Low-rebound shotcrete admixture, preparation method and application thereof

Abstract

The present application discloses a low-rebound shotcrete admixture, a preparation method thereof, and an application thereof, relating to the technical field of engineering materials. The admixture raw materials include, by weight, 400-500 parts of silica fume, 100-250 parts of fluff ash, 200-320 parts of pretreated coal gasification furnace slag powder, 20-30 parts of disodium dihydrogen pyrophosphate, 10-15 parts of sodium dihydrogen phosphate, 20-30 parts of sodium hexametaphosphate, 5-10 parts of rubber powder, and 5-10 parts of cellulose ether; each raw material is weighed by weight, and the raw materials are added to a concrete mixer for stirring, and uniform stirring is performed for 15-30 minutes; the uniformly stirred mixture is bagged to obtain a low-rebound shotcrete admixture; the obtained admixture is applied to shotcrete to obtain low-rebound shotcrete. The present application solves the problem that the existing coal gasification furnace slag shotcrete construction efficiency is low and the engineering quality is difficult to meet the requirements.

Description

Technical Field

[0001] The present application relates to the field of engineering material technology, and in particular to a low-rebound shotcrete admixture, a preparation method thereof, and applications thereof. Background Art

[0002] In underground coal mining projects, shotcrete is a commonly used material for supporting coal mine tunnels. By using a pressure spray gun to spray shotcrete composed of cement, sand, gravel, and accelerator onto the top and side of the tunnel, it plays a supporting role in the coal mine tunnels.

[0003] Coal gasification slag is an industrial solid waste generated within the gasifier during the coal-to-liquids process. It typically has a fineness modulus similar to that of fine sand, high porosity and water absorption, and exhibits gelling activity after grinding. Coal gasification slag contains a large amount of amorphous gelling active substances. These substances can undergo a secondary reaction with cement hydration products in concrete to produce more hydrated calcium silicate gel, thereby improving the concrete's density and compressive strength.

[0004] However, coal gasification furnace slag has high water absorption and potential alkali-aggregate activity, making its direct application in shotcrete difficult. This can lead to problems such as high water consumption, high rebound, poor early strength, and segregation. Therefore, it is necessary to develop a low-rebound shotcrete admixture and a method for preparing shotcrete with a high coal gasification furnace slag content to increase the absorption capacity of coal gasification furnace slag and address the low construction efficiency and substandard quality of existing coal gasification furnace slag shotcrete. Summary of the Invention

[0005] In order to overcome the problems of high water consumption, high rebound rate, poor early strength and segregation when directly applying coal gasification furnace slag to shotcrete, and to solve the problem that the existing coal gasification furnace slag shotcrete has low construction efficiency and difficult to meet the engineering quality requirements, the present application provides a low-rebound shotcrete admixture, its preparation method and application.

[0006] The present application provides a low-rebound shotcrete admixture, which adopts the following technical solution:

[0007] A low-rebound shotcrete admixture comprises, by weight, 400-500 parts of silica fume, 100-250 parts of fluff ash, 200-320 parts of pretreated coal gasification furnace slag powder, 20-30 parts of disodium dihydrogen pyrophosphate, 10-15 parts of sodium dihydrogen phosphate, 20-30 parts of sodium hexametaphosphate, 5-10 parts of rubber powder, and 5-10 parts of cellulose ether.

[0008] Preferably, the method for preparing the pretreated coal gasification furnace slag powder comprises the following steps:

[0009] S1. The coal gasification slag was crushed, screened, washed, and dried, then fully immersed in a hydrochloric acid solution, then washed to neutrality, and dried to obtain hydrochloric acid-treated coal gasification slag;

[0010] S2. The treated gasifier slag was mixed with an alkaline activator, water was added and the mixture was stirred evenly, stirred thoroughly at room temperature and dried to obtain a gasifier slag impregnated with an alkaline activator and microwave activated under a nitrogen atmosphere, then washed with water until neutral and dried to obtain the pretreated gasifier slag;

[0011] S3. The pre-treated coal gasification slag is first pre-ground by a roller press and then further ground by an ultra-fine ball mill to obtain a specific surface area of ​​≥700m 2 / kg pretreated coal gasification slag powder.

[0012] Preferably, the power of the microwave activation is 650-750 W, and the time is 10-15 min.

[0013] Preferably, the cellulose ether is hydroxypropyl methylcellulose with a viscosity of 100,000-200,000 mPa.s.

[0014] Preferably, the rubber powder is prepared from the following raw materials: polyvinyl alcohol, tert-butyl hydroperoxide solution, sodium formaldehyde sulfoxylate, vinyl acetate, ethylene, sodium bicarbonate, and water.

[0015] Preferably, the method for preparing the rubber powder comprises the following steps:

[0016] S1. Add 6-10 parts of a 4.8wt% tert-butyl hydroperoxide solution to the initiator tank and stir to dissolve; stir 2-3 parts of polyvinyl alcohol and 80-120 parts of water at room temperature for 15-25min, then heat to 80-90°C and stir for 60-70min to dissolve to obtain a polyvinyl alcohol solution;

[0017] S2. The polyvinyl alcohol solution, 0.2-0.3 parts of sodium formaldehyde sulfoxylate and 10-15 parts of water were added to the reactor, stirred, and then 50-75 parts of vinyl acetate was added and stirred. Ethylene was introduced and the pressure was raised to 2.5-3 MPa and heated. When the temperature rose to 50-60 ° C, tert-butyl hydroperoxide solution was added dropwise. After the temperature reached 80-85 ° C, the ethylene pressure was increased to 6.0-6.5 MPa; 50-75 parts of vinyl acetate was then added dropwise, and the reaction temperature and ethylene pressure were maintained unchanged until the addition of vinyl acetate was completed;

[0018] S3. Cool to 50-60°C, degas, filter, cool, add 0.3-0.4 parts of sodium bicarbonate, and discharge; freeze-dry the product and sieve it to obtain rubber powder.

[0019] The present application provides a method for preparing a low-rebound shotcrete admixture, which adopts the following technical solution:

[0020] A method for preparing a low-rebound shotcrete admixture comprises the following steps:

[0021] Raw materials including silica fume, fluff ash, pre-treated coal gasification furnace slag powder, disodium dihydrogen pyrophosphate, sodium dihydrogen phosphate, sodium hexametaphosphate, rubber powder and cellulose ether are weighed according to their weight proportions; the raw materials are added into a concrete mixer and stirred evenly for 15-30 minutes; the evenly stirred mixture is bagged to prepare a low-rebound shotcrete admixture.

[0022] The application of a low-rebound shotcrete admixture provided in this application adopts the following technical solution:

[0023] The invention discloses an application of a low-rebound shotcrete admixture, and the application of the admixture in shotcrete. The shotcrete raw materials include, by weight, 350-400 parts of cement, 100-150 parts of admixture, 800-850 parts of sand, 800-850 parts of crushed stone, 4-10 parts of water reducer, 28-30 parts of accelerating setting agent, and 150-200 parts of water.

[0024] Preferably, the sand comprises 30-50% pre-treated coal gasification furnace slag powder and 50-70% natural sand.

[0025] Preferably, the method for preparing shotcrete comprises the following steps:

[0026] S1: Weigh the raw materials according to weight, and add cement, admixtures, gravel and sand into the concrete mixing equipment;

[0027] S2: stirring the components to form a mixture;

[0028] S3: After adding water, water reducing agent and accelerating setting agent into the mixture, continue stirring to obtain shotcrete.

[0029] In summary, this application includes at least one of the following beneficial technical effects:

[0030] 1. This application reduces the hydrophilicity of the surface of the gasification slag and weakens its water absorption capacity by crushing, screening, washing, and drying the gasification slag, immersing it in a hydrochloric acid solution and then washing it to neutrality, and then mixing it with an alkaline activator and subjecting it to microwave activation treatment, thereby reducing the water consumption of concrete. At the same time, the alkaline activator treatment can stimulate the potential activity of the gasification slag, allowing it to participate in the secondary hydration reaction in the concrete, generating more hydration products, and thus improving the early strength of the concrete. The microwave activation treatment can also optimize the pore structure of the gasification slag, making it more evenly dispersed in the concrete and reducing segregation.

[0031] 2. The present application adopts silica fume, fluff ash, pretreated coal gasification slag powder, disodium dihydrogen pyrophosphate, sodium dihydrogen phosphate, sodium hexametaphosphate, glue powder and cellulose ether as raw materials to prepare low-rebound shotcrete admixture, which can effectively overcome the problems of large water consumption, high rebound rate, poor early strength and segregation when directly applying coal gasification slag to shotcrete, and solves the problem that the existing coal gasification slag shotcrete has low construction efficiency and difficult to meet the requirements of engineering quality; among them, silica fume and pretreated coal gasification slag powder can improve the density and later strength of concrete, and prevent alkali-aggregate reaction; the addition of fluff ash and composite phosphates can promote cement hydration, improve the early strength and crack resistance of concrete; glue powder and cellulose ether, as water-retaining agents and thickeners, can improve the wrapping performance of concrete slurry on aggregate.

[0032] 3. Coal gasification slag is industrial solid waste. This application also solves the problem of resource utilization of industrial solid waste, which is in line with the logic of circular economic development. DETAILED DESCRIPTION

[0033] The present application is further described in detail below with reference to the embodiments.

[0034] Preparation Example 1 Preparation of Pretreated Coal Gasification Slag Powder

[0035] Preparation Example 1.1

[0036] S1. The coal gasification slag was crushed and sieved to 0.1 mm, washed and dried, and then immersed in a 0.5 mol / L hydrochloric acid solution for 24 h, then washed with water until neutral, and dried to obtain hydrochloric acid-treated coal gasification slag;

[0037] S2. 1 kg of treated gasifier slag was mixed with 2 kg of alkaline activator sodium carbonate, 9.3 kg of water was added and mixed evenly, stirred at room temperature for 3 h and then dried to obtain gasifier slag impregnated with an alkaline activator and placed in a nitrogen atmosphere at a power of 650 W for 10 min, then washed with water until neutral and dried to obtain the pretreated gasifier slag;

[0038] S3. The pre-treated coal gasification slag is first pre-ground by a roller press and then further ground by an ultra-fine ball mill to obtain a specific surface area of ​​≥700m 2 / kg pretreated coal gasification slag powder.

[0039] Preparation Example 1.2

[0040] S1. The coal gasification slag was crushed and sieved to 0.1 mm, washed and dried, and then immersed in a 0.5 mol / L hydrochloric acid solution for 26 h, then washed with water until neutral, and dried to obtain hydrochloric acid-treated coal gasification slag;

[0041] S2. 1.5 kg of treated gasifier slag was mixed with 3 kg of alkaline activator sodium carbonate, 14 kg of water was added and mixed, stirred at room temperature for 3.5 h and then dried to obtain gasifier slag impregnated with an alkaline activator and placed in a nitrogen atmosphere at a power of 700 W for 13 min, then washed with water until neutral and dried to obtain the pretreated gasifier slag;

[0042] S3. The pre-treated coal gasification slag is first pre-ground by a roller press and then further ground by an ultra-fine ball mill to obtain a specific surface area of ​​≥700m 2 / kg pretreated coal gasification slag powder.

[0043] Preparation Example 1.3

[0044] S1. The coal gasification slag was crushed and sieved to 0.1 mm, washed and dried, and then fully immersed in a 0.5 mol / L hydrochloric acid solution for 28 h, then washed to neutrality, and dried to obtain hydrochloric acid-treated coal gasification slag;

[0045] S2. 2kg of treated gasifier slag was mixed with 4kg of alkaline activator sodium carbonate, 18.6kg of water was added and mixed evenly, stirred at room temperature for 4h and then dried to obtain gasifier slag impregnated with an alkaline activator and placed in a nitrogen atmosphere at a power of 750W for 15min, then washed with water until neutral and dried to obtain the pretreated gasifier slag;

[0046] S3. The pre-treated coal gasification slag is first pre-ground by a roller press and then further ground by an ultra-fine ball mill to obtain a specific surface area of ​​≥700m 2 / kg pretreated coal gasification slag powder.

[0047] Preparation Example 2 Preparation of Rubber Powder

[0048] Preparation Example 2.1

[0049] S1. 6 g of 4.8 wt% tert-butyl hydroperoxide solution was added to the initiator tank and stirred to dissolve; 2 g of polyvinyl alcohol and 80 g of water were stirred at room temperature for 15 min, then heated to 80 ° C and stirred for 60 min to dissolve to obtain a polyvinyl alcohol solution;

[0050] S2. The polyvinyl alcohol solution, 0.2g of sodium formaldehyde sulfoxylate and 10g of water were added to the reactor, stirred, and then 50g of vinyl acetate was added and stirred. Ethylene was introduced and the pressure was raised to 2.5MPa and heated. When the temperature reached 50°C, tert-butyl hydroperoxide solution was added dropwise. After the temperature reached 80°C, the ethylene pressure was increased to 6.0MPa; 50g of vinyl acetate was then added dropwise, and the reaction temperature and ethylene pressure were maintained unchanged until the addition of vinyl acetate was complete.

[0051] S3. Cool to 50°C, degas, filter, cool, add 0.3g of sodium bicarbonate, and discharge; freeze-dry and sieve the product to obtain rubber powder.

[0052] Preparation Example 2.2

[0053] S1. 8 g of a 4.8 wt% tert-butyl hydroperoxide solution was added to the initiator tank and stirred to dissolve; 2.5 g of polyvinyl alcohol and 100 g of water were stirred at room temperature for 20 min, then heated to 85 ° C and stirred for 65 min to dissolve to obtain a polyvinyl alcohol solution;

[0054] S2. The polyvinyl alcohol solution, 0.25g of sodium formaldehyde sulfoxylate and 12.5g of water were added to the reactor, stirred, and then 62g of vinyl acetate was added and stirred. Ethylene was introduced and the pressure was raised to 2.7MPa and heated. When the temperature rose to 55°C, tert-butyl hydroperoxide solution was added dropwise. After the temperature reached 83°C, the ethylene pressure was increased to 6.3MPa; 62g of vinyl acetate was then added dropwise, and the reaction temperature and ethylene pressure were maintained unchanged until the addition of vinyl acetate was complete.

[0055] S3. Cool to 55°C, degas, filter, cool, add 0.35g of sodium bicarbonate, and discharge; freeze-dry and sieve the product to obtain rubber powder.

[0056] Preparation Example 2.3

[0057] S1. 10 g of 4.8 wt% tert-butyl hydroperoxide solution was added to the initiator tank and stirred to dissolve; 3 g of polyvinyl alcohol and 120 g of water were stirred at room temperature for 25 min, then heated to 90 ° C and stirred for 70 min to dissolve to obtain a polyvinyl alcohol solution;

[0058] S2. The polyvinyl alcohol solution, 0.3g of sodium formaldehyde sulfoxylate and 15g of water were added to the reactor and stirred. After that, 75g of vinyl acetate was added and stirred. Ethylene was introduced and the pressure was raised to 3MPa and heated. When the temperature reached 60°C, tert-butyl hydroperoxide solution was added dropwise. After the temperature reached 85°C, the ethylene pressure was increased to 6.5MPa; 75g of vinyl acetate was then added dropwise, and the reaction temperature and ethylene pressure were maintained unchanged until the addition of vinyl acetate was complete.

[0059] S3. Cool to 60°C, degas, filter, cool, add 0.4g of sodium bicarbonate, and discharge; freeze-dry and sieve the product to obtain rubber powder.

[0060] Example 1

[0061] The raw materials were weighed according to their weight: 400 g of silica fume, 100 g of fluff ash, 200 g of the pretreated coal gasification furnace slag powder obtained in Preparation Example 1.1, 20 g of disodium dihydrogen pyrophosphate, 10 g of sodium dihydrogen phosphate, 20 g of sodium hexametaphosphate, 5 g of the rubber powder obtained in Preparation Example 2.1, and 5 g of hydroxypropyl methylcellulose with a viscosity of 100,000 mPa.s; the raw materials were added to a concrete mixer and stirred evenly for 15 minutes; the evenly stirred mixture was bagged to obtain a low-rebound shotcrete admixture.

[0062] Example 2

[0063] The raw materials were weighed according to their weight: 450 g of silica fume, 170 g of fluff ash, 260 g of pretreated coal gasification furnace slag powder obtained in Preparation Example 1.1, 25 g of disodium dihydrogen pyrophosphate, 12.5 g of sodium dihydrogen phosphate, 25 g of sodium hexametaphosphate, 7.5 g of rubber powder obtained in Preparation Example 2.1, and 7.5 g of hydroxypropyl methylcellulose with a viscosity of 150,000 mPa.s; the raw materials were added to a concrete mixer and stirred evenly for 23 minutes; the evenly stirred mixture was bagged to obtain a low-rebound shotcrete admixture.

[0064] Example 3

[0065] The raw materials were weighed according to their weight: 500 g of silica fume, 250 g of fluff ash, 320 g of the pretreated coal gasification furnace slag powder obtained in Preparation Example 1.1, 30 g of disodium dihydrogen pyrophosphate, 15 g of sodium dihydrogen phosphate, 30 g of sodium hexametaphosphate, 10 g of the rubber powder obtained in Preparation Example 2.1, and 10 g of hydroxypropyl methylcellulose with a viscosity of 200,000 mPa.s; the raw materials were added to a concrete mixer and stirred evenly for 30 minutes; the evenly stirred mixture was bagged to obtain a low-rebound shotcrete admixture.

[0066] Example 4

[0067] The difference between Example 4 and Example 1 is that the pretreated coal gasification furnace slag powder used in Example 4 comes from Preparation Example 1.2.

[0068] Example 5

[0069] The difference between Example 5 and Example 1 is that the pretreated coal gasification furnace slag powder used in Example 5 comes from Preparation Example 1.3.

[0070] Example 6

[0071] The difference between Example 6 and Example 1 is that the rubber powder used in Example 6 comes from Preparation Example 2.2.

[0072] Example 7

[0073] The difference between Example 7 and Example 1 is that the rubber powder used in Example 7 comes from Preparation Example 2.3.

[0074] Comparative Example 1

[0075] The difference between Comparative Example 1 and Example 1 is that the coal gasification furnace slag powder in Comparative Example 1 is ordinary coal gasification furnace slag powder that has not been pretreated, and the specific surface area is ≥700m 2 / kg.

[0076] Comparative Example 2

[0077] The difference between Comparative Example 2 and Example 1 is that the rubber powder used in Comparative Example 2 is ethylene vinyl acetate.

[0078] Application Example 1

[0079] S1: Weigh the raw materials by weight and add 350 g of P·O42.5 ordinary Portland cement, 100 g of the admixture prepared in Example 1, 800 g of crushed stone, and 800 g of sand to a concrete mixing device. In this application example, the sand comprises 30% of the pretreated coal gasification furnace slag powder prepared in Preparation Example 1.1 and 70% of natural sand. The crushed stone has a particle size of ≤10 mm and a mud content of ≤3%.

[0080] S2: stirring the components to form a mixture;

[0081] S3: After adding 150g of water, 4g of polycarboxylic acid-based high-efficiency water reducing agent and 28g of quick-setting agent aluminum sulfate into the mixture, stirring is continued to obtain sprayed concrete.

[0082] Application Example 2

[0083] S1: Weigh the raw materials by weight and add 375 g of P·O42.5 ordinary Portland cement, 125 g of the admixture prepared in Example 1, 825 g of crushed stone, and 825 g of sand to a concrete mixing apparatus. In this application example, the sand comprises 30% of the pretreated coal gasification furnace slag powder prepared in Preparation Example 1.1 and 70% of natural sand. The crushed stone has a particle size of ≤10 mm and a mud content of ≤3%.

[0084] S2: stirring the components to form a mixture;

[0085] S3: After adding 175 g of water, 7 g of polycarboxylic acid-based high-efficiency water reducing agent and 29 g of accelerator aluminum sulfate into the mixture, stirring is continued to obtain sprayed concrete.

[0086] Application Example 3

[0087] S1: Weigh the raw materials by weight, and add 400 g of P·O42.5 ordinary Portland cement, 150 g of the admixture prepared in Example 1, 850 g of crushed stone, and 850 g of sand to a concrete mixing apparatus. In this application example, the sand comprises 30% of the pretreated coal gasification furnace slag powder prepared in Preparation Example 1.1 and 70% of natural sand. The crushed stone has a particle size of ≤10 mm and a mud content of ≤3%.

[0088] S2: stirring the components to form a mixture;

[0089] S3: After adding 200g of water, 10g of polycarboxylic acid-based high-efficiency water reducing agent and 30g of quick-setting agent aluminum sulfate into the mixture, stirring is continued to obtain sprayed concrete.

[0090] Application Example 4

[0091] The difference between Application Example 4 and Application Example 1 is that the admixture used in Application Example 4 is prepared from Example 2.

[0092] Application Example 5

[0093] The difference between Application Example 5 and Application Example 1 is that the admixture used in Application Example 5 is prepared from Example 3.

[0094] Application Example 6

[0095] The difference between Application Example 6 and Application Example 1 is that the admixture used in Application Example 6 is prepared from Example 4.

[0096] Application Example 7

[0097] The difference between Application Example 7 and Application Example 1 is that the admixture used in Application Example 7 is prepared from Example 5.

[0098] Application Example 8

[0099] The difference between Application Example 8 and Application Example 1 is that the admixture used in Application Example 8 is prepared from Example 6.

[0100] Application Example 9

[0101] Application Example 9 differs from Application Example 1 in that the admixture used in Application Example 9 is prepared from Example 7.

[0102] Application Example 10

[0103] Application Example 10 is different from Application Example 1 in that the sand in Application Example 10 includes 40% of the pretreated coal gasification furnace slag powder obtained in Preparation Example 1.1 and 60% of natural sand.

[0104] Application Example 11

[0105] Application Example 11 is different from Application Example 1 in that the sand in Application Example 11 includes 50% of the pretreated coal gasification furnace slag powder obtained in Preparation Example 1.1 and 50% of natural sand.

[0106] Application Example 12

[0107] Application Example 12 is different from Application Example 1 in that the sand in Application Example 12 includes 20% of the pretreated coal gasification furnace slag powder obtained in Preparation Example 1.1 and 80% of natural sand.

[0108] Application Example 13

[0109] Application Example 13 is different from Application Example 1 in that the sand in Application Example 13 includes 60% of the pretreated coal gasification furnace slag powder obtained in Preparation Example 1.1 and 40% of natural sand.

[0110] Comparative Application Example 1

[0111] The difference between Comparative Application Example 1 and Application Example 1 is that the admixture in Comparative Application Example 1 is replaced by the pretreated coal gasification furnace slag powder prepared in Preparation Example 1.1.

[0112] Comparative Application Example 2

[0113] The difference between Comparative Application Example 2 and Application Example 1 is that the admixture in Comparative Application Example 2 is replaced by silica fume.

[0114] Comparative Application Example 3

[0115] The difference between Comparative Application Example 3 and Application Example 1 is that the admixture used in Comparative Application Example 3 is prepared from Comparative Example 1.

[0116] Comparative Application Example 4

[0117] The difference between Comparative Application Example 4 and Application Example 1 is that the admixture used in Comparative Application Example 4 is prepared from Comparative Example 2.

[0118] Performance testing

[0119] 1. The setting time of shotcrete obtained from Example 1-13 and Comparative Example 1-4 in GB / T 35159-2017 "Accelerators for Shotcrete" was tested, and the results are shown in Table 1.

[0120] 2. The compressive strength of shotcrete obtained from Example 1-13 and Comparative Application Example 1-4 according to GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete" was tested, and the results are shown in Table 1.

[0121] 3. The rebound rate of shotcrete obtained from Example 1-13 and Comparative Application Example 1-4 according to NB-T 11535-2024 "Test method for determination of rebound rate of shotcrete" was tested, and the results are shown in Table 1.

[0122] The specific test results are as follows:

[0123] Table 1 Performance test results

[0124]

[0125]

[0126] It can be seen from the test results in Table 1 that the low-rebound shotcrete admixture provided in this application, its preparation method and its application in shotcrete can obtain shotcrete with fast setting speed, high compressive strength and low rebound rate, which effectively improves the construction efficiency and project quality.

[0127] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A low-rebound shotcrete admixture, characterized by: The raw materials include, by weight, 400-500 parts of silica fume, 100-250 parts of fluff ash, 200-320 parts of pretreated coal gasification furnace slag powder, 20-30 parts of disodium dihydrogen pyrophosphate, 10-15 parts of sodium dihydrogen phosphate, 20-30 parts of sodium hexametaphosphate, 5-10 parts of rubber powder, and 5-10 parts of cellulose ether; The method for preparing the pretreated coal gasification furnace slag fine powder comprises the following steps: S1. The coal gasification slag was crushed, screened, washed, and dried, then fully immersed in a hydrochloric acid solution, then washed to neutrality, and dried to obtain hydrochloric acid-treated coal gasification slag; S2. The treated gasifier slag was mixed with an alkaline activator, water was added and the mixture was stirred evenly, stirred thoroughly at room temperature and dried to obtain a gasifier slag impregnated with an alkaline activator and microwave activated under a nitrogen atmosphere, then washed with water until neutral and dried to obtain the pretreated gasifier slag; S3. The pre-treated coal gasification slag is first pre-ground by a roller press and then further ground by an ultra-fine ball mill to obtain a specific surface area of ​​≥700m 2 / kg pretreated coal gasification slag powder.

2. The low-rebound shotcrete admixture according to claim 1, characterized in that: The power of the microwave activation is 650-750W, and the time is 10-15 minutes.

3. The low-rebound shotcrete admixture according to claim 1, characterized in that: The cellulose ether is hydroxypropyl methylcellulose, and has a viscosity of 100,000-200,000 mPa·s.

4. The low-rebound shotcrete admixture according to claim 1, characterized in that: The rubber powder is prepared from the following raw materials: polyvinyl alcohol, tert-butyl hydroperoxide solution, sodium formaldehyde sulfoxylate, vinyl acetate, ethylene, sodium bicarbonate and water.

5. The low-rebound shotcrete admixture according to claim 4, characterized in that: The preparation method of the rubber powder comprises the following steps: S1. Add 6-10 parts of a 4.8wt% tert-butyl hydroperoxide solution to the initiator tank and stir to dissolve; stir 2-3 parts of polyvinyl alcohol and 80-120 parts of water at room temperature for 15-25min, then heat to 80-90°C and stir for 60-70min to dissolve to obtain a polyvinyl alcohol solution; S2. The polyvinyl alcohol solution, 0.2-0.3 parts of sodium formaldehyde sulfoxylate and 10-15 parts of water were added to the reactor, stirred, and then 50-75 parts of vinyl acetate was added and stirred. Ethylene was introduced and the pressure was raised to 2.5-3 MPa and heated. When the temperature rose to 50-60 ° C, tert-butyl hydroperoxide solution was added dropwise. After the temperature reached 80-85 ° C, the ethylene pressure was increased to 6.0-6.5 MPa; 50-75 parts of vinyl acetate was then added dropwise, and the reaction temperature and ethylene pressure were maintained unchanged until the addition of vinyl acetate was completed; S3. Cool to 50-60°C, degas, filter, cool, add 0.3-0.4 parts of sodium bicarbonate, and discharge; freeze-dry the product and sieve it to obtain rubber powder.

6. A method for preparing a low-rebound shotcrete admixture according to any one of claims 1 to 5, characterized in that: The following steps are involved: Raw materials including silica fume, fluff ash, pre-treated coal gasification furnace slag powder, disodium dihydrogen pyrophosphate, sodium dihydrogen phosphate, sodium hexametaphosphate, rubber powder and cellulose ether are weighed according to their weight proportions; the raw materials are added into a concrete mixer and stirred evenly for 15-30 minutes; the evenly stirred mixture is bagged to prepare a low-rebound shotcrete admixture.

7. Use of a low-rebound shotcrete admixture according to any one of claims 1 to 5, characterized in that: The admixture is used in shotcrete; the raw materials of the shotcrete include 350-400 parts of cement, 100-150 parts of admixture, 800-850 parts of sand, 800-850 parts of crushed stone, 4-10 parts of water reducer, 28-30 parts of accelerating setting agent and 150-200 parts of water in parts by weight.

8. The use of a low-rebound shotcrete admixture according to claim 7, characterized in that: The sand comprises 30-50% of pre-treated coal gasification furnace slag powder and 50-70% of natural sand.

9. The use of a low-rebound shotcrete admixture according to claim 7, characterized in that: The preparation method of the shotcrete, The following steps are involved: S1: Weigh the raw materials according to weight, and add cement, admixtures, gravel and sand into the concrete mixing equipment; S2: stirring the components to form a mixture; S3: After adding water, water reducing agent and accelerating setting agent into the mixture, continue stirring to obtain shotcrete.

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