0008] The objective of this invention can be achieved through the following technical solution: a concrete material that is impermeable and resistant to freeze-thaw cycles, comprising the following raw materials by weight: 80-100 parts cement, 150-200 parts aggregate, 5-15 parts modified polyurethane emulsion, 3-10 parts epoxy resin, 1-5 parts modified phase change capsules and 45-55 parts auxiliary materials.

[0009] Furthermore, the cement is silicate cement, and the aggregate is composed of coarse aggregate and fine aggregate in a mass ratio of 2-4:3-5, wherein the coarse aggregate is 5-20mm crushed stone, and the fine aggregate is 1-4mm quartz sand.

[0010] Furthermore, the auxiliary material is composed of a water-reducing agent, a curing agent, and deionized water in a mass ratio of 4-8:1-2:40-45, wherein the water-reducing agent is a polycarboxylate water-reducing agent and the curing agent is 4,4'-diaminodiphenylmethane.

[0011] Furthermore, the modified polyurethane emulsion is prepared by the following steps:

[0012] A1. Place polyethylene glycol and tetrahydrofuran in a reaction vessel and stir. Cool the reaction vessel to 0-5℃, add triethylamine, keep warm and stir for 5-10 min, slowly add dichlorodiphenylsilane solution according to the calculated amount, keep warm and react for 6-8 h, and then process to obtain intermediate I.

[0013] A2. Place intermediate I and tetrahydrofuran in a reaction vessel under nitrogen atmosphere and stir. Add hexamethylene diisocyanate according to the calculated amount. Heat the reaction vessel to 55-65℃ and keep it at this temperature for 4-6 hours. After post-treatment, obtain the modified polyurethane emulsion.

[0014] The preparation reaction formula for modified polyurethane emulsion is as follows:

[0015]

[0016] In the formula:

[0017] The preparation reaction principle of modified polyurethane emulsion is as follows:

[0018] During the reaction, the hydroxyl groups of polyethylene glycol undergo a condensation reaction with dichlorodiphenylsilane, releasing HCl. Triethylamine is added as an acid scavenger, ultimately forming intermediate I with O-Si-O bonds. Further, after adding hexamethylene diisocyanate, the terminal hydroxyl groups of intermediate I undergo an addition reaction with the isocyanate groups of hexamethylene diisocyanate to form urethane bonds. Post-treatment yields a modified polyurethane emulsion.

[0019] Further, in step A1, the ratio of polyethylene glycol, tetrahydrofuran, and triethylamine is 5-10 g: 50-70 mL: 6-8 mL, and the amount of dichlorodiphenylsilane solution added is 0.45 times the molar amount of the hydroxyl groups in polyethylene glycol. The dichlorodiphenylsilane solution is composed of dichlorodiphenylsilane and tetrahydrofuran in a ratio of 4-6 g: 50-70 mL. The post-treatment step includes: after the reaction is completed, the reaction system is allowed to cool to room temperature, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 80-90°C. Rotary evaporation is performed until no liquid is collected to obtain intermediate I; in step A2, the ratio of intermediate I to tetrahydrofuran is 8-10g:100-120mL, and the amount of hexamethylene diisocyanate added is 0.45 times the molar amount of hydroxyl groups in intermediate I. The post-processing steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 80-90℃, rotary evaporated until no liquid is collected, 50-70mL of deionized water is added, and the mixture is mixed evenly to obtain the modified polyurethane emulsion.

[0020] Furthermore, the modified phase change capsule is prepared by: placing the phase change capsule, ethanol, deionized water and γ-aminopropyltriethoxysilane in a reaction vessel and stirring, adding an ammonia solution, heating the reaction vessel to 45-55℃, maintaining the temperature for 2-4 hours, and then processing to obtain the modified phase change capsule.

[0021] The reaction principle for preparing modified phase change capsules is as follows:

[0022] During the reaction, under alkaline and heating conditions, γ-aminopropyltriethoxysilane hydrolyzes into silanol, which further undergoes a condensation reaction with the hydroxyl groups on the surface of the phase change capsule to obtain a modified phase change capsule modified with a silane coupling agent.

[0023] Furthermore, the ratio of the phase change capsules, ethanol, deionized water, γ-aminopropyltriethoxysilane, and ammonia solution is 2-4g:50-70mL:5-10mL:0.5-1g:1-2mL, and the concentration of the ammonia solution is 50-70wt%. The post-processing steps include: after the reaction is completed, the reaction is allowed to cool to room temperature, filtered, the filter cake is washed 2-4 times with deionized water and ethanol, transferred to an oven at 30-40℃, and dried for 4-6 hours to obtain modified phase change microcapsules.

[0024] Furthermore, the phase change capsule is prepared by the following steps:

[0025] B1. Place n-tetradecane, deionized water and nanocellulose in a single-necked flask and sonicate for 2-5 minutes to obtain a mixture.

[0026] B2. Place formaldehyde aqueous solution and melamine in a reaction vessel and stir. Heat the reaction vessel to 65-75℃, add nano alumina, keep the reaction at this temperature for 0.5-1h, add triethanolamine, adjust the pH to 8-9, and obtain the prepolymer solution.

[0027] The reaction principle for preparing the prepolymer solution is as follows:

[0028] Under heating conditions, melamine and formaldehyde undergo a condensation reaction to produce hydroxymethyl melamine. Nano-alumina is used as a reinforcing material, and the addition of triethanolamine to adjust the pH to 8-9 can terminate the condensation reaction, ultimately yielding a prepolymer solution.

[0029] B3. Place the mixture in a reaction vessel and stir. Add the prepolymer solution dropwise. Heat the reaction vessel to 75-85℃ and keep it at that temperature for 2-4 hours. Then, perform post-processing to obtain phase change capsules.

[0030] The reaction principle for the preparation of phase change capsules is as follows:

[0031] During the reaction, under the emulsification of nanocellulose, molten n-tetradecane is emulsified in the aqueous phase and ultrasonically broken to form a stable oil-in-water mixture. Under conditions of 75-85℃, the prepolymer in the prepolymer solution undergoes further condensation and polymerizes and deposits on the surface of the emulsion droplets. The polymerization reaction occurs along the surface of the emulsion droplets, gradually forming a shell to obtain a phase change capsule.

[0032] Further, in step B1, the ratio of n-tetradecane, deionized water, and nanocellulose is 2-4g:20-40mL:0.1-0.2g; in step B2, the ratio of formaldehyde aqueous solution, melamine, and nanoalumina is 15-20mL:1-2g:0.1-0.2g, and the concentration of formaldehyde aqueous solution is 35-40wt%; in step B3, the volume ratio of the mixture to the prepolymer solution is 4-6:10-12, the dropping rate of the dropping operation is 3-6s / drop, and the post-processing steps include: after the reaction is completed, wait for the reaction to cool to room temperature, filter, wash the filter cake with deionized water and ethanol 2-4 times, transfer it to an oven at 30-40℃, and dry it for 4-6 hours to obtain phase change capsules.

[0033] This invention also proposes a method for preparing a water-resistant and freeze-thaw resistant concrete material, comprising the following steps:

[0034] S1. Add cement and aggregate to the mixer and mix for 1-2 minutes. Add modified polyurethane emulsion, epoxy resin and auxiliary materials and mix for 1-3 minutes to obtain mixed slurry.

[0035] S2. Mix the mixed mud and modified phase change capsules evenly to obtain concrete material.

[0036] The reaction principle for the preparation of concrete materials is as follows:

[0037] During the reaction, cement and aggregates are fully dispersed under mechanical stirring. Modified polyurethane emulsion, epoxy resin and additives are added. The hydroxyl groups in the modified polyurethane emulsion can enhance the adhesion with cement hydration products through hydrogen bonding and complexation. Together with the curing agent in the additives and the amino groups on the surface of the modified phase change capsules, they participate in the curing of epoxy resin to form a three-dimensional network cross-linked structure, thus obtaining concrete material.

[0038] The present invention has the following beneficial effects:

[0039] 1. This invention involves preparing a silicon-modified polyurethane emulsion and adding it to concrete materials. The organosilicon segments in the modified polyurethane emulsion have excellent hydrophobicity, which can form a dense hydrophobic film in the capillary pores of the hardened cement, effectively blocking the water penetration path and significantly improving the impermeability of the concrete material. At the same time, its polyurethane backbone can also form hydrogen bonds or physically fill with cement hydration products, further reinforcing the pore walls and improving the mechanical properties of the concrete material. The flexible polyethylene glycol segments in the polyurethane have the ability to buffer micro-stress, which can reduce the damage caused by ice expansion stress in concrete materials during freeze-thaw cycles. The O-Si-O structure itself has good cold resistance and stability, which can improve the crack resistance of concrete materials in low-temperature environments, thereby improving the freeze-thaw resistance of concrete.

[0040] 2. This invention prepares a phase change capsule using n-tetradecane as the core material and melamine resin as the wall material. By modifying the capsule with a silane coupling agent, amino groups are introduced, resulting in a modified phase change capsule. The n-tetradecane core material possesses high latent heat storage capacity, delaying the freezing process of pore water in low-temperature environments by releasing latent heat, thus reducing the freezing rate and ice expansion stress inside the concrete and effectively mitigating the propagation of microcracks caused by freeze-thaw cycles. Furthermore, the high-strength capsule wall layer constructed from melamine resin, nano-alumina, and nano-cellulose... This process ensures that the capsule remains stable and resistant to breakage in alkaline cement-based environments and freeze-thaw cycles, thus providing long-term buffering and temperature regulation. Further modification with γ-aminopropyltriethoxysilane introduces amino and silane groups onto the capsule surface, enabling chemical bonding with epoxy resin and cement hydration products. This enhances the interfacial adhesion between the capsule and the matrix, preventing interfacial delamination caused by freeze-thaw stress. Simultaneously, the capsule is evenly distributed in the concrete and partially fills pores, improving overall density, reducing water penetration and the content of freezeable water, and enhancing the freeze-thaw resistance of the concrete material.

[0041] 3. In the preparation of modified phase change capsules, this invention incorporates nano-alumina as an inorganic reinforcing material for the capsule wall layer. Nano-alumina possesses a high specific surface area and excellent mechanical properties, enabling it to form a stable three-dimensional network structure with melamine resin. This significantly improves the mechanical strength and crack resistance of the modified phase change capsules, ensuring their structural stability in alkaline cement systems and freeze-thaw environments. Furthermore, the surface of nano-alumina is rich in hydroxyl groups, exhibiting good chemical activity. It can undergo interfacial reactions with γ-aminopropyltriethoxysilane, further promoting the interfacial bonding between the modified phase change capsules and epoxy resin and cement hydration products. This enhances the crack resistance and freeze-thaw resistance of concrete materials. In addition, nano-alumina acts as a micro-filler and nucleator in the concrete system, helping to fill pores, promote cement hydration reactions, increase the density and strength of the matrix, and improve the mechanical properties of concrete materials. Detailed Implementation

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0043] The silicate cement used in this invention is white in color, has a service temperature of -30 to 156°C, is grade one, and has a content of 100%.

[0044] The crushed stone used in this invention has a specific gravity of 1.7, a porosity of 5.2%, a size of 5-20mm, and a mud content of 0.01%.

[0045] The quartz sand used in this invention has a size of 1-4mm, a hardness of 7.5, and a porosity of 56%.

[0046] The polycarboxylate superplasticizer used in this invention has a solid content of 65%, a pH of 9.2, and a moisture content of 2.45%.

[0047] The polyethylene glycol used in this invention has a molecular weight of 400, a density of 1.128 g / mL, and an effective ingredient content of 99%.

[0048] The epoxy resin used in this invention has a viscosity of 11000-15000 mPas, a softening point of 65-85℃, an epoxy equivalent of 185-186.6 g / eq, and is of type E44.

[0049] Example 1

[0050] This embodiment provides a method for preparing a modified polyurethane emulsion for impermeable and freeze-thaw resistant concrete materials, comprising the following steps:

[0051] Step I: Preparation of intermediate I

[0052] Dichlorodiphenylsilane and tetrahydrofuran were mixed evenly at a ratio of 40g:500mL to obtain a dichlorodiphenylsilane solution for later use.

[0053] Weigh out 50g of polyethylene glycol and 500mL of tetrahydrofuran and place them in a reaction vessel and stir. Cool the reaction vessel to 0℃, add 60mL of triethylamine, keep warm and stir for 5min, and slowly add dichlorodiphenylsilane solution dropwise at 0.45 times the molar amount of hydroxyl groups of polyethylene glycol. Keep the reaction at 6h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, and transfer the filtrate to a rotary evaporator at 80℃. Evaporate until no liquid is collected to obtain intermediate I.

[0054] Step II: Preparation of modified polyurethane emulsion

[0055] Weigh 80g of intermediate I and 1000mL of tetrahydrofuran and place them in a reaction vessel under nitrogen atmosphere and stir. Add hexamethylene diisocyanate at 0.45 times the molar amount of hydroxyl group in intermediate I. Heat the reaction vessel to 55℃ and keep it at that temperature for 4 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, and transfer the filtrate to a rotary evaporator at 80℃. Evaporate until no liquid is collected, add 500mL of deionized water, mix well, and obtain the modified polyurethane emulsion.

[0056] Example 2

[0057] This embodiment provides a method for preparing a modified polyurethane emulsion for impermeable and freeze-thaw resistant concrete materials, comprising the following steps:

[0058] Step I: Preparation of intermediate I

[0059] Dichlorodiphenylsilane and tetrahydrofuran were mixed evenly at a ratio of 50g:60mL to obtain a dichlorodiphenylsilane solution for later use.

[0060] Weigh out 75g of polyethylene glycol and 600mL of tetrahydrofuran and place them in a reaction vessel and stir. Cool the reaction vessel to 3℃, add 70mL of triethylamine, keep warm and stir for 7min, and slowly add dichlorodiphenylsilane solution dropwise at 0.45 times the molar amount of hydroxyl groups of polyethylene glycol. Keep the reaction at the temperature for 7h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, and transfer the filtrate to a rotary evaporator at 85℃. Evaporate until no liquid is collected to obtain intermediate I.

[0061] Step II: Preparation of modified polyurethane emulsion

[0062] Weigh 90g of intermediate I and 1100mL of tetrahydrofuran and place them in a reaction vessel under nitrogen atmosphere and stir. Add hexamethylene diisocyanate at 0.45 times the molar amount of hydroxyl group in intermediate I. Heat the reaction vessel to 60℃ and keep it at that temperature for 5h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, and transfer the filtrate to a rotary evaporator at 85℃. Evaporate until no liquid is collected, add 600mL of deionized water, mix well, and obtain the modified polyurethane emulsion.

[0063] Example 3

[0064] This embodiment provides a method for preparing a modified polyurethane emulsion for impermeable and freeze-thaw resistant concrete materials, comprising the following steps:

[0065] Step I: Preparation of intermediate I

[0066] Dichlorodiphenylsilane and tetrahydrofuran were mixed evenly at a ratio of 60g:700mL to obtain a dichlorodiphenylsilane solution for later use.

[0067] Weigh out 100g of polyethylene glycol and 700mL of tetrahydrofuran and place them in a reaction vessel and stir. Cool the reaction vessel to 5℃, add 80mL of triethylamine, keep warm and stir for 10min, and slowly add dichlorodiphenylsilane solution dropwise at 0.45 times the molar amount of hydroxyl groups in polyethylene glycol. Keep the reaction at the temperature for 8h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter, and transfer the filtrate to a rotary evaporator at 90℃. Evaporate until no liquid is collected to obtain intermediate I.

[0068] Step II: Preparation of modified polyurethane emulsion

[0069] Weigh 100g of intermediate I and 1200mL of tetrahydrofuran and place them in a reaction vessel under nitrogen atmosphere and stir. Add hexamethylene diisocyanate at 0.45 times the molar amount of hydroxyl group in intermediate I. Heat the reaction vessel to 65℃ and keep it at that temperature for 6 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, and transfer the filtrate to a rotary evaporator at 90℃. Evaporate until no liquid is collected, add 700mL of deionized water, mix well, and obtain the modified polyurethane emulsion.

[0070] Example 4

[0071] This embodiment provides a method for preparing modified phase change capsules for impermeable and freeze-thaw resistant concrete materials, including the following steps:

[0072] Step ①: Prepare the mixture

[0073] Weigh out 20g of n-tetradecane, 200mL of deionized water and 1g of nanocellulose and place them in a single-necked bottle. Sonicate for 2 minutes to obtain a mixture.

[0074] Step 2: Preparation of prepolymer solution

[0075] Weigh out 150 mL of 35 wt% formaldehyde aqueous solution and 10 g of melamine and place them in a reaction vessel and stir. Heat the reaction vessel to 65 ℃, add 1 g of nano alumina, keep the reaction at this temperature for 0.5 h, add triethanolamine, and adjust the pH to 8 to obtain a prepolymer solution.

[0076] Step 3: Preparation of phase change capsules

[0077] Weigh 40 mL of the mixture and place it in a reaction vessel and stir. Add 100 mL of the prepolymer solution dropwise at a rate of 3 drops / second. Heat the reaction vessel to 75°C and keep it at that temperature for 2 hours. After the reaction is complete, wait for the reaction to cool to room temperature, filter the mixture, wash the filter cake twice with deionized water and ethanol, transfer it to an oven at 30°C, and dry it for 5 hours to obtain phase change capsules.

[0078] Step 4: Preparation of modified phase change capsules

[0079] Weigh out 20g of phase change capsules, 500mL of ethanol, 50mL of deionized water and 5g of γ-aminopropyltriethoxysilane and place them in a reaction vessel and stir. Add 10mL of 50wt% ammonia solution and heat the reaction vessel to 45℃. Keep the temperature for 2h. After the reaction is complete, wait for the reaction to cool to room temperature, filter, wash the filter cake twice with deionized water and ethanol, transfer it to an oven at 30℃ and dry for 4h to obtain modified phase change capsules.

[0080] Example 5

[0081] This embodiment provides a method for preparing modified phase change capsules for impermeable and freeze-thaw resistant concrete materials, including the following steps:

[0082] Step ①: Prepare the mixture

[0083] Weigh out 30g of n-tetradecane, 300mL of deionized water and 1.5g of nanocellulose and place them in a single-necked bottle. Sonicate for 3 minutes to obtain a mixture.

[0084] Step 2: Preparation of prepolymer solution

[0085] Weigh out 170 mL of 37 wt% formaldehyde aqueous solution and 15 g of melamine and place them in a reaction vessel and stir. Heat the reaction vessel to 70 °C, add 1.5 g of nano alumina, keep the reaction at this temperature for 1 h, add triethanolamine, and adjust the pH to 8.5 to obtain a prepolymer solution.

[0086] Step 3: Preparation of phase change capsules

[0087] Weigh 50 mL of the mixture and place it in a reaction vessel and stir. Add 110 mL of the prepolymer solution dropwise at a rate of 5 S / drop. Heat the reaction vessel to 80 °C and keep it at that temperature for 3 h. After the reaction is complete, wait for the reaction to cool to room temperature, filter the mixture, wash the filter cake three times with deionized water and ethanol, transfer it to an oven at 35 °C and dry it for 5 h to obtain phase change capsules.

[0088] Step 4: Preparation of modified phase change capsules

[0089] Weigh out 30g of phase change capsules, 600mL of ethanol, 700mL of deionized water and 7g of γ-aminopropyltriethoxysilane and place them in a reaction vessel and stir. Add 15mL of 60wt% ammonia solution and heat the reaction vessel to 50℃. Keep the temperature for 3h. After the reaction is complete, wait for the reaction to cool to room temperature, filter, wash the filter cake three times with deionized water and ethanol, transfer it to an oven at 35℃ and dry for 5h to obtain modified phase change capsules.

[0090] Example 6

[0091] This embodiment provides a method for preparing modified phase change capsules for impermeable and freeze-thaw resistant concrete materials, including the following steps:

[0092] Step ①: Prepare the mixture

[0093] Weigh out 40g of n-tetradecane, 400mL of deionized water and 2g of nanocellulose and place them in a single-necked bottle. Sonicate for 5 minutes to obtain a mixture.

[0094] Step 2: Preparation of prepolymer solution

[0095] Weigh 200 mL of 40 wt% formaldehyde aqueous solution and 20 g of melamine and place them in a reaction vessel and stir. Heat the reaction vessel to 75 ℃, add 2 g of nano alumina, keep the reaction at this temperature for 1 h, add triethanolamine, adjust the pH to 9, and obtain the prepolymer solution.

[0096] Step 3: Preparation of phase change capsules

[0097] Weigh 60 mL of the mixture and place it in a reaction vessel and stir. Add 120 mL of the prepolymer solution dropwise at a rate of 6 S / drop. Heat the reaction vessel to 85 °C and keep it at that temperature for 4 h. After the reaction is complete, wait for the reaction to cool to room temperature, filter the mixture, wash the filter cake four times with deionized water and ethanol, transfer it to an oven at 40 °C and dry it for 6 h to obtain phase change capsules.

[0098] Step 4: Preparation of modified phase change capsules

[0099] Weigh out 40g of phase change capsules, 700mL of ethanol, 100mL of deionized water and 10g of γ-aminopropyltriethoxysilane and place them in a reaction vessel and stir. Add 20mL of 70wt% ammonia solution and heat the reaction vessel to 55℃. Keep the temperature for 4h. After the reaction is complete, wait for the reaction to cool to room temperature, filter, wash the filter cake 4 times with deionized water and ethanol, transfer it to an oven at 40℃ and dry for 6h to obtain modified phase change capsules.

[0100] Example 7

[0101] This embodiment provides a method for preparing a water-resistant and freeze-thaw resistant concrete material, including the following steps:

[0102] Mix 5mm crushed stone and 1mm quartz sand evenly to obtain aggregate;

[0103] Polycarboxylate superplasticizer, 4,4'-diaminodiphenylmethane and deionized water were mixed evenly at a mass ratio of 4:1:40 to obtain the auxiliary material.

[0104] Weigh out the following by weight: Add 80 parts of cement and 150 parts of aggregate to a mixer and stir for 1 minute. Add 5 parts of the modified polyurethane emulsion prepared in Example 1, 3 parts of epoxy resin and 45 parts of auxiliary materials and stir for 1 minute. Add 1 part of the modified phase change capsule prepared in Example 4 and mix evenly to obtain concrete material.

[0105] Example 8

[0106] This embodiment provides a method for preparing a water-resistant and freeze-thaw resistant concrete material, including the following steps:

[0107] Mix 10mm crushed stone and 2mm quartz sand evenly to obtain aggregate;

[0108] Polycarboxylate superplasticizer, 4,4'-diaminodiphenylmethane and deionized water were mixed evenly at a mass ratio of 6:1.5:42 to obtain the auxiliary material;

[0109] Weigh out the following parts by weight: Add 90 parts of cement and 170 parts of aggregate to a mixer and mix for 1.5 minutes. Add 10 parts of the modified polyurethane emulsion prepared in Example 2, 6 parts of epoxy resin and 50 parts of auxiliary materials, and mix for 2 minutes. Add 3 parts of the modified phase change capsule prepared in Example 5 and mix evenly to obtain concrete material.

[0110] Example 9

[0111] This embodiment provides a method for preparing a water-resistant and freeze-thaw resistant concrete material, including the following steps:

[0112] Mix 20mm crushed stone and 4mm quartz sand evenly to obtain aggregate;

[0113] Polycarboxylate superplasticizer, 4,4'-diaminodiphenylmethane and deionized water were mixed evenly at a mass ratio of 8:2:45 to obtain the auxiliary material.

[0114] Weigh out the following parts by weight: Add 100 parts of cement and 200 parts of aggregate to a mixer and stir for 2 minutes. Add 15 parts of the modified polyurethane emulsion prepared in Example 3, 10 parts of epoxy resin and 55 parts of auxiliary materials and stir for 3 minutes. Add 5 parts of the modified phase change capsule prepared in Example 6 and mix evenly to obtain concrete material.

[0115] Comparative Example 1

[0116] The difference between this comparative example and Example 9 is that the modified polyurethane emulsion was omitted when preparing the concrete material.

[0117] Comparative Example 2

[0118] The difference between this comparative example and Example 9 is that, in step ② when preparing the prepolymer solution, the addition of nano-alumina is omitted.

[0119] Comparative Example 3

[0120] The difference between this comparative example and Example 9 is that, in the preparation of concrete materials, phase change capsules are used in an equal amount instead of modified phase change capsules.

[0121] Performance testing:

[0122] Concrete specimens were made from the concrete materials prepared in Examples 7-9 and Comparative Examples 1-3 in accordance with the standard GB / T 50082-2024 "Standard for Test Methods of Long-Term Performance and Durability of Concrete".

[0123] The impermeability of concrete specimens prepared in Examples 7-9 and Comparative Examples 1-3 and the strength loss rate of concrete specimens after 50 cycles of slow freezing test were tested in accordance with the standard GB / T 50082-2024 "Standard for Test Methods of Long-term Performance and Durability of Concrete".

[0124] The splitting tensile strength and flexural strength of the concrete specimens prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The specific data are shown in Table 1.

[0125] Table 1 - Performance Test Data for Each Sample

[0126]

[0127]

[0128] Data Analysis:

[0129] Comparative analysis of the data in Table 1 reveals that the concrete specimens prepared in this invention exhibit a permeability grade of P10, a strength loss rate of 5.2%, a splitting tensile strength of 3.9 MPa, and a flexural strength of 8.1 MPa after curing. All these data are superior to those of the comparative example. This invention involves preparing a silicone-modified polyurethane emulsion, using n-tetradecane as the core material and melamine resin as the wall material to prepare a phase change capsule. By modifying the capsule with a silane coupling agent, amino groups are introduced, resulting in a modified phase change capsule. Adding these two modifying materials to the concrete material promotes the curing of the epoxy resin, thereby improving not only the permeability and freeze-thaw resistance of the concrete material but also its mechanical properties.

[0130] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A concrete material that is impermeable and resistant to freeze-thaw cycles, characterized in that, It includes the following raw materials by weight: 80-100 parts cement, 150-200 parts aggregate, 5-15 parts modified polyurethane emulsion, 3-10 parts epoxy resin, 1-5 parts modified phase change capsules and 45-55 parts auxiliary materials. The cement is silicate cement, and the aggregate is composed of coarse aggregate and fine aggregate in a mass ratio of 2-4:3-5, wherein the coarse aggregate is 5-20mm crushed stone and the fine aggregate is 1-4mm quartz sand. The auxiliary material is composed of water-reducing agent, curing agent and deionized water in a mass ratio of 4-8:1-2:40-45, wherein the water-reducing agent is a polycarboxylate water-reducing agent and the curing agent is 4,4'-diaminodiphenylmethane.

2. The impermeable and freeze-thaw resistant concrete material according to claim 1, characterized in that, The modified polyurethane emulsion is prepared by the following steps: A1. Place polyethylene glycol and tetrahydrofuran in a reaction vessel and stir. Cool the reaction vessel to 0-5℃, add triethylamine, keep warm and stir for 5-10 min, slowly add dichlorodiphenylsilane solution according to the calculated amount, keep warm and react for 6-8 h, and then process to obtain intermediate I. A2. Place intermediate I and tetrahydrofuran in a reaction vessel under nitrogen atmosphere and stir. Add hexamethylene diisocyanate according to the calculated amount. Heat the reaction vessel to 55-65℃ and keep it at this temperature for 4-6 hours. After post-treatment, obtain the modified polyurethane emulsion.

3. The impermeable and freeze-thaw resistant concrete material according to claim 2, characterized in that, In step A1, the ratio of polyethylene glycol, tetrahydrofuran, and triethylamine is 5-10g:50-70mL:6-8mL, and the amount of dichlorodiphenylsilane solution added is 0.45 times the molar amount of the hydroxyl group in polyethylene glycol. The dichlorodiphenylsilane solution is composed of dichlorodiphenylsilane and tetrahydrofuran in a ratio of 4-6g:50-70mL. In step A2, the ratio of intermediate I and tetrahydrofuran is 8-10g:100-120mL, and the amount of hexamethylene diisocyanate added is 0.45 times the molar amount of the hydroxyl group in intermediate I.

4. The impermeable and freeze-thaw resistant concrete material according to claim 1, characterized in that, The modified phase change capsule is prepared by placing phase change capsules, ethanol, deionized water and γ-aminopropyltriethoxysilane in a reaction vessel and stirring, adding ammonia solution, heating the reaction vessel to 45-55℃, keeping it at that temperature for 2-4 hours, and then processing it to obtain the modified phase change capsule.

5. The impermeable and freeze-thaw resistant concrete material according to claim 4, characterized in that, The ratio of the phase change capsule, ethanol, deionized water, γ-aminopropyltriethoxysilane, and ammonia solution is 2-4g:50-70mL:5-10mL:0.5-1g:1-2mL, and the concentration of the ammonia solution is 50-70wt%.

6. The impermeable and freeze-thaw resistant concrete material according to claim 4, characterized in that, The phase change capsule is prepared by the following steps: B1. Place n-tetradecane, deionized water and nanocellulose in a single-necked flask and sonicate for 2-5 minutes to obtain a mixture. B2. Place formaldehyde aqueous solution and melamine in a reaction vessel and stir. Heat the reaction vessel to 65-75℃, add nano alumina, keep the reaction at this temperature for 0.5-1h, add triethanolamine, adjust the pH to 8-9, and obtain the prepolymer solution. B3. Place the mixture in a reaction vessel and stir. Add the prepolymer solution dropwise. Heat the reaction vessel to 75-85℃ and keep it at that temperature for 2-4 hours. Then, perform post-processing to obtain phase change capsules.

7. A water-resistant and freeze-thaw resistant concrete material according to claim 6, characterized in that, In step B1, the ratio of the amount of n-tetradecane, deionized water, and nanocellulose is 2-4g:20-40mL:0.1-0.2g; in step B2, the ratio of the amount of formaldehyde aqueous solution, melamine, and nano-alumina is 15-20mL:1-2g:0.1-0.2g, and the concentration of the formaldehyde aqueous solution is 35-40wt%; in step B3, the volume ratio of the mixture to the prepolymer solution is 4-6:10-12, and the dropping rate of the dropping operation is 3-6s / drop.

8. A method for preparing a concrete material with impermeability and freeze-thaw resistance as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Add cement and aggregate to the mixer and mix for 1-2 minutes. Add modified polyurethane emulsion, epoxy resin and auxiliary materials and mix for 1-3 minutes to obtain mixed slurry. S2. Mix the mixed mud and modified phase change capsules evenly to obtain concrete material.

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