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

Abstract

The application discloses a kind of freeze-thaw damage self-repairing foam concrete materials and preparation method thereof, it is related to building material technical field.The fly ash with higher hydration activity can induce in-situ self-repairing of microstructure primary defect of cement stone.The microcrack is initiated in concrete under initial freeze-thaw, the fly ash is added in the application, hydration is triggered, the water-absorbing resin material is added to maintain the suitable humidity inside concrete, the generated hydration product seals the crack, so that the density of concrete is restored.The water-absorbing resin material can continuously absorb and release water in freeze-thaw cycle, and the process can be triggered cyclically, thereby realizing the autonomous repair of multiple freeze-thaw damage.The carboxymethyl cellulose is used to prepare water-absorbing resin in the application, and the carboxymethyl cellulose has good water absorption, which improves the water absorption performance of water-absorbing resin.Calcium carbonate is added in water-absorbing resin to form a crosslinked network, which improves the stability in concrete.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a freeze-thaw damage self-healing foamed concrete material and its preparation method. Background Technology

[0002] Foamed concrete is widely used in transportation engineering and construction fields such as roadbed filling due to its thermal insulation, lightweight, and sound insulation properties. However, the porous structure of foamed concrete is prone to severe damage under freeze-thaw cycles: open pores allow water to penetrate rapidly, and the expansion of ice causes internal stress concentration, leading to the gradual propagation of microcracks and a decrease in the material's freeze-thaw durability, thus limiting the widespread application of foamed concrete in cold regions.

[0003] Concrete self-healing technology repairs cracks by reacting with cement hydration products under crack-induced conditions. It is low-cost, but this technology is limited by its poor environmental adaptability.

[0004] To address the aforementioned problems and improve the self-healing ability of concrete to withstand freeze-thaw damage, this invention provides a freeze-thaw damage self-healing foamed concrete material and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a self-healing foamed concrete material for freeze-thaw damage and its preparation method, so as to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a freeze-thaw damaged self-healing foamed concrete material includes the following steps:

[0008] S1: Take foaming agent sodium dodecyl sulfate, γ-aminopropyltriethoxysilane and deionized water, stir evenly, and foam using a foaming machine to obtain foam;

[0009] S2: Take silicate cement, fly ash, and water-absorbing resin composite material, stir for 1-2 minutes to obtain powder; dissolve polycarboxylate superplasticizer in deionized water, then add it to the powder, stir evenly to obtain cement mixture;

[0010] S3: Add foam to the cement mixture and stir for 1-2 minutes to obtain foamed concrete; grout and mold, cure, demold, and continue curing for 28-30 days to obtain freeze-thaw damage self-healing foamed concrete material.

[0011] More preferably, the foamed concrete material comprises the following substances in parts by weight: 40-55 parts silicate cement, 10-25 parts fly ash, 5-8 parts water-absorbing resin composite material, 0.06-0.12 parts polycarboxylate superplasticizer, 10-15 parts deionized water, and 35-50 parts foam.

[0012] A more optimized method for preparing the water-absorbing resin composite material includes the following steps:

[0013] Step 1: Take the granules and modified xanthan gum, mix them evenly, add fine sand, mix for 15-20 seconds, sieve and solidify to obtain granules coated with fine sand;

[0014] Step 2: Take epoxy resin and deionized water, stir evenly, add particles coated with fine sand, mix evenly, and dry to obtain water-absorbing resin composite material.

[0015] A more optimized method for preparing the particles is as follows: take calcium carbonate, calcium acetate, and water-absorbing resin, heat to 40-45℃, stir for 30-35s, add to polyethylene glycol at 40-42℃, stir for 2-3min, cool to 31-33℃, extrude, granulate, and obtain particles.

[0016] A more optimized method for preparing the modified xanthan gum is as follows: xanthan gum and deionized water are taken, stirred evenly, 2-acrylamide-2-methylpropanesulfonic acid is added, nitrogen gas is passed through, the temperature is raised to 55-58℃, cerium ammonium nitrate, potassium persulfate and sodium bisulfite are added, and the reaction is carried out for 3-4 hours to obtain modified xanthan gum.

[0017] A more optimized method for preparing the absorbent resin is as follows: Take carboxymethyl cellulose and deionized water, heat to 75-80℃, and stir for 30-40 minutes to obtain a carboxymethyl cellulose solution; take sodium hydroxide and deionized water, and stir until homogeneous to obtain a sodium hydroxide solution; take N,N-methylenebisacrylamide, potassium persulfate, and deionized water, and stir until homogeneous to obtain a mixed solution; under an ice-water bath, add the sodium hydroxide solution dropwise to acrylic acid, stir until homogeneous, add the carboxymethyl cellulose solution and urea, stir for 20-30 minutes, add the mixed solution, stir for 10-15 minutes, heat to 75-77℃, react for 3-3.5 hours, filter, wash, and dry to obtain the absorbent resin.

[0018] In a more optimized manner, in S2, the polycarboxylate superplasticizer is dissolved in deionized water and then added to the powder. The mixture is stirred at 50-100 r / min for 30-35 s and then at 80-150 r / min for 60-65 min to obtain the cement mixture.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. Fly ash, with its high hydration activity, can induce in-situ self-repair of original defects in the microstructure of cement paste. Simultaneously, the internal curing effect of the water-absorbing resin material can regulate internal humidity by absorbing and releasing water, creating a favorable hydration environment for the later hydration of fly ash, including sufficient moisture and calcium hydroxide. Concrete develops microcracks under initial freeze-thaw cycles. This invention, by adding fly ash to induce hydration and adding water-absorbing resin material to maintain suitable internal humidity in the concrete, allows the generated hydration products to seal the cracks, restoring the concrete's density. Because fly ash has low pozzolanic activity, the water-absorbing resin material can continuously absorb and release water during freeze-thaw cycles. This process can be cyclically triggered, thereby achieving self-repair of repeated freeze-thaw damage.

[0021] 2. This invention adds a water-absorbing resin to ensure sufficient moisture release during freeze-thaw cycles; however, excessive addition of the resin can significantly reduce mechanical properties. This invention uses carboxymethyl cellulose to prepare the water-absorbing resin, which has excellent water absorption properties, thus improving its absorption performance. Calcium carbonate is added to the resin to form a cross-linked network, improving its stability in concrete. Modified xanthan gum is coated onto the particles; this modified xanthan gum has a certain degree of viscosity, facilitating the 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 enhances the self-healing ability of concrete against freeze-thaw damage.

[0022] 3. Xanthan gum has good viscoelasticity and can form a network structure in concrete, reducing the porosity of concrete and thus improving its resistance to chloride ion erosion, avoiding the problem of a significant reduction in mechanical properties caused by the addition of large amounts of water-absorbing resin.

[0023] The introduction of long-chain 2-acrylamide-2-methylpropanesulfonic acid into xanthan gum shields the anions on the side chains, reduces the complexation between the cations and the xanthan gum molecular chains, and enhances the chloride ion resistance of the modified xanthan gum, thereby improving the crack resistance of concrete and reducing freeze-thaw damage to concrete. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0025] The sources and types of substances involved in this invention are not specifically limited. Exemplary examples include: water-absorbing resin: available from Dongying Qimai New Materials Co., Ltd., type: CA-90; polyethylene glycol: average molecular weight: 950-1050, available from Sinopharm Chemical Reagent Co., Ltd.; epoxy resin: type: M02, available from Kunshan Chemical; polycarboxylate superplasticizer: type: SP-409, available from Liaoning Kelong Fine Chemical Co., Ltd.

[0026] Example 1: A method for preparing a freeze-thaw damaged self-healing foamed concrete material, comprising the following steps:

[0027] Step 1: Preparation of water-absorbing resin:

[0028] Take 2g of carboxymethyl cellulose and 20mL of deionized water, heat to 78℃, and stir for 35min to obtain a carboxymethyl cellulose solution; take 8g of sodium hydroxide and 20mL of deionized water, stir evenly to obtain a sodium hydroxide solution; take 0.2g of N,N-methylenebisacrylamide, 0.4g of potassium persulfate, and 30mL of deionized water, stir evenly to obtain a mixed solution; under an ice-water bath, add the sodium hydroxide solution dropwise to 25g of acrylic acid, stir evenly, add the carboxymethyl cellulose solution and 2g of urea, stir for 25min, add the mixed solution, stir for 12min, heat to 76℃, react for 3h, filter, wash, and dry to obtain a water-absorbing resin;

[0029] Step 2: Preparation of modified xanthan gum:

[0030] Take 5g xanthan gum and 30mL deionized water, stir well, add 2g 2-acrylamide-2-methylpropanesulfonic acid, purge with nitrogen, heat to 56℃, add 1g cerium ammonium nitrate, 0.3g potassium persulfate and 0.5g sodium bisulfite, react for 3.5h to obtain modified xanthan gum;

[0031] Step 3: Preparation of water-absorbing resin composite material:

[0032] Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 42℃, stir for 32s, add to 24g of polyethylene glycol at 41℃, stir for 2.5min, cool to 32℃, extrude, and granulate to obtain granules.

[0033] 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.

[0034] Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of fine sand-coated particles, mix evenly, and dry to obtain a water-absorbing resin composite material.

[0035] Step 4: Preparation of self-healing foamed concrete material for freeze-thaw damage:

[0036] S1: Take 33g of foaming agent sodium dodecyl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir evenly, and foam using a foaming machine to obtain foam;

[0037] S2: Take silicate cement, fly ash, and water-absorbing resin composite material, stir for 1.5 min to obtain powder; dissolve polycarboxylate superplasticizer in deionized water, then add it to the powder, stir at 80 r / min for 32 s, and then stir at 100 r / min for 62 min to obtain cement mixture;

[0038] S3: Add foam to the cement mixture at a speed of 40 r / min and stir for 1.5 min to obtain foamed concrete; grout and mold, cure for 10 h, remove the mold, and continue curing for 29 days to obtain freeze-thaw damage self-healing foamed concrete material;

[0039] Foamed concrete materials include the following substances, by weight: 50 parts silicate cement, 20 parts fly ash, 6 parts water-absorbing resin composite material, 0.08 parts polycarboxylate superplasticizer, 12 parts deionized water, and 40 parts foam.

[0040] Example 2: A method for preparing a freeze-thaw damaged self-healing foamed concrete material, comprising the following steps:

[0041] Step 1: Preparation of water-absorbing resin:

[0042] Take 2g of carboxymethyl cellulose and 20mL of deionized water, heat to 75℃, and stir for 30min to obtain a carboxymethyl cellulose solution; take 8g of sodium hydroxide and 20mL of deionized water, stir evenly to obtain a sodium hydroxide solution; take 0.2g of N,N-methylenebisacrylamide, 0.4g of potassium persulfate, and 30mL of deionized water, stir evenly to obtain a mixed solution; under an ice-water bath, add the sodium hydroxide solution dropwise to 25g of acrylic acid, stir evenly, add the carboxymethyl cellulose solution and 2g of urea, stir for 20min, add the mixed solution, stir for 10min, heat to 75℃, react for 3h, filter, wash, and dry to obtain a water-absorbing resin;

[0043] Step 2: Preparation of modified xanthan gum:

[0044] Take 5g xanthan gum and 30mL deionized water, stir well, add 2g 2-acrylamide-2-methylpropanesulfonic acid, purge with nitrogen, heat to 55℃, add 1g cerium ammonium nitrate, 0.3g potassium persulfate and 0.5g sodium bisulfite, react for 3h to obtain modified xanthan gum;

[0045] Step 3: Preparation of water-absorbing resin composite material:

[0046] Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 40℃, stir for 30s, add to 24g of polyethylene glycol at 40℃, stir for 2min, cool to 31℃, extrude, and granulate to obtain granules.

[0047] 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.

[0048] Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of fine sand-coated particles, mix evenly, and dry to obtain a water-absorbing resin composite material.

[0049] Step 4: Preparation of self-healing foamed concrete material for freeze-thaw damage:

[0050] S1: Take 33g of foaming agent sodium dodecyl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir evenly, and foam using a foaming machine to obtain foam;

[0051] S2: Take silicate cement, fly ash, and water-absorbing resin composite material, stir for 1 min to obtain powder; dissolve polycarboxylate superplasticizer in deionized water, then add it to the powder, stir at 50 r / min for 30 s, then stir at 80 r / min for 60 min to obtain cement mixture;

[0052] S3: Add foam to the cement mixture at a speed of 30 r / min, stir for 1 min to obtain foamed concrete; grout and mold, cure for 8 h, remove the mold, and continue curing for 28 days to obtain freeze-thaw damage self-healing foamed concrete material.

[0053] Foamed concrete materials include the following substances, by weight: 40 parts silicate cement, 10 parts fly ash, 5 parts water-absorbing resin composite material, 0.06 parts polycarboxylate superplasticizer, 10 parts deionized water, and 35 parts foam.

[0054] Example 3: A method for preparing a freeze-thaw damaged self-healing foamed concrete material, comprising the following steps:

[0055] Step 1: Preparation of water-absorbing resin:

[0056] Take 2g of carboxymethyl cellulose and 20mL of deionized water, heat to 80℃, and stir for 40min to obtain a carboxymethyl cellulose solution; take 8g of sodium hydroxide and 20mL of deionized water, stir evenly to obtain a sodium hydroxide solution; take 0.2g of N,N-methylenebisacrylamide, 0.4g of potassium persulfate, and 30mL of deionized water, stir evenly to obtain a mixed solution; under an ice-water bath, add the sodium hydroxide solution dropwise to 25g of acrylic acid, stir evenly, add the carboxymethyl cellulose solution and 2g of urea, stir for 30min, add the mixed solution, stir for 15min, heat to 77℃, react for 3.5h, filter, wash, and dry to obtain a water-absorbing resin;

[0057] Step 2: Preparation of modified xanthan gum:

[0058] Take 5g xanthan gum and 30mL deionized water, stir well, add 2g 2-acrylamide-2-methylpropanesulfonic acid, purge with nitrogen, heat to 58℃, add 1g cerium ammonium nitrate, 0.3g potassium persulfate and 0.5g sodium bisulfite, react for 4h to obtain modified xanthan gum;

[0059] Step 3: Preparation of water-absorbing resin composite material:

[0060] Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 45℃, stir for 35s, add to 24g of polyethylene glycol at 42℃, stir for 3min, cool to 33℃, extrude, and granulate to obtain granules.

[0061] 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.

[0062] Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of fine sand-coated particles, mix evenly, and dry to obtain a water-absorbing resin composite material.

[0063] Step 4: Preparation of self-healing foamed concrete material for freeze-thaw damage:

[0064] S1: Take 33g of foaming agent sodium dodecyl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir evenly, and foam using a foaming machine to obtain foam;

[0065] S2: Take silicate cement, fly ash, and water-absorbing resin composite material, stir for 2 minutes to obtain powder; dissolve polycarboxylate superplasticizer in deionized water, then add it to the powder, stir at 100 r / min for 35 s, and then stir at 150 r / min for 65 minutes to obtain cement mixture;

[0066] S3: Add foam to the cement mixture at a speed of 50 r / min, stir for 2 min to obtain foamed concrete; grout and mold, cure for 16 h, remove the mold, and continue curing for 30 days to obtain freeze-thaw damage self-healing foamed concrete material.

[0067] Foamed concrete materials include the following substances, by weight: 55 parts silicate cement, 25 parts fly ash, 8 parts water-absorbing resin composite material, 0.12 parts polycarboxylate superplasticizer, 10-15 parts deionized water, and 50 parts foam.

[0068] Comparative Example 1: No modification was made to xanthan gum; all other aspects were the same as in Example 1.

[0069] Step 1: Preparation of water-absorbing resin:

[0070] Take 2g of carboxymethyl cellulose and 20mL of deionized water, heat to 78℃, and stir for 35min to obtain a carboxymethyl cellulose solution; take 8g of sodium hydroxide and 20mL of deionized water, stir evenly to obtain a sodium hydroxide solution; take 0.2g of N,N-methylenebisacrylamide, 0.4g of potassium persulfate, and 30mL of deionized water, stir evenly to obtain a mixed solution; under an ice-water bath, add the sodium hydroxide solution dropwise to 25g of acrylic acid, stir evenly, add the carboxymethyl cellulose solution and 2g of urea, stir for 25min, add the mixed solution, stir for 12min, heat to 76℃, react for 3h, filter, wash, and dry to obtain a water-absorbing resin;

[0071] Step 2: Preparation of water-absorbing resin composite material:

[0072] Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 42℃, stir for 32s, add to 24g of polyethylene glycol at 41℃, stir for 2.5min, cool to 32℃, extrude, and granulate to obtain granules.

[0073] Take the granules and 5g xanthan gum, mix them evenly, add 8g fine sand, mix for 18s, sieve and solidify to obtain granules coated with fine sand.

[0074] Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of fine sand-coated particles, mix evenly, and dry to obtain a water-absorbing resin composite material.

[0075] Step 3: Preparation of self-healing foamed concrete material for freeze-thaw damage:

[0076] S1: Take 33g of foaming agent sodium dodecyl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir evenly, and foam using a foaming machine to obtain foam;

[0077] S2: Take silicate cement, fly ash, and water-absorbing resin composite material, stir for 1.5 min to obtain powder; dissolve polycarboxylate superplasticizer in deionized water, then add it to the powder, stir at 80 r / min for 32 s, and then stir at 100 r / min for 62 min to obtain cement mixture;

[0078] S3: Add foam to the cement mixture at a speed of 40 r / min and stir for 1.5 min to obtain foamed concrete; grout and mold, cure for 10 h, remove the mold, and continue curing for 29 days to obtain freeze-thaw damage self-healing foamed concrete material;

[0079] Foamed concrete materials include the following substances, by weight: 50 parts silicate cement, 20 parts fly ash, 6 parts water-absorbing resin composite material, 0.08 parts polycarboxylate superplasticizer, 12 parts deionized water, and 40 parts foam.

[0080] Comparative Example 2: A commercially available absorbent resin of type CA-90 was used instead of the absorbent resin prepared in this invention, and the rest was the same as in Example 1:

[0081] Step 1: Preparation of modified xanthan gum:

[0082] Take 5g xanthan gum and 30mL deionized water, stir well, add 2g 2-acrylamide-2-methylpropanesulfonic acid, purge with nitrogen, heat to 56℃, add 1g cerium ammonium nitrate, 0.3g potassium persulfate and 0.5g sodium bisulfite, react for 3.5h to obtain modified xanthan gum;

[0083] Step 2: Preparation of water-absorbing resin composite material:

[0084] Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 42℃, stir for 32s, add to 24g of polyethylene glycol at 41℃, stir for 2.5min, cool to 32℃, extrude, and granulate to obtain granules.

[0085] 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.

[0086] Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of fine sand-coated particles, mix evenly, and dry to obtain a water-absorbing resin composite material.

[0087] Step 3: Preparation of self-healing foamed concrete material for freeze-thaw damage:

[0088] S1: Take 33g of foaming agent sodium dodecyl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir evenly, and foam using a foaming machine to obtain foam;

[0089] S2: Take silicate cement, fly ash, and water-absorbing resin composite material, stir for 1.5 min to obtain powder; dissolve polycarboxylate superplasticizer in deionized water, then add it to the powder, stir at 80 r / min for 32 s, and then stir at 100 r / min for 62 min to obtain cement mixture;

[0090] S3: Add foam to the cement mixture at a speed of 40 r / min and stir for 1.5 min to obtain foamed concrete; grout and mold, cure for 10 h, remove the mold, and continue curing for 29 days to obtain freeze-thaw damage self-healing foamed concrete material;

[0091] Foamed concrete materials include the following substances, by weight: 50 parts silicate cement, 20 parts fly ash, 6 parts water-absorbing resin composite material, 0.08 parts polycarboxylate superplasticizer, 12 parts deionized water, and 40 parts foam.

[0092] Comparative Example 3: No modified xanthan gum was added; all other aspects were the same as in Example 1.

[0093] Step 1: Preparation of water-absorbing resin:

[0094] Take 2g of carboxymethyl cellulose and 20mL of deionized water, heat to 78℃, and stir for 35min to obtain a carboxymethyl cellulose solution; take 8g of sodium hydroxide and 20mL of deionized water, stir evenly to obtain a sodium hydroxide solution; take 0.2g of N,N-methylenebisacrylamide, 0.4g of potassium persulfate, and 30mL of deionized water, stir evenly to obtain a mixed solution; under an ice-water bath, add the sodium hydroxide solution dropwise to 25g of acrylic acid, stir evenly, add the carboxymethyl cellulose solution and 2g of urea, stir for 25min, add the mixed solution, stir for 12min, heat to 76℃, react for 3h, filter, wash, and dry to obtain a water-absorbing resin;

[0095] Step 2: Preparation of water-absorbing resin composite material:

[0096] Take 10g of calcium carbonate, 7g of calcium acetate, and 2g of water-absorbing resin, heat to 42℃, stir for 32s, add to 24g of polyethylene glycol at 41℃, stir for 2.5min, cool to 32℃, extrude, and granulate to obtain granules.

[0097] Take granules and 5g of epoxy resin, mix them evenly, add 8g of fine sand, mix for 18s, sieve and solidify to obtain granules coated with fine sand.

[0098] Take 5g of epoxy resin and 20mL of deionized water, stir evenly, add 30g of fine sand-coated particles, mix evenly, and dry to obtain a water-absorbing resin composite material.

[0099] Step 3: Preparation of self-healing foamed concrete material for freeze-thaw damage:

[0100] S1: Take 33g of foaming agent sodium dodecyl sulfate, 200g of γ-aminopropyltriethoxysilane, and 10kg of deionized water, stir evenly, and foam using a foaming machine to obtain foam;

[0101] S2: Take silicate cement, fly ash, and water-absorbing resin composite material, stir for 1.5 min to obtain powder; dissolve polycarboxylate superplasticizer in deionized water, then add it to the powder, stir at 80 r / min for 32 s, and then stir at 100 r / min for 62 min to obtain cement mixture;

[0102] S3: Add foam to the cement mixture at a speed of 40 r / min and stir for 1.5 min to obtain foamed concrete; grout and mold, cure for 10 h, remove the mold, and continue curing for 29 days to obtain freeze-thaw damage self-healing foamed concrete material;

[0103] Foamed concrete materials include the following substances, by weight: 50 parts silicate cement, 20 parts fly ash, 6 parts water-absorbing resin composite material, 0.08 parts polycarboxylate superplasticizer, 12 parts deionized water, and 40 parts foam.

[0104] experiment:

[0105] The freeze-thaw damaged self-healing foamed concrete materials prepared in Examples 1-3 and Comparative Examples 1-3 were used for performance testing. They were prepared into 100mm×100mm×100mm specimens. Freeze-thaw cycle tests were conducted on the specimens according to JTG 3420-2020 and JGJ / T341-2014. 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 after 150 freeze-thaw cycles were calculated. The data are shown in Table 1 below.

[0106] Table 1

[0107]

[0108] Conclusion: The data comparison in the table shows that Comparative Example 1, without modification of xanthan gum, exhibits worse mechanical properties than Examples 1-3 after 150 freeze-thaw cycles. Comparative Example 2, using commercially available CA-90 superabsorbent resin instead of the superabsorbent resin prepared in this invention, shows poor self-healing performance of the foamed concrete material against freeze-thaw damage. Comparative Example 3, without modified xanthan gum, also shows poor self-healing performance against freeze-thaw damage. Examples 1-3 of this invention, by adding fly ash to initiate hydration and adding superabsorbent resin to maintain suitable internal humidity in the concrete, allow the generated hydration products to seal cracks, restoring the concrete's density. Because fly ash has low pozzolanic activity, the superabsorbent resin can continuously absorb and release water during freeze-thaw cycles; this process can be cyclically triggered, thus achieving self-healing from repeated freeze-thaw damage. This invention adds calcium carbonate to the superabsorbent resin to form a cross-linked network, improving its stability in concrete. The modified xanthan gum, with its adhesive properties, coats the particles, facilitating the adhesion of subsequent fine sand. The addition of fine sand helps to extend the service life of water-absorbing resin materials, maintain good cracking efficiency, and thus enhance the self-healing ability of concrete against freeze-thaw damage. The long-chain 2-acrylamido-2-methylpropanesulfonic acid introduced into xanthan gum shields the anions on the side chains, reduces the complexation between cations and xanthan gum molecular chains, and enhances the chloride ion resistance of modified xanthan gum, thereby improving the crack resistance of concrete and reducing freeze-thaw damage.

[0109] 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 implemented 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 exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a freeze-thaw damaged self-healing foamed concrete material, characterized in that: Includes the following steps: S1: Take foaming agent sodium dodecyl sulfate, γ-aminopropyltriethoxysilane and deionized water, stir evenly, and foam using a foaming machine to obtain foam; S2: Take silicate cement, fly ash, and water-absorbing resin composite material, stir for 1-2 minutes to obtain powder; dissolve polycarboxylate superplasticizer in deionized water, then add it to the powder, stir evenly to obtain cement mixture; S3: Add foam to the cement mixture and stir for 1-2 minutes to obtain foamed concrete; grout and mold, cure, demold, and continue curing for 28-30 days to obtain freeze-thaw damage self-healing foamed concrete material. The method for preparing the water-absorbing resin composite material includes the following steps: Step 1: Take the granules and modified xanthan gum, mix them evenly, add fine sand, mix for 15-20 seconds, sieve and solidify to obtain granules coated with fine sand; Step 2: Take epoxy resin and deionized water, stir evenly, add particles coated with fine sand, mix evenly, and dry to obtain water-absorbing resin composite material. The method for preparing the granules is as follows: take calcium carbonate, calcium acetate, and water-absorbing resin, heat to 40-45℃, stir for 30-35s, add to polyethylene glycol at 40-42℃, stir for 2-3min, cool to 31-33℃, extrude, granulate, and obtain granules. The modified xanthan gum is prepared by taking xanthan gum and deionized water, stirring evenly, adding 2-acrylamide-2-methylpropanesulfonic acid, purging with nitrogen, heating to 55-58℃, adding cerium ammonium nitrate, potassium persulfate, and sodium bisulfite, and reacting for 3-4 hours to obtain modified xanthan gum. The method for preparing the water-absorbing resin is as follows: Take carboxymethyl cellulose and deionized water, heat to 75-80℃, stir for 30-40 min to obtain a carboxymethyl cellulose solution; take sodium hydroxide and deionized water, stir evenly to obtain a sodium hydroxide solution; take N,N-methylenebisacrylamide, potassium persulfate, and deionized water, stir evenly to obtain a mixed solution; under an ice-water bath, add the sodium hydroxide solution dropwise to acrylic acid, stir evenly, add the carboxymethyl cellulose solution and urea, stir for 20-30 min, add the mixed solution, stir for 10-15 min, heat to 75-77℃, react for 3-3.5 h, filter, wash, and dry to obtain the water-absorbing resin.

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

3. The method for preparing a freeze-thaw damaged self-healing foamed concrete material according to claim 1, characterized in that: In S2, polycarboxylate superplasticizer is dissolved in deionized water and then added to the powder. The mixture is stirred at 50-100 r / min for 30-35 s and then at 80-150 r / min for 60-65 min to obtain cement mixture.

4. The freeze-thaw damage self-healing foamed concrete material prepared by the preparation method of freeze-thaw damage self-healing foamed concrete material according to any one of claims 1-3.

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