A water-reducing agent for reducing the rebound and a preparation method thereof and concrete

Abstract

The present application relates to the technical field of concrete, and particularly discloses a water reducing agent for reducing rebound, a preparation method thereof and concrete, which comprises the following components in parts by weight: cohesive energy enhanced water reducing agent 200-230 parts, self-made air entraining agent 2-5 parts, self-made thickening agent 10-20 parts, lithium carbonate 15-30 parts, and deionized water 745-788 parts. The water reducing agent for reducing rebound is added in concrete mixing, improves the cohesion of the concrete, cooperates with a high-performance alkali-free accelerator, significantly improves the spraying construction effect, solves the problem of high rebound rate of sprayed concrete in the construction process, reduces the waste of engineering materials, improves the working surface environment, and significantly reduces the spraying construction cost.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to a water-reducing agent for rebound molding, its preparation method, and concrete. Background Technology

[0002] With the large-scale development of engineering construction in my country, the construction of tunnels in railways and highways has also developed rapidly. Shotcrete, as an important component of the lining support system in tunnel construction, has the characteristics of rapid setting and hardening and high early strength. It is widely used in the initial support, playing an important role in controlling the stability of the surrounding rock and ensuring construction safety. Shotcrete has two processes: dry spraying and wet spraying.

[0003] Among them, the dry spraying process has been gradually replaced by the wet spraying process due to problems such as high dust, harsh construction environment, difficulty in controlling water-cement ratio, large fluctuations in concrete quality, and large loss of strength in the later stage.

[0004] Wet spraying is currently the most important construction method in tunnel construction. This process can improve the working environment, increase construction efficiency, and shorten the construction period. However, the high rebound rate of concrete still exists during spraying, with many tunnel projects experiencing rebound rates as high as 30%-40%, resulting in huge material waste. The high rebound rate problem is a major challenge that the industry urgently needs to solve.

[0005] There are two main factors affecting the rebound rate of wet-sprayed concrete: one is the concrete materials and mix proportions, such as the amount of cementitious materials, mineral admixtures, quick-setting agent, and sand ratio; the other is the spraying construction technology, such as spraying air pressure, spraying angle, and single spraying thickness.

[0006] Therefore, in order to solve the problem of large rebound in shotcrete construction, it is urgent to develop a high-performance shotcrete that can effectively reduce the rebound rate of shotcrete, improve construction safety, and be economical and environmentally friendly. Summary of the Invention

[0007] The purpose of this invention is to provide a water-reducing agent for reducing rebound, which is added to concrete mixing to improve the cohesiveness of concrete and solve the problem of high rebound rate of shotcrete during construction.

[0008] At this point, the present invention also provides a method for preparing the above-mentioned water-reducing agent for rebound springs and concrete with the water-reducing agent for rebound springs added.

[0009] This invention is achieved through the following technical solution:

[0010] A water-reducing agent for recoil reduction grenades comprises the following components in parts by weight:

[0011] 200-230 parts of cohesive energy-enhancing water-reducing agent, 2-5 parts of self-made air-entraining agent, 10-20 parts of self-made thickener, 15-30 parts of lithium carbonate, and 745-788 parts of deionized water;

[0012] The preparation process of the cohesive energy-enhancing water-reducing agent is as follows:

[0013] Under stirring, add sodium p-aminobenzenesulfonate and hydroquinone to deionized water, heat to 50-55℃, then add 30% sodium hydroxide solution, heat to 60-70℃, stir for 30-40 min, add formaldehyde aqueous solution (35% mass concentration) dropwise, react for 60-80 min; continue heating to 90-95℃, add polyethylene glycol, react for 220-230 min; then add deionized water and 30% sodium hydroxide, keep warm for 90-100 min, and then cool down.

[0014] The preparation process of the self-made air-entraining agent is as follows:

[0015] Heat the sodium hydroxide solution to 80-85℃, add oleic acid, react for 120-150 min, then add hydroxypropyl cellulose, keep warm for 60-90 min, and then cool down.

[0016] The preparation process of the homemade thickener is as follows:

[0017] After heating the aqueous solution of ethyl acrylate to 60-65℃, add aqueous solutions of methacrylic acid and ammonium persulfate dropwise. React for 60-70 minutes, then add 1,4-butadiene and react for 45-60 minutes before cooling.

[0018] The cohesive-enhancing water-reducing agent of this invention contains hydrophilic sulfonate groups and polyethylene glycol groups in its molecular structure. These groups form hydrogen bonds with water molecules, creating a solvation layer on the surface of cement particles (formed after the cement particles are dispersed; the particle surface is a water molecule layer, and this water molecule layer is the solvation effect). This prevents the cement particles from agglomerating, thereby reducing water content. Meanwhile, the phenyl and methylene (introduced by formaldehyde) strong hydrophobic groups in the molecule form intermolecular association, thereby increasing the cohesive energy of the system, effectively increasing the cohesiveness of concrete, significantly reducing concrete drop during spraying, increasing the adhesion between concrete and rock walls, and effectively reducing the rebound rate of sprayed concrete.

[0019] The self-made air-entraining agent of this invention contains fatty acid salt molecules, whose linear structure allows them to move faster in cement paste and quickly align in the air bubbles, thereby enhancing the air-entraining efficiency. The hydroxypropyl cellulose in the agent can increase the thickness of the air bubble wall, thereby improving the air-stabilizing performance of the air-entraining agent, increasing the concrete encapsulation, and playing a vibration damping role when the concrete is sprayed onto the tunnel wall, reducing concrete rebound.

[0020] The self-made thickener of this invention has a cross-linked acrylate molecular structure. In neutral or slightly acidic solutions, it has a low viscosity. However, in cement paste, the ester undergoes hydrolysis, resulting in charge repulsion between anionic groups, molecular chain expansion, and increased system viscosity. This reduces the fluidity of concrete, increases cohesive energy, and decreases the rebound rate of sprayed concrete.

[0021] The lithium carbonate of this invention can be used in conjunction with an alkali-free quick-setting agent to improve the early strength of shotcrete, thereby reducing the rebound rate of shotcrete.

[0022] In summary, the water-reducing agent for reducing rebound of the present invention is added to the concrete mixing process to improve the cohesiveness of the concrete, thereby solving the problem of high rebound rate of shotcrete during construction.

[0023] In a preferred embodiment, when preparing the cohesive energy-enhancing water-reducing agent, the weight ratio of sodium p-aminobenzenesulfonate, hydroquinone, formaldehyde aqueous solution and polyethylene glycol is (30-38):(40-48):(40-45):(5-10).

[0024] In a preferred embodiment, when preparing the cohesive energy-enhancing water-reducing agent, the weight ratio of the first added deionized water, the first added sodium hydroxide solution, sodium aminobenzenesulfonate, and hydroquinone is (100-110):(5-10):(30-38):(40-48).

[0025] The weight ratio of the second addition of deionized water, the second addition of sodium hydroxide solution, and formaldehyde aqueous solution is (100-110):(10-15):(40-45).

[0026] In a preferred embodiment, when preparing the cohesive energy-enhancing water-reducing agent, the formaldehyde aqueous solution is added over a time of 85-105 minutes.

[0027] In a preferred embodiment, when preparing the homemade air-entraining agent, the weight ratio of solid sodium hydroxide to deionized water in the sodium hydroxide solution is (4-8):(70-80); the weight ratio of solid sodium hydroxide, oleic acid, and hydroxypropyl cellulose is (4-8):(12-18):(0.1-0.5).

[0028] In a preferred embodiment, when preparing the homemade thickener, the ethyl acrylate aqueous solution is obtained by uniformly mixing 10-15 parts of methacrylic acid and 10-12 parts of deionized water; the ammonium persulfate aqueous solution is obtained by uniformly mixing 0.8-1.0 parts of ammonium persulfate and 10-15 parts of deionized water; and the ethyl acrylate aqueous solution is obtained by uniformly mixing 25-30 parts of ethyl acrylate and 110-120 parts of deionized water.

[0029] In a preferred embodiment, the weight ratio of ethyl acrylate, methacrylic acid, ammonium persulfate, and 1,4-butadiene is (25-30):(10-15):(0.8-1.0):(0.1-0.5).

[0030] In a preferred embodiment, when preparing the homemade thickener, the ethyl acrylate aqueous solution is added over a time of 60-75 min, and the ammonium persulfate aqueous solution is added over a time of 90-105 min.

[0031] A method for preparing a water-reducing agent for rebound bombs involves adding deionized water to a container, adding a cohesive energy-enhancing water-reducing agent while stirring, stirring for 5-10 minutes, adding a self-made air-entraining agent, stirring for 10-20 minutes, then adding a self-made thickener and lithium carbonate, stirring for 20-30 minutes, stopping stirring, and obtaining the water-reducing agent for rebound bombs.

[0032] A type of concrete in which the aforementioned water-reducing agent for rebound is added during the mixing process.

[0033] The concrete of the present invention can specifically be sprayed concrete, which can be applied to infrastructure construction projects such as transportation, mining, structural reinforcement and underground facilities.

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] The rebound-reducing water-reducing agent of this invention is added to the concrete mix to improve the cohesiveness of the concrete. Combined with a high-performance alkali-free quick-setting agent, it significantly improves the spraying construction effect and solves the problem of high rebound rate in sprayed concrete during construction. It not only reduces the waste of engineering materials and improves the working environment, but also significantly reduces the cost of spraying construction, promotes cost reduction and efficiency improvement in concrete projects, and reduces the safety risks of engineering construction. It has important practical significance for improving the research of sprayed concrete industrial technology. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The illustrative embodiments and descriptions of this invention are for illustrative purposes only and are not intended to limit the invention. The embodiments described below are some, but not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, materials, or methods are not specifically described to avoid obscuring the invention. Unless otherwise specified, the materials, instruments, and reagents used in the following embodiments are commercially available. Unless otherwise specified, the techniques used in the embodiments are conventional methods well known to those skilled in the art.

[0038] A water-reducing agent for recoil reduction grenades comprises the following components in parts by weight:

[0039] 200-230 parts of cohesive energy-enhancing water-reducing agent, 2-5 parts of self-made air-entraining agent, 10-20 parts of self-made thickener, 15-30 parts of lithium carbonate, and 745-788 parts of deionized water.

[0040] The preparation process of the cohesive energy-enhancing water-reducing agent is as follows:

[0041] In a 1L three-necked flask, add 100-110 parts deionized water and 30-38 parts sodium p-aminobenzenesulfonate. Start stirring, add 40-48 parts hydroquinone, and heat to 50-55℃. Add 5-10 parts of 30% sodium hydroxide solution. Heat to 60-70℃ and stir for 30-40 minutes. Add 40-45 parts of formaldehyde aqueous solution (35% mass concentration) dropwise over 85-105 minutes. After the addition is complete, allow the reaction to proceed for 60-80 minutes. Continue heating to 90-95℃, add 5-10 parts of polyethylene glycol, and react for 220-230 minutes. Add 100-115 parts deionized water and 10-15 parts of 30% sodium hydroxide. Maintain the temperature for 90-100 minutes, then cool to room temperature. Discharge the product to obtain a cohesive-enhancing water-reducing agent.

[0042] In the above preparation process, sodium hydroxide mainly acts as a catalyst, and the specific reaction process is as follows:

[0043]

[0044]

[0045]

[0046] The preparation process of the self-made air-entraining agent is as follows:

[0047] Add 70-80 parts of deionized water and 4-8 parts of solid sodium hydroxide to a 250mL three-necked flask, turn on mechanical stirring, heat to 80-85℃, add 12-18 parts of oleic acid, react for 120-150min, add 0.1-0.5 parts of hydroxypropyl cellulose, keep warm for 60-90min; cool to room temperature, and discharge to obtain the self-made air-entraining agent.

[0048] The preparation process of the homemade thickener is as follows:

[0049] In a 250mL three-necked flask, add 110-120 parts deionized water, 0.2 parts emulsifier OP-10, and 25-30 parts ethyl acrylate. Start stirring and heat to 60-65℃. Prepare dropping solutions A and B. Solution A is obtained by uniformly mixing 10-15 parts methacrylic acid and 10-12 parts deionized water. Solution B is composed of 0.8-1.0 parts ammonium persulfate and 10-15 parts deionized water. Add solutions A and B dropwise simultaneously. Solution A is added dropwise for 60-75 minutes, and solution B is added dropwise for 90-105 minutes. Continue the reaction for 60-70 minutes, then add 0.1-0.5 parts 1,4-butadiene and react for 45-60 minutes. Cool to room temperature to obtain the thickener.

[0050] The above-mentioned method for preparing the water-reducing agent for recoil reduction bombs involves adding deionized water to a container, adding a cohesive energy-enhancing water-reducing agent while stirring, stirring for 5-10 minutes, adding a self-made air-entraining agent, stirring for 10-20 minutes, then adding a self-made thickener and lithium carbonate, stirring for 20-30 minutes, stopping stirring, and obtaining the water-reducing agent for recoil reduction bombs.

[0051] A type of shotcrete, wherein the aforementioned water-reducing agent for rebound reduction is added to the mix. This shotcrete can be applied to infrastructure projects in transportation, mining, structural reinforcement, and underground facilities.

[0052] To better illustrate the technology of this embodiment, the following specific examples are used for explanation:

[0053] Example 1:

[0054] A water-reducing agent for recoil reduction projectiles comprises the following components in parts by weight:

[0055] 200 parts of cohesive energy-enhancing water-reducing agent, 2 parts of self-made air-entraining agent, 10 parts of self-made thickener, 15 parts of lithium carbonate, and 745 parts of deionized water.

[0056] The preparation process of the water-reducing agent for the above-mentioned recoil reduction projectile:

[0057] First, cohesive energy-enhancing water-reducing agent, self-made air-entraining agent, and self-made thickener were prepared separately. In a 2L three-necked flask, deionized water was added, and an electric mechanical stirrer was turned on. The self-made cohesive energy-enhancing water-reducing agent was added and stirred for 5 minutes. The self-made high-efficiency air-entraining agent was added and stirred for 10 minutes. Then, the self-made thickener and lithium carbonate were added and stirred for 20 minutes. Stirring was stopped to obtain the water-reducing agent for rebounding.

[0058] The preparation process of the cohesive energy-enhancing water-reducing agent is as follows:

[0059] In a 1L three-necked flask, add 100 parts deionized water and 30 parts sodium p-aminobenzenesulfonate, start stirring, add 40 parts hydroquinone, heat to 50℃, and add 5 parts 30% sodium hydroxide solution. Heat to 60℃, stir for 30-40 minutes, and add 40 parts formaldehyde aqueous solution (35% mass concentration) dropwise over 85 minutes. After the addition is complete, react for 60 minutes. Continue heating to 90℃, add 5 parts polyethylene glycol, react for 220 minutes, then add 100 parts water and 10 parts 30% sodium hydroxide. Maintain the temperature for 90 minutes, then cool to room temperature and discharge to obtain a cohesive-enhancing water-reducing agent.

[0060] The preparation process of the self-made air-entraining agent is as follows:

[0061] In a 250 mL three-necked flask, add 70 parts deionized water and 4 parts solid sodium hydroxide, turn on mechanical stirring, heat to 80 °C, add 12 parts oleic acid, react for 120 min, add 0.1 parts hydroxypropyl cellulose, and keep warm for 60 min. Cool to room temperature and discharge to obtain the self-made air-entraining agent.

[0062] The preparation process of the homemade thickener is as follows:

[0063] In a 250 mL three-necked flask, add 110 parts deionized water, 0.2 parts emulsifier OP-10, and 25 parts ethyl acrylate. Start stirring and heat to 60°C. Prepare dropwise solution A, which is a mixture of 10 parts methacrylic acid and 10 parts deionized water. Solution B is composed of 0.8 parts ammonium persulfate and 10 parts deionized water. Add solutions A and B dropwise simultaneously, with solution A added for 60 min and solution B added for 90 min. Continue the reaction for another 60 min, then add 0.1 parts 1,4-butadiene and react for 45 min. Cool to room temperature to prepare a homemade thickener.

[0064] Example 2:

[0065] A water-reducing agent for recoil reduction projectiles comprises the following components in parts by weight:

[0066] 230 parts of cohesive energy-enhancing water-reducing agent, 5 parts of self-made air-entraining agent, 20 parts of self-made thickener, 30 parts of lithium carbonate, and 788 parts of deionized water.

[0067] The preparation process of the water-reducing agent for the above-mentioned recoil reduction projectile:

[0068] First, cohesive energy-enhancing water-reducing agent, self-made air-entraining agent, and self-made thickener were prepared separately. In a 2L three-necked flask, deionized water was added, and an electric mechanical stirrer was turned on. The self-made cohesive energy-enhancing water-reducing agent was added and stirred for 10 minutes. The self-made high-efficiency air-entraining agent was added and stirred for 20 minutes. Then, the self-made thickener and lithium carbonate were added and stirred for 30 minutes. Stirring was stopped to obtain the water-reducing agent for rebounding.

[0069] The preparation process of the cohesive energy-enhancing water-reducing agent is as follows:

[0070] In a 1L three-necked flask, add 110 parts deionized water and 38 parts sodium p-aminobenzenesulfonate, start stirring, add 48 parts hydroquinone, heat to 55°C, and add 10 parts 30% sodium hydroxide solution. Heat to 70°C, stir for 40 minutes, and add 45 parts formaldehyde aqueous solution (35% mass concentration) dropwise over 105 minutes. After the addition is complete, react for 80 minutes. Continue heating to 95°C, add 7 parts polyethylene glycol, react for 230 minutes, and add 115 parts water and 15 parts 30% sodium hydroxide. Maintain the temperature for 100 minutes, then cool to room temperature; discharge to obtain a cohesive-enhancing water-reducing agent.

[0071] The preparation process of the self-made air-entraining agent is as follows:

[0072] In a 250 mL three-necked flask, add 80 parts of deionized water and 8 parts of solid sodium hydroxide, turn on mechanical stirring, heat to 85 °C, add 18 parts of oleic acid, react for 150 min, add 0.5 parts of hydroxypropyl cellulose, and keep warm for 90 min. Cool to room temperature and discharge to obtain the self-made air-entraining agent.

[0073] The preparation process of the homemade thickener is as follows:

[0074] In a 250 mL three-necked flask, add 120 parts deionized water, 0.2 parts emulsifier OP-10, and 30 parts ethyl acrylate. Start stirring and heat to 65°C. Prepare dropping solutions A and B. Solution A is obtained by mixing 15 parts methacrylic acid and 12 parts deionized water evenly, and solution B is composed of 1.0 part ammonium persulfate and 15 parts deionized water. Add solutions A and B dropwise simultaneously. Solution A is added dropwise for 75 min, and solution B is added dropwise for 105 min. Continue the reaction for 70 min, then add 0.5 parts 1,4-butadiene and react for 60 min. Cool to room temperature to obtain a homemade thickener.

[0075] Example 3:

[0076] A water-reducing agent for recoil reduction projectiles comprises the following components in parts by weight:

[0077] 220 parts of cohesive energy-enhancing water-reducing agent, 3 parts of self-made air-entraining agent, 15 parts of self-made thickener, 22 parts of lithium carbonate, and 761 parts of deionized water.

[0078] The preparation process of the water-reducing agent for the above-mentioned recoil reduction projectile:

[0079] First, cohesive energy-enhancing water-reducing agent, self-made air-entraining agent, and self-made thickener were prepared separately. In a 2L three-necked flask, deionized water was added, and an electric mechanical stirrer was turned on. The self-made cohesive energy-enhancing water-reducing agent was added and stirred for 7 minutes. The self-made high-efficiency air-entraining agent was added and stirred for 15 minutes. Then, the self-made thickener and lithium carbonate were added and stirred for 25 minutes. Stirring was stopped to obtain the water-reducing agent for rebounding.

[0080] The preparation process of the cohesive energy-enhancing water-reducing agent is as follows:

[0081] In a 1L three-necked flask, add 105 parts deionized water and 35 parts sodium p-aminobenzenesulfonate, start stirring, add 44 parts hydroquinone, heat to 53°C, and add 7 parts 30% sodium hydroxide solution. Heat to 65°C, stir for 35 minutes, and add 43 parts formaldehyde aqueous solution (35% mass concentration) dropwise over 92 minutes. After the addition is complete, react for 70 minutes. Continue heating to 92°C, add 8 parts polyethylene glycol, react for 225 minutes, and add 112 parts water and 13 parts 30% sodium hydroxide. Maintain the temperature for 95 minutes, then cool to room temperature; discharge to obtain a cohesive-enhancing water-reducing agent.

[0082] The preparation process of the self-made air-entraining agent is as follows:

[0083] In a 250 mL three-necked flask, add 75 parts deionized water and 6 parts solid sodium hydroxide, turn on mechanical stirring, heat to 83°C, add 15 parts oleic acid, react for 135 min, add 0.3 parts hydroxypropyl cellulose, and keep warm for 75 min. Cool to room temperature and discharge to obtain the self-made air-entraining agent.

[0084] The preparation process of the homemade thickener is as follows:

[0085] In a 250 mL three-necked flask, add 115 parts deionized water, 0.2 parts emulsifier OP-10, and 28 parts ethyl acrylate. Start stirring and heat to 63°C. Prepare dropping solutions A and B. Solution A is obtained by mixing 13 parts methacrylic acid and 11 parts deionized water evenly, and solution B is composed of 0.9 parts ammonium persulfate and 13 parts deionized water. Add solutions A and B dropwise simultaneously. Solution A is added dropwise for 70 min, and solution B is added dropwise for 98 min. Continue the reaction for 65 min, then add 0.3 parts 1,4-butadiene and react for 52 min. Cool to room temperature to prepare a homemade thickener.

[0086] Example 4:

[0087] A water-reducing agent for recoil reduction projectiles comprises the following components in parts by weight:

[0088] 200 parts of cohesive energy-enhancing water-reducing agent, 5 parts of self-made air-entraining agent, 10 parts of self-made thickener, 30 parts of lithium carbonate, and 745 parts of deionized water.

[0089] The preparation process of the water-reducing agent for the above-mentioned recoil reduction projectile:

[0090] First, cohesive energy-enhancing water-reducing agent, self-made air-entraining agent, and self-made thickener were prepared separately. In a 2L three-necked flask, deionized water was added, and an electric mechanical stirrer was turned on. The self-made cohesive energy-enhancing water-reducing agent was added and stirred for 10 minutes. The self-made high-efficiency air-entraining agent was added and stirred for 10 minutes. Then, the self-made thickener and lithium carbonate were added and stirred for 30 minutes. Stirring was stopped to obtain the water-reducing agent for rebounding.

[0091] The preparation process of the cohesive energy-enhancing water-reducing agent is as follows:

[0092] In a 1L three-necked flask, add 100 parts deionized water and 38 parts sodium p-aminobenzenesulfonate, start stirring, add 40 parts hydroquinone, heat to 55°C, and add 5 parts 30% sodium hydroxide solution. Heat to 70°C, stir for 30 minutes, and add 45 parts formaldehyde aqueous solution (35% mass concentration) dropwise over 85 minutes. After the addition is complete, react for 80 minutes. Continue heating to 90°C, add 10 parts polyethylene glycol, react for 230 minutes, and add 100 parts water and 15 parts 30% sodium hydroxide. Maintain the temperature for 90 minutes, then cool to room temperature; discharge to obtain a cohesive-enhancing water-reducing agent.

[0093] The preparation process of the self-made air-entraining agent is as follows:

[0094] In a 250 mL three-necked flask, add 70 parts of deionized water and 8 parts of solid sodium hydroxide, turn on mechanical stirring, heat to 80 °C, add 18 parts of oleic acid, react for 120 min, add 0.5 parts of hydroxypropyl cellulose, and keep warm for 60 min. Cool to room temperature and discharge to obtain the self-made air-entraining agent.

[0095] The preparation process of the homemade thickener is as follows:

[0096] In a 250 mL three-necked flask, add 110 parts deionized water, 0.2 parts emulsifier OP-10, and 30 parts ethyl acrylate. Start stirring and heat to 60°C. Prepare dropping solutions A and B. Solution A is obtained by mixing 15 parts methacrylic acid and 10 parts deionized water evenly, and solution B is composed of 1.0 part ammonium persulfate and 10 parts deionized water. Add solutions A and B dropwise simultaneously. Solution A is added dropwise for 60 min, and solution B is added dropwise for 105 min. Continue the reaction for another 60 min, then add 0.5 parts 1,4-butadiene and react for 45 min. Cool to room temperature to obtain a homemade thickener.

[0097] Comparative Example 1:

[0098] The water-reducing agent used in this comparative example for reducing rebound is commercially available PCE, specifically Point-THS polycarboxylate-based high-performance water-reducing agent.

[0099] Comparative Example 2:

[0100] The water-reducing agent used in this comparative example is a combination of commercially available PCE and SD-JK-SNJ alkali-free quick-setting agent; the commercially available PCE is Point-THS polycarboxylate-based high-performance water-reducing agent.

[0101] The above four embodiments and commercially available PCE were used for C30 concrete testing. Esheng PO 42.5 ordinary Portland cement was selected as the cementitious material, and Fangyuan Grade II fly ash was used. The manufactured sand was fine aggregate with a fineness modulus of 2.6; the crushed stone was continuously graded with a particle size of 5-31.5 mm. Water-reducing agent concrete tests were conducted according to GB8076-2016. Initial slump, spread, and rebound rate of the concrete after adding 8% SD-JK-SNJ alkali-free quick-setting agent (SD-JK-SNJ alkali-free quick-setting agent was added after mixing; the dosage of SD-JK-SNJ alkali-free quick-setting agent was calculated based on the cementitious material of the concrete; SD-JK-SNJ alkali-free quick-setting agent is a commercially available product) were tested. The concrete mix design is shown in Table 1, and the concrete test results are shown in Table 2.

[0102] Table 1 Concrete Mix Proportions

[0103] cement coal ash sand stone water 430 40 913 843 174

[0104] Table 2 Concrete Test Results

[0105]

[0106]

[0107] Note: The dosage of water-reducing agent for rebound is 1.0% of the cementitious material.

[0108] Note: The data in Table 2 for Examples 1-4 and commercially available PCE are test data of concrete prepared by adding SD-JK-SNJ alkali-free quick-setting agent to the admixture formulations of Examples 1-4 and commercially available PCE during concrete mixing.

[0109] The data in Table 2 shows that:

[0110] 1) Adding a water-reducing agent to the concrete mix can improve the cohesiveness of the concrete. Combined with a high-performance alkali-free quick-setting agent (SD-JK-SNJ alkali-free quick-setting agent), it significantly improves the shotcrete application effect and solves the problem of high rebound rate in shotcrete during construction. Concrete prepared using commercially available PCE combined with SD-JK-SNJ alkali-free quick-setting agent can achieve a rebound rate of 32%. The rebound reduction rate of this invention can reach up to 90.6%, which is a significant reduction in shotcrete performance.

[0111] 2) The amount of water-reducing agent for rebound reduction in this invention is only 1% of the cementitious material, which is a relatively low addition amount. Compared with the 7-8% amount of water-reducing agent for rebound reduction in the prior art, the amount of water-reducing agent for rebound reduction is greatly reduced, which can also achieve a significant reduction in the rebound rate of shotcrete.

[0112] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A water-reducing agent for rebound bombs, characterized in that, Includes the following components by weight: 200-230 parts of cohesive energy-enhancing water-reducing agent, 2-5 parts of self-made air-entraining agent, 10-20 parts of self-made thickener, 15-30 parts of lithium carbonate, and 745-788 parts of deionized water; The preparation process of the cohesive energy-enhancing water-reducing agent is as follows: Under stirring, add sodium p-aminobenzenesulfonate and hydroquinone to deionized water, heat to 50-55℃, then add 30% sodium hydroxide solution, heat to 60-70℃, stir for 30-40 min, add formaldehyde aqueous solution dropwise and react for 60-80 min; continue heating to 90-95℃, add polyethylene glycol, react for 220-230 min; then add deionized water and 30% sodium hydroxide, keep warm for 90-100 min, and then cool down. The preparation process of the self-made air-entraining agent is as follows: Heat the sodium hydroxide solution to 80-85℃, add oleic acid, react for 120-150 min, then add hydroxypropyl cellulose, keep warm for 60-90 min, and then cool down. The preparation process of the self-made thickener is as follows: After heating the ethyl acrylate emulsion to 60-65℃, add aqueous methacrylic acid and ammonium persulfate solution dropwise, react for 60-70 min, add 1,4-butadiene, react for 45-60 min, and then cool down. When preparing the cohesive-enhancing water-reducing agent, the weight ratio of sodium p-aminobenzenesulfonate, hydroquinone, formaldehyde aqueous solution and polyethylene glycol is (30-38):(40-48):(40-45):(5-10). When preparing the cohesive energy-enhancing water-reducing agent, the weight ratio of the first added deionized water, the first added sodium hydroxide solution, the sodium p-aminobenzenesulfonate, and the hydroquinone is (100-110):(5-10):(30-38):(40-48). The weight ratio of the second addition of deionized water, the second addition of sodium hydroxide solution, and the formaldehyde aqueous solution is (100-110):(10-15):(40-45).

2. The water-reducing agent for rebound bombs according to claim 1, characterized in that, When preparing the cohesive energy-enhancing water-reducing agent, the formaldehyde aqueous solution is added over a time of 85-105 minutes.

3. The water-reducing agent for rebound bombs according to claim 1, characterized in that, When preparing the self-made air-entraining agent, the weight ratio of solid sodium hydroxide to deionized water in the preparation of the sodium hydroxide solution is (4-8):(70-80); the weight ratio of solid sodium hydroxide, oleic acid and hydroxypropyl cellulose is (4-8):(12-18):(0.1-0.5).

4. The water-reducing agent for rebound bombs according to claim 1, characterized in that, In preparing the self-made thickener, the aqueous methacrylic acid solution is obtained by uniformly mixing 10-15 parts of methacrylic acid and 10-12 parts of deionized water; the aqueous persulfate solution is obtained by uniformly mixing 0.8-1.0 parts of ammonium persulfate and 10-15 parts of deionized water; and the ethyl acrylate emulsion is obtained by uniformly mixing 25-30 parts of ethyl acrylate, 110-120 parts of deionized water and 0.2 parts of emulsifier.

5. The water-reducing agent for rebound bombs according to claim 4, characterized in that, The weight ratio of the ethyl acrylate, the methacrylic acid, the ammonium persulfate and the 1,4-butadiene is (25-30):(10-15):(0.8-1.0):(0.1-0.5).

6. The water-reducing agent for rebound bombs according to claim 1, characterized in that, When preparing the homemade thickener, the methacrylic acid aqueous solution is added at a time of 60-75 min, and the ammonium persulfate aqueous solution is added at a time of 90-105 min.

7. The method for preparing the water-reducing agent for recoil reduction shells according to any one of claims 1-6, characterized in that, Add deionized water to a container, and while stirring, add the cohesive energy-enhancing water-reducing agent and stir for 5-10 minutes. Then add the self-made air-entraining agent and stir for 10-20 minutes. Next, add the self-made thickener and lithium carbonate and stir for 20-30 minutes. Stop stirring to obtain the water-reducing agent for rebound springs.

8. A type of concrete, characterized in that, The concrete was mixed with a water-reducing agent for rebound as described in any one of claims 1-6.

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