A shotcrete and a method for producing the same

Abstract

The application discloses a kind of shotcrete and its preparation method, belong to building material technical field.It mainly includes the following weight parts of raw materials made: Portland cement 200~260 parts, fine sand 240~280 parts, 260~300 parts of gravel, fly ash 10~35 parts, composite steel fiber 5~10 parts, admixture 10~15 parts, no alkali accelerator 2~5 parts, water reducing agent 1~3 parts and water 80~110 parts.The shotcrete provided by the application adopts steel fiber and has excellent tensile strength and elastic modulus and other characteristics, and the composite steel fiber forms a three-dimensional network structure in the concrete to support the concrete;After adding fly ash and admixture to the concrete, it is beneficial to improve the compactness of the concrete, promote the development of early strength, and improve the compressive performance of the concrete.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a shotcrete and a preparation method thereof. BACKGROUND

[0002] Shotcrete is a kind of material which is formed by spraying the cement mortar with high pressure and high speed to the surface of rock or structure, so as to form a layer of concrete on the surface of rock or structure, and to strengthen and protect the rock or structure. Shotcrete is developed from shotcrete mortar, and is mainly used in underground structures such as mine, shaft, traffic tunnel, water conservancy culvert, underground power station, concrete support or anchor support, anti-permeable concrete construction of underground pool, oil tank and large pipeline, rapid repair of special projects such as various thermal kiln and chimney, and reinforcement and repair of large concrete structures.

[0003] Shotcrete support can ensure the close bonding between the shotcrete and the intersecting rock stratum, and cause the redistribution of the stress in the rock mass and the support. In the past, the steel, wood support, stone and concrete support only passively bear the weight of the upper loose surrounding rock, and maintain the stability of the tunnel. Shotcrete support actively takes into account and plays the self-stabilizing role of the surrounding rock, and combines the shotcrete with the self-stabilizing ability of the surrounding rock, so as to change from passive to active, and from negative to positive.

[0004] The construction of shotcrete generally does not need formwork, and can save the processes of formwork erection, pouring and formwork removal. The shotcrete can combine the processes of mixing, conveying, pouring and tamping into one process, and has the advantages of accelerating the construction progress, fast strength growth, good compactness, simple construction preparation, strong adaptability, wide application range, easy-to-master construction technology, and less engineering investment.

[0005] For the surrounding rock with poor geological conditions, the shotcrete thickness is often increased to increase the initial support stiffness of the shotcrete. Research shows that the excessive thickness of the shotcrete will cause a series of adverse effects on the initial support structure, such as increasing the bending stress, brittleness and construction cost. SUMMARY

[0006] The present application aims to provide a kind of shotcrete and a preparation method thereof, which solves the problem of poor stability of soft surrounding rock and high requirement for early strength of shotcrete.

[0007] The present application is achieved by the following technical solutions:

[0008] A kind of shotcrete, mainly including the following weight parts of raw materials:

[0009] portland cement 200-260 parts, fine sand 240-280 parts, crushed stone 260-300 parts, fly ash 10-35 parts, composite steel fiber 5-10 parts, admixture 10-15 parts, non-alkali accelerator 2-5 parts, water reducing agent 1-3 parts, and water 80-110 parts;

[0010] The admixture includes nano-silicon nitride, modified sepiolite fiber, and calcium aluminum sulfate.

[0011] Further, in the shotcrete, the following raw materials are included by weight: portland cement 220-240 parts, fine sand 250-260 parts, crushed stone 270-290 parts, fly ash 15-25 parts, composite steel fiber 7-9 parts, admixture 12-14 parts, non-alkali accelerator 3-4 parts, water reducing agent 1.5-2.5 parts, and water 90-100 parts.

[0012] Further, in the shotcrete, the following raw materials are included by weight: portland cement 230 parts, fine sand 255 parts, crushed stone 280 parts, fly ash 20 parts, composite steel fiber 8 parts, admixture 13 parts, non-alkali accelerator 3.5 parts, water reducing agent 2 parts, and water 90 parts.

[0013] Further, in the shotcrete, the admixture includes: nano-silicon nitride 20-30 parts, modified sepiolite fiber 25-45 parts, and 10-18 parts.

[0014] Further, in the shotcrete, the preparation of the modified sepiolite fiber includes:

[0015] The sepiolite fiber is heated and treated at a temperature of 100-300°C for 1-3 hours;

[0016] The heated and treated sepiolite fiber is subjected to plasma treatment at a pressure of 10-20 Pa and a power of 100-300 W for 5-10 minutes;

[0017] Ethyl orthosilicate and aluminum isopropoxide are mixed into a solution at a mass ratio of 1:(0.1-0.5), and 3-aminopropyltriethylsilane is added to the solution, which is stirred uniformly to obtain a mixed solution;

[0018] The plasma-treated sepiolite fiber is soaked in the mixed solution and treated at a temperature of 100-120°C for 2-5 hours to obtain the modified sepiolite fiber.

[0019] The mass ratio of the sepiolite fiber, ethyl orthosilicate, and 3-aminopropyltriethylsilane is 1:(0.05-0.1):(0.01-0.05).

[0020] Further, in the shotcrete, the nano silicon nitride has a particle size of 10-20 nm, and the modified sepiolite fiber has a length of 1-200 microns.

[0021] Further, in the shotcrete, the composite steel fiber comprises 0.1-0.3 mm diameter steel fiber and 0.6-1.0 mm diameter steel fiber in a mass ratio of 2:(3-5), the 0.1-0.3 mm diameter steel fiber has a length of 10-12 mm, and the 0.6-1.0 mm diameter steel fiber has a length of 3-7 mm.

[0022] Further, in the shotcrete, the alkali-free accelerator is a liquid aluminum sulfate accelerator.

[0023] Further, in the shotcrete, the water-binder ratio of the shotcrete is 0.4-0.5.

[0024] The application further provides a preparation method of the shotcrete, comprising:

[0025] Mixing silicate cement, fine sand, gravel and water, and stirring uniformly to obtain a mixture;

[0026] Mixing the composite steel fiber, the admixture, the alkali-free accelerator and the water reducing agent uniformly, and then adding them into the mixture, and stirring for 5-10 min at a temperature of 10-30 DEG C.

[0027] The application has the following advantages:

[0028] The shotcrete provided by the application has excellent tensile strength and elastic modulus, and the composite steel fiber forms a three-dimensional network structure in the concrete to support the concrete.

[0029] The shotcrete provided by the application uses the admixture obtained by mixing nano silicon nitride, modified sepiolite fiber and aluminum sulfate calcium, the nano silicon nitride can induce more gel of the fly ash to further improve the early strength of the concrete, and can fill the pores of the concrete material to improve the compactness of the concrete and the compressive strength; the modified sepiolite fiber and the steel fiber further improve the combination of the components of the concrete, the modified sepiolite fiber can have a hydration reaction to provide more aluminum and silica gel, and can improve the early strength of the concrete and reduce the generation of micro cracks; the added calcium sulphoaluminate can be hydrated with gypsum to generate ettringite and aluminum gel, the generated ettringite can quickly form a skeleton structure to provide a skeleton structure for the cement paste, the generated ettringite promotes the setting of the concrete, and is beneficial to improve the compactness of the concrete, promote the development of the early strength and improve the compressive performance of the concrete.

[0030] The sprayed concrete provided by the application uses steel fibers with different diameters and lengths, and the steel fibers with small diameters and long lengths and the steel fibers with large diameters and short lengths are used in combination, so that the uneven distribution of the steel fibers can be avoided, and the compressive performance is improved.

[0031] The preparation method of the sprayed concrete provided by the application controls the mixing temperature at 10-30 DEG C, improves the mixing reaction temperature of the concrete, and can improve the adaptability of the alkali-free accelerator and help the rapid setting of the cement slurry. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application clearer, specific embodiments are used to further describe the present application, and the illustrative embodiments and the description thereof are only used to explain the present application, and are not used to limit the present application. The specific conditions are not indicated in the embodiments, and the conventional conditions or the conditions suggested by the manufacturer are used. The reagents or instruments are not indicated by the manufacturer, and are conventional products that can be purchased in the market.

[0033] The technical scheme of the present application is:

[0034] A sprayed concrete mainly comprises the following raw materials in parts by weight:

[0035] 200-260 parts of Portland cement, 240-280 parts of fine sand, 260-300 parts of crushed stone, 10-35 parts of fly ash, 5-10 parts of composite steel fiber, 10-15 parts of admixture, 2-5 parts of alkali-free accelerator, 1-3 parts of water reducing agent and 80-110 parts of water;

[0036] The admixture comprises nano silicon nitride, modified sepiolite fiber and calcium aluminum sulfate.

[0037] The steel fiber used in the present application has excellent tensile strength and elastic modulus, and the composite steel fiber forms a three-dimensional network structure in the concrete to support the concrete. After adding fly ash to the concrete, the interface properties of the steel fiber and the concrete material are improved, the interface area is strengthened, the interface bonding strength is improved, and the composite effect of the steel fiber and the fly ash is formed. The pozzolanic effect and micro-filling effect of the fly ash can form a gel to fill the gap between the steel fiber and the base concrete, thereby improving the compactness of the concrete and further improving the strength of the concrete.

[0038] The admixture comprises 20-30 parts of nano silicon nitride, 25-45 parts of modified sepiolite fiber and 10-18 parts of calcium aluminum sulfate.

[0039] In the early stage of cement hydration process, nano-silicon nitride has an inducing effect on fly ash, and a part of it participates in the hydration reaction to provide more C-H-S gel, thereby further improving the early strength of concrete. The nano-silicon nitride particles are small enough to fill into the pores of the concrete material, further reducing the porosity of the concrete, improving its density and compressive strength.

[0040] Further, the preparation of the modified sepiolite fiber comprises:

[0041] (1) heating treatment of sepiolite fiber at a temperature of 100-300℃ for 1-3h;

[0042] (2) plasma treatment of the heated sepiolite fiber at a pressure of 10-20Pa and a power of 100-300W for 5-10min;

[0043] (3) preparation of a solution by mixing tetraethyl orthosilicate and aluminum isopropoxide at a mass ratio of 1:(0.1-0.5), adding 3-aminopropyltriethylsilane to the solution, and stirring uniformly to obtain a mixed solution;

[0044] (4) treatment of the plasma-treated sepiolite fiber in the mixed solution at a temperature of 100-120℃ for 2-5h to obtain the modified sepiolite fiber;

[0045] wherein the mass ratio of sepiolite fiber, tetraethyl orthosilicate and 3-aminopropyltriethylsilane is 1:(0.05-0.1):(0.01-0.05).

[0046] The modified sepiolite fiber in the present application, as an admixture, further improves the binding between the components of concrete with the addition of steel fibers. The modified sepiolite fiber can undergo hydration reaction to provide more aluminum and silica gel, thereby improving the early strength of concrete and reducing the generation of micro-cracks.

[0047] The added calcium sulphoaluminate can hydrate with gypsum to form ettringite and aluminum gel. The formed ettringite quickly forms a skeleton structure for the cement paste, and the formed ettringite promotes the setting of concrete, which is beneficial to improve the compactness of concrete, promote the development of early strength, and improve the compressive performance of concrete.

[0048] Further, the composite steel fiber comprises: a mixture of steel fibers with a diameter of 0.1-0.3mm and steel fibers with a diameter of 0.6-1.0mm at a mass ratio of 2:(3-5); the length of the steel fibers with a diameter of 0.1-0.3mm is 10-12mm; and the length of the steel fibers with a diameter of 0.6-1.0mm is 3-7mm.

[0049] The steel fiber composite of different diameters and different lengths is used in the embodiment of the application, the steel fiber with small diameter and long length and the steel fiber with large diameter and short length are used in cooperation, so that the uneven distribution of the steel fiber can be avoided, and the compression resistance is improved.

[0050] Further, the nano-silicon nitride has a particle size of 10-20 nm, and the modified sepiolite fiber has a length of 1-200 microns.

[0051] Further, the alkali-free accelerator is a liquid aluminum sulfate accelerator, and the water reducing agent is a polycarboxylic acid water reducing agent.

[0052] Further, the water-binder ratio of the sprayed concrete is 0.4-0.5.

[0053] If the water-binder ratio exceeds 0.5, the strength of the concrete is low, and the concrete is prone to peeling during spraying; if the water-binder ratio is less than 0.4, the rebound and dust of the sprayed concrete are large. When the water-binder ratio is 0.4-0.5, the strength of the concrete can be ensured, and the rebound and dust of the sprayed concrete are reduced.

[0054] The preparation method of the sprayed concrete comprises the following steps:

[0055] Mixing silicate cement, fine sand, gravel and water, and stirring uniformly to obtain a mixture;

[0056] After the composite steel fiber, the admixture, the alkali-free accelerator and the water reducing agent are mixed uniformly, the mixture is added, and stirring is performed at a temperature of 10-30 DEG C for 5-10 minutes.

[0057] By increasing the stirring reaction temperature of the concrete, the adaptability of the alkali-free accelerator can be improved, and the cement paste can be rapidly solidified.

[0058] In order to further illustrate the application, a kind of sprayed concrete provided by the application is described below in conjunction with examples, but it should be understood that these examples are implemented on the premise of the technical scheme of the application, detailed implementation mode and specific operation process are given, only for further illustrating the features and advantages of the application, and not the limitation of the claims of the application, the protection scope of the application is not limited to the following examples.

[0059] Example 1:

[0060] The sprayed concrete of the embodiment is mainly prepared from the following raw materials in parts by weight:

[0061] The silicate cement is 200 parts, the fine sand is 240 parts, the gravel is 2600 parts, the fly ash is 10 parts, the composite steel fiber is 5 parts, the admixture is 10 parts, the alkali-free accelerator is 2 parts, the water reducing agent is 1 part, and the water is 80 parts.

[0062] The admixture comprises: 20 parts of nano-silicon nitride, 25 parts of modified sepiolite fiber and 10 parts of calcium aluminum sulfate.

[0063] The preparation of the modified sepiolite fiber comprises:

[0064] The sepiolite fiber is heated and treated for 1h at a temperature of 100℃;

[0065] The sepiolite fiber after the heating treatment is subjected to plasma treatment for 5min at a pressure of 10Pa and a power of 100W;

[0066] Ethyl silicate and aluminum isopropoxide with a mass ratio of 1:0.1 are mixed into a solution, 3-aminopropyltriethylsilane is added into the solution, and the mixture is stirred uniformly to obtain a mixed solution;

[0067] The sepiolite fiber after the plasma treatment is soaked in the mixed solution and treated for 2h at a temperature of 100℃ to obtain the modified sepiolite fiber;

[0068] The mass ratio of the sepiolite fiber, the ethyl silicate and the 3-aminopropyltriethylsilane is 1:0.05:0.01.

[0069] The composite steel fiber comprises: 0.1-0.3mm diameter steel fiber and 0.6-1.0mm diameter steel fiber mixed with a mass ratio of 2:3; the length of the 0.1-0.3mm diameter steel fiber is 10-12mm; and the length of the 0.6-1.0mm diameter steel fiber is 3-7mm.

[0070] The preparation method of the sprayed concrete of the embodiment comprises:

[0071] The silicate cement, fine sand, gravel and water are mixed and stirred uniformly to obtain a mixture;

[0072] The composite steel fiber, the admixture, the non-alkali accelerator and the water reducing agent are mixed uniformly and then added into the mixture, and stirred for 5min at a temperature of 10℃.

[0073] Example 2:

[0074] The sprayed concrete of the embodiment mainly comprises the following raw materials made with the following weight parts:

[0075] The silicate cement 220 parts, the fine sand 250 parts, the gravel 270 parts, the fly ash 15 parts, the composite steel fiber 7 parts, the admixture 12 parts, the non-alkali accelerator 3 parts, the water reducing agent 1.5 parts and the water 90 parts.

[0076] The admixture comprises: 25 parts of nano-silicon nitride, 35 parts of modified sepiolite fiber and 15 parts of calcium aluminum sulfate.

[0077] The preparation of the modified sepiolite fiber comprises:

[0078] The sepiolite fiber is heated and treated for 1.5 hours at a temperature of 220℃;

[0079] The heated and treated sepiolite fiber is subjected to plasma treatment for 7 minutes at a pressure of 15 Pa and a power of 275 W;

[0080] Ethyl silicate and aluminum isopropoxide with a mass ratio of 1:0.3 are mixed to form a solution, 3-aminopropyltriethylsilane is added to the solution, and the mixture is stirred uniformly to obtain a mixed solution;

[0081] The plasma-treated sepiolite fiber is soaked in the mixed solution and treated at a temperature of 115℃ for 3.5 hours to obtain the modified sepiolite fiber;

[0082] The mass ratio of the sepiolite fiber, the ethyl silicate and the 3-aminopropyltriethylsilane is 1:0.07:0.03.

[0083] The composite steel fiber comprises: 0.1-0.3 mm diameter steel fiber and 0.6-1.0 mm diameter steel fiber mixed at a mass ratio of 2:3.5; the 0.1-0.3 mm diameter steel fiber has a length of 10-12 mm; and the 0.6-1.0 mm diameter steel fiber has a length of 3-7 mm.

[0084] The preparation method of the sprayed concrete of the embodiment comprises:

[0085] The silicate cement, fine sand, gravel and water are mixed and stirred uniformly to obtain a mixture;

[0086] The composite steel fiber, the admixture, the non-alkali accelerator and the water reducing agent are mixed uniformly and then added to the mixture, and the mixture is stirred for 7 minutes at a temperature of 22℃.

[0087] Example 3:

[0088] The sprayed concrete of the embodiment is mainly prepared from the following raw materials by weight:

[0089] The silicate cement 230 parts, the fine sand 255 parts, the gravel 280 parts, the fly ash 20 parts, the composite steel fiber 8 parts, the admixture 13 parts, the non-alkali accelerator 3.5 parts, the water reducing agent 2 parts and the water 90 parts.

[0090] The admixture comprises: 30 parts of nano-silicon nitride, 45 parts of modified sepiolite fiber and 18 parts of calcium aluminum sulfate.

[0091] The preparation of the modified sepiolite fiber comprises:

[0092] The sepiolite fiber is heated and treated for 3 hours at a temperature of 300℃;

[0093] The sepiolite fiber after the heating treatment is subjected to plasma treatment for 10 minutes at a pressure of 20 Pa and a power of 300 W;

[0094] Ethyl silicate and aluminum isopropoxide with a mass ratio of 1:0.5 are mixed into a solution, 3-aminopropyltriethylsilane is added into the solution, and the mixture is stirred uniformly to obtain a mixed solution;

[0095] The sepiolite fiber after the plasma treatment is soaked in the mixed solution and treated at a temperature of 120℃ for 5 hours to obtain the modified sepiolite fiber;

[0096] The mass ratio of the sepiolite fiber, the ethyl silicate and the 3-aminopropyltriethylsilane is 1:0.1:0.05.

[0097] The composite steel fiber comprises: 0.1-0.3 mm diameter steel fiber and 0.6-1.0 mm diameter steel fiber mixed with a mass ratio of 2:5; the length of the 0.1-0.3 mm diameter steel fiber is 10-12 mm; and the length of the 0.6-1.0 mm diameter steel fiber is 3-7 mm.

[0098] The preparation method of the sprayed concrete of the embodiment comprises:

[0099] The silicate cement, fine sand, gravel and water are mixed and stirred uniformly to obtain a mixture;

[0100] The composite steel fiber, the admixture, the non-alkali accelerator and the water reducing agent are mixed uniformly and then added into the mixture, and stirred for 10 minutes at a temperature of 30℃.

[0101] Embodiment 4:

[0102] The sprayed concrete of the embodiment mainly comprises the following raw materials in parts by weight:

[0103] The silicate cement is 240 parts, the fine sand is 260 parts, the gravel is 290 parts, the fly ash is 25 parts, the composite steel fiber is 9 parts, the admixture is 14 parts, the non-alkali accelerator is 4 parts, the water reducing agent is 2.5 parts and the water is 100 parts.

[0104] The composition of the admixture and the preparation of the modified sepiolite fiber are the same as those of Embodiment 1.

[0105] The preparation method of the sprayed concrete of the present embodiment is consistent with that of Example 1.

[0106] Example 5

[0107] The sprayed concrete of the present embodiment is mainly prepared from the following raw materials in parts by weight:

[0108] Silicate cement 260 parts, fine sand 280 parts, crushed stone 300 parts, fly ash 35 parts, composite steel fiber 10 parts, admixture 15 parts, non-alkali accelerator 5 parts, water reducing agent 3 parts, and water 110 parts.

[0109] The preparation method of the sprayed concrete of the present embodiment is consistent with that of Example 1.

[0110] The composition of the admixture and the preparation of the modified sepiolite fiber are consistent with those of Example 1.

[0111] Comparative Example 1

[0112] The sprayed concrete of the present comparative example is consistent with the sprayed concrete of Example 1 in composition and preparation, except that a single diameter of steel fiber is used.

[0113] Comparative Example 2

[0114] The sprayed concrete of the present comparative example is consistent with the sprayed concrete of Example 1 in composition and preparation, except that fly ash is not added.

[0115] Comparative Example 3

[0116] The sprayed concrete of the present comparative example is consistent with the sprayed concrete of Example 3 in composition and preparation, except that the admixture is not added.

[0117] Test Example

[0118] The sprayed concrete prepared in Examples 1-5 of the present application and the sprayed concrete prepared in Comparative Examples 1-3 are subjected to mechanical property testing, and the rebound rate of the sprayed concrete is tested according to the Technical Specification for Reinforced Concrete (CECS161-2004); the compressive strength and the rebound rate of the sprayed concrete are tested according to the Application Technical Specification for Sprayed Concrete (JGJ / T 372-2016), and the results are as follows:

[0119] Table 1

[0120] Rebound / % 1 d strength / MPa 14 d strength / MPa 28 d strength / MPa Example 1 7.2 28.5 57.7 65.3 Example 2 7.5 29.7 58.5 68.0 Example 3 8.7 31.4 60.2 72.5 Example 4 8.5 30.5 59.3 70.3 Example 5 7.7 29.3 58.0 66.7 Comparative Example 1 10.3 22.8 38.2 42.3 Comparative Example 2 15.7 20.5 35.2 39.6 Comparative Example 3 18.5 17.8 32.9 35.8

[0121] It can be seen that the sprayed concrete of the present application exhibits good rebound rate and early strength, and excellent compressive performance.

[0122] The above detailed description of the specific embodiments of the present application has been given to understand the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A shotcrete, characterized in that, It is made from the following raw materials by weight: Silicate cement 200-260 parts, fine sand 240-280 parts, broken stone 260-300 parts, fly ash 10-35 parts, composite steel fiber 5-10 parts, admixture 10-15 parts, non-alkali accelerator 2-5 parts, water reducing agent 1-3 parts and water 80-110 parts; The admixture comprises: nano silicon nitride, modified sepiolite fiber and calcium aluminum sulfate; The admixture comprises: nano silicon nitride 20-30 parts, modified sepiolite fiber 25-45 parts and calcium aluminum sulfate 10-18 parts; The preparation of the modified sepiolite fiber comprises: The sepiolite fiber is heated and treated at a temperature of 100-300 DEG C for 1-3 hours; and the sepiolite fiber after the heating treatment is subjected to plasma treatment at a pressure of 10-20 Pa and a power of 100-300 W for 5-10 minutes; A solution of tetraethyl orthosilicate and aluminum isopropoxide with a mass ratio of 1:(0.1-0.5) is prepared, 3-aminopropyltriethylsilane is added to the solution, and the mixture is stirred uniformly to obtain a mixed solution; The sepiolite fiber after the plasma treatment is soaked in the mixed solution, and is treated at a temperature of 100-120 DEG C for 2-5 hours to obtain the modified sepiolite fiber. The mass ratio of the sepiolite fiber, tetraethyl orthosilicate and 3-aminopropyltriethylsilane is 1:(0.05-0.1):(0.01-0.05).

2. The sprayed concrete according to claim 1, characterized in that It is made from the following raw materials by weight: Silicate cement 200-260 parts, fine sand 240-280 parts, broken stone 260-300 parts, fly ash 10-35 parts, composite steel fiber 5-10 parts, admixture 10-15 parts, non-alkali accelerator 2-5 parts, water reducing agent 1-3 parts and water 80-110 parts; 3. The sprayed concrete according to claim 2, characterized in that It is made from the following raw materials by weight: Silicate cement 200-260 parts, fine sand 240-280 parts, broken stone 260-300 parts, fly ash 10-35 parts, composite steel fiber 5-10 parts, admixture 10-15 parts, non-alkali accelerator 2-5 parts, water reducing agent 1-3 parts and water 80-110 parts; 4. The sprayed concrete according to claim 1, characterized in that The nano silicon nitride has a particle size of 10-20 nm, and the modified sepiolite fiber has a length of 1-200 microns.

5. The sprayed concrete according to any one of claims 1 to 3, characterized in that The composite steel fiber comprises: steel fibers with a diameter of 0.1-0.3 mm and steel fibers with a diameter of 0.6-1.0 mm mixed at a mass ratio of 2:(3-5); the steel fibers with a diameter of 0.1-0.3 mm have a length of 10-12 mm; and the steel fibers with a diameter of 0.6-1.0 mm have a length of 3-7 mm.

6. The sprayed concrete according to any one of claims 1 to 3, characterized in that The non-alkali accelerator is a liquid aluminum sulfate accelerator.

7. The sprayed concrete according to any one of claims 1 to 3, characterized in that The water-binder ratio of the sprayed concrete is 0.4-0.

5.

8. A method of preparing the shotcrete according to any one of claims 1 to 7, characterized in that, It comprises: Silicate cement, fine sand, broken stone and water are mixed and stirred uniformly to obtain a mixture; The composite steel fiber, the admixture, the non-alkali accelerator and the water reducing agent are mixed uniformly, and then are added to the mixture and stirred at a temperature of 10-30 DEG C for 5-10 minutes.