High-strength rapid-setting repair mortar and preparation process thereof

Abstract

The application relates to the field of mortar, in particular to high-strength rapid-setting repair mortar and a preparation process thereof. The preparation process of the high-strength rapid-setting repair mortar comprises the following steps: preparing a coagulant; preparing modified bamboo fiber; preparing composite polypropylene fiber; preparing an anti-freezing agent; and preparing the repair mortar. The coagulant is prepared by taking acrylic acid, potassium persulfate and deionized water as raw materials to prepare A liquid, taking L-ascorbic acid, thio glycolic acid and deionized water as raw materials to prepare B liquid, then uniformly mixing methyl alkenyl polyoxyethylene ether, sodium methallyl sulfonate, acrylic amine and deionized water, and adding the A liquid and the B liquid to react, and finally adding the coagulant into the repair mortar. The coagulant can not only efficiently disperse the cement particle flocculation structure, release the free water wrapped therein, greatly reduce the mixing water consumption and reduce the water-cement ratio, but also effectively shorten the setting time of the repair mortar and improve the early strength.

Description

Technical Field

[0001] This invention relates to the field of mortar, specifically to a high-strength, fast-setting repair mortar and its preparation process. Background Technology

[0002] In municipal infrastructure and road engineering, the repair and reinforcement of manholes, manholes, and their surrounding areas has always been a technical challenge and a key maintenance focus. The manhole itself differs significantly from the surrounding road surface materials in structure, density, and physical properties. Under the combined effects of repeated impacts from long-term vehicle dynamic loads, changes in ambient temperature, and moisture erosion, the road surface materials around the manhole are highly susceptible to settlement, cracking, breakage, and peeling, forming the so-called "manhole perimeter damage" phenomenon. This not only seriously affects the smoothness of the road, driving safety, and comfort, but also further exacerbates the damage to the underlying structure, significantly increasing subsequent maintenance costs and frequency.

[0003] Currently, for such repair projects, ordinary cement mortar, rapid-hardening cement, or asphalt concrete are traditionally used. However, ordinary cement mortar generally suffers from defects such as slow setting and hardening, low early strength, high drying shrinkage, and insufficient adhesion to both new and old concrete substrates. It cannot meet the requirements of municipal construction that needs to quickly open to traffic, and it is prone to cracking again under dynamic loads. Although rapid-hardening cement has a shorter setting time, its later strength stability is poor, its volume shrinkage is large, and its durability is often difficult to guarantee. Asphalt concrete, due to its inherent material incompatibility with cement concrete substrates, suffers from weak adhesion, easy softening at high temperatures, and embrittlement at low temperatures, resulting in a short service life after repair and a high tendency for recurrence.

[0004] Furthermore, in the vast northern and cold regions, under the action of freeze-thaw cycles, the capillary pore water inside ordinary repair materials repeatedly freezes and expands, generating huge internal stress, which leads to the peeling of the material surface, a sharp decrease in strength, and ultimately the failure of the repair operation.

[0005] Therefore, it is necessary to propose a high-strength, fast-setting repair mortar with antifreeze properties and its preparation process to extend its service life. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a high-strength, fast-setting repair mortar and its preparation process.

[0007] This invention provides a preparation process for high-strength, fast-setting repair mortar, comprising the following steps: S1: Preparation of coagulant First, solution A is prepared using acrylic acid, potassium persulfate and deionized water as raw materials, and solution B is prepared using L-ascorbic acid, thioglycolic acid and deionized water as raw materials. Then, methyl allyl polyoxyethylene ether, sodium methacrylate sulfonate, amine acrylate and deionized water are mixed evenly and added to solution A and solution B to react and obtain a coagulant. S2: Preparation of modified bamboo fiber Polyvinylpyrrolidone and cellulose nanofibers were added to an aqueous solution of silane coupling agent to prepare a modified solution. Pretreated bamboo fibers were then added to the modified solution to obtain modified bamboo fibers. S3: Preparation of composite polypropylene fibers Polypropylene, microsilica, and polypropylene grafted with maleic anhydride are melt-extruded and granulated, and then melt-spun to obtain composite polypropylene fibers. S4: Preparation of antifreeze S4.1: After drying and dehydrating pentaerythritol and catalyst, ethylene oxide is added. Under nitrogen protection, the mixture is heated and stirred at 120-130℃ for 2-3 hours. After cooling to 80-90℃, an 85% phosphoric acid solution is added for neutralization. The mixture is then filtered, and the filtrate is extracted with n-hexane. The solvent is then removed by rotary evaporation under reduced pressure to obtain the intermediate. S4.2: Add the above intermediate to N,N-dimethylformamide at a ratio of 1g:(6-8)mL, stir and mix evenly to obtain an intermediate solution, then dissolve urea and aminosulfonic acid in N,N-dimethylformamide at a ratio of 1g:(76-80)g:(220-230)mL to obtain a mixed solution; S4.3: Add the above intermediate solution to the above mixed solution at a volume ratio of 1:2, heat and stir under reflux at 100-110℃ for 5-6 hours, cool, add 2 mol / L sodium hydroxide solution to adjust the pH to 9.5-10.5, continue stirring for 30-40 minutes, then wash 3-5 times with anhydrous ethanol, and dry to obtain the antifreeze. S5: Preparation of Repair Mortar Mix sulfoaluminate cement, silicate cement, fly ash, quartz sand, metakaolin, redispersible latex powder, the above-mentioned modified bamboo fiber, the above-mentioned composite polypropylene fiber, the above-mentioned accelerator and antifreeze agent evenly, then add water and stir for 10-20 minutes to obtain repair mortar.

[0008] Furthermore, S1 specifically includes the following steps: S1.1: Mix acrylic acid, potassium persulfate and 1 / 5 deionized water thoroughly to obtain solution A. Then mix L-ascorbic acid, thioglycolic acid and 1 / 5 deionized water thoroughly to obtain solution B. S1.2: Mix methyl allyl polyoxyethylene ether, sodium methacrylate sulfonate, amine acrylate and the remaining deionized water evenly, then add the above solution A and solution B, heat and stir at 30-40℃ for 1-2 hours, and adjust the pH to 7-8 with sodium hydroxide solution to obtain the coagulant.

[0009] Furthermore, S2 specifically includes the following steps: S2.1: Add bamboo raw fibers to a 5% sodium hydroxide solution and soak for 6-8 hours. Then remove the fibers and wash them with water until the pH reaches 7. Dry them at 70-80℃ for 6-8 hours to obtain pretreated bamboo raw fibers. S2.2: Add silane coupling agent and deionized water to anhydrous ethanol and stir for 20-30 min to obtain an aqueous solution of silane coupling agent; S2.3: Polyvinylpyrrolidone and cellulose nanofibers are added to the above-mentioned aqueous solution of silane coupling agent and stirred thoroughly to obtain a modified solution; S2.4: Add the pretreated bamboo fiber to the modified solution at a ratio of 1g:(10-20)mL, stir and modify for 1-2 hours, then remove and dry at 70-80℃ for 6-8 hours, and cool naturally to room temperature to obtain modified bamboo fiber.

[0010] Furthermore, S3 specifically includes the following steps: S3.1: Place polypropylene resin, micro silica and polypropylene grafted maleic anhydride in a high-speed mixer at a mass ratio of (90-95):(4-6):1 and mix at 350-450 r / min for 8-10 min to obtain a mixture. S3.2: Add the above mixture to a twin-screw extruder, melt-blend at 180-200℃, and then extrude and granulate to obtain composite masterbatch; S3.3: Add the above composite masterbatch into a melt spinning machine for melt spinning, and after cooling and solidification, obtain composite polypropylene fiber.

[0011] Further, by weight, the raw material composition of the coagulant is as follows: 90-100 parts methyl allyl polyoxyethylene ether, 1.8-2 parts sodium methacrylate sulfonate, 0.4-0.6 parts acrylamide, 11-13 parts acrylic acid, 1.8-2.8 parts potassium persulfate, 1.2-1.4 parts L-ascorbic acid, 0.1-0.3 parts thioglycolic acid, and 170-180 parts deionized water.

[0012] Furthermore, the mass ratio of silane coupling agent, deionized water and anhydrous ethanol is (4-5):1:(38-42).

[0013] Furthermore, the mass ratio of polyvinylpyrrolidone, cellulose nanofibers and silane coupling agent aqueous solution is 1:(10-12):(200-210).

[0014] Furthermore, the mass ratio of ethylene oxide to pentaerythritol is (3.8-3.9):1, the amount of catalyst added is 1-1.5% of the mass of pentaerythritol, and the catalyst is potassium hydroxide.

[0015] Furthermore, the repair mortar comprises the following components by weight: 50-60 parts sulfoaluminate cement, 10-20 parts silicate cement, 10-20 parts fly ash, 65-75 parts quartz sand, 3-5 parts metakaolin, 1-3 parts redispersible latex powder, 1-3 parts modified bamboo fiber, 2-3 parts composite polypropylene fiber, 2-3 parts accelerator, 1-2 parts antifreeze agent, and 31-35 parts water.

[0016] A high-strength, fast-setting repair mortar, which is prepared by the preparation process of a high-strength, fast-setting repair mortar as described in any one of the above claims.

[0017] The present invention has the following advantages: 1. In this invention, solution A is first prepared using acrylic acid, potassium persulfate, and deionized water as raw materials, and solution B is prepared using L-ascorbic acid, thioglycolic acid, and deionized water as raw materials. Then, methyl allyl polyoxyethylene ether, sodium methacrylate sulfonate, amine acrylic acid, and deionized water are mixed evenly and added to solutions A and B for reaction to produce an accelerator. After the accelerator is added to the repair mortar, the amide groups of the accelerator hydrolyze in the highly alkaline environment of the cement paste and interact with calcium ions, providing numerous nucleation sites for the precipitation of hydration products and accelerating the formation rate of hydration products. Sodium methacrylate sulfonate, on the other hand, reacts with tricalcium aluminate, the fastest hydrating mineral in cement. Furthermore, calcium sulfoaluminate in sulfoaluminate cement has strong adsorption selectivity, which can promote the rapid reaction of mineral phases and sulfate components to form ettringite, helping to establish a solid crystal skeleton. This can effectively shorten the setting time of repair mortar and improve early strength. In addition, the carboxyl and sulfonic acid groups on the main chain of the accelerator are firmly adsorbed on the surface of cement particles through electrostatic interaction. The long polyoxyethylene side chains provided by methyl allyl polyoxyethylene ether fully extend in water, forming a huge physical spatial barrier between cement particles, preventing particles from getting close to each other. This can efficiently break down the flocculated structure of cement particles, release the encapsulated free water, significantly reduce the amount of mixing water, and lower the water-cement ratio.

[0018] 2. In this invention, bamboo fibers are first treated with alkali, and then surface modified by adding an aqueous solution of silane coupling agent containing cellulose nanofibers to obtain cellulose nanofiber-modified bamboo fibers. Then, polypropylene resin, microsilica, and compatibilizer polypropylene grafted with maleic anhydride are melt-extruded and granulated, and then melt-spun into composite polypropylene fibers. Microsilica can reduce the agglomeration tendency of polypropylene fibers, making them uniformly dispersed in mortar and forming a uniformly distributed tough network. After the modified bamboo fibers and composite polypropylene fibers are added to the repair mortar, the natural cellulose inside the modified bamboo fibers and the introduced cellulose nanofibers can promote the growth of hydration products on their surface, thereby refining capillaries, optimizing pore structure, and making the matrix more compact. The composite polypropylene fibers can bridge and constrain larger-scale cracks and participate in the hydration reaction to generate CSH gel, further strengthening the interfacial bonding. Therefore, the modified bamboo fibers and composite polypropylene fibers can jointly form a "crack constraint network" from nano to macro, thereby synergistically improving the compressive strength of the repair mortar.

[0019] 3. In this invention, an intermediate polyether is first synthesized using pentaerythritol and ethylene oxide as raw materials. After dissolving it, it is reacted with a mixed solution of urea and aminosulfonic acid to produce an antifreeze agent. When this agent is added to the repair mortar, it forms a stable hydrogen-bonded complex with the free water inside the mortar, disrupting the hydrogen bond network between water molecules, lowering the freezing point, and preventing some free water from freezing at low temperatures. This reduces the pressure caused by the expansion of ice crystals from the source. At the same time, its terminal sulfonamide groups can be adsorbed on the surface of ice crystals, inhibiting ice crystal growth and significantly relieving the internal compressive stress on the mortar matrix, thereby effectively improving the antifreeze performance of the repair mortar. In addition, since the sulfonamide groups in the antifreeze agent can combine with calcium ions produced by cement hydration, the concentration of calcium ions in the liquid phase is reduced, the dissolution-precipitation balance of hydration products is broken, and the hydration reaction of sulfoaluminate cement and silicate cement is accelerated, thereby further improving the early strength of the repair mortar. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the preparation process of the high-strength, rapid-setting repair mortar used in an embodiment of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0022] Example 1: A preparation process for a high-strength, rapid-setting repair mortar, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of coagulant S1.1: Mix acrylic acid, potassium persulfate and 1 / 5 deionized water thoroughly to obtain solution A. Then mix L-ascorbic acid, thioglycolic acid and 1 / 5 deionized water thoroughly to obtain solution B. S1.2: Mix methyl allyl polyoxyethylene ether, sodium methacrylate sulfonate, methacrylamide, and the remaining deionized water evenly. Then add the above solution A and solution B, heat and stir at 30°C for 1 hour, and adjust the pH to 7 with sodium hydroxide solution to obtain a coagulant. The raw material composition of the coagulant, by mass, is: 90 parts methyl allyl polyoxyethylene ether, 1.8 parts sodium methacrylate sulfonate, 0.4 parts methacrylamide, 11 parts acrylic acid, 1.8 parts potassium persulfate, 1.2 parts L-ascorbic acid, 0.1 parts thioglycolic acid, and 170 parts deionized water. S2: Preparation of modified bamboo fiber S2.1: Add bamboo raw fibers to a 5% sodium hydroxide solution and soak for 6 hours. Then remove the fibers and wash them with water until the pH reaches 7. Dry them at 70°C for 6 hours to obtain pretreated bamboo raw fibers. S2.2: Add silane coupling agent and deionized water to anhydrous ethanol and stir for 20 min to obtain an aqueous solution of silane coupling agent, wherein the mass ratio of silane coupling agent, deionized water and anhydrous ethanol is 4:1:38; S2.3: Polyvinylpyrrolidone and cellulose nanofibers are added to the above-mentioned aqueous solution of silane coupling agent and stirred thoroughly to obtain a modified solution, wherein the mass ratio of polyvinylpyrrolidone, cellulose nanofibers and aqueous solution of silane coupling agent is 1:10:200. S2.4: Add the pretreated bamboo fiber to the modified solution at a ratio of 1g:10mL, stir and modify for 1 hour, take it out, dry it at 70℃ for 6 hours, and cool it naturally to room temperature to obtain modified bamboo fiber. S3: Preparation of composite polypropylene fibers S3.1: Polypropylene resin, micro silica and polypropylene grafted maleic anhydride are placed in a high-speed mixer at a mass ratio of 90:4:1 and mixed at 350 r / min for 8 min to obtain a mixture. S3.2: Add the above mixture to a twin-screw extruder, melt-blend at 180°C, and then extrude and granulate to obtain composite masterbatch; S3.3: The above composite masterbatch is added to a melt spinning machine for melt spinning. After cooling and solidification, composite polypropylene fiber is obtained. S4: Preparation of antifreeze S4.1: After drying and dehydrating pentaerythritol and potassium hydroxide, ethylene oxide is added. Under nitrogen protection, the mixture is heated and stirred at 120°C for 2 hours. After cooling to 80°C, an 85% phosphoric acid solution is added for neutralization. The mixture is then filtered, and the filtrate is extracted with n-hexane. The solvent is then removed by rotary evaporation under reduced pressure to obtain the intermediate. The mass ratio of ethylene oxide to pentaerythritol is 3.8:1, and the amount of potassium hydroxide added is 1% of the mass of pentaerythritol. S4.2: Add the above intermediate to N,N-dimethylformamide at a ratio of 1g:6mL, stir and mix evenly to obtain an intermediate solution, then dissolve urea and aminosulfonic acid in N,N-dimethylformamide at a ratio of 1g:76g:220mL to obtain a mixed solution; S4.3: Add the above intermediate solution to the above mixed solution at a volume ratio of 1:2, heat and stir under reflux at 100°C for 5 hours, cool, add 2 mol / L sodium hydroxide solution to adjust the pH to 9.5, continue stirring for 30 minutes, then wash three times with anhydrous ethanol, and dry to obtain the antifreeze. S5: Preparation of Repair Mortar The following ingredients are mixed evenly: sulfoaluminate cement, silicate cement, fly ash, quartz sand, metakaolin, redispersible latex powder, the above-mentioned modified bamboo fiber, the above-mentioned composite polypropylene fiber, the above-mentioned accelerator and antifreeze agent. Water is then added and stirred for 10 minutes to obtain the repair mortar. The repair mortar comprises the following weight components: 50 parts sulfoaluminate cement, 10 parts silicate cement, 10 parts fly ash, 65 parts quartz sand, 3 parts metakaolin, 1 part redispersible latex powder, 1 part modified bamboo fiber, 2 parts composite polypropylene fiber, 2 parts accelerator, 1 part antifreeze agent and 31 parts water.

[0023] Example 2: A preparation process for a high-strength, rapid-setting repair mortar, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of coagulant S1.1: Mix acrylic acid, potassium persulfate and 1 / 5 deionized water thoroughly to obtain solution A. Then mix L-ascorbic acid, thioglycolic acid and 1 / 5 deionized water thoroughly to obtain solution B. S1.2: Mix methyl allyl polyoxyethylene ether, sodium methacrylate sulfonate, methacrylamide, and the remaining deionized water thoroughly. Then add the above solutions A and B, heat and stir at 35°C for 1.5 hours, and adjust the pH to 7.5 with sodium hydroxide solution to obtain the coagulant. The raw material composition of the coagulant, by mass, is: 95 parts methyl allyl polyoxyethylene ether, 1.9 parts sodium methacrylate sulfonate, 0.5 parts methacrylamide, 12 parts acrylic acid, 2.3 parts potassium persulfate, 1.3 parts L-ascorbic acid, 0.2 parts thioglycolic acid, and 175 parts deionized water. S2: Preparation of modified bamboo fiber S2.1: Add bamboo raw fibers to a 5% sodium hydroxide solution and soak for 7 hours. Then remove the fibers and wash them with water until the pH reaches 7. Dry them at 75°C for 7 hours to obtain pretreated bamboo raw fibers. S2.2: Add silane coupling agent and deionized water to anhydrous ethanol and stir for 25 min to obtain an aqueous solution of silane coupling agent, wherein the mass ratio of silane coupling agent, deionized water and anhydrous ethanol is 4.5:1:40; S2.3: Polyvinylpyrrolidone and cellulose nanofibers are added to the above-mentioned aqueous solution of silane coupling agent and stirred thoroughly to obtain a modified solution, wherein the mass ratio of polyvinylpyrrolidone, cellulose nanofibers and aqueous solution of silane coupling agent is 1:11:205. S2.4: Add the pretreated bamboo fiber to the modified solution at a ratio of 1g:15mL, stir and modify for 1.5h, take it out, dry at 75℃ for 7h, and cool naturally to room temperature to obtain modified bamboo fiber. S3: Preparation of composite polypropylene fibers S3.1: Polypropylene resin, microsilica and polypropylene grafted maleic anhydride are placed in a high-speed mixer at a mass ratio of 92.5:5:1 and mixed at 400 r / min for 9 min to obtain a mixture. S3.2: Add the above mixture to a twin-screw extruder, melt-blend at 190°C, and then extrude and granulate to obtain composite masterbatch; S3.3: The above composite masterbatch is added to a melt spinning machine for melt spinning. After cooling and solidification, composite polypropylene fiber is obtained. S4: Preparation of antifreeze S4.1: After drying and dehydrating pentaerythritol and potassium hydroxide, ethylene oxide is added. Under nitrogen protection, the mixture is heated and stirred at 125°C for 2.5 h. After cooling to 85°C, an 85% phosphoric acid solution is added for neutralization. The mixture is then filtered, and the filtrate is extracted with n-hexane. The solvent is then removed by rotary evaporation under reduced pressure to obtain the intermediate. The mass ratio of ethylene oxide to pentaerythritol is 3.85:1, and the amount of potassium hydroxide added is 1.25% of the mass of pentaerythritol. S4.2: Add the above intermediate to N,N-dimethylformamide at a ratio of 1g:7mL, stir and mix evenly to obtain an intermediate solution, then dissolve urea and aminosulfonic acid in N,N-dimethylformamide at a ratio of 1g:78g:225mL to obtain a mixed solution; S4.3: Add the above intermediate solution to the above mixed solution at a volume ratio of 1:2, heat and stir under reflux at 105°C for 5.5 h, cool, add 2 mol / L sodium hydroxide solution to adjust the pH to 10, continue stirring for 35 min, then wash 4 times with anhydrous ethanol, and dry to obtain the antifreeze. S5: Preparation of Repair Mortar The following ingredients are mixed evenly: sulfoaluminate cement, silicate cement, fly ash, quartz sand, metakaolin, redispersible latex powder, the above-mentioned modified bamboo fiber, the above-mentioned composite polypropylene fiber, the above-mentioned accelerator and antifreeze agent. Water is then added and stirred for 15 minutes to obtain the repair mortar. The repair mortar comprises the following weight components: 55 parts sulfoaluminate cement, 15 parts silicate cement, 15 parts fly ash, 70 parts quartz sand, 4 parts metakaolin, 2 parts redispersible latex powder, 2 parts modified bamboo fiber, 2.5 parts composite polypropylene fiber, 2.5 parts accelerator, 1.5 parts antifreeze agent and 33 parts water.

[0024] Example 3: A preparation process for a high-strength, rapid-setting repair mortar, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of coagulant S1.1: Mix acrylic acid, potassium persulfate and 1 / 5 deionized water thoroughly to obtain solution A. Then mix L-ascorbic acid, thioglycolic acid and 1 / 5 deionized water thoroughly to obtain solution B. S1.2: Mix methyl allyl polyoxyethylene ether, sodium methacrylate sulfonate, amine acrylate and the remaining deionized water evenly, then add the above solution A and solution B, heat and stir at 40°C for 2 hours, and adjust the pH to 8 with sodium hydroxide solution to obtain the coagulant. The raw material composition of the coagulant by mass is: 100 parts methyl allyl polyoxyethylene ether, 2 parts sodium methacrylate sulfonate, 0.6 parts amine acrylate, 13 parts acrylic acid, 2.8 parts potassium persulfate, 1.4 parts L-ascorbic acid, 0.3 parts thioglycolic acid and 180 parts deionized water; S2: Preparation of modified bamboo fiber S2.1: Add bamboo raw fibers to a 5% sodium hydroxide solution and soak for 8 hours. Then remove the bamboo raw fibers and wash them with water until the pH reaches 7. Finally, dry them at 80°C for 8 hours to obtain pretreated bamboo raw fibers. S2.2: Add silane coupling agent and deionized water to anhydrous ethanol and stir for 30 min to obtain an aqueous solution of silane coupling agent, wherein the mass ratio of silane coupling agent, deionized water and anhydrous ethanol is 5:1:42. S2.3: Polyvinylpyrrolidone and cellulose nanofibers are added to the above-mentioned aqueous solution of silane coupling agent and stirred thoroughly to obtain a modified solution, wherein the mass ratio of polyvinylpyrrolidone, cellulose nanofibers and aqueous solution of silane coupling agent is 1:12:210. S2.4: Add the pretreated bamboo fiber to the modified solution at a ratio of 1g:20mL, stir and modify for 2 hours, take it out, dry it at 80℃ for 8 hours, and cool it naturally to room temperature to obtain modified bamboo fiber. S3: Preparation of composite polypropylene fibers S3.1: Polypropylene resin, micro silica and polypropylene grafted maleic anhydride are placed in a high-speed mixer at a mass ratio of 95:6:1 and mixed at 450 r / min for 10 min to obtain a mixture. S3.2: Add the above mixture to a twin-screw extruder, melt-blend at 200°C, and then extrude and granulate to obtain composite masterbatch; S3.3: The above composite masterbatch is added to a melt spinning machine for melt spinning. After cooling and solidification, composite polypropylene fiber is obtained. S4: Preparation of antifreeze S4.1: After drying and dehydrating pentaerythritol and potassium hydroxide, ethylene oxide is added. Under nitrogen protection, the mixture is heated and stirred at 130°C for 3 hours. After cooling to 90°C, an 85% phosphoric acid solution is added for neutralization. The mixture is then filtered, and the filtrate is extracted with n-hexane. The solvent is then removed by rotary evaporation under reduced pressure to obtain the intermediate. The mass ratio of ethylene oxide to pentaerythritol is 3.9:1, and the amount of potassium hydroxide added is 1.5% of the mass of pentaerythritol. S4.2: Add the above intermediate to N,N-dimethylformamide at a ratio of 1g:8mL, stir and mix evenly to obtain an intermediate solution, then dissolve urea and aminosulfonic acid in N,N-dimethylformamide at a ratio of 1g:80g:230mL to obtain a mixed solution; S4.3: Add the above intermediate solution to the above mixed solution at a volume ratio of 1:2, heat and stir under reflux at 110°C for 6 hours, cool, add 2 mol / L sodium hydroxide solution to adjust the pH to 10.5, continue stirring for 40 minutes, then wash 5 times with anhydrous ethanol, and dry to obtain the antifreeze. S5: Preparation of Repair Mortar The following ingredients are mixed evenly: sulfoaluminate cement, silicate cement, fly ash, quartz sand, metakaolin, redispersible latex powder, the above-mentioned modified bamboo fiber, the above-mentioned composite polypropylene fiber, the above-mentioned accelerator and antifreeze agent. Water is then added and stirred for 20 minutes to obtain the repair mortar. The repair mortar comprises the following weight components: 60 parts sulfoaluminate cement, 20 parts silicate cement, 20 parts fly ash, 75 parts quartz sand, 5 parts metakaolin, 3 parts redispersible latex powder, 3 parts modified bamboo fiber, 3 parts composite polypropylene fiber, 3 parts accelerator, 2 parts antifreeze agent and 35 parts water.

[0025] Comparative Example 1 differs from Example 1 in that the coagulant in step S5 is removed.

[0026] Comparative Example 2 differs from Example 1 in that the composite polypropylene fiber in step S5 is replaced with an equal amount of modified bamboo fiber.

[0027] Comparative Example 3 differs from Example 1 in that the modified bamboo fiber in step S5 is replaced with an equal amount of composite polypropylene fiber.

[0028] Comparative Example 4 differs from Example 1 in that the antifreeze in step S5 is removed.

[0029] Test example: Test 1: The initial setting time of the repair mortar prepared in Examples 1-3 and Comparative Example 1 was tested according to GB / T1346-2019. The test environment temperature was -10℃. The test was conducted in parallel three times, and the average value was taken. The results are shown in Table 1.

[0030] Table 1: Results of Initial Setting Time Test

[0031] Test 2: The 2-hour compressive strength of the repair mortars prepared in Examples 1-3, Comparative Examples 1 and 4 were tested according to GB / T17671-2021. The tests were conducted in parallel three times, and the average value was taken. The results are shown in Table 2.

[0032] Table 2: Results of 2h compressive strength test

[0033] As shown in Tables 1 and 2, in Comparative Example 1, after removing the accelerator, the initial setting time of the repair mortar was higher than that of Example 1, while the early strength was lower. This shows that by first preparing liquid A using acrylic acid, potassium persulfate, and deionized water as raw materials, and then preparing liquid B using L-ascorbic acid, thioglycolic acid, and deionized water as raw materials, and then mixing methyl allyl polyoxyethylene ether, sodium methacrylate sulfonate, amine acrylate, and deionized water evenly, and adding liquid A and liquid B to react, an accelerator can be prepared. After adding the accelerator to the repair mortar, the setting time of the repair mortar can be effectively shortened and the early strength improved.

[0034] In Comparative Example 4, the early strength of the repair mortar obtained after removing the antifreeze was lower than that of Example 1. This shows that by first synthesizing intermediate polyether using pentaerythritol and ethylene oxide as raw materials, dissolving it, and then reacting it with a mixed solution of urea and aminosulfonic acid to produce an antifreeze, and then adding it to the repair mortar, the early strength of the repair mortar can be improved.

[0035] Test 3: The 28-day compressive strength of the repair mortars prepared in Examples 1-3 and Comparative Examples 2-3 were tested in parallel three times according to GB / T17671-2021, and the average value was taken. The results are shown in Table 3.

[0036] Table 3: Results of 28-day compressive strength test

[0037] As shown in Table 3, when only one of the modified bamboo fiber or composite polypropylene fiber was added in Comparative Examples 2 and 3, the 28-day compressive strength of the repair mortar was lower than that in Example 1. This shows that the modified bamboo fiber and composite polypropylene fiber can synergistically improve the compressive strength of the repair mortar.

[0038] Test 4: The water reduction rate of the repair mortar prepared after adding the accelerator in Examples 1-3 of GB8076-2008 Concrete Admixtures was tested in parallel three times, and the average value was taken. The results are shown in Table 4.

[0039] Table 4: Test Results of Water Reduction Rate of Accelerator

[0040] As shown in Table 4, the water reduction rate of the repair mortars prepared after adding the accelerator in Examples 1-3 is all above 38%. It can be seen that by first preparing liquid A with acrylic acid, potassium persulfate and deionized water as raw materials, and then preparing liquid B with L-ascorbic acid, thioglycolic acid and deionized water as raw materials, and then mixing methyl allyl polyoxyethylene ether, sodium methacrylate sulfonate, amine acrylic acid and deionized water evenly, and adding liquid A and liquid B to react to prepare the accelerator, the amount of mixing water can be greatly reduced and the water-cement ratio can be lowered.

[0041] Test 5: After curing the ordinary silicate cement mortar test block for 28 days, the repair mortar prepared in Examples 1-3 and Comparative Example 4 was poured onto its surface. After curing for 7 days, 25 freeze-thaw cycles were conducted. Each freeze-thaw cycle consisted of holding the sample at -15℃ for 2 hours and then holding it in water at 25℃ for 2 hours. The bond strength was then tested. The tests were conducted in parallel three times, and the average value was taken. The results are shown in Table 5.

[0042] Table 5: Bond strength test results after 25 freeze-thaw cycles

[0043] As shown in Table 5, after removing the antifreeze in Comparative Example 4, the bonding strength of the repair mortar after 25 freeze-thaw cycles was lower than that in Example 1. This shows that by first synthesizing intermediate polyether using pentaerythritol and ethylene oxide as raw materials, dissolving it, and then reacting it with a mixed solution of urea and aminosulfonic acid to prepare an antifreeze, and then adding it to the repair mortar, the antifreeze performance of the repair mortar can be effectively improved.

[0044] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A preparation process for a high-strength, rapid-setting repair mortar, characterized in that, Includes the following steps: S1: Preparation of coagulant First, solution A is prepared using acrylic acid as a raw material, and solution B is prepared using L-ascorbic acid and thioglycolic acid as raw materials. Then, methyl allyl polyoxyethylene ether, sodium methacrylate sulfonate, amine acrylate and deionized water are mixed evenly and added to solution A and solution B to react and obtain a coagulant. S2: Preparation of modified bamboo fiber Polyvinylpyrrolidone and cellulose nanofibers were added to an aqueous solution of silane coupling agent to prepare a modified solution. Pretreated bamboo fibers were then added to the modified solution to obtain modified bamboo fibers. S3: Preparation of composite polypropylene fibers Polypropylene, microsilica, and polypropylene grafted with maleic anhydride are melt-extruded and granulated, and then melt-spun to obtain composite polypropylene fibers. S4: Preparation of antifreeze S4.1: After drying and dehydrating pentaerythritol and catalyst, ethylene oxide is added. Under nitrogen protection, the mixture is heated and stirred at 120-130℃ for 2-3 hours. After cooling to 80-90℃, an 85% phosphoric acid solution is added for neutralization. The mixture is then filtered, and the filtrate is extracted with n-hexane. The solvent is then removed by rotary evaporation under reduced pressure to obtain the intermediate. S4.2: Add the above intermediate to N,N-dimethylformamide at a ratio of 1g:(6-8)mL, stir and mix evenly to obtain an intermediate solution, then dissolve urea and aminosulfonic acid in N,N-dimethylformamide at a ratio of 1g:(76-80)g:(220-230)mL to obtain a mixed solution; S4.3: Add the above intermediate solution to the above mixed solution at a volume ratio of 1:2, heat and stir under reflux at 100-110℃ for 5-6 hours, cool, add 2 mol / L sodium hydroxide solution to adjust the pH to 9.5-10.5, continue stirring for 30-40 minutes, then wash 3-5 times with anhydrous ethanol, and dry to obtain the antifreeze. S5: Preparation of Repair Mortar Mix sulfoaluminate cement, silicate cement, fly ash, quartz sand, metakaolin, redispersible latex powder, the above-mentioned modified bamboo fiber, the above-mentioned composite polypropylene fiber, the above-mentioned accelerator and antifreeze agent evenly, then add water and stir for 10-20 minutes to obtain repair mortar.

2. The preparation process of a high-strength, rapid-setting repair mortar according to claim 1, characterized in that, S1 specifically includes the following steps: S1.1: Mix acrylic acid, potassium persulfate and 1 / 5 deionized water thoroughly to obtain solution A. Then mix L-ascorbic acid, thioglycolic acid and 1 / 5 deionized water thoroughly to obtain solution B. S1.2: Mix methyl allyl polyoxyethylene ether, sodium methacrylate sulfonate, amine acrylate and the remaining deionized water evenly, then add the above solution A and solution B, heat and stir at 30-40℃ for 1-2 hours, and adjust the pH to 7-8 with sodium hydroxide solution to obtain the coagulant.

3. The preparation process of a high-strength, rapid-setting repair mortar according to claim 2, characterized in that, S2 specifically includes the following steps: S2.1: Add bamboo raw fibers to a 5% sodium hydroxide solution and soak for 6-8 hours. Then remove the fibers and wash them with water until the pH reaches 7. Dry them at 70-80℃ for 6-8 hours to obtain pretreated bamboo raw fibers. S2.2: Add silane coupling agent and deionized water to anhydrous ethanol and stir for 20-30 min to obtain an aqueous solution of silane coupling agent; S2.3: Polyvinylpyrrolidone and cellulose nanofibers are added to the above-mentioned aqueous solution of silane coupling agent and stirred thoroughly to obtain a modified solution; S2.4: Add the pretreated bamboo fiber to the modified solution at a ratio of 1g:(10-20)mL, stir and modify for 1-2 hours, then remove and dry at 70-80℃ for 6-8 hours, and cool naturally to room temperature to obtain modified bamboo fiber.

4. The preparation process of a high-strength, rapid-setting repair mortar according to claim 3, characterized in that, S3 specifically includes the following steps: S3.1: Place polypropylene resin, micro silica and polypropylene grafted maleic anhydride in a high-speed mixer at a mass ratio of (90-95):(4-6):1 and mix at 350-450 r / min for 8-10 min to obtain a mixture. S3.2: Add the above mixture to a twin-screw extruder, melt-blend at 180-200℃, and then extrude and granulate to obtain composite masterbatch; S3.3: Add the above composite masterbatch into a melt spinning machine for melt spinning, and after cooling and solidification, obtain composite polypropylene fiber.

5. The preparation process of a high-strength, rapid-setting repair mortar according to claim 2, characterized in that, The raw material composition of the coagulant by weight is as follows: 90-100 parts methyl allyl polyoxyethylene ether, 1.8-2 parts sodium methacrylate sulfonate, 0.4-0.6 parts acrylamide, 11-13 parts acrylic acid, 1.8-2.8 parts potassium persulfate, 1.2-1.4 parts L-ascorbic acid, 0.1-0.3 parts thioglycolic acid and 170-180 parts deionized water.

6. The preparation process of a high-strength, rapid-setting repair mortar according to claim 3, characterized in that, The mass ratio of silane coupling agent, deionized water and anhydrous ethanol is (4-5):1:(38-42).

7. The preparation process of a high-strength, rapid-setting repair mortar according to claim 3, characterized in that, The mass ratio of polyvinylpyrrolidone, cellulose nanofibers and silane coupling agent aqueous solution is 1:(10-12):(200-210).

8. The preparation process of a high-strength, rapid-setting repair mortar according to claim 1, characterized in that, The mass ratio of ethylene oxide to pentaerythritol is (3.8-3.9):1, the amount of catalyst added is 1-1.5% of the mass of pentaerythritol, and the catalyst is potassium hydroxide.

9. The preparation process of a high-strength, rapid-setting repair mortar according to claim 1, characterized in that, The repair mortar comprises the following components by weight: 50-60 parts sulfoaluminate cement, 10-20 parts silicate cement, 10-20 parts fly ash, 65-75 parts quartz sand, 3-5 parts metakaolin, 1-3 parts redispersible latex powder, 1-3 parts modified bamboo fiber, 2-3 parts composite polypropylene fiber, 2-3 parts accelerator, 1-2 parts antifreeze agent, and 31-35 parts water.

10. A high-strength, fast-setting repair mortar, characterized in that, It is prepared by the preparation process of a high-strength, fast-setting repair mortar as described in any one of claims 1-9.

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