Freeze-thaw damage self-repairing foam concrete material and preparation method thereof

Abstract

The invention discloses a freeze-thaw damage self-repairing foam concrete material and a preparation method thereof, and relates to the technical field of building materials. The fly ash with high hydration activity can induce in-situ self-repairing of original defects of the cement stone microstructure. The concrete initiates microcracks under initial freezing and thawing, the proper humidity in the concrete is maintained by adding the fly ash, initiating hydration and adding the water-absorbent resin material, and the cracks are sealed by generated hydration products, so that the compactness of the concrete is recovered. The water-absorbent resin material can continuously absorb and release water in a freeze-thaw cycle, and the process can be triggered circularly, so that the self-repair of multiple freeze-thaw damages is realized. The carboxymethyl cellulose is used for preparing the water-absorbent resin, and the carboxymethyl cellulose has good water absorbability, so that the water absorbability of the water-absorbent resin is improved. Calcium carbonate is added into the water-absorbent resin to form a cross-linked network, so that the stability in the concrete is improved.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to a freeze-thaw damage self-repairing foam concrete material and a preparation method thereof. Background Art

[0002] Foamed concrete is widely used in transportation projects such as roadbed filling and in construction due to its thermal insulation, lightweight, and soundproofing properties. However, its porous structure is susceptible to severe damage from freeze-thaw cycles: open pores allow for rapid water intrusion, and ice expansion triggers internal stress concentration, leading to the gradual propagation of microcracks and a decrease in the material's frost resistance, thus limiting its widespread application in cold regions.

[0003] Concrete self-repair technology repairs cracks through cement hydration reaction or reaction with hydration products under crack-inducing conditions. It is low-cost, but the technology is limited by its poor environmental adaptability.

[0004] In order to solve the above problems and improve the self-repairing ability of concrete freeze-thaw damage, the present invention provides a freeze-thaw damage self-repairing foam concrete material and a preparation method thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a freeze-thaw damage self-repairing foam concrete material and a preparation method thereof, so as to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions: A method for preparing a freeze-thaw damage self-repairing foam concrete material comprises the following steps: S1: Take a foaming agent of sodium lauryl sulfate, γ-aminopropyltriethoxysilane, and deionized water, stir them evenly, and use a foaming machine to foam to obtain foam; S2: Take a composite material of Portland cement, fly ash, and a water-absorbing resin, stir for 1-2 minutes to obtain a powder; dissolve a polycarboxylate water-reducing agent in deionized water, then add the mixture to the powder and stir evenly to obtain a cement mixture; S3: adding foam to the cement mixture and stirring for 1-2 minutes to obtain foamed concrete; grouting and forming, curing, demoulding, and continuing curing for 28-30 days to obtain freeze-thaw damage self-repairing foamed concrete material.

[0007] More optimally, the foam concrete material includes the following substances, calculated by weight: 40-55 parts of Portland cement, 10-25 parts of fly ash, 5-8 parts of water-absorbing resin composite material, 0.06-0.12 parts of polycarboxylate water reducer, 10-15 parts of deionized water, and 35-50 parts of foam.

[0008] More optimally, the preparation method of the water-absorbing resin composite material comprises the following steps: Step 1: Take granular material and modified xanthan gum, mix them evenly, add fine sand, mix for 15-20 seconds, sieve and solidify to obtain granular material coated with fine sand; Step 2: Take epoxy resin and deionized water, stir them evenly, add particles coated with fine sand, mix them evenly, and dry them to obtain a water-absorbing resin composite material.

[0009] More optimally, the preparation method of the granules is: take calcium carbonate, calcium acetate, and water-absorbing resin, heat to 40-45°C, stir for 30-35s, add to polyethylene glycol at 40-42°C, stir for 2-3min, cool to 31-33°C, extrude, granulate, and obtain granules.

[0010] More optimally, the preparation method of the modified xanthan gum is: take xanthan gum and deionized water, stir evenly, add 2-acrylamide-2-methylpropanesulfonic acid, pass nitrogen, heat to 55-58°C, add ammonium cerium nitrate, potassium persulfate, and sodium bisulfite, react for 3-4 hours, and obtain modified xanthan gum.

[0011] More optimally, the preparation method of the water-absorbing resin is as follows: taking carboxymethyl cellulose and deionized water, heating to 75-80°C, and stirring for 30-40 minutes to obtain a carboxymethyl cellulose solution; taking sodium hydroxide and deionized water, stirring evenly to obtain a sodium hydroxide solution; taking N,N-methylenebisacrylamide, potassium persulfate, and deionized water, stirring evenly to obtain a mixed solution; in an ice-water bath, adding the sodium hydroxide solution dropwise to acrylic acid, stirring evenly, adding the carboxymethyl cellulose solution and urea, stirring for 20-30 minutes, adding the mixed solution, stirring for 10-15 minutes, heating to 75-77°C, reacting for 3-3.5 hours, filtering, washing, and drying to obtain the water-absorbing resin.

[0012] More optimally, in S2, the polycarboxylate water reducer is dissolved in deionized water, then added to the powder, stirred at 50-100 r / min for 30-35 s, and then stirred at 80-150 r / min for 60-65 min to obtain a cement mixture.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. Fly ash with high hydration activity can induce in-situ self-repair of native defects in the microstructure of cement stone. At the same time, the internal curing effect of the water-absorbing resin material can adjust the internal humidity by absorbing and releasing water, creating a good hydration environment for the later hydration of fly ash, including sufficient water and calcium hydroxide. Concrete induces microcracks under the initial freeze-thaw cycle. The present invention adds fly ash to induce hydration, adds water-absorbing resin material to maintain the appropriate humidity inside the concrete, and the generated hydration products seal the cracks, allowing the concrete to restore its density. Since fly ash has low pozzolanic activity, the water-absorbing resin material can continuously absorb and release water during the freeze-thaw cycle. This process can be triggered cyclically, thereby achieving self-repair of multiple freeze-thaw damage.

[0014] 2. The present invention adds a water-absorbing resin to ensure that it releases sufficient water during the freeze-thaw process, but the large-scale addition of water-absorbing resin will cause the mechanical properties to be greatly reduced. The present invention uses carboxymethyl cellulose to prepare the water-absorbing resin, which has good water absorption and improves the water absorption performance of the water-absorbing resin. Calcium carbonate is added to the water-absorbing resin to form a cross-linked network, which improves the stability in concrete. Modified xanthan gum is coated on the outside of the particles, and the modified xanthan gum has a certain viscosity, which is conducive to the adhesion of subsequent fine sand. The addition of fine sand is conducive to improving the service life of the water-absorbing resin material, maintaining a good cracking efficiency, thereby improving the freeze-thaw damage self-repair ability of the concrete.

[0015] 3. Xanthan gum has good viscoelasticity and can form a network structure in concrete, reducing the porosity of concrete, thereby improving its ability to resist chloride ion corrosion and avoiding the problem of a significant reduction in mechanical properties caused by the large addition of absorbent resin.

[0016] The long-chain 2-acrylamide-2-methylpropanesulfonic acid introduced into xanthan gum shields the anions on the side chain, reduces the complexation between the cations and the xanthan gum molecular chain, and enhances the chloride ion resistance of the modified xanthan gum, thereby improving the crack resistance of concrete and reducing freeze-thaw damage of concrete. DETAILED DESCRIPTION

[0017] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0018] The sources and models of the substances involved in the present invention are not particularly limited, and illustratively include: water-absorbing resin: can be purchased from Dongying Qimai New Materials Co., Ltd., model: CA-90; polyethylene glycol: average molecular weight: 950-1050, can be purchased from Sinopharm Chemical Reagent Co., Ltd.; epoxy resin: model: M02, can be purchased from Kunshan Chemical; polycarboxylic acid water reducer: model: SP-409, can be purchased from Liaoning Kelong Fine Chemical Co., Ltd.

[0019] Example 1: A method for preparing a freeze-thaw damage self-repairing foam concrete material, comprising the following steps: Step 1: Preparation of water-absorbing resin: 2 g of carboxymethyl cellulose and 20 mL of deionized water were heated to 78°C and stirred for 35 minutes to obtain a carboxymethyl cellulose solution; 8 g of sodium hydroxide and 20 mL of deionized water were stirred to obtain a sodium hydroxide solution; 0.2 g of N,N-methylenebisacrylamide, 0.4 g of potassium persulfate, and 30 mL of deionized water were stirred to obtain a mixed solution; in an ice-water bath, the sodium hydroxide solution was added dropwise to 25 g of acrylic acid and stirred to obtain a mixed solution; the carboxymethyl cellulose solution and 2 g of urea were added and stirred for 25 minutes; the mixed solution was added and stirred for 12 minutes; the temperature was raised to 76°C and the reaction was carried out for 3 hours; the mixture was filtered, washed, and dried to obtain a water-absorbing resin; Step 2: Preparation of modified xanthan gum: Take 5g of xanthan gum and 30mL of deionized water, stir evenly, add 2g of 2-acrylamide-2-methylpropanesulfonic acid, pass nitrogen, raise the temperature to 56°C, add 1g of ammonium cerium nitrate, 0.3g of potassium persulfate, and 0.5g of sodium bisulfite, and react for 3.5h to obtain modified xanthan gum; Step 3: Preparation of water-absorbent resin composite material: Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 42°C, stir for 32s, add to 24g of polyethylene glycol at 41°C, stir for 2.5min, cool to 32°C, extrude, and granulate to obtain granules; Take the granules and 5g of modified xanthan gum, mix them evenly, add 8g of fine sand, mix for 18s, sieve and solidify to obtain granules coated with fine sand; Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of particles coated with fine sand, mix evenly, and dry to obtain a water-absorbing resin composite material; Step 4: Preparation of freeze-thaw damage self-repairing foam concrete material: S1: Take 33g of sodium lauryl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir well, and use a foaming machine to foam to obtain foam; S2: Portland cement, fly ash, and a water-absorbing resin composite material were stirred for 1.5 minutes to obtain a powder; a polycarboxylate superplasticizer was dissolved in deionized water and then added to the powder, and stirred at 80 rpm for 32 seconds and then at 100 rpm for 62 minutes to obtain a cement mixture; S3: Add the foam to the cement mixture at a rotation speed of 40 r / min and stir for 1.5 minutes to obtain foamed concrete; grouting is performed, and the mixture is cured for 10 hours. The mold is removed and the mixture is cured for another 29 days to obtain a freeze-thaw damage self-repairing foamed concrete material; The foam concrete material includes the following substances, calculated by weight: 50 parts of Portland cement, 20 parts of fly ash, 6 parts of water-absorbing resin composite material, 0.08 parts of polycarboxylate water reducer, 12 parts of deionized water, and 40 parts of foam.

[0020] Example 2: A method for preparing a freeze-thaw damage self-repairing foam concrete material, comprising the following steps: Step 1: Preparation of water-absorbing resin: 2 g of carboxymethyl cellulose and 20 mL of deionized water were heated to 75°C and stirred for 30 minutes to obtain a carboxymethyl cellulose solution; 8 g of sodium hydroxide and 20 mL of deionized water were stirred to obtain a sodium hydroxide solution; 0.2 g of N,N-methylenebisacrylamide, 0.4 g of potassium persulfate, and 30 mL of deionized water were stirred to obtain a mixed solution; in an ice-water bath, the sodium hydroxide solution was added dropwise to 25 g of acrylic acid and stirred to obtain a mixed solution; the carboxymethyl cellulose solution and 2 g of urea were added and stirred for 20 minutes; the mixed solution was added and stirred for 10 minutes; the temperature was raised to 75°C and the reaction was carried out for 3 hours; the mixture was filtered, washed, and dried to obtain a water-absorbing resin; Step 2: Preparation of modified xanthan gum: Take 5g of xanthan gum and 30mL of deionized water, stir evenly, add 2g of 2-acrylamide-2-methylpropanesulfonic acid, pass nitrogen, heat to 55°C, add 1g of ammonium cerium nitrate, 0.3g of potassium persulfate, and 0.5g of sodium bisulfite, and react for 3h to obtain modified xanthan gum; Step 3: Preparation of water-absorbent resin composite material: Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 40°C, stir for 30s, add to 24g of polyethylene glycol at 40°C, stir for 2min, cool to 31°C, extrude, and granulate to obtain granules; Take the granules and 5g of modified xanthan gum, mix them evenly, add 8g of fine sand, mix for 15s, sieve and solidify to obtain granules coated with fine sand; Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of particles coated with fine sand, mix evenly, and dry to obtain a water-absorbing resin composite material; Step 4: Preparation of freeze-thaw damage self-repairing foam concrete material: S1: Take 33g of sodium lauryl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir well, and use a foaming machine to foam to obtain foam; S2: Portland cement, fly ash, and a water-absorbing resin composite material were stirred for 1 minute to obtain a powder; a polycarboxylate superplasticizer was dissolved in deionized water and then added to the powder, and stirred at 50 rpm for 30 seconds and then at 80 rpm for 60 minutes to obtain a cement mixture; S3: Add the foam to the cement mixture at a speed of 30 r / min and stir for 1 minute to obtain foamed concrete; perform grouting and molding, cure for 8 hours, remove the mold, and continue curing for 28 days to obtain a freeze-thaw damage self-repairing foamed concrete material; The foam concrete material includes the following substances, calculated by weight: 40 parts of Portland cement, 10 parts of fly ash, 5 parts of water-absorbing resin composite material, 0.06 parts of polycarboxylate water reducer, 10 parts of deionized water, and 35 parts of foam.

[0021] Example 3: A method for preparing a freeze-thaw damage self-repairing foam concrete material, comprising the following steps: Step 1: Preparation of water-absorbing resin: 2 g of carboxymethyl cellulose and 20 mL of deionized water were heated to 80°C and stirred for 40 min to obtain a carboxymethyl cellulose solution; 8 g of sodium hydroxide and 20 mL of deionized water were stirred to obtain a sodium hydroxide solution; 0.2 g of N,N-methylenebisacrylamide, 0.4 g of potassium persulfate, and 30 mL of deionized water were stirred to obtain a mixed solution; in an ice-water bath, the sodium hydroxide solution was added dropwise to 25 g of acrylic acid and stirred to obtain a mixed solution; the carboxymethyl cellulose solution and 2 g of urea were added and stirred for 30 min; the mixed solution was added and stirred for 15 min, the temperature was raised to 77°C, the reaction was carried out for 3.5 h, and the mixture was filtered, washed, and dried to obtain a water-absorbing resin; Step 2: Preparation of modified xanthan gum: Take 5g of xanthan gum and 30mL of deionized water, stir evenly, add 2g of 2-acrylamide-2-methylpropanesulfonic acid, pass nitrogen, heat to 58°C, add 1g of ammonium cerium nitrate, 0.3g of potassium persulfate, and 0.5g of sodium bisulfite, and react for 4h to obtain modified xanthan gum; Step 3: Preparation of water-absorbent resin composite material: Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 45°C, stir for 35s, add to 24g of polyethylene glycol at 42°C, stir for 3min, cool to 33°C, extrude, and granulate to obtain granules; Take the granules and 5g of modified xanthan gum, mix them evenly, add 8g of fine sand, mix for 20s, sieve and solidify to obtain granules coated with fine sand; Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of particles coated with fine sand, mix evenly, and dry to obtain a water-absorbing resin composite material; Step 4: Preparation of freeze-thaw damage self-repairing foam concrete material: S1: Take 33g of sodium lauryl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir well, and use a foaming machine to foam to obtain foam; S2: Take a composite material of Portland cement, fly ash, and water-absorbing resin and stir it for 2 minutes to obtain a powder; dissolve a polycarboxylate superplasticizer in deionized water and then add it to the powder, stir at 100 rpm for 35 seconds, and then stir at 150 rpm for 65 minutes to obtain a cement mixture; S3: Add the foam to the cement mixture at a rotation speed of 50 r / min and stir for 2 minutes to obtain foamed concrete; grouting is performed, and the mixture is cured for 16 hours. The mold is removed and the mixture is cured for another 30 days to obtain a freeze-thaw damage self-repairing foamed concrete material; The foam concrete material includes the following substances, calculated by weight: 55 parts of Portland cement, 25 parts of fly ash, 8 parts of water-absorbing resin composite material, 0.12 parts of polycarboxylate water reducer, 10-15 parts of deionized water, and 50 parts of foam.

[0022] Comparative Example 1: The xanthan gum was not modified, and the rest was the same as in Example 1: Step 1: Preparation of water-absorbing resin: 2 g of carboxymethyl cellulose and 20 mL of deionized water were heated to 78°C and stirred for 35 minutes to obtain a carboxymethyl cellulose solution; 8 g of sodium hydroxide and 20 mL of deionized water were stirred to obtain a sodium hydroxide solution; 0.2 g of N,N-methylenebisacrylamide, 0.4 g of potassium persulfate, and 30 mL of deionized water were stirred to obtain a mixed solution; in an ice-water bath, the sodium hydroxide solution was added dropwise to 25 g of acrylic acid and stirred to obtain a mixed solution; the carboxymethyl cellulose solution and 2 g of urea were added and stirred for 25 minutes; the mixed solution was added and stirred for 12 minutes; the temperature was raised to 76°C and the reaction was carried out for 3 hours; the mixture was filtered, washed, and dried to obtain a water-absorbing resin; Step 2: Preparation of water-absorbing resin composite material: Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 42°C, stir for 32s, add to 24g of polyethylene glycol at 41°C, stir for 2.5min, cool to 32°C, extrude, and granulate to obtain granules; Take the granules and 5g of xanthan gum, mix them evenly, add 8g of fine sand, mix for 18s, sieve and solidify to obtain granules coated with fine sand; Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of particles coated with fine sand, mix evenly, and dry to obtain a water-absorbing resin composite material; Step 3: Preparation of freeze-thaw damage self-repairing foam concrete material: S1: Take 33g of sodium lauryl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir well, and use a foaming machine to foam to obtain foam; S2: Portland cement, fly ash, and a water-absorbing resin composite material were stirred for 1.5 minutes to obtain a powder; a polycarboxylate superplasticizer was dissolved in deionized water and then added to the powder, and stirred at 80 rpm for 32 seconds and then at 100 rpm for 62 minutes to obtain a cement mixture; S3: Add the foam to the cement mixture at a rotation speed of 40 r / min and stir for 1.5 minutes to obtain foamed concrete; grouting is performed, and the mixture is cured for 10 hours. The mold is removed and the mixture is cured for another 29 days to obtain a freeze-thaw damage self-repairing foamed concrete material; The foam concrete material includes the following substances, calculated by weight: 50 parts of Portland cement, 20 parts of fly ash, 6 parts of water-absorbing resin composite material, 0.08 parts of polycarboxylate water reducer, 12 parts of deionized water, and 40 parts of foam.

[0023] Comparative Example 2: A commercially available water-absorbing resin of model CA-90 was used instead of the water-absorbing resin prepared by the present invention, and the rest was the same as in Example 1: Step 1: Preparation of modified xanthan gum: Take 5g of xanthan gum and 30mL of deionized water, stir evenly, add 2g of 2-acrylamide-2-methylpropanesulfonic acid, pass nitrogen, raise the temperature to 56°C, add 1g of ammonium cerium nitrate, 0.3g of potassium persulfate, and 0.5g of sodium bisulfite, and react for 3.5h to obtain modified xanthan gum; Step 2: Preparation of water-absorbing resin composite material: Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 42°C, stir for 32s, add to 24g of polyethylene glycol at 41°C, stir for 2.5min, cool to 32°C, extrude, and granulate to obtain granules; Take the granules and 5g of modified xanthan gum, mix them evenly, add 8g of fine sand, mix for 18s, sieve and solidify to obtain granules coated with fine sand; Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of particles coated with fine sand, mix evenly, and dry to obtain a water-absorbing resin composite material; Step 3: Preparation of freeze-thaw damage self-repairing foam concrete material: S1: Take 33g of sodium lauryl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir well, and use a foaming machine to foam to obtain foam; S2: Portland cement, fly ash, and a water-absorbing resin composite material were stirred for 1.5 minutes to obtain a powder; a polycarboxylate superplasticizer was dissolved in deionized water and then added to the powder, and stirred at 80 rpm for 32 seconds and then at 100 rpm for 62 minutes to obtain a cement mixture; S3: Add the foam to the cement mixture at a rotation speed of 40 r / min and stir for 1.5 minutes to obtain foamed concrete; grouting is performed, and the mixture is cured for 10 hours. The mold is removed and the mixture is cured for another 29 days to obtain a freeze-thaw damage self-repairing foamed concrete material; The foam concrete material includes the following substances, calculated by weight: 50 parts of Portland cement, 20 parts of fly ash, 6 parts of water-absorbing resin composite material, 0.08 parts of polycarboxylate water reducer, 12 parts of deionized water, and 40 parts of foam.

[0024] Comparative Example 3: No modified xanthan gum was added, and the rest was the same as in Example 1: Step 1: Preparation of water-absorbing resin: 2 g of carboxymethyl cellulose and 20 mL of deionized water were heated to 78°C and stirred for 35 minutes to obtain a carboxymethyl cellulose solution; 8 g of sodium hydroxide and 20 mL of deionized water were stirred to obtain a sodium hydroxide solution; 0.2 g of N,N-methylenebisacrylamide, 0.4 g of potassium persulfate, and 30 mL of deionized water were stirred to obtain a mixed solution; in an ice-water bath, the sodium hydroxide solution was added dropwise to 25 g of acrylic acid and stirred to obtain a mixed solution; the carboxymethyl cellulose solution and 2 g of urea were added and stirred for 25 minutes; the mixed solution was added and stirred for 12 minutes; the temperature was raised to 76°C and the reaction was carried out for 3 hours; the mixture was filtered, washed, and dried to obtain a water-absorbing resin; Step 2: Preparation of water-absorbing resin composite material: Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 42°C, stir for 32s, add to 24g of polyethylene glycol at 41°C, stir for 2.5min, cool to 32°C, extrude, and granulate to obtain granules; Take the granules and 5g of epoxy resin, mix them evenly, add 8g of fine sand, mix for 18s, sieve and cure to obtain granules coated with fine sand; Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of particles coated with fine sand, mix evenly, and dry to obtain a water-absorbing resin composite material; Step 3: Preparation of freeze-thaw damage self-repairing foam concrete material: S1: Take 33g of sodium lauryl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir well, and use a foaming machine to foam to obtain foam; S2: Portland cement, fly ash, and a water-absorbing resin composite material were stirred for 1.5 minutes to obtain a powder; a polycarboxylate superplasticizer was dissolved in deionized water and then added to the powder, and stirred at 80 rpm for 32 seconds and then at 100 rpm for 62 minutes to obtain a cement mixture; S3: Add the foam to the cement mixture at a rotation speed of 40 r / min and stir for 1.5 minutes to obtain foamed concrete; grouting is performed, and the mixture is cured for 10 hours. The mold is removed and the mixture is cured for another 29 days to obtain a freeze-thaw damage self-repairing foamed concrete material; The foam concrete material includes the following substances, calculated by weight: 50 parts of Portland cement, 20 parts of fly ash, 6 parts of water-absorbing resin composite material, 0.08 parts of polycarboxylate water reducer, 12 parts of deionized water, and 40 parts of foam.

[0025] experiment: The freeze-thaw damage self-repairing foam concrete materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to performance testing. 100 mm × 100 mm × 100 mm specimens were prepared. Referring to JTG 3420-2020 and JGJ / T341-2014, freeze-thaw cycle tests were performed on the specimens. The compressive strength of the specimens after 29 days of curing, the compressive strength loss rate after 50 freeze-thaw cycles, and the compressive strength loss rate of the specimens after 150 freeze-thaw cycles were calculated. The data obtained are shown in Table 1 below: Table 1

[0026] Conclusion: From the comparison of the data in the table, it can be seen that in Comparative Example 1, the xanthan gum is not modified, and the mechanical properties after 150 freeze-thaw cycles are worse than those of Examples 1-3. Comparative Example 2 uses a commercially available water-absorbing resin model CA-90 instead of the water-absorbing resin prepared by the present invention, and the foam concrete material has poor self-repair performance against freeze-thaw damage. Comparative Example 3 does not add modified xanthan gum, and the self-repair performance against freeze-thaw damage is poor. Examples 1-3 of the present invention add fly ash to induce hydration, and add water-absorbing resin materials to maintain a suitable humidity inside the concrete. The generated hydration products seal cracks, allowing the concrete to restore its density. Because fly ash has low pozzolanic activity, the water-absorbing resin material can continuously absorb and release water during the freeze-thaw cycle. This process can be triggered cyclically, thereby achieving self-repair of multiple freeze-thaw damage. The present invention adds calcium carbonate to the water-absorbing resin to form a cross-linked network, thereby improving its stability in concrete. Modified xanthan gum is coated on the outside of the particles, and the modified xanthan gum has a certain viscosity, which is beneficial to the subsequent adhesion of fine sand. The addition of fine sand helps extend the service life of the water-absorbing resin material, maintains good cracking efficiency, and thus improves the concrete's ability to repair freeze-thaw damage. The long-chain 2-acrylamide-2-methylpropanesulfonic acid introduced into the xanthan gum shields the anions on the side chains, reduces the complexation between the cations and the xanthan gum molecular chains, and enhances the modified xanthan gum's resistance to chloride ions, thereby improving the concrete's crack resistance and reducing freeze-thaw damage.

[0027] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing a freeze-thaw damage self-repairing foam concrete material, characterized by: The following steps are involved: S1: Take a foaming agent of sodium lauryl sulfate, γ-aminopropyltriethoxysilane, and deionized water, stir them evenly, and use a foaming machine to foam to obtain foam; S2: Take a composite material of Portland cement, fly ash, and a water-absorbing resin, stir for 1-2 minutes to obtain a powder; dissolve a polycarboxylate water-reducing agent in deionized water, then add the mixture to the powder and stir evenly to obtain a cement mixture; S3: adding foam to the cement mixture and stirring for 1-2 minutes to obtain foamed concrete; grouting and forming, curing, demoulding, and continuing curing for 28-30 days to obtain freeze-thaw damage self-repairing foamed concrete material.

2. The method for preparing a freeze-thaw damage self-repairing foam concrete material according to claim 1, characterized in that: The foam concrete material comprises the following substances, calculated by weight: 40-55 parts of Portland cement, 10-25 parts of fly ash, 5-8 parts of water-absorbing resin composite material, 0.06-0.12 parts of polycarboxylate water reducer, 10-15 parts of deionized water, and 35-50 parts of foam.

3. The method for preparing a freeze-thaw damage self-repairing foam concrete material according to claim 1, characterized in that: The preparation method of the water-absorbing resin composite material comprises the following steps: Step 1: Take granular material and modified xanthan gum, mix them evenly, add fine sand, mix for 15-20 seconds, sieve and solidify to obtain granular material coated with fine sand; Step 2: Take epoxy resin and deionized water, stir them evenly, add particles coated with fine sand, mix them evenly, and dry them to obtain a water-absorbing resin composite material.

4. The method for preparing a freeze-thaw damage self-repairing foam concrete material according to claim 3, characterized in that: The preparation method of the granules is as follows: calcium carbonate, calcium acetate and water-absorbing resin are heated to 40-45° C., stirred for 30-35 seconds, added to polyethylene glycol at 40-42° C., stirred for 2-3 minutes, cooled to 31-33° C., extruded and granulated to obtain the granules.

5. The method for preparing a freeze-thaw damage self-repairing foam concrete material according to claim 3, characterized in that: The preparation method of the modified xanthan gum comprises the following steps: taking xanthan gum and deionized water, stirring evenly, adding 2-acrylamide-2-methylpropanesulfonic acid, passing nitrogen, heating to 55-58° C., adding cerium ammonium nitrate, potassium persulfate, and sodium bisulfite, and reacting for 3-4 hours to obtain the modified xanthan gum.

6. The method for preparing a freeze-thaw damage self-repairing foam concrete material according to claim 4, characterized in that: The preparation method of the water-absorbing resin comprises the following steps: taking carboxymethyl cellulose and deionized water, heating the mixture to 75-80° C., and stirring the mixture for 30-40 minutes to obtain a carboxymethyl cellulose solution; taking sodium hydroxide and deionized water, stirring the mixture evenly to obtain a sodium hydroxide solution; taking N,N-methylenebisacrylamide, potassium persulfate, and deionized water, and stirring the mixture evenly to obtain a mixed solution; adding the sodium hydroxide solution dropwise to acrylic acid in an ice-water bath, stirring the mixture evenly, adding the carboxymethyl cellulose solution and urea, stirring the mixture for 20-30 minutes, adding the mixed solution, stirring the mixture for 10-15 minutes, heating the mixture to 75-77° C., reacting the mixture for 3-3.5 hours, filtering, washing, and drying the mixture to obtain the water-absorbing resin.

7. The method for preparing a freeze-thaw damage self-repairing foam concrete material according to claim 1, characterized in that: In S2, the polycarboxylate water reducer is dissolved in deionized water, and then added to the powder, stirred at 50-100 r / min for 30-35 seconds, and then stirred at 80-150 r / min for 60-65 minutes to obtain a cement mixture.

8. A freeze-thaw damage self-repairing foam concrete material prepared by the method for preparing a freeze-thaw damage self-repairing foam concrete material according to any one of claims 1 to 7.

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