Wet spraying concrete for tunnel engineering as well as preparation and application methods of wet spraying concrete

Abstract

The invention discloses wet shotcrete for tunnel engineering as well as preparation and application methods thereof, and belongs to the technical field of wet shotcrete. The wet spraying concrete for tunnel engineering is characterized by being prepared from the following components in parts by weight: 410 to 440 parts of cement, 850 to 980 parts of medium sand, 780 to 860 parts of coarse aggregate, 195 to 215 parts of water, 35 to 45 parts of coated modified porous aggregate, 9 to 13 parts of water reducing agent and 12 to 25 parts of accelerator. The porous aggregate is subjected to coating modification treatment, so that in the preparation and production process of the wet-sprayed concrete for tunnel engineering, the state of the concrete is not influenced, but in the concrete spraying process, due to the fact that the porous aggregate subjected to coating modification and a film coated by the porous aggregate are damaged under the action of pumping and pumping pressure, the wet-sprayed concrete for tunnel engineering is not influenced. The porous aggregate is exposed, and the porous aggregate can adsorb free water in the concrete due to the characteristics of porosity and extremely easy water absorption of the porous aggregate, so that the concrete becomes viscous during spraying, and the rebound rate of the concrete is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of wet spraying concrete, and specifically relates to wet spraying concrete for tunnel engineering and a preparation and application method thereof. Background Art

[0002] At present, the main form of support for tunnels and tunnels in my country is anchor spraying support, and anchor spraying support technology is also widely used in water conservancy projects. The key link of anchor spraying support operation is shotcrete technology, which has the advantages of simple process, fast construction, wide application, low cost, etc. It has the functions of sealing the surface and maintaining the strength of the surrounding rocks. The quality of the shotcrete spray layer directly affects the quality of the support, so the equipment and process quality used in shotcrete spraying have a significant impact on excavation and support.

[0003] Wet shotcrete is formed by transporting pre-mixed concrete to the tunnel operation area, loading it into a sprayer, using high-pressure air to send it to the nozzle, mixing it with an accelerator, and then spraying it onto the surface of rock or concrete at a very high speed.

[0004] If the viscosity of concrete is not enough during spraying, the rebound rate of concrete will be very large, resulting in waste of concrete. Increasing the viscosity of concrete, such as reducing the amount of water used during mixing, increasing the amount of water reducing agent, adding mineral admixtures, etc., will cause the spraying pipe to be blocked during spraying, which is not conducive to the spraying operation.

[0005] Among them, the pumping process is a very important stage before concrete spraying. When the concrete wet spraying machine pipe transportation is abnormal, it will seriously affect the work efficiency of wet spraying support and even cause pipe blockage, which has an adverse impact on the safety and economy of wet spraying concrete production operations.

[0006] For example, the Chinese invention patent with application number: CN202410299139.4 discloses a low-rebound and high-strength shotcrete material and a preparation method thereof. The raw materials include, by mass percentage: 12~20% cement, 25~45% machine-made sand, 15~25% gravel, 0.1~1% water reducer, 0.5~1.5% accelerator, 1~3% modified additive, 0.5~3% functional additive, and the balance is made up of water.

[0007] The above-mentioned prior art can effectively improve the mechanical properties and cohesiveness of shotcrete by adopting various types of molecular chain starches and modified additives to work together, thereby enhancing its durability, corrosion resistance and stability, and effectively preventing water seepage; however, the defect is that the concrete is already quite viscous before entering the pump, and a larger wind pressure of the sprayer is required to spray the concrete during spraying. The actual construction process has high professional requirements on equipment and operators, and the rebound rate of the above-mentioned prior art still has room for improvement.

[0008] Therefore, in order to solve the above problems, the present application provides a wet sprayed concrete for tunnel engineering and a preparation and application method thereof. Summary of the invention

[0009] In order to solve the defects existing in the above technical solutions, the purpose of the present invention is to provide a wet sprayed concrete for tunnel engineering and its preparation and application method. The purpose of the present invention can be achieved by the following technical solution: a wet sprayed concrete for tunnel engineering, which is composed of the following parts by weight: 410-440 parts of cement, 850-980 parts of medium sand, 780-860 parts of coarse aggregate, 195-215 parts of water, 35-45 parts of coated modified porous aggregate, 9-13 parts of water reducer, and 12-25 parts of accelerating agent.

[0010] The cement is P.O42.5 cement; The medium sand fineness modulus is 2.3-3.0; The coarse aggregate is crushed stone with continuous grading and a particle size range of 5-10 mm; The porous aggregate is a porous aggregate with a water absorption rate greater than 5%, including a mixture of one or more of ceramsite, red brick, recycled aggregate, air-cooled titanium slag aggregate, and zeolite; The water reducer is a polycarboxylate water reducer; The quick-setting agent is a silicate liquid quick-setting agent.

[0011] The preparation method of the coated modified porous aggregate comprises the following steps: wrapping the porous aggregate with a fine fishing net and placing the porous aggregate in a homemade potassium silicate solution, wherein the porous aggregate needs to be completely immersed in the homemade potassium silicate solution, and the porous aggregate is fully turned over every 5 minutes. After soaking for 15 minutes, the soaked porous aggregate is taken out, and excess homemade potassium silicate solution is filtered out; finally, the treated porous aggregate is placed in an oven for drying. After drying, the coated modified porous aggregate is prepared.

[0012] During the preparation of the coated modified porous aggregate, the drying temperature is set at 60 degrees Celsius and the drying time is set at 8 hours.

[0013] The preparation method of the homemade potassium silicate solution is as follows: pouring silica sol into a three-necked flask, then placing the three-necked flask in a constant temperature water bath equipped with a high-speed stirrer and a temperature control device, heating it to 50 degrees Celsius, slowly adding potassium hydroxide and deionized water into the three-necked flask while stirring, continuing to stir the mixed solution for 15 minutes, then pouring it into a flask under constant temperature water bath conditions, setting the temperature to 30 degrees Celsius, slowly adding homemade silicon-modified acrylic emulsion while stirring, and stirring for 1 hour; finally, adding hydroxyethyl cellulose as a thickener and sodium polyacrylate as a dispersant, and continuing to stir for 15 minutes, so as to prepare the homemade potassium silicate solution modified by the silicone-acrylic emulsion.

[0014] The preparation method of the self-made silicon-modified acrylic emulsion is as follows: 15g of styrene, 7g of butyl acrylate, 11g of butyl acrylate, 7g of methyl methacrylate, 6g of butyl methacrylate, 5g of sulfonic acrylate, 80g of deionized water, 0.6g of polyethylene glycol p-isooctylphenyl ether, and 0.2g of sodium dodecyl sulfate are weighed; the mixture is placed in a beaker, and stirred at room temperature at a speed of 650r / min for 30min to obtain a milky white mixture, which is named component A; 0.8g of ammonium persulfate is dissolved in 40g of deionized water, which is named component B; 0.4g of sodium bicarbonate, 10g of A mixture of deionized water and 60 g of component A is placed in a four-necked round-bottom flask, and then 20 g of component B is added dropwise to the flask to obtain a uniform mixture; subsequently, the remaining mixed solutions of component A and component B are added dropwise to the flask within 2 hours, and the reaction temperature is maintained at 85 degrees Celsius; subsequently, 1.3 g of 3-(trimethoxysilyl)propyl methacrylate is slowly added to the four-necked round-bottom flask, and the reaction is maintained at 85 degrees Celsius for 1 hour; finally, the temperature is adjusted to 90 degrees Celsius for 1 hour, and ammonia water is added to adjust the pH to 7-8, thereby preparing a homemade silicon-modified acrylic emulsion.

[0015] A method for preparing wet shotcrete for tunnel engineering comprises the following steps: firstly, adding cement and coarse aggregate into a forced mixer and stirring for 30 seconds; then, evenly mixing a water reducer with water, adding the mixture into a stirring pot and stirring for 45 seconds; finally, adding a coated modified porous aggregate and medium sand into the stirring pot and continuing to stir for 2 minutes; finally, during the spraying operation, automatically adding an accelerating setting agent through a nozzle, thereby preparing wet shotcrete for tunnel engineering.

[0016] The invention discloses an application of wet shotcrete for tunnel engineering in tunnel engineering construction.

[0017] During the application of the wet shotcrete for tunnel engineering, the wind pressure of the shotcrete sprayer is controlled at 0.5-0.8MPa, and the spraying angle is between 60-100°.

[0018] The spraying distance between the nozzle of the wet spraying machine and the rock surface is 0.8-1.2m.

[0019] The present invention has the beneficial effects: 1. The present application performs coating modification on porous aggregates, so that the wet spraying concrete for tunnel engineering will not affect the concrete state during the preparation and production process. However, during the concrete spraying process, the membrane coated on the coated porous aggregate may be destroyed under the action of pumping and pump pressure, exposing the porous aggregate. In addition, due to the porous and highly water-absorbing properties of the porous aggregate material itself, it can absorb the free water in the concrete, causing the concrete to become viscous during spraying, thereby reducing the rebound rate of the concrete and improving the compressive strength of the concrete. 2. The present application introduces a homemade potassium silicate solution to coat and modify the porous aggregate, wherein the silicon-modified acrylic emulsion introduced into the homemade potassium silicate solution has a special structure of silicon groups, which can enhance the adhesion of the homemade potassium silicate solution to the porous aggregate; a film with strong adhesion but poor stability is formed, and after drying and curing, it has excellent water resistance but low toughness; during the pumping process, the Si-O-Si mesh film may partially depolymerize in the latter part of the pumping process, resulting in defects in the coating, which will lose its bond to the porous aggregate, so that the porous aggregate can complete partial adsorption of free water during the pumping process. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment, and the illustrative embodiments of the present invention and its description are only used to explain the present invention, and are not used as limitation of the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper limit and lower limit of these smaller ranges can be independently included or excluded in the scope.

[0021] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0022] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0023] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0024] The "parts" indicated in the following examples are all parts by weight.

[0025] Example 1 A wet sprayed concrete for tunnel engineering comprises the following components by weight: 410 parts of cement, 850 parts of medium sand, 780 parts of coarse aggregate, 195 parts of water, 35 parts of coated modified porous aggregate, 9 parts of water reducing agent and 12 parts of accelerating setting agent.

[0026] The cement is P.O42.5 cement, purchased from Sichuan Esheng Cement Group Co., Ltd.; The medium sand fineness modulus is 2.3-3.0; The coarse aggregate is crushed stone with continuous grading and a particle size range of 5-10 mm; The water absorption rate of the porous aggregate is greater than 5%; The porous aggregate is a mixture of red bricks and recycled aggregates, purchased from a commercially available brand; The water reducer is a polycarboxylate water reducer; The quick-setting agent is a silicate liquid quick-setting agent purchased from Shandong Zhengyu Chemical Technology Co., Ltd.

[0027] The preparation method of the coated modified porous aggregate comprises the following steps: wrapping the porous aggregate with a fine fishing net and placing the porous aggregate in a homemade potassium silicate solution, wherein the porous aggregate needs to be completely immersed in the homemade potassium silicate solution, and the porous aggregate is fully turned over every 5 minutes. After soaking for 15 minutes, the soaked porous aggregate is taken out, and excess homemade potassium silicate solution is filtered out; finally, the treated porous aggregate is placed in an oven for drying. After drying, the coated modified porous aggregate is prepared.

[0028] During the preparation of the coated modified porous aggregate, the drying temperature is set at 60 degrees Celsius and the drying time is set at 8 hours.

[0029] The preparation method of the homemade potassium silicate solution is as follows: 10g of silica sol is poured into a three-necked flask, and then the three-necked flask is placed in a constant temperature water bath equipped with a high-speed stirrer and a temperature control device, and the temperature is raised to 50 degrees Celsius, and 8g of potassium hydroxide and 25g of deionized water are slowly added into the three-necked flask while stirring, and the mixed solution is continuously stirred for 15 minutes, and then the mixture is poured into a flask under a constant temperature water bath condition, the temperature is set to 30 degrees Celsius, and 15g of homemade silicon-modified acrylic emulsion is slowly added under stirring, and stirred for 1 hour; finally, hydroxyethyl cellulose is added as a thickener and sodium polyacrylate as a dispersant, and stirring is continued for 15 minutes, so as to prepare a homemade potassium silicate solution modified by the silicon-acrylic emulsion.

[0030] The preparation method of the self-made silicon-modified acrylic emulsion is as follows: 15g of styrene, 7g of butyl acrylate, 11g of butyl acrylate, 7g of methyl methacrylate, 6g of butyl methacrylate, 5g of sulfonic acrylate, 80g of deionized water, 0.6g of polyethylene glycol p-isooctylphenyl ether, and 0.2g of sodium dodecyl sulfate are weighed; the mixture is placed in a beaker, and stirred at room temperature at a speed of 650r / min for 30min to obtain a milky white mixture, which is named component A; 0.8g of ammonium persulfate is dissolved in 40g of deionized water, which is named component B; 0.4g of sodium bicarbonate, 10g of A mixture of deionized water and 60 g of component A is placed in a four-necked round-bottom flask, and then 20 g of component B is added dropwise to the flask to obtain a uniform mixture; subsequently, the remaining mixed solutions of component A and component B are added dropwise to the flask within 2 hours, and the reaction temperature is maintained at 85 degrees Celsius; subsequently, 2.6 g of 3-(trimethoxysilyl)propyl methacrylate is slowly added to the four-necked round-bottom flask, and the reaction is maintained at 85 degrees Celsius for 1 hour; finally, the temperature is adjusted to 90 degrees Celsius for 1 hour, and ammonia water is added to adjust the pH to 7-8, thereby preparing a homemade silicon-modified acrylic emulsion.

[0031] A method for preparing wet shotcrete for tunnel engineering comprises the following steps: firstly, adding cement and coarse aggregate into a forced mixer and stirring for 30 seconds; then, evenly mixing a water reducer with water, adding the mixture into a stirring pot and stirring for 45 seconds; finally, adding a coated modified porous aggregate and medium sand into the stirring pot and continuing to stir for 2 minutes; finally, during the spraying operation, automatically adding an accelerating setting agent through a nozzle, thereby preparing wet shotcrete for tunnel engineering.

[0032] Example 2 A wet sprayed concrete for tunnel engineering, comprising the following components by weight: 420 parts of cement, 880 parts of medium sand, 800 parts of coarse aggregate, 200 parts of water, 37 parts of coated modified porous aggregate, 10 parts of water reducing agent, and 15 parts of accelerating setting agent; The cement is P.O42.5 cement, purchased from Sichuan Esheng Cement Group Co., Ltd.; The medium sand fineness modulus is 2.3-3.0; The coarse aggregate is crushed stone with continuous grading and a particle size range of 5-10 mm; The water absorption rate of the porous aggregate is greater than 5%; The porous aggregate is recycled aggregate, purchased from a commercially available brand; The water reducer is a polycarboxylate water reducer; The quick-setting agent is a silicate liquid quick-setting agent purchased from Shandong Zhengyu Chemical Technology Co., Ltd.

[0033] Among them, in Example 2, the preparation method of the coated modified porous aggregate and the preparation method of wet sprayed concrete for tunnel engineering are consistent with those in Example 1.

[0034] Example 3 A wet sprayed concrete for tunnel engineering, comprising the following components by weight: 425 parts of cement, 920 parts of medium sand, 820 parts of coarse aggregate, 205 parts of water, 40 parts of coated modified porous aggregate, 11 parts of water reducing agent, and 18 parts of accelerating setting agent; The cement is P.O42.5 cement, purchased from Sichuan Esheng Cement Group Co., Ltd.; The medium sand fineness modulus is 2.3-3.0; The coarse aggregate is crushed stone with continuous grading and a particle size range of 5-10 mm; The water absorption rate of the porous aggregate is greater than 5%; The porous aggregate is a mixture of ceramsite and zeolite, purchased from a commercial brand; The water reducer is a polycarboxylate water reducer; The quick-setting agent is a silicate liquid quick-setting agent purchased from Shandong Zhengyu Chemical Technology Co., Ltd.

[0035] Among them, in Example 3, the preparation method of the coated modified porous aggregate and the preparation method of wet sprayed concrete for tunnel engineering are consistent with those in Example 1.

[0036] Example 4 A wet sprayed concrete for tunnel engineering, comprising the following components by weight: 430 parts of cement, 950 parts of medium sand, 840 parts of coarse aggregate, 210 parts of water, 42 parts of coated modified porous aggregate, 12 parts of water reducing agent, and 22 parts of accelerating setting agent; The cement is P.O42.5 cement, purchased from Sichuan Esheng Cement Group Co., Ltd.; The medium sand fineness modulus is 2.3-3.0; The coarse aggregate is crushed stone with continuous grading and a particle size range of 5-10 mm; The water absorption rate of the porous aggregate is greater than 5%; The porous aggregate is air-cooled titanium slag aggregate purchased from a commercially available brand; The water reducer is a polycarboxylate water reducer; The quick-setting agent is a silicate liquid quick-setting agent purchased from Shandong Zhengyu Chemical Technology Co., Ltd.

[0037] Among them, in Example 4, the preparation method of the coated modified porous aggregate and the preparation method of wet sprayed concrete for tunnel engineering are consistent with those in Example 1.

[0038] Example 5 A wet sprayed concrete for tunnel engineering, comprising the following components by weight: 440 parts of cement, 980 parts of medium sand, 860 parts of coarse aggregate, 215 parts of water, 45 parts of coated modified porous aggregate, 13 parts of water reducing agent, and 25 parts of accelerating setting agent; The cement is P.O42.5 cement, purchased from Sichuan Esheng Cement Group Co., Ltd.; The medium sand fineness modulus is 2.3-3.0; The coarse aggregate is crushed stone with continuous grading and a particle size range of 5-10 mm; The water absorption rate of the porous aggregate is greater than 5%; The porous aggregate is a mixture of ceramsite and red brick, purchased from a commercially available brand; The water reducer is a polycarboxylate water reducer; The quick-setting agent is a silicate liquid quick-setting agent purchased from Shandong Zhengyu Chemical Technology Co., Ltd.

[0039] Among them, in Example 5, the preparation method of the coated modified porous aggregate and the preparation method of wet sprayed concrete for tunnel engineering are consistent with those in Example 1.

[0040] Comparative Example 1 A wet sprayed concrete for tunnel engineering, comprising the following components by weight: 430 parts of cement, 950 parts of medium sand, 840 parts of coarse aggregate, 210 parts of water, 42 parts of coated modified porous aggregate, 12 parts of water reducing agent, and 22 parts of accelerating setting agent; Among them, in Comparative Example 1, the preparation method of the coated modified porous aggregate and the preparation method of wet sprayed concrete for tunnel engineering are consistent with those in Example 1.

[0041] This comparative example 1 is based on Example 4, except that, in the comparative example 1, no pumping method is used, and the rebound rate and pumping conditions are not measured. Instead, the prepared concrete is directly prepared into a standard 10*10*10 cm cubic test block, and cured under standard conditions for 28 days, and only the compressive strength test is carried out.

[0042] Comparative Example 2 A wet shotcrete for tunnel engineering, comprising the following components by weight: 430 parts of cement, 950 parts of medium sand, 840 parts of coarse aggregate, 210 parts of water, 42 parts of porous aggregate, 12 parts of water reducing agent, and 22 parts of accelerating setting agent; Among them, in Comparative Example 2, the preparation method of wet sprayed concrete for tunnel engineering is consistent with that of Example 1.

[0043] This comparative example 2 is based on Example 4, except that the comparative example 2 uses porous aggregate air-cooled titanium slag aggregate that has not undergone any modification.

[0044] Comparative Example 3 A wet shotcrete for tunnel engineering, comprising the following components by weight: 430 parts of cement, 950 parts of medium sand, 840 parts of coarse aggregate, 210 parts of water, 42 parts of porous aggregate, 12 parts of water reducing agent, and 22 parts of accelerating setting agent; Among them, in Comparative Example 3, the preparation method of wet sprayed concrete for tunnel engineering is consistent with that of Example 1.

[0045] Comparative Example 3 is based on Example 4, with the difference that, in Comparative Example 3, no pumping method is used, and the rebound rate and pumping conditions are not measured. Instead, the prepared concrete is directly prepared into a standard 10*10*10 cm cubic test block, and cured under standard conditions for 28 days, and only a compressive strength test is performed.

[0046] Comparative Example 4 A wet shotcrete for tunnel engineering, comprising the following components by weight: 430 parts of cement, 950 parts of medium sand, 840 parts of coarse aggregate, 210 parts of water, 12 parts of water reducing agent, and 22 parts of accelerating setting agent; This comparative example 4 is based on Example 4, except that, in the comparative example 3, the addition of porous aggregate is omitted in the wet shotcrete for tunnel engineering.

[0047] Test example Compressive strength test: concrete is sprayed into a 45*35*12cm cast iron mold. After the concrete in the mold reaches a certain strength, it is processed into a 10*10*10cm cubic test block and cured for 28 days under standard conditions for a compressive strength test. Rebound rate test: spray concrete onto a spray plate fixed on an iron frame; the spray plate has an area of ​​2000mm*800mm, a thickness of 30mm, and an angle of 45° with the ground; the spray plate has sufficient hardness and does not deform under the impact of the spray concrete; the iron frame has sufficient stability and does not shake during the spraying process; two small floor scales are placed on both sides of the iron frame to measure the concrete adhered to the spray plate; a 3m*3m plastic sheet is laid directly under the iron frame to receive the rebound concrete; a fixed amount of concrete is sprayed in each test, and after the spraying is completed, the mass of the concrete on the spray plate and the plastic sheet is weighed respectively according to the formula: W r = (W2*100) / (W s +W2); calculate the rebound rate of shotcrete and take the average of the two rebound rates as the final result; The W in the formula r is the rebound rate (%), W s is the mass of shotcrete adhered to the spray plate (kg); W2 is the mass of shotcrete rebounded on the plastic sheet (kg).

[0048] During the performance test, the wind pressure of the jet machine is controlled between 0.5-0.8 MPa, and the jet angle is between 60-100°.

[0049] The spraying distance between the nozzle of the wet spraying machine and the spraying plate is 0.8-1.2m.

[0050] The performance test results are shown in Table 1; Table 1 Comprehensive performance analysis: Examples 1-5 of the present application all have excellent 28-day compressive strength and excellent resilience; and the pumping conditions are good and can be pumped smoothly.

[0051] The formula components of Comparative Example 1 are exactly the same as those of Example 4, except that pumping is not used. Its 28-day compressive strength is significantly different from that of Examples 1-5. The possible reason is that during the pumping process, the membrane coated on the membrane-modified porous aggregate may be destroyed under the action of pumping and pump pressure, exposing the porous aggregate. In addition, due to the porous and highly water-absorbing properties of the porous aggregate material itself, it can absorb the free water in the concrete, causing the concrete to become viscous during spraying, thereby reducing the rebound rate of the concrete and improving the compressive strength of the concrete. The wet spraying concrete for tunnel engineering of this application can achieve the best use effect after pumping.

[0052] Comparative Example 2 uses porous aggregate that has not been modified in any way, and has the property of being extremely water-absorbent, and can absorb the free water in the concrete. As it becomes too viscous, it is difficult to pump under the pumping conditions of this test, and therefore its rebound rate is not measured; Comparative Example 3 directly uses porous aggregate without any modification to prepare cubic test blocks, and cures them under standard conditions for 28 days to conduct a compressive strength test; the compressive strength of Comparative Example 3 is close to that of Comparative Example 2.

[0053] Comparative Example 4 omits the addition of porous aggregate, and its pumping is smooth, but the rebound rate is high and it cannot be well applied to tunnel engineering.

[0054] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method 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 in the scope of protection of the present invention.

Claims

1. A wet shotcrete for tunnel engineering, characterized in that: The composition is as follows by weight: 410-440 parts of cement, 850-980 parts of medium sand, 780-860 parts of coarse aggregate, 195-215 parts of water, 35-45 parts of coated modified porous aggregate, 9-13 parts of water reducer, and 12-25 parts of accelerator.

2. The wet sprayed concrete for tunnel engineering according to claim 1, characterized in that: The composition is as follows by weight, including: 430 parts of cement, 950 parts of medium sand, 840 parts of coarse aggregate, 210 parts of water, 42 parts of coated modified porous aggregate, 12 parts of water reducer, and 22 parts of accelerator.

3. The wet sprayed concrete for tunnel engineering according to claim 1, characterized in that: The medium sand fineness modulus is 2.3-3.

0.

4. The wet sprayed concrete for tunnel engineering according to claim 1, characterized in that: The coarse aggregate is crushed stone with continuous grading and a particle size range of 5-10 mm.

5. A wet shotcrete for tunnel engineering according to any one of claims 1 to 4, characterized in that: The preparation method of the coated modified porous aggregate is as follows: the porous aggregate is wrapped with a fine fishing net and placed in a homemade potassium silicate solution, the porous aggregate needs to be completely immersed in the homemade potassium silicate solution, the porous aggregate is fully turned over every 5 minutes, after soaking for 15 minutes, the soaked porous aggregate is taken out, and the excess homemade potassium silicate solution is filtered out; finally, the treated porous aggregate is placed in an oven for drying. After drying, the coated modified porous aggregate is prepared.

6. The wet sprayed concrete for tunnel engineering according to claim 5, characterized in that: The porous aggregate is a porous aggregate with a water absorption rate greater than 5%, and includes a mixture of one or more of ceramsite, red brick, recycled aggregate, air-cooled titanium slag aggregate, and zeolite.

7. The wet sprayed concrete for tunnel engineering according to claim 5, characterized in that: The preparation and synthesis method of the homemade potassium silicate solution is as follows: pouring silica sol into a three-necked flask, then placing the three-necked flask in a constant temperature water bath equipped with a high-speed stirrer and a temperature control device, heating it to 50 degrees Celsius, slowly adding potassium hydroxide and deionized water into the three-necked flask while stirring, continuing to stir the mixed solution for 15 minutes, then pouring it into a flask under constant temperature water bath conditions, the temperature is set to 30 degrees Celsius, slowly adding homemade silicon-modified acrylic emulsion while stirring, and stirring for 1 hour; finally, adding hydroxyethyl cellulose as a thickener and sodium polyacrylate as a dispersant, and continuing to stir for 15 minutes, so as to prepare the homemade potassium silicate solution modified by the silicone-acrylic emulsion.

8. The wet sprayed concrete for tunnel engineering according to claim 7, characterized in that: The preparation and synthesis method of the self-made silicon-modified acrylic emulsion is as follows: weigh 15g of styrene, 7g of butyl acrylate, 11g of butyl acrylate, 7g of methyl methacrylate, 6g of butyl methacrylate, 5g of sulfonic acrylate, 80g of deionized water, 0.6g of polyethylene glycol p-isooctylphenyl ether, and 0.2g of sodium dodecyl sulfate; place them in a beaker, and stir at room temperature at a speed of 650r / min for 30min to obtain a milky white mixture, which is named component A; dissolve 0.8g of ammonium persulfate in 40g of deionized water, which is named component B; and add 0.4g of sodium bicarbonate, 10 A mixture of 60 g of component A and 60 g of deionized water was placed in a four-necked round-bottom flask, and then 20 g of component B was dropped into the flask to obtain a uniform mixture; subsequently, the remaining mixed solutions of component A and component B were dropped into the flask respectively within 2 hours, and the reaction temperature was maintained at 85 degrees Celsius; subsequently, 1.3 g of 3-(trimethoxysilyl)propyl methacrylate was slowly added to the four-necked round-bottom flask, and the reaction was maintained at 85 degrees Celsius for 1 hour; finally, the temperature was adjusted to 90 degrees Celsius for 1 hour, and ammonia water was added to adjust the pH to 7-8, thereby preparing a homemade silicon-modified acrylic emulsion.

9. A method for preparing wet sprayed concrete for tunnel engineering according to any one of claims 1 to 4, characterized in that: The preparation method of wet shotcrete for tunnel engineering is as follows: firstly, cement and coarse aggregate are added into a forced mixer and stirred for 30 seconds; then, a water reducer is mixed evenly with water, and then added into a stirring pot and stirred for 45 seconds; finally, coated modified porous aggregate and medium sand are added into the stirring pot together and stirred for 2 minutes; finally, during the spraying operation, an accelerating setting agent is automatically added through a nozzle, so that wet shotcrete for tunnel engineering is prepared.

10. Use of the wet shotcrete for tunnel engineering as claimed in claim 9 in tunnel engineering construction.

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