Cement mortar material repair coating and preparation process thereof

Abstract

The invention provides a cement mortar material repair coating and a preparation process thereof. The cement mortar material repair coating is prepared from the following raw materials in parts by weight: 4 to 6 parts of nano silicon dioxide composite liquid, 6 to 10 parts of bridging agent, 2 to 5 parts of rubber powder, 0.5 to 1.0 part of nano carbon fiber, 3 to 6 parts of modified polyacrylate, 0.8 to 1.2 parts of water reducing agent and 0.3 to 0.7 part of plasticizer. Through the synergistic effect of the nano silicon dioxide composite liquid, the bridging agent and the modified polyacrylate, a'rigid framework-flexible network-dynamic repair 'multilevel structure is formed, so that the performance of the repair agent exceeds that of a traditional repair material. When the thickness of the repaired surface of the cement mortar material repair coating is 10-20 mm, the repair strength requirement can be met, the repair time can be saved, and the repair material can be saved.

Description

Technical Field

[0001] The present invention relates to the technical field of cement mortar materials, and particularly relates to a repair coating for cement mortar materials and a preparation process thereof. Background Art

[0002] Cement mortar materials are composite materials formed by mixing cement as a gelling material with fine aggregates and water in a certain proportion. According to the composition differences, they can be divided into cement mortar and cement concrete. Among them, cement mortar is cement + fine aggregate + water, and cement concrete is cement + fine aggregate + gravel + water. Both harden through cement hydration reaction to form a high-strength structure. Cement mortar materials have the advantages of high strength, good durability, strong water resistance, excellent frost resistance, and low cost. At the same time, the raw materials are widely sourced, so they are widely used in road engineering, bridge structures, and the construction field. However, the hardening process of cement mortar materials generates shrinkage, which easily causes cracks on the road surface and wall surface. The existing repair materials for repairing the cracks in cement mortar materials have a long setting time and are difficult to meet the time requirements for rapid repair. Summary of the Invention

[0003] In view of this, the present invention provides a repair coating for cement mortar materials and a preparation process thereof to solve the above problems.

[0004] The technical solution of the present invention is realized as follows:

[0005] A repair coating for cement mortar materials comprises the following raw materials in parts by weight: 4 - 6 parts of nano-silica composite liquid, 6 - 10 parts of bridging agent, 2 - 5 parts of rubber powder, 0.5 - 1.0 part of nano-carbon fiber, 3 - 6 parts of modified polyacrylate, 0.8 - 1.2 parts of water reducing agent, 0.3 - 0.7 part of plasticizer.

[0006] Further, a repair coating for cement mortar materials comprises the following raw materials in parts by weight: 5 parts of nano-silica composite liquid, 8 parts of bridging agent, 3.5 parts of rubber powder, 0.8 part of carbon nano-fiber, 4.5 parts of modified polyacrylate, 1.0 part of water reducing agent, 0.5 part of plasticizer.

[0007] Furthermore, the nano-silica composite liquid is prepared by the following method: adding nano-silica powder into sodium hydroxide solution at a material-liquid ratio of g / mL of (9 - 11):(180 - 220), performing ultrasonic treatment at 30 - 50 kHz for 25 - 35 min, filtering out the nano-silica powder, centrifugally washing at 4000 - 6000 rpm for 10 - 15 min, adding the washed silica powder into deionized water to obtain an activated nano-silica suspension, and the mass-volume ratio of silica powder to deionized water is g / mL of (9 - 11):(80 - 120); mixing sodium silicate solution and deionized water, then adding polyvinyl alcohol, and stirring at 55 - 65 °C until completely dissolved to obtain solution A, and the mass-volume ratio of sodium silicate solution, deionized water, and polyvinyl alcohol is g / mL of (40 - 60):(250 - 350):(4 - 6); slowly pouring the activated nano-silica suspension into solution A, magnetically stirring at a rotation speed of 400 - 600 rpm for 55 - 65 min to obtain a composite suspension B; adding triethanolamine into composite suspension B at a material-liquid ratio of g / mL of (250 - 300):1, and continuously stirring for 25 - 35 min to obtain a nano-silica composite sol; placing the nano-silica composite sol in a water bath at 45 - 50 °C for aging for 18 - 22 h, and then adjusting the pH to 8.0 - 9.0 with citric acid to obtain the nano-silica composite liquid.

[0008] Furthermore, the bridging agent is prepared by the following method: Sodium silicate is added to deionized water at a material-liquid ratio of g / mL of 1:(9 - 11), and stirred until completely dissolved to obtain solution C; Acrylic acid, 2-hydroxyethyl methacrylate, and tetrasodium ethylenediaminetetraacetate are added to deionized water, stirred until completely dissolved, and sodium hydroxide is added to adjust the pH to 9.0 - 10.0 to obtain solution D, where the mass-volume ratio of acrylic acid, 2-hydroxyethyl methacrylate, tetrasodium ethylenediaminetetraacetate, and deionized water is g / mL (4 - 6):(2.5 - 3.5):(0.9 - 1.1):(45 - 55); Solution D is added dropwise to solution C, and then hydroquinone is added to obtain a mixed solution E, where the volume ratio of solution D, solution C, and hydroquinone is (1.8 - 2.2):(0.9 - 1.1):(0.01 - 0.02); N,N'-methylenebisacrylamide and a silane coupling agent are added to the mixed solution E at a material-liquid ratio of g / mL of (120 - 180):(0.4 - 0.6):(0.6 - 0.9), and stirred at 25 - 30 °C for 25 - 35 min to form a homogeneous hybrid sol; The temperature is raised to 65 - 70 °C, and an ammonium persulfate solution is added at a volume ratio of (135 - 165):(3.0 - 3.5), and the reaction is carried out for 2.0 - 2.5 h under a nitrogen atmosphere. The ammonium persulfate solution is prepared by dissolving ammonium persulfate in deionized water at a material-liquid ratio of g / mL of 1:(30 - 35). Subsequently, carboxylated nano-hydroxyapatite is added at a material-liquid ratio of g / mL of (110 - 190):(1.5 - 2.5), and stirred and reacted for 40 - 60 min. After the reaction is completed, it is cooled to 20 - 30 °C to obtain a gel; The gel is placed under vacuum drying at 50 - 55 °C for 8 - 10 h, and then under vacuum drying at 60 - 65 °C for 10 - 12 h, and passed through a 100 - 200 mesh sieve to obtain the bridging agent.

[0009] Further, the modified polyacrylate is prepared by the following method: Dissolve acrylic acid, methyl methacrylate, and N,N'-methylenebisacrylamide in deionized water to obtain solution F, where the mass-volume ratio of acrylic acid, methyl methacrylate, N,N'-methylenebisacrylamide, and deionized water (g / mL) is (28 - 32):(9 - 11):(0.5 - 1.0):(120 - 180); Dissolve ammonium persulfate in deionized water to obtain an ammonium persulfate solution, where the mass-volume ratio of ammonium persulfate to deionized water (g / mL) is 1:(30 - 35); Adjust the pH of solution F to 7.5 - 8.0 with sodium hydroxide, introduce nitrogen for 35 - 45 min, then raise the temperature to 48 - 52 °C, add the ammonium persulfate solution dropwise to solution F, react for 0.8 - 1.0 h, then raise the temperature to 65 - 75 °C and react for 2.0 - 2.5 h to obtain a polyacrylate copolymer solution, where the volume ratio of solution F to the ammonium persulfate solution is (18 - 20):1; Cool the polyacrylate copolymer solution to 48 - 52 °C, then add ethylenediaminetetraacetic acid tetrasodium at a material-liquid ratio (g / mL) of (12 - 14):1, raise the temperature to 68 - 72 °C and react for 2.5 - 3.5 h, after the reaction is completed, cool to 20 - 30 °C, and add citric acid to adjust the pH to 6.8 - 7.2 to obtain the modified polyacrylate.

[0010] Further, the water reducer is a polycarboxylate water reducer, and the plasticizer is a lignosulfonate solution.

[0011] Further, the particle size of the rubber powder is 80 - 120 mesh, and the particle size of the nano-carbon fiber is 100 - 200 nm.

[0012] Further, the above-mentioned repair agent for cement mortar materials is prepared according to the following process, including the following steps:

[0013] S1. Add the bridging agent, rubber powder, and nano-carbon fiber into a mixer, stir and mix to obtain mixture I;

[0014] S2. Add the nano-silica composite liquid, water reducer, and plasticizer into a stirring kettle, stir and mix to obtain mixture II;

[0015] S3. Add the modified polyacrylate to mixture II, stir and mix to obtain mixture III, and use triethanolamine to adjust the pH to maintain it at 9.0 - 11.0;

[0016] S4. Slowly add mixture I to mixture III, stir evenly and then perform degassing treatment to obtain mixture IV;

[0017] S5. Seal and cure mixture IV to obtain a repair coating for cement mortar materials.

[0018] Further, the stirring speed in S1 is 400 - 600 rpm, and the stirring time is 5 - 10 min; the stirring speed in S2 is 300 - 500 rpm, and the stirring time is 15 - 25 min; the stirring speed in S3 is 150 - 250 rpm, and the stirring time is 10 - 20 min; the stirring speed in S4 is 200 - 400 rpm, the stirring time is 25 - 35 min, the degassing treatment pressure is -0.06 to -0.10 MPa, and the vacuum treatment time is 8 - 12 min; in S5, the sealed curing is carried out at 23 - 27 °C for 22 - 26 h.

[0019] Further, the viscosity of a kind of cement mortar material repair coating prepared in S5 is 500 - 1000 mPa·s.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] For the cement mortar repair coating of the present invention, the silica composite liquid therein can undergo a pozzolanic reaction with calcium hydroxide in the old cement mortar material to generate secondary hydration product C-S-H gel, thereby breaking the inert structure in the old cement mortar material, activating unhydrated cement particles, and forming a dense cross-linked network. The generated C-S-H gel is both the activation product of the old cement mortar material and the bonding medium for cement hydration of the new cement mortar material, thereby realizing chemical bonding at the interface between the new and old cement mortar materials and further fusing the new and old cements. The silanol generated by the hydrolysis of sodium silicate contained in the bridging agent reacts with Ca 2 + at the crack interface to form a three-dimensional calcium silicate gel network, providing immediate rigid support; at the same time, carboxylated nano-hydroxyapatite grows directionally under the guidance of the active interface provided by the nano-silica composite liquid to form C-S-H / nHA hybrid crystals, and realizes mechanical interlocking through the whisker strengthening effect across both sides of the crack, constituting an inorganic reinforcing phase. On this basis, a flexible polymer network formed by the copolymerization of acrylic acid and hydroxyethyl methacrylate interpenetrates the inorganic skeleton, thereby forming an organic-inorganic hybrid network. The modified polyacrylate contains grafted chains of EDTA that can dissolve calcium carbonate and tricalcium silicate in the old cement mortar material, thereby converting calcium carbonate in the crack into soluble EDTA-Ca, and the Ca 2 + dissolved by the modified polyacrylate can be captured by the bridging agent, thereby accelerating mineral deposition. Through the synergistic action of the three, a multi-level structure of "rigid skeleton - flexible network - dynamic repair" is formed, so that the performance of the repair coating exceeds that of traditional repair materials. Detailed implementation manners

[0022] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0023] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0024] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can all be obtained from commercial channels.

[0025] Example 1

[0026] A repair coating of cement mortar material comprises the following raw materials in parts by weight: 4 parts of nano-silica composite liquid, 6 parts of bridging agent, 2 parts of rubber powder, 0.5 part of nano-carbon fiber, 3 parts of modified polyacrylate, 0.8 part of water reducing agent, and 0.3 part of plasticizer. The water reducing agent is a polycarboxylate water reducing agent, and the plasticizer is a lignosulfonate solution. The particle size of the rubber powder is 80 mesh, and the particle size of the nano-carbon fiber is 100 nm.

[0027] Among them, the nano-silica composite liquid is prepared by the following method: adding nano-silica powder to sodium hydroxide solution at a material-liquid ratio of g / mL of 9:180, performing ultrasonic treatment at 30 kHz for 35 min, filtering out the nano-silica powder, centrifugally washing at 4000 rpm for 15 min, adding the washed silica powder to deionized water to obtain an activated nano-silica suspension, and the mass-volume ratio of silica powder to deionized water is g / mL of 9:80; mixing sodium silicate solution and deionized water, then adding polyvinyl alcohol, and stirring at 55 °C until completely dissolved to obtain solution A, and the mass-volume ratio of sodium silicate solution, deionized water, and polyvinyl alcohol is g / mL of 40:250:4; slowly pouring the activated nano-silica suspension into solution A, and magnetically stirring at a rotation speed of 400 rpm for 65 min to obtain a composite suspension B; adding triethanolamine to the composite suspension B at a material-liquid ratio of g / mL of 250:1, and continuing to stir for 35 min to obtain a nano-silica composite sol; placing the nano-silica composite sol in a water bath at 45 °C for 22 h, and then adjusting the pH to 8.0 with citric acid to obtain the nano-silica composite liquid.

[0028] Among them, the bridging agent is prepared by the following method: Sodium silicate is added to deionized water at a material-liquid ratio of g / mL of 1:9 and stirred until completely dissolved to obtain solution C; acrylic acid, 2-hydroxyethyl methacrylate, and tetrasodium ethylenediaminetetraacetate are added to deionized water and stirred until completely dissolved, and sodium hydroxide is added to adjust the pH to 9.0 to obtain solution D. The mass-volume ratio of acrylic acid, 2-hydroxyethyl methacrylate, tetrasodium ethylenediaminetetraacetate, and deionized water is 4:2.5:0.9:45 g / mL; solution D is added dropwise to solution C, and then hydroquinone is added to obtain a mixed solution E. The volume ratio of solution D, solution C, and hydroquinone is 1.8:0.9:0.01; N,N'-methylenebisacrylamide and a silane coupling agent are added to the mixed solution E at a material-liquid ratio of g / mL of 120:0.4:0.6, and stirred at 25°C for 35 min to form a homogeneous hybrid sol; the temperature is raised to 65°C, and an ammonium persulfate solution is added at a volume ratio of 135:3.0, and the reaction is carried out for 2.5 h under a nitrogen atmosphere. The ammonium persulfate solution is prepared by dissolving ammonium persulfate in deionized water at a material-liquid ratio of g / mL of 1:30. Subsequently, carboxylated nano-hydroxyapatite is added at a material-liquid ratio of g / mL of 110:1.5, and stirred and reacted for 60 min. After the reaction is completed, it is cooled to 20°C to obtain a gel; the gel is placed under vacuum drying at 50°C for 10 h, and then under vacuum drying at 60°C for 12 h, and passed through a 100-mesh sieve to obtain the bridging agent.

[0029] Among them, the modified polyacrylate is prepared by the following method: Acrylic acid, methyl methacrylate, and N,N'-methylenebisacrylamide are dissolved in deionized water to obtain solution F. The mass-volume ratio of acrylic acid, methyl methacrylate, N,N'-methylenebisacrylamide, and deionized water is 28:9:0.5:120 g / mL; ammonium persulfate is dissolved in deionized water to obtain an ammonium persulfate solution. The mass-volume ratio of ammonium persulfate to deionized water is 1:30 g / mL; the pH of solution F is adjusted to 7.5 with sodium hydroxide, nitrogen is introduced for 45 min, and then the temperature is raised to 48°C. The ammonium persulfate solution is added dropwise to solution F, and the reaction is carried out for 1.0 h, and then the temperature is raised to 65°C and the reaction is carried out for 2.5 h to obtain a polyacrylate copolymer solution. The volume ratio of solution F to the ammonium persulfate solution is 18:1; the polyacrylate copolymer solution is cooled to 48°C, and then tetrasodium ethylenediaminetetraacetate is added at a material-liquid ratio of g / mL of 12:1, and the temperature is raised to 68°C and the reaction is carried out for 3.5 h. After the reaction is completed, the temperature is cooled to 20°C, and citric acid is added to adjust the pH to 6.8 to obtain the modified polyacrylate.

[0030] Example 2

[0031] A repair coating of cement mortar material, comprising the following raw materials in parts by weight: 6 parts of nano-silica composite liquid, 10 parts of bridging agent, 5 parts of rubber powder, 1.0 part of nano-carbon fiber, 6 parts of modified polyacrylate, 1.2 parts of water reducing agent, 0.7 part of plasticizer. The water reducing agent is a polycarboxylate water reducing agent, and the plasticizer is a lignosulfonate solution. The particle size of the rubber powder is 120 mesh, and the particle size of the nano-carbon fiber is 200 nm.

[0032] Among them, the nano-silica composite liquid is prepared by the following method: adding nano-silica powder to sodium hydroxide solution at a material-liquid ratio of g / mL of 11:220, ultrasonic treating for 25 min at 50 kHz, filtering out the nano-silica powder, centrifugally washing at 6000 rpm for 10 min, adding the washed silica powder to deionized water to obtain an activated nano-silica suspension, and the mass-volume ratio of the silica powder to deionized water is g / mL of 11:120; mixing sodium silicate solution and deionized water, then adding polyvinyl alcohol, and stirring at 65 °C until completely dissolved to obtain solution A, and the mass-volume ratio of the sodium silicate solution, deionized water, and polyvinyl alcohol is g / mL of 60:350:6; slowly pouring the activated nano-silica suspension into solution A, and magnetically stirring at a rotation speed of 600 rpm for 55 min to obtain a composite suspension B; adding triethanolamine to the composite suspension B at a material-liquid ratio of g / mL of 300:1, and continuing to stir for 25 min to obtain a nano-silica composite sol; placing the nano-silica composite sol in a water bath at 50 °C for 18 h, and then adjusting the pH to 9.0 with citric acid to obtain the nano-silica composite liquid.

[0033] Among them, the bridging agent is prepared by the following method: Sodium silicate is added to deionized water at a material-liquid ratio of g / mL of 1:11, and stirred until completely dissolved to obtain solution C; Acrylic acid, 2-hydroxyethyl methacrylate, and tetrasodium ethylenediaminetetraacetate are added to deionized water, stirred until completely dissolved, and sodium hydroxide is added to adjust the pH to 10.0 to obtain solution D. The mass-volume ratio of acrylic acid, 2-hydroxyethyl methacrylate, tetrasodium ethylenediaminetetraacetate, and deionized water is 6:3.5:1.1:55 g / mL; Solution D is added dropwise to solution C, and then hydroquinone is added to obtain a mixed solution E. The volume ratio of solution D, solution C, and hydroquinone is 2.2:1.1:0.02; N,N'-methylenebisacrylamide and silane coupling agent are added to the mixed solution E at a material-liquid ratio of g / mL of 180:0.6:0.9, and stirred at 30 °C for 25 min to form a homogeneous hybrid sol; The temperature is raised to 70 °C, and ammonium persulfate solution is added at a volume ratio of 165:3.5, and reacted for 2.0 h under a nitrogen atmosphere. The ammonium persulfate solution is prepared by dissolving ammonium persulfate in deionized water at a material-liquid ratio of g / mL of 1:35. Subsequently, carboxylated nano-hydroxyapatite is added at a material-liquid ratio of g / mL of 190:2.5, and stirred and reacted for 40 min. After the reaction is completed, it is cooled to 30 °C to obtain a gel; The gel is placed under vacuum drying at 55 °C for 8 h, and then under vacuum drying at 65 °C for 10 h, and passed through a 200-mesh sieve to obtain the bridging agent.

[0034] Among them, the modified polyacrylate is prepared by the following method: Acrylic acid, methyl methacrylate, and N,N'-methylenebisacrylamide are dissolved in deionized water to obtain solution F. The mass-volume ratio of acrylic acid, methyl methacrylate, N,N'-methylenebisacrylamide, and deionized water is 32:11:1.0:180 g / mL; Ammonium persulfate is dissolved in deionized water to obtain an ammonium persulfate solution. The mass-volume ratio of ammonium persulfate to deionized water is 1:35 g / mL; The pH of solution F is adjusted to 8.0 with sodium hydroxide, nitrogen is introduced for 35 min, and then the temperature is raised to 52 °C. The ammonium persulfate solution is added dropwise to solution F, and the reaction is carried out for 0.8 h, and then the temperature is raised to 75 °C and reacted for 2.0 h to obtain a polyacrylate copolymer solution. The volume ratio of solution F to the ammonium persulfate solution is 20:1; The polyacrylate copolymer solution is cooled to 52 °C, and then tetrasodium ethylenediaminetetraacetate is added at a material-liquid ratio of g / mL of 14:1, and the temperature is raised to 72 °C and reacted for 2.5 h. After the reaction is completed, it is cooled to 30 °C, and citric acid is added to adjust the pH to 7.2 to obtain the modified polyacrylate.

[0035] Example 3

[0036] A repair coating of cement mortar material, comprising the following raw materials in parts by weight: 5 parts of nano-silica composite liquid, 8 parts of bridging agent, 3.5 parts of rubber powder, 0.8 part of carbon nanofiber, 4.5 parts of modified polyacrylate, 1.0 part of water reducing agent, and 0.5 part of plasticizer. The water reducing agent is a polycarboxylate water reducing agent, and the plasticizer is a lignosulfonate solution. The particle size of the rubber powder is 100 mesh, and the particle size of the carbon nanofiber is 150 nm.

[0037] Among them, the nano-silica composite liquid is prepared by the following method: Add nano-silica powder to sodium hydroxide solution at a material-liquid ratio of g / mL of 10:200, ultrasonically treat for 30 min at 40 kHz, filter out the nano-silica powder, centrifuge and wash at 5000 rpm for 12.5 min, add the washed silica powder to deionized water to obtain an activated nano-silica suspension, and the mass-volume ratio of silica powder to deionized water is g / mL of 10:100; Mix sodium silicate solution and deionized water, then add polyvinyl alcohol, and stir at 60 °C until completely dissolved to obtain solution A. The mass-volume ratio of sodium silicate solution, deionized water, and polyvinyl alcohol is g / mL of 50:300:5; Slowly pour the activated nano-silica suspension into solution A, and magnetically stir at 500 rpm for 60 min to obtain a composite suspension B; Add triethanolamine to composite suspension B at a material-liquid ratio of g / mL of 275:1, and continue to stir for 30 min to obtain nano-silica composite sol; Place the nano-silica composite sol in a water bath at 47.5 °C and cure for 20 h, and then adjust the pH to 8.5 with citric acid to obtain the nano-silica composite liquid.

[0038] Among them, the bridging agent is prepared by the following method: Sodium silicate is added to deionized water at a material-liquid ratio of g / mL of 1:10 and stirred until completely dissolved to obtain solution C; acrylic acid, 2-hydroxyethyl methacrylate, and tetrasodium ethylenediaminetetraacetate are added to deionized water and stirred until completely dissolved, and then sodium hydroxide is added to adjust the pH to 9.5 to obtain solution D, where the mass-volume ratio of acrylic acid, 2-hydroxyethyl methacrylate, tetrasodium ethylenediaminetetraacetate, and deionized water is g / mL of 5:3.0:1.0:50; solution D is added dropwise to solution C, and then hydroquinone is added to obtain a mixed solution E, where the volume ratio of solution D, solution C, and hydroquinone is 2.0:1.0:0.015; N,N'-methylenebisacrylamide and a silane coupling agent are added to the mixed solution E at a material-liquid ratio of g / mL of 150:0.5:0.75, and stirred at 27.5 °C for 30 min to form a homogeneous hybrid sol; the temperature is raised to 67.5 °C, and an ammonium persulfate solution is added at a volume ratio of 150:3.3, and reacted under a nitrogen atmosphere for 2.0 - 2.5 h. The ammonium persulfate solution is prepared by dissolving ammonium persulfate in deionized water at a material-liquid ratio of g / mL of 1:33. Subsequently, carboxylated nano-hydroxyapatite is added at a material-liquid ratio of g / mL of 150:2.0, and stirred and reacted for 50 min. After the reaction is completed, it is cooled to 25 °C to obtain a gel; the gel is placed under vacuum drying at 52.5 °C for 9 h, and then under vacuum drying at 62.5 °C for 11 h, and passed through a 150-mesh sieve to obtain the bridging agent.

[0039] Among them, the modified polyacrylate is prepared by the following method: Acrylic acid, methyl methacrylate, and N,N'-methylenebisacrylamide are dissolved in deionized water to obtain solution F, where the mass-volume ratio of acrylic acid, methyl methacrylate, N,N'-methylenebisacrylamide, and deionized water is g / mL of 30:10:0.7:150; ammonium persulfate is taken and dissolved in deionized water to obtain an ammonium persulfate solution, where the mass-volume ratio of ammonium persulfate to deionized water is g / mL of 1:32.5; the pH of solution F is adjusted to 7.8 with sodium hydroxide, nitrogen is introduced for 30 min, and then the temperature is raised to 50 °C. The ammonium persulfate solution is added dropwise to solution F, and the reaction is carried out for 0.9 h, and then the temperature is raised to 70 °C and reacted for 2.2 h to obtain a polyacrylate copolymer solution, where the volume ratio of solution F to the ammonium persulfate solution is 19:1; the polyacrylate copolymer solution is cooled to 50 °C, and then tetrasodium ethylenediaminetetraacetate is added at a material-liquid ratio of g / mL of 13:1, and the temperature is raised to 70 °C and reacted for 3.0 h. After the reaction is completed, it is cooled to 25 °C, and citric acid is added to adjust the pH to 7.0 to obtain the modified polyacrylate.

[0040] The repair coating of a cement mortar material described in Examples 1 - 3 is prepared according to the following process, including the following steps:

[0041] S1. Add the bridging agent, rubber powder, and nano-carbon fiber into a blender and stir at 500 rpm for 7.5 min to obtain mixture Ⅰ;

[0042] S2. Add the nano-silica composite liquid, water reducing agent, and plasticizer into a stirring kettle and stir at 400 rpm for 20 min to obtain mixture Ⅱ;

[0043] S3. Add the modified polyacrylate into mixture Ⅱ and stir at 200 rpm for 15 min to obtain mixture Ⅲ. Use triethanolamine to adjust the pH to maintain it at 10.0;

[0044] S4. Slowly add mixture Ⅰ into mixture Ⅲ and stir at 300 rpm for 30 min. Then, perform degassing treatment under a treatment pressure of -0.080 MPa and vacuum treatment for 10 min to obtain mixture Ⅳ;

[0045] S5. Seal and cure mixture Ⅳ at 25 °C for 24 h to obtain a repair coating for cement mortar material. The viscosity of this cement mortar material repair agent is 750 mPa·s.

[0046] Example 4

[0047] This example is compared with Example 3. The difference is that the repair coating for cement mortar material is prepared according to the following process, including the following steps:

[0048] S1. Add the bridging agent, rubber powder, and nano-carbon fiber into a blender and stir at 400 rpm for 10 min to obtain mixture Ⅰ;

[0049] S2. Add the nano-silica composite liquid, water reducing agent, and plasticizer into a stirring kettle and stir at 300 rpm for 25 min to obtain mixture Ⅱ;

[0050] S3. Add the modified polyacrylate into mixture Ⅱ and stir at 150 rpm for 20 min to obtain mixture Ⅲ. Use triethanolamine to adjust the pH to maintain it at 9.0;

[0051] S4. Slowly add mixture Ⅰ into mixture Ⅲ and stir at 200 rpm for 35 min. Then, perform degassing treatment under a treatment pressure of -0.06 MPa and vacuum treatment for 12 min to obtain mixture Ⅳ;

[0052] S5. Seal and cure mixture Ⅳ at 23 °C for 26 h to obtain a repair coating for cement mortar material. The viscosity of this cement mortar material repair agent is 500 mPa·s.

[0053] Example 5

[0054] This embodiment is compared with Embodiment 3. The difference lies in that a repair coating of a cement mortar material is prepared according to the following process, including the following steps:

[0055] S1. Add a bridging agent, rubber powder, and nano-carbon fiber into a blender, and stir at 600 rpm for 5 min to obtain Mixture Ⅰ;

[0056] S2. Add a nano-silica composite liquid, water reducing agent, and plasticizer into a stirring kettle, and stir at 500 rpm for 15 min to obtain Mixture Ⅱ;

[0057] S3. Add a modified polyacrylate into Mixture Ⅱ, and stir at 250 rpm for 10 min to obtain Mixture Ⅲ. Use triethanolamine to adjust the pH to maintain it at 11.0;

[0058] S4. Slowly add Mixture Ⅰ into Mixture Ⅲ, stir at 400 rpm for 25 min, and then perform degassing treatment under a treatment pressure of -0.10 MPa, and vacuum treat for 8 min to obtain Mixture Ⅳ;

[0059] S5. Seal and cure Mixture Ⅳ at 27 °C for 22 h to obtain a repair coating of a cement mortar material. The viscosity of this cement mortar material repair agent is 1000 mPa·s.

[0060] Comparative Example 1

[0061] This comparative example is compared with Embodiment 3. The difference lies in that the raw materials of a repair coating of a cement mortar material do not include a nano-silica composite liquid.

[0062] Comparative Example 2

[0063] This comparative example is compared with Embodiment 3. The difference lies in that the raw materials of a repair coating of a cement mortar material do not include a bridging agent.

[0064] Comparative Example 3

[0065] This comparative example is compared with Embodiment 3. The difference lies in that the raw materials of a repair coating of a cement mortar material do not include a modified polyacrylate.

[0066] Comparative Example 4

[0067] This comparative example is compared with Example 3. The difference is that an equal-volume polyacrylate copolymer solution is used instead of the modified polyacrylate. The polyacrylate copolymer solution is prepared by the following method: Acrylic acid, methyl methacrylate, and N,N'-methylenebisacrylamide are dissolved in deionized water to obtain Solution F. The mass-volume ratio of acrylic acid, methyl methacrylate, N,N'-methylenebisacrylamide, and deionized water is 30:10:0.7:150 g / mL. Ammonium persulfate is dissolved in deionized water to obtain an ammonium persulfate solution. The mass-volume ratio of ammonium persulfate to deionized water is 1:32.5 g / mL. The pH of Solution F is adjusted to 7.8 with sodium hydroxide, nitrogen is introduced for 30 min, and then the temperature is raised to 50 °C. The ammonium persulfate solution is added dropwise to Solution F, and the reaction is carried out for 0.9 h. Then the temperature is raised to 70 °C and the reaction is carried out for 2.2 h to obtain the polyacrylate copolymer solution.

[0068] Comparative Example 5

[0069] This comparative example is compared with Example 3. The difference is that the repair coating of the cement mortar material is a commercially available cement mortar material repair agent.

[0070] Determination of repair effect

[0071] Cement concrete matrix specimens of 200×200×100 mm are made, and cracks with a length of 100 mm and a width of 0.5 mm penetrate through the specimens. The repair agents of Examples 1-5 and Comparative Examples 1-5 are added to the cement concrete composed of cement + fine aggregate + gravel + water at a ratio of 5%, stirred evenly, and respectively applied to the surface of the specimens with a coating thickness of 15 mm. Then, they are cured for 48 h at 25 °C and a humidity of 95%. Subsequently, the bond strength between the repair layer and the matrix and the cracking strain threshold of the repair layer are tested. 5 specimens are tested in each group, and the average results are recorded in Table 1.

[0072] Determination of setting time

[0073] Under the conditions of a temperature of 20 °C and a humidity of 50%, the repair agents of Examples 1-5 and Comparative Examples 1-5 are added to the cement mortar composed of cement + fine aggregate + water at a ratio of 5%, stirred evenly, and the initial setting time and final setting time are measured. 3 specimens are tested in each group, and the average results are recorded in Table 1.

[0074] Table 1

[0075]

[0076] As can be seen from Table 1, the repair coatings of the cement mortar materials prepared in Examples 1-5 can better bond with the cement mortar materials, so that the repaired cement mortar materials have stronger bonding strength and higher anti-strain cracking ability. Moreover, the repair additive coatings of the cement mortar prepared in Examples 1-5 can save the initial setting time and final setting time of the cement mortar materials. Therefore, it can better meet the time requirements for rapid repair during road repair.

[0077] When the repair coating of the cement mortar material of the present invention is used, it can not only chemically react with the underlying cement to achieve deep repair, but also form a dense protective layer on the surface, thus providing a dual protection effect. Its core mechanism is as follows: 1. Activation and penetration of the nano-silica composite liquid: The hydroxyl groups on the surface of the nano-silica contained in the nano-silica composite liquid can undergo a pozzolanic reaction with calcium hydroxide in the old cement mortar material to generate secondary hydration product C-S-H gel, thereby breaking the inert structure in the old cement mortar material, activating unhydrated cement particles, and forming a dense cross-linked network. The generated C-S-H gel is both the activation product of the old cement mortar material and the bonding medium for the cement hydration of the new cement mortar material, thus realizing chemical bonding at the interface between the new and old cement mortar materials and further promoting the deep fusion of the new and old cements. The unhydrated cement particles in the old cement mortar material are eroded by nano-silica, the silicon-oxygen bonds on the surface are broken, and Ca 2 + participates in secondary hydration. Moreover, the nano-silica composite liquid can also penetrate into cracks through capillary action, fill micro-pores, and form a nano-level protective layer on the surface, improving impermeability and durability. 2. Dynamic crack bridging and strengthening of the bridging agent: The bridging agent realizes dynamic crack repair through an organic-inorganic hybrid network: Inorganic strengthening: Sodium ethylenediaminetetraacetate in the bridging agent can chelate Ca 2 +, locally increasing the calcium ion concentration and accelerating C-S-H nucleation, thereby shortening the setting time. Ammonium persulfate in the bridging agent can initiate polymerization to form a pre-crosslinked network, reducing the curing waiting time. Moreover, the active interface provided by the nano-silica in the nano-silica composite liquid can promote the directional growth of carboxylated nano-hydroxyapatite in the bridging agent, guiding the formation of C-S-H / nHA hybrid crystals at the crack interface, penetrating both sides of the crack to form mechanical interlocking, thereby enhancing the bonding strength. The silane coupling agent in the bridging agent forms Si-O-Si covalent bonds at the interface, thus improving the water resistance of the cement mortar material. Organic toughening: 2-Hydroxyethyl methacrylate in the bridging agent provides flexible chain segments, and sodium ethylenediaminetetraacetate forms a carboxyl group with Ca 2+ After forming dynamic coordination bonds to absorb strain energy, through the dynamic bond recombination of EDTA-Ca, the crack propagation is inhibited, thereby improving the anti-strain cracking ability. 3. Synergistic strengthening and self-healing of modified polyacrylate: The carboxyl groups in the modified polyacrylate can capture free calcium ions at the crack interface, form an ionic cross-linked network, accelerate mineral deposition, and accelerate the structuring of the paste, thereby shortening the setting time. By grafting tetrasodium ethylenediaminetetraacetate, Ca 2 + chelating sites are continuously released and react with unhydrated cement particles at the crack interface to generate secondary C-S-H, further enhancing the bond strength. When microcracks appear, the EDTA-Ca complex dissociates and recombines dynamically to achieve self-healing, thereby providing anti-strain cracking ability. Moreover, hydrogen bonds are formed between the hydroxyl groups on the surface of the nano-silica in the nano-silica composite liquid and the carboxyl groups in the modified polyacrylate, increasing the elastic modulus of the material and further improving the anti-strain cracking ability. 4. Synergistic effect and formation of protective layer: When the repair coating of the cement mortar material of the present invention is used, it not only undergoes a chemical reaction with the underlying cement to achieve deep repair, but also forms a dense nano-composite protective layer on the surface, effectively blocking the erosion of harmful media such as moisture and chloride ions. Through the synergistic effect of the three, a multi-level structure of "rigid skeleton - flexible network - dynamic repair" is formed, so that the performance of the repair agent exceeds that of traditional repair materials.

[0078] By comparing Examples 1-5 with Comparative Example 5, the repair coatings of the cement mortar materials prepared in Examples 1-5 not only have a short setting time and can better meet the time requirements for rapid repair. At the same time, the bond strength and anti-strain cracking ability of Examples 1-5 are higher than those of commercially available cement mortar material repair agents. Using the cement mortar repair coatings of Examples 1-5 to repair the surface with a thickness of 10-20 mm can meet the repair strength requirements, saving both time and materials.

[0079] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A repair coating of cement mortar material, characterized in that, It comprises the following raw materials in parts by weight: 4 - 6 parts of nano - silica composite liquid, 6 - 10 parts of bridging agent, 2 - 5 parts of rubber powder, 0.5 - 1.0 part of nano - carbon fiber, 3 - 6 parts of modified polyacrylate, 0.8 - 1.2 parts of water - reducing agent, and 0.3 - 0.7 part of plasticizer.

2. The repair coating of a cement mortar material according to claim 1, wherein It comprises the following raw materials in parts by weight: 5 parts of nano - silica composite liquid, 8 parts of bridging agent, 3.5 parts of rubber powder, 0.8 part of carbon nano - fiber, 4.5 parts of modified polyacrylate, 1.0 part of water - reducing agent, and 0.5 part of plasticizer.

3. A repair coating of a cement mortar material as described in claim 1, wherein, The nano - silica composite liquid is prepared by the following method: The nano - silica powder is added to the sodium hydroxide solution at a material - to - liquid ratio of g / mL of (9 - 11):(180 - 220), and ultrasonic treatment is carried out at 30 - 50 kHz for 25 - 35 min. The nano - silica powder is filtered out, centrifugally washed at 4000 - 6000 rpm for 10 - 15 min, and the washed silica powder is added to deionized water to obtain an activated nano - silica suspension. The mass - to - volume ratio of the silica powder to deionized water is g / mL of (9 - 11):(80 - 120); The sodium silicate solution is mixed with deionized water, and then polyvinyl alcohol is added, and stirred at 55 - 65 °C until completely dissolved to obtain solution A. The mass - to - volume ratio of the sodium silicate solution, deionized water, and polyvinyl alcohol is g / mL of (40 - 60):(250 - 350):(4 - 6); The activated nano - silica suspension is slowly poured into solution A, and magnetic stirring is carried out at a rotation speed of 400 - 600 rpm for 55 - 65 min to obtain a composite suspension B; Triethanolamine is added to the composite suspension B at a material - to - liquid ratio of g / mL of (250 - 300):1, and stirring is continued for 25 - 35 min to obtain a nano - silica composite sol; The nano - silica composite sol is placed in a water bath at 45 - 50 °C for aging for 18 - 22 h, and then the pH is adjusted to 8.0 - 9.0 with citric acid to obtain the nano - silica composite liquid.

4. The repair coating of a cement mortar material according to claim 1, characterized in that, The bridging agent is prepared by the following method: Sodium silicate is added to deionized water at a material-liquid ratio of g / mL of 1:(9 - 11), and stirred until completely dissolved to obtain solution C; Acrylic acid, 2-hydroxyethyl methacrylate, and tetrasodium ethylenediaminetetraacetate are added to deionized water, stirred until completely dissolved, and sodium hydroxide is added to adjust the pH to 9.0 - 10.0 to obtain solution D, where the mass-volume ratio of acrylic acid, 2-hydroxyethyl methacrylate, tetrasodium ethylenediaminetetraacetate, and deionized water is g / mL (4 - 6):(2.5 - 3.5):(0.9 - 1.1):(45 - 55); Solution D is added dropwise to solution C, and then hydroquinone is added to obtain a mixed solution E, where the volume ratio of solution D, solution C, and hydroquinone is (1.8 - 2.2):(0.9 - 1.1):(0.01 - 0.02); N,N'-methylenebisacrylamide and silane coupling agent are added to the mixed solution E at a material-liquid ratio of g / mL of (120 - 180):(0.4 - 0.6):(0.6 - 0.9), and stirred at 25 - 30 °C for 25 - 35 min to form a homogeneous hybrid sol; The temperature is raised to 65 - 70 °C, and ammonium persulfate solution is added at a volume ratio of (135 - 165):(3.0 - 3.5), and the reaction is carried out for 2.0 - 2.5 h under a nitrogen atmosphere. The ammonium persulfate solution is prepared by dissolving ammonium persulfate in deionized water at a material-liquid ratio of g / mL of 1:(30 - 35). Subsequently, carboxylated nano-hydroxyapatite is added at a material-liquid ratio of g / mL of (110 - 190):(1.5 - 2.5), and stirred and reacted for 40 - 60 min. After the reaction, it is cooled to 20 - 30 °C to obtain a gel; The gel is placed under vacuum drying at 50 - 55 °C for 8 - 10 h, and then under vacuum drying at 60 - 65 °C for 10 - 12 h, and passed through a 100 - 200 mesh sieve to obtain the bridging agent.

5. A repair coating of a cement mortar material as described in claim 1, characterized in that, The modified polyacrylate is prepared by the following method: Acrylic acid, methyl methacrylate, and N,N'-methylenebisacrylamide are dissolved in deionized water to obtain solution F. The mass-volume ratio of acrylic acid, methyl methacrylate, N,N'-methylenebisacrylamide, and deionized water (g / mL) is (28 - 32):(9 - 11):(0.5 - 1.0):(120 - 180); Ammonium persulfate is dissolved in deionized water to obtain an ammonium persulfate solution. The mass-volume ratio of ammonium persulfate to deionized water (g / mL) is 1:(30 - 35); The pH of solution F is adjusted to 7.5 - 8.0 with sodium hydroxide, nitrogen is introduced for 35 - 45 min, and then the temperature is raised to 48 - 52 °C. The ammonium persulfate solution is added dropwise to solution F, and the reaction is carried out for 0.8 - 1.0 h. Then the temperature is raised to 65 - 75 °C and the reaction is carried out for 2.0 - 2.5 h to obtain a polyacrylate copolymer solution. The volume ratio of solution F to the ammonium persulfate solution is (18 - 20):1; The polyacrylate copolymer solution is cooled to 48 - 52 °C, and then sodium ethylenediaminetetraacetate is added at a material-liquid ratio (g / mL) of (12 - 14):

1. The temperature is raised to 68 - 72 °C and the reaction is carried out for 2.5 - 3.5 h. After the reaction is completed, the temperature is cooled to 20 - 30 °C, and citric acid is added to adjust the pH to 6.8 - 7.2, thus obtaining the modified polyacrylate.

6. A repair coating of a cement mortar material as described in claim 1, characterized in that, The water reducer is a polycarboxylate water reducer, and the plasticizer is a lignosulfonate solution.

7. A repair coating of cement mortar material according to claim 1, characterized in that, The particle size of the rubber powder is 80 - 120 mesh, and the particle size of the nano-carbon fiber is 100 - 200 nm.

8. The preparation process of a repair coating of a cement mortar material according to any one of claims 1-7, characterized in that, It includes the following steps: S1. Add the bridging agent, rubber powder, and nano-carbon fiber into a blender and stir and mix to obtain mixture I; S2. Add the nano-silica composite liquid, water reducer, and plasticizer into a stirring kettle and stir and mix to obtain mixture II; S3. Add the modified polyacrylate into mixture II and stir and mix to obtain mixture III. Use triethanolamine to adjust the pH to maintain it at 9.0 - 11.0; S4. Slowly add mixture I into mixture III, stir evenly and then carry out degassing treatment to obtain mixture IV; S5. Seal and cure mixture IV to obtain a repair coating for cement mortar materials.

9. The preparation process of a repair coating of a cement mortar material according to claim 8, characterized in that, In S1, the stirring speed is 400 - 600 rpm and the stirring time is 5 - 10 min. In S2, the stirring speed is 300 - 500 rpm and the stirring time is 15 - 25 min. In S3, the stirring speed is 150 - 250 rpm and the stirring time is 10 - 20 min. In S4, the stirring speed is 200 - 400 rpm, the stirring time is 25 - 35 min, the degassing treatment pressure is -0.06 to -0.10 MPa, and the vacuum treatment time is 8 - 12 min. In S5, the sealing and curing is carried out at 23 - 27 °C for 22 - 26 h.

10. The preparation process of a repair coating of a cement mortar material according to claim 8, characterized in that, The viscosity of the repair coating for cement mortar materials prepared in S5 is 500 - 1000 mPa·s.

Images