Concrete anti-cracking and anti-seepage material and preparation method thereof

Abstract

This application relates to the technical field of concrete anti-seepage materials. Specifically, it provides a concrete anti-cracking and anti-seepage material and a preparation method thereof. The concrete anti-cracking and anti-seepage material comprises the following raw materials in parts by weight: 80-120 parts cement, 20-30 parts silica fume, 5-10 parts polyurea composition, 10-15 parts fly ash, 5-10 parts bentonite, 2-3 parts silane coupling agent, and 1.5-2 parts water reducer. The polyurea composition includes polyurea@LDHs, which are prepared by doping polyurea with a layered magnesium-aluminum composite material. The concrete anti-cracking and anti-seepage material prepared in this application has the advantages of crack resistance and good anti-seepage performance.

Description

Technical Field

[0001] The present application belongs to the technical field of concrete anti-seepage materials, and in particular relates to a concrete anti-cracking and anti-seepage material and a preparation method thereof. Background Art

[0002] Concrete has become a key building material due to its wide availability, low cost, high strength, and durability. It is widely used in civil engineering, water conservancy, and other infrastructure construction both domestically and internationally. However, concrete is brittle, making it susceptible to cracking during service. This not only affects the appearance and proper use of the structure, but also seriously impacts its safety.

[0003] Concrete cracks are caused by many factors. Studies have shown that the combined effects of temperature, humidity, concrete shrinkage, and various load conditions in the concrete environment lead to the formation of tiny cracks and cracking. Early cracks in concrete are often small and poorly located, making them difficult to detect. Over time, these tiny cracks spread and expand until they become larger cracks. As water molecules and harmful substances in these cracks penetrate the concrete, the concrete structure is degraded, causing damage. These corrosive media promote corrosion of internal steel reinforcement and intensify the carbonization process of concrete, significantly reducing its durability.

[0004] Improving concrete's crack resistance and impermeability is crucial, and some progress has been made. For example, cement-based penetrating crystalline waterproofing materials, whose primary components include raw materials such as Portland cement or ordinary Portland cement and quartz sand, are infused with active substances. These active substances, under the influence of water, penetrate the concrete, migrate along cracks and pores, and react with cement hydration products to form insoluble crystalline products, which fill cracks and pores, increasing the concrete's compactness and repairing cracks, thereby improving concrete's waterproofing properties.

[0005] For example, the patent application document with application publication number CN116854436A discloses a fixed-particle-size polyurea powder concrete and its preparation method, which includes 100 parts of cement, 132-146 parts of fine aggregate mesoporous calcium sulfate, 283-285 parts of coarse aggregate, 5.8-6 parts of polyurea powder, and 50 parts of water in parts by mass; wherein, the polyurea powder is obtained by mixed polymerization reaction of phenylene-1,4-diisocyanate and 3-aminopropyltrimethoxysilane, followed by crushing, grinding, and sieving; the prepared fixed-particle-size polyurea powder concrete has strong compressive strength and good waterproof properties.

[0006] The above-mentioned use of polyurea and concrete materials can improve the waterproof performance to a certain extent, but compared with the polyurea spray waterproof construction method, direct mixing and adaptation will lead to poor compatibility, and the crack resistance performance still has room for improvement. Summary of the Invention

[0007] In view of the above problems, in order to further improve the anti-cracking and anti-seepage performance of the polyurea / concrete mixed system, the present application provides a concrete anti-cracking and anti-seepage material and a preparation method thereof.

[0008] The present application first provides a concrete anti-cracking and anti-seepage material, comprising the following raw materials in parts by weight: 80-120 parts of cement, 20-30 parts of silica fume, 5-10 parts of a polyurea composition, 10-15 parts of fly ash, 5-10 parts of bentonite, 2-3 parts of a silane coupling agent, and 1.5-2 parts of a water reducer; the polyurea composition comprises polyurea@LDHs, which is prepared by doping polyurea with a layered magnesium-aluminum composite material.

[0009] Furthermore, the polyurea@LDHs is prepared by the following steps:

[0010] 1) Dissolve magnesium nitrate and aluminum nitrate in deionized water to prepare a base solution; add aminocyclodextrin and glycine to the deionized water, mix well, and adjust the pH to 10-11 to prepare a buffer solution;

[0011] 2) Adding the base liquid and sodium hydroxide solution simultaneously to the buffer solution, filtering after aging, drying and calcining to obtain a layered support;

[0012] 3) Disperse the polyurea and layered carrier in acetone, and then slowly evaporate to a viscous state.

[0013] Furthermore, in step 1), the molar ratio of magnesium nitrate to aluminum nitrate is (5-5.5):1;

[0014] And / or, in step 1), the mass ratio of aminocyclodextrin to glycine is 1:(2-3.5);

[0015] And / or, in step 1), adjusting the pH value to 10-11 is done by using sodium hydroxide.

[0016] Furthermore, in step 2), the volume ratio of the base liquid to the sodium hydroxide solution is 1:(1-1.1);

[0017] And / or, in step 2), the calcination is carried out at 500-600° C. for 5-6.5 hours under an inert gas atmosphere.

[0018] Furthermore, in step 3), polyurea is prepared by reacting diphenylmethane diisocyanate with polytetramethylene ether glycol bis-p-aminobenzoate.

[0019] Furthermore, the polyurea composition further comprises modified polyurea, and the modified polyurea is prepared by a method comprising the following steps:

[0020] S1: Mix water, anhydrous ethanol, and a template agent, then add ammonia water, add tetraethyl orthosilicate under constant stirring, centrifuge after reaction, and collect the precipitate; disperse the obtained precipitate in anhydrous ethanol, then add hydrochloric acid, reflux the reaction, remove the template agent, centrifuge, collect the precipitate, wash, and freeze-dry to obtain the pre-material;

[0021] S2: Mix isophorone diisocyanate and 2,2-dimethylolpropionic acid evenly, then slowly add the acetone solution of polyetheramine dropwise. After the reaction is complete, add hydroxyethyl acrylate and continue the reaction. Add triethylamine to neutralize, then add deionized water, disperse evenly, remove the acetone, add the pre-mixed material, shake and stir, and filter to obtain the intermediate material;

[0022] S3: Add chitosan and aldehyde to anhydrous ethanol, stir for reaction, then add the intermediate material and calcium lactate, disperse evenly, dry and grind to obtain the product.

[0023] Furthermore, in step S1, the template agent is one of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and dioctadecyldimethylammonium chloride.

[0024] Furthermore, in step S2, the molar ratio of isophorone diisocyanate to polyetheramine is (3-5):1;

[0025] And / or, in step S2, the 2,2-dimethylol propionic acid accounts for 10-15% of the mass of isophorone diisocyanate.

[0026] Furthermore, in step S3, the molar ratio of chitosan to aldehyde is 1:(3-3.5);

[0027] And / or, in step S3, the aldehyde is one or more of cinnamaldehyde, citronellal, citral, and syringaldehyde;

[0028] And / or, in step S3, the mass ratio of the intermediate material to calcium lactate is 1:(0.1-0.15).

[0029] The present application also provides a method for preparing a concrete anti-cracking and anti-seepage material, comprising the following steps: uniformly mixing cement, silica fume, polyurea composition, fly ash, bentonite, silane coupling agent, and water reducer in proportion to obtain the material.

[0030] Compared with the prior art, this application has the following beneficial effects:

[0031] 1. This application utilizes a concrete / polyurea composite anti-seepage system, which effectively fills and seals large wall cracks, underground engineering cracks, and other point, line, and surface leaks. It can also be used as a basic gel component for hydraulic structures, significantly improving the anti-crack and anti-seepage properties of the building. Furthermore, the use of a layered magnesium-aluminum composite material doped with polyurea can form a three-dimensional interlocking structure, and a certain amount of polyurea is also permeated and loaded within the interlayers of the layered magnesium-aluminum composite material. This not only improves the compatibility between the polyurea component and other components, but also allows for better bonding between the layered magnesium-aluminum composite material and other components during the curing process, enhancing the strength of the interlocking structure, inhibiting and preventing crack propagation, and improving the system's anti-crack and anti-seepage properties.

[0032] 2. The present application also introduces modified polyurea on the basis of the layered interlocking structure, and absorbs the water-based polyurea component through the pre-material with a mesoporous structure, and then uses Schiff base gel and calcium lactate to jointly seal and coat the surface of the pre-material. In the subsequent service process, calcium lactate and Schiff base gel can be unsealed in a water environment, which has a certain degree of self-repair effect. Moreover, after unsealing, calcium lactate and Schiff base gel can slowly produce calcium ions, aldehydes and chitosan components, among which calcium ions can participate in the hydration reaction and improve the strength of the concrete structure; aldehydes can inhibit bacteria and corrosion, hinder the corrosion of corrosive media on steel bars, and reduce the corrosion and expansion of the tendons; chitosan components can provide crystal nucleus sites for concrete hydration products, promote the formation of solidification phases such as calcite, and further improve the toughness and anti-leakage performance of the system. In addition, the cross-linked structure of the water-based polyurea in the unsealed pre-material can be slightly dissolved and swelled to a certain extent when it comes into contact with water, thereby filling the microcracks inside the system, thereby improving the long-term anti-seepage effect of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of performance test data of concrete anti-cracking and anti-seepage materials of Examples 1-3 and Control Groups 1-2 of the present application;

[0034] Figure 2 This is the SEM image of the modified polyurea of ​​Example 2 of the present application;

[0035] Figure 3 This is the TEM image of the modified polyurea of ​​Example 2 of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] After extensive experimental research, this application utilizes a combination of two polyurea components to significantly enhance the crack resistance and seepage control performance of a concrete-based anti-seepage system. This embodiment provides a concrete anti-cracking and anti-seepage material comprising the following raw materials in parts by weight: 80-120 parts cement, 20-30 parts silica fume, 5-10 parts polyurea composition, 10-15 parts fly ash, 5-10 parts bentonite, 2-3 parts silane coupling agent, and 1.5-2 parts water reducer. The polyurea composition comprises polyurea@LDHs, which are prepared by doping polyurea with a layered magnesium-aluminum composite material.

[0038] In some specific embodiments, the concrete anti-cracking and anti-seepage material includes the following raw materials in parts by weight: 120 parts of cement, 30 parts of silica fume, 10 parts of polyurea composition, 10 parts of fly ash, 8 parts of bentonite, 3 parts of silane coupling agent, and 2 parts of water reducer. At this time, better experimental results can be obtained.

[0039] Furthermore, the polyurea@LDHs is prepared by the following steps:

[0040] 1) Dissolve magnesium nitrate and aluminum nitrate in deionized water to prepare a base solution; add aminocyclodextrin and glycine to the deionized water, mix well, and adjust the pH to 10-11 to prepare a buffer solution;

[0041] 2) Adding the base liquid and sodium hydroxide solution simultaneously to the buffer solution, filtering after aging, drying and calcining to obtain a layered support;

[0042] 3) Disperse the polyurea and layered carrier in acetone, and then slowly evaporate to a viscous state.

[0043] Furthermore, in step 1), the molar ratio of magnesium nitrate to aluminum nitrate is (5-5.5):1;

[0044] And / or, in step 1), the mass ratio of aminocyclodextrin to glycine is 1:(2-3.5);

[0045] And / or, in step 1), adjusting the pH value to 10-11 is done by using sodium hydroxide.

[0046] In some specific embodiments, in step 1), the molar ratio of magnesium nitrate to aluminum nitrate can be 5:1, 5.1:1, 5.2:1, 5.3:1, 5.4:1, or 5.5:1. Generally, in step 1), a molar ratio of magnesium nitrate to aluminum nitrate of 5:1 can achieve better experimental results.

[0047] In some specific embodiments, in step 1), the mass ratio of aminocyclodextrin to glycine can be 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.3, or 1:3.5. Generally, in step 1), a mass ratio of aminocyclodextrin to glycine of 1:3 can achieve better experimental results.

[0048] In some specific embodiments, in step 1), adjusting the pH value to 10-11 is to use sodium hydroxide to adjust the pH value to 10, in which case better experimental results can be obtained.

[0049] Furthermore, in step 2), the volume ratio of the base liquid to the sodium hydroxide solution is 1:(1-1.1);

[0050] And / or, in step 2), the calcination is carried out at 500-600° C. for 5-6.5 hours under an inert gas atmosphere.

[0051] Furthermore, in step 3), polyurea is prepared by reacting diphenylmethane diisocyanate with polytetramethylene ether glycol bis-p-aminobenzoate.

[0052] In some specific embodiments, in step 2), the volume ratio of the base liquid to the sodium hydroxide solution can be 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09, or 1:1.1. Generally, in step 2), a volume ratio of the base liquid to the sodium hydroxide solution of 1:1.05 achieves better results.

[0053] In some specific embodiments, in step 2), the calcination is carried out at 550° C. for 5.5 h under an inert gas atmosphere, and the experimental effect is better at this time.

[0054] Furthermore, the polyurea composition further comprises modified polyurea, and the modified polyurea is prepared by a method comprising the following steps:

[0055] S1: Mix water, anhydrous ethanol, and a template agent, then add ammonia water, add tetraethyl orthosilicate under constant stirring, centrifuge after reaction, and collect the precipitate; disperse the obtained precipitate in anhydrous ethanol, then add hydrochloric acid, reflux the reaction, remove the template agent, centrifuge, collect the precipitate, wash, and freeze-dry to obtain the pre-material;

[0056] S2: Mix isophorone diisocyanate and 2,2-dimethylolpropionic acid evenly, then slowly add the acetone solution of polyetheramine dropwise. After the reaction is complete, add hydroxyethyl acrylate and continue the reaction. Add triethylamine to neutralize, then add deionized water, disperse evenly, remove the acetone, add the pre-mixed material, shake and stir, and filter to obtain the intermediate material;

[0057] S3: Add chitosan and aldehyde to anhydrous ethanol, stir for reaction, then add the intermediate material and calcium lactate, disperse evenly, dry and grind to obtain the product.

[0058] Furthermore, in step S1, the template agent is one of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and dioctadecyldimethylammonium chloride. More preferably, under normal circumstances, better experimental results can be obtained when hexadecyltrimethylammonium bromide is used as the template agent.

[0059] Furthermore, in step S2, the molar ratio of isophorone diisocyanate to polyetheramine is (3-5):1;

[0060] And / or, in step S2, the 2,2-dimethylol propionic acid accounts for 10-15% of the mass of isophorone diisocyanate.

[0061] Furthermore, in step S3, the molar ratio of chitosan to aldehyde is 1:(3-3.5);

[0062] And / or, in step S3, the aldehyde is one or more of cinnamaldehyde, citronellal, citral, and syringaldehyde;

[0063] And / or, in step S3, the mass ratio of the intermediate material to calcium lactate is 1:(0.1-0.15).

[0064] In some specific embodiments, in step S2, the molar ratio of isophorone diisocyanate to polyetheramine can be 3: 1, 3.5: 1, 4: 1, 4.5: 1, or 5: 1. Generally, in step S2, when the molar ratio of isophorone diisocyanate to polyetheramine is 3.5: 1, better experimental results can be obtained.

[0065] In some specific embodiments, in step S2, the 2,2-dimethylolpropionic acid may account for 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, or 15% of the mass of isophorone diisocyanate. Generally, in step S2, when the 2,2-dimethylolpropionic acid accounts for 15% of the mass of isophorone diisocyanate, better experimental results can be achieved.

[0066] In some specific embodiments, in step S3, the molar ratio of chitosan to aldehyde can be 1:3, 1:3.1, 1:3.2, 1:3.3, 1:3.4, or 1:3.5. Generally, in step S3, when the molar ratio of chitosan to aldehyde is 1:3.5, better experimental results can be obtained.

[0067] In some specific embodiments, in step S3, better experimental results can be obtained when the aldehyde is cinnamaldehyde.

[0068] In some specific embodiments, in step S3, the mass ratio of the intermediate material to calcium lactate can be 1:0.1, 1:0.11, 1:0.12, 1:0.13, 1:0.14, or 1:0.15. Generally, in step S3, a mass ratio of the intermediate material to calcium lactate of 1:0.1 can achieve better experimental results.

[0069] The present application also provides a method for preparing a concrete anti-cracking and anti-seepage material, comprising the following steps: uniformly mixing cement, silica fume, polyurea composition, fly ash, bentonite, silane coupling agent, and water reducer in proportion to obtain the material.

[0070] Example 1

[0071] The concrete anti-cracking and anti-seepage material of this embodiment includes the following raw materials by weight: 12 kg of cement, 3 kg of silica fume, 1 kg of polyurea composition, 1 kg of fly ash, 0.8 kg of bentonite, 0.3 kg of silane coupling agent, and 0.2 kg of water reducer.

[0072] The cement is PO42.5 ordinary Portland cement. The fly ash is first-grade fly ash. The bentonite is sodium bentonite. The silane coupling agent is KH550. The water reducer is a polycarboxylate high-efficiency water reducer.

[0073] The polyurea composition of this embodiment is polyurea@LDHs, which is prepared by the following steps:

[0074] 1) Dissolve 128.2 g of magnesium nitrate and 37.5 g of aluminum nitrate in 2 L of deionized water to prepare a base solution. Add 38.3 g of aminocyclodextrin and 115 g of glycine to 2 L of deionized water and mix thoroughly. Adjust the pH to 10 with sodium hydroxide to prepare a buffer solution.

[0075] 2) Add 1 L of buffer to a reactor equipped with a stirrer and a thermometer. Then, simultaneously add 2 L of base solution and 2 L of sodium hydroxide solution to the buffer at a rate of 1 mL / min. After aging at room temperature for 12 hours, filter the filtrate. Wash the filtrate with deionized water, freeze-dry, and then transfer to a tube furnace and calcine at 550°C for 5.5 hours under a nitrogen atmosphere to obtain a layered support.

[0076] 3) Disperse 120 g of polyurea and 30 g of the layered carrier in acetone, ultrasonically disperse, and slowly evaporate to a viscous state. The polyurea is prepared by the reaction of diphenylmethane diisocyanate and polytetramethylene ether glycol bis-p-aminobenzoate.

[0077] The preparation method of the concrete anti-cracking and anti-seepage material of this embodiment comprises the following steps: placing cement, silica fume, polyurea composition, fly ash, bentonite, silane coupling agent and water reducing agent in a high-speed mixer according to the above proportions and mixing them evenly.

[0078] Example 2

[0079] The concrete anti-cracking and anti-seepage material of this embodiment includes the following raw materials by weight: 12 kg of cement, 3 kg of silica fume, 1 kg of polyurea composition, 1 kg of fly ash, 0.8 kg of bentonite, 0.3 kg of silane coupling agent, and 0.2 kg of water reducer.

[0080] The cement is PO42.5 ordinary Portland cement. The fly ash is first-grade fly ash. The bentonite is sodium bentonite. The silane coupling agent is KH550. The water reducer is a polycarboxylic acid high-efficiency water reducer. The polyurea composition comprises polyurea@LDHs and modified polyurea in a mass ratio of 1:0.35.

[0081] The polyurea@LDHs of this embodiment was prepared by the following steps:

[0082] 1) Dissolve 128.2 g of magnesium nitrate and 37.5 g of aluminum nitrate in 2 L of deionized water to prepare a base solution. Add 38.3 g of aminocyclodextrin and 115 g of glycine to 2 L of deionized water and mix thoroughly. Adjust the pH to 10 with sodium hydroxide to prepare a buffer solution.

[0083] 2) Add 1 L of buffer to a reactor equipped with a stirrer and a thermometer. Then, simultaneously add 2 L of base solution and 2 L of sodium hydroxide solution to the buffer at a rate of 1 mL / min. After aging at room temperature for 12 hours, filter the filtrate. Wash the filtrate with deionized water, freeze-dry, and then transfer to a tube furnace and calcine at 550°C for 5.5 hours under a nitrogen atmosphere to obtain a layered support.

[0084] 3) Disperse 120 g of polyurea and 30 g of the layered carrier in acetone, ultrasonically disperse, and slowly evaporate to a viscous state. The polyurea is prepared by the reaction of diphenylmethane diisocyanate and polytetramethylene ether glycol bis-p-aminobenzoate.

[0085] The modified polyurea of ​​this embodiment is prepared by a method comprising the following steps:

[0086] S1: 1.5 L of water, 0.5 L of anhydrous ethanol, and 6.5 g of hexadecyltrimethylammonium bromide were ultrasonically mixed, and then 15 mL of ammonia water was added. 16 mL of ethyl orthosilicate was added under continuous stirring. After the reaction, centrifugation was performed to collect the precipitate. The obtained precipitate was dispersed in 1 L of anhydrous ethanol, and then 2 mL of 35% hydrochloric acid was added. After the reaction was refluxed at 60°C, the template was removed, and the precipitate was centrifuged and collected. After washing, it was freeze-dried in a vacuum freeze dryer to obtain the pre-material.

[0087] S2: Take isophorone diisocyanate (IPDI) and 2,2-dihydroxymethylpropionic acid and mix them evenly, with 2,2-dihydroxymethylpropionic acid accounting for 15% of the mass of isophorone diisocyanate. Then, slowly add a solution of polyetheramine (D2000, dehydrated and dried before use) in acetone, control the addition time to 1 hour, and control the molar ratio of isophorone diisocyanate to polyetheramine to be 3.5:1; after the reaction is complete at 75°C, add hydroxyethyl acrylate, continue the reaction at 60°C until -NCO cannot be detected, cool to 45°C, add triethylamine and react for 30 minutes, then add deionized water, disperse evenly, remove acetone, then add the pre-mixed material and shake and stir for 30 minutes, filter out to obtain the intermediate material;

[0088] S3: Add 30 g of chitosan (150 kDa) to 1 L of anhydrous ethanol to swell it, then add cinnamaldehyde, controlling the molar ratio of chitosan to cinnamaldehyde to be 1:3.5, and stir the reaction at 60°C for 20 h. Then add 500 g of the intermediate material and 50 g of calcium lactate, disperse them evenly, dry them, and then ultrafine jet grind them to obtain the product.

[0089] The preparation method of the concrete anti-cracking and anti-seepage material of this embodiment comprises the following steps: placing cement, silica fume, polyurea composition, fly ash, bentonite, silane coupling agent and water reducing agent in a high-speed mixer according to the above proportions and mixing them evenly.

[0090] Example 3

[0091] The concrete anti-cracking and anti-seepage material of this embodiment includes the following raw materials by weight: 12 kg of cement, 3 kg of silica fume, 1 kg of polyurea composition, 1 kg of fly ash, 0.8 kg of bentonite, 0.3 kg of silane coupling agent, and 0.2 kg of water reducer.

[0092] The cement is PO42.5 ordinary Portland cement. The fly ash is first-grade fly ash. The bentonite is sodium bentonite. The silane coupling agent is KH550. The water reducer is a polycarboxylic acid high-efficiency water reducer. The polyurea composition comprises polyurea@LDHs and modified polyurea in a mass ratio of 1:0.35.

[0093] The polyurea@LDHs of this embodiment was prepared by the following steps:

[0094] 1) Dissolve 128.2 g of magnesium nitrate and 37.5 g of aluminum nitrate in 2 L of deionized water to prepare a base solution. Add 38.3 g of aminocyclodextrin and 115 g of glycine to 2 L of deionized water and mix thoroughly. Adjust the pH to 10 with sodium hydroxide to prepare a buffer solution.

[0095] 2) Add 1 L of buffer to a reactor equipped with a stirrer and a thermometer. Then, simultaneously add 2 L of base solution and 2 L of sodium hydroxide solution to the buffer at a rate of 1 mL / min. After aging at room temperature for 12 hours, filter the filtrate. Wash the filtrate with deionized water, freeze-dry, and then transfer to a tube furnace and calcine at 550°C for 5.5 hours under a nitrogen atmosphere to obtain a layered support.

[0096] 3) Disperse 120 g of polyurea and 30 g of the layered carrier in acetone, ultrasonically disperse, and slowly evaporate to a viscous state. The polyurea is prepared by the reaction of diphenylmethane diisocyanate and polytetramethylene ether glycol bis-p-aminobenzoate.

[0097] The modified polyurea of ​​this embodiment is prepared by a method comprising the following steps:

[0098] S1: 1.5 L of water, 0.5 L of anhydrous ethanol, and 6.5 g of hexadecyltrimethylammonium bromide were ultrasonically mixed, and then 15 mL of ammonia water was added. 16 mL of ethyl orthosilicate was added under continuous stirring. After the reaction, centrifugation was performed to collect the precipitate. The obtained precipitate was dispersed in 1 L of anhydrous ethanol, and then 2 mL of 35% hydrochloric acid was added. After the reaction was refluxed at 60°C, the template was removed, and the precipitate was centrifuged and collected. After washing, it was freeze-dried in a vacuum freeze dryer to obtain the pre-material.

[0099] S2: Take isophorone diisocyanate (IPDI) and 2,2-dihydroxymethylpropionic acid and mix them evenly, with 2,2-dihydroxymethylpropionic acid accounting for 15% of the mass of isophorone diisocyanate. Then, slowly add the acetone solution of polyetheramine (D2000, dehydrated and dried before use) dropwise, control the dropwise addition time to 1 hour, and control the molar ratio of isophorone diisocyanate to polyetheramine to be 3.5:1; after the reaction is complete at 75°C, add hydroxyethyl acrylate, continue the reaction at 60°C until -NCO cannot be detected, cool to 45°C, add triethylamine and react for 30 minutes, then add deionized water, disperse evenly, remove acetone, then add the pre-mixed material and shake and stir for 30 minutes, filter out, and dry to obtain.

[0100] The preparation method of the concrete anti-cracking and anti-seepage material of this embodiment comprises the following steps: placing cement, silica fume, polyurea composition, fly ash, bentonite, silane coupling agent and water reducing agent in a high-speed mixer according to the above proportions and mixing them evenly.

[0101] Control group 1

[0102] The concrete anti-cracking and anti-seepage materials of this control group include the following raw materials by weight: cement 12 kg, silica fume 3 kg, polyurea 1 kg, fly ash 1 kg, bentonite 0.8 kg, silane coupling agent 0.3 kg, and water reducer 0.2 kg.

[0103] The cement is PO42.5 ordinary Portland cement. The fly ash is first-grade fly ash. The bentonite is sodium bentonite. The silane coupling agent is KH550. The water reducer is a polycarboxylic acid high-efficiency water reducer. The polyurea is prepared by the reaction of diphenylmethane diisocyanate and polytetramethylene ether glycol bis-p-aminobenzoate.

[0104] The preparation method of the concrete anti-cracking and anti-seepage material of the control group comprises the following steps: cement, silica fume, polyurea, fly ash, bentonite, silane coupling agent and water reducing agent are placed in a high-speed mixer and mixed evenly according to the above proportions.

[0105] Control group 2

[0106] The concrete anti-cracking and anti-seepage material of this control group includes the following raw materials by weight: 12 kg of cement, 3 kg of silica fume, 1 kg of polyurea composition, 1 kg of fly ash, 0.8 kg of bentonite, 0.3 kg of silane coupling agent, and 0.2 kg of water reducer.

[0107] The cement is PO42.5 ordinary Portland cement. The fly ash is first-grade fly ash. The bentonite is sodium bentonite. The silane coupling agent is KH550. The water reducer is a polycarboxylate high-efficiency water reducer.

[0108] The polyurea composition of the control group was prepared by a method comprising the following steps:

[0109] S1: 1.5 L of water, 0.5 L of anhydrous ethanol, and 6.5 g of hexadecyltrimethylammonium bromide were ultrasonically mixed, and then 15 mL of ammonia water was added. 16 mL of ethyl orthosilicate was added under continuous stirring. After the reaction, centrifugation was performed to collect the precipitate. The obtained precipitate was dispersed in 1 L of anhydrous ethanol, and then 2 mL of 35% hydrochloric acid was added. After the reaction was refluxed at 60°C, the template was removed, and the precipitate was centrifuged and collected. After washing, it was freeze-dried in a vacuum freeze dryer to obtain the pre-material.

[0110] S2: Take isophorone diisocyanate (IPDI) and 2,2-dihydroxymethylpropionic acid and mix them evenly, with 2,2-dihydroxymethylpropionic acid accounting for 15% of the mass of isophorone diisocyanate. Then, slowly add a solution of polyetheramine (D2000, dehydrated and dried before use) in acetone, control the addition time to 1 hour, and control the molar ratio of isophorone diisocyanate to polyetheramine to be 3.5:1; after the reaction is complete at 75°C, add hydroxyethyl acrylate, continue the reaction at 60°C until -NCO cannot be detected, cool to 45°C, add triethylamine and react for 30 minutes, then add deionized water, disperse evenly, remove acetone, then add the pre-mixed material and shake and stir for 30 minutes, filter out to obtain the intermediate material;

[0111] S3: Add 30 g of chitosan (150 kDa) to 1 L of anhydrous ethanol to swell it, then add cinnamaldehyde, controlling the molar ratio of chitosan to cinnamaldehyde to be 1:3.5, and stir the reaction at 60°C for 20 h. Then add 500 g of the intermediate material and 125 g of nano-calcium peroxide, disperse them evenly, dry them, and then ultrafine jet mill them to obtain the product.

[0112] The preparation method of the concrete anti-cracking and anti-seepage material of the control group comprises the following steps: cement, silica fume, polyurea composition, fly ash, bentonite, silane coupling agent and water reducing agent are placed in a high-speed mixer and mixed evenly according to the above proportions.

[0113] Performance testing

[0114] 1. The concrete anti-cracking and anti-seepage materials and aggregates of Examples 1-3 and Control Groups 1-2 were mixed and stirred for 5 minutes, and then water was added and mixed for 5 minutes. Then, the mixture was poured into a mold and vibrated to compact it. After 24 hours, the mixture was demoulded and cured in a standard curing room (temperature 20±2°C, RH>90%). After the curing, samples were obtained for use.

[0115] The mass ratio of concrete anti-cracking and anti-seepage materials, water, and aggregate is 1:0.4:3. The aggregate is composed of coarse aggregate and fine aggregate in a mass ratio of 1:0.58. The fine aggregate is quartz sand with a particle size of 0.38-0.83mm, and the coarse aggregate is 5-15mm crushed stone. The water absorption rate is less than 0.4%, and the apparent density is 2682kg / m 3 .

[0116] According to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", the specimen size is 100×100×100mm, 3 specimens per group, and the 28d splitting tensile strength is tested using a YAW-2000 universal press with a loading speed of 0.05MPa / s. The results are as follows Figure 1 shown.

[0117] 2. Take the above samples and cut them into cylindrical specimens with a diameter of 100mm and a height of 50mm. Each group of specimens has 3 pieces. According to GB / T 50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete", the anti-permeability performance at 28d and 56d was tested. The results are as follows: Figure 1 As shown, it can be seen that Example 2 and Example 3 have better long-term anti-seepage effects than Example 1, but the crack resistance of Example 3 is slightly worse.

[0118] 3. Take the modified polyurea of ​​Example 2 and test its morphology using scanning electron microscopy and transmission electron microscopy. The results are as follows: Figure 2 and Figure 3As shown, it can be seen that the modified polyurea of ​​the present application has a core-shell structure, which can play a self-repairing role during the service process of the material and obtain better long-term anti-seepage performance.

[0119] Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present invention.

Claims

1. A concrete anti-cracking and anti-seepage material, characterized by: The invention comprises the following raw materials in parts by weight: 80-120 parts of cement, 20-30 parts of silica fume, 5-10 parts of polyurea composition, 10-15 parts of fly ash, 5-10 parts of bentonite, 2-3 parts of silane coupling agent, and 1.5-2 parts of water reducer; the polyurea composition comprises polyurea@LDHs and modified polyurea, wherein the polyurea@LDHs is prepared by doping polyurea with a layered magnesium-aluminum composite material; and the modified polyurea is prepared by a method comprising the following steps: S1: Mix water, anhydrous ethanol, and a template agent, then add ammonia water, add tetraethyl orthosilicate under constant stirring, centrifuge after reaction, and collect the precipitate; disperse the obtained precipitate in anhydrous ethanol, then add hydrochloric acid, reflux the reaction, remove the template agent, centrifuge, collect the precipitate, wash, and freeze-dry to obtain the pre-material; S2: Mix isophorone diisocyanate and 2,2-dimethylolpropionic acid evenly, then slowly add the acetone solution of polyetheramine dropwise. After the reaction is complete, add hydroxyethyl acrylate and continue the reaction. Add triethylamine to neutralize, then add deionized water, disperse evenly, remove the acetone, add the pre-mixed material, shake and stir, and filter to obtain the intermediate material; S3: Add chitosan and aldehyde to anhydrous ethanol, stir for reaction, then add the intermediate material and calcium lactate, disperse evenly, dry and grind to obtain the product.

2. The concrete anti-cracking and anti-seepage material according to claim 1, characterized in that: The polyurea@LDHs is prepared by the following steps: 1) Dissolve magnesium nitrate and aluminum nitrate in deionized water to prepare a base solution; add aminocyclodextrin and glycine to the deionized water, mix well, and adjust the pH to 10-11 to prepare a buffer solution; 2) Adding the base liquid and sodium hydroxide solution simultaneously to the buffer solution, filtering after aging, drying and calcining to obtain a layered support; 3) Disperse the polyurea and layered carrier in acetone, and then slowly evaporate to a viscous state.

3. The concrete anti-cracking and anti-seepage material according to claim 2, characterized in that: In the step 1), the molar ratio of magnesium nitrate to aluminum nitrate is (5-5.5):1; And / or, in step 1), the mass ratio of aminocyclodextrin to glycine is 1:(2-3.5); And / or, in step 1), adjusting the pH value to 10-11 is done by using sodium hydroxide.

4. The concrete anti-cracking and anti-seepage material according to claim 2, characterized in that: In the step 2), the volume ratio of the base liquid to the sodium hydroxide solution is 1:(1-1.1); And / or, in step 2), the calcination is carried out at 500-600° C. for 5-6.5 hours under an inert gas atmosphere.

5. The concrete anti-cracking and anti-seepage material according to claim 2, characterized in that: In the step 3), polyurea is prepared by reacting diphenylmethane diisocyanate with polytetramethylene ether glycol bis-p-aminobenzoate.

6. The concrete anti-cracking and anti-seepage material according to claim 1, characterized in that: In the step S1, the template agent is one of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and dioctadecyldimethylammonium chloride.

7. The concrete anti-cracking and anti-seepage material according to claim 1, characterized in that: In step S2, the molar ratio of isophorone diisocyanate to polyetheramine is (3-5):1; And / or, in step S2, the 2,2-dimethylol propionic acid accounts for 10-15% of the mass of isophorone diisocyanate.

8. The concrete anti-cracking and anti-seepage material according to claim 1, characterized in that: In step S3, the molar ratio of chitosan to aldehyde is 1:(3-3.5); And / or, in step S3, the aldehyde is one or more of cinnamaldehyde, citronellal, citral, and syringaldehyde; And / or, in step S3, the mass ratio of the intermediate material to calcium lactate is 1:(0.1-0.15).

9. A method for preparing the concrete anti-cracking and anti-seepage material according to claim 1, characterized in that: The method comprises the following steps: uniformly mixing cement, silica fume, polyurea composition, fly ash, bentonite, silane coupling agent and water reducing agent according to proportion.

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