Sprayed concrete and method of construction thereof

Abstract

The application relates to the technical field of building construction, and particularly discloses a shotcrete and a construction method thereof. A mixture of the shotcrete comprises the following components: Portland cement, fine aggregate, coarse aggregate, a quick-setting agent, steel fibers and premix, the premix is obtained by mixing diatomite, cyclodextrin, polycarboxylate superplasticizer and modified bentonite and then grinding and sieving, the modified bentonite is obtained by drying a mixture of bentonite and a modified liquid to a constant weight, the components of the modified liquid include polyethylene glycol and water, and the total amount of the polyethylene glycol in the modified liquid is 70-90% of the weight of the bentonite. The modified bentonite is prepared through adsorption between polyethylene glycol and bentonite, adsorption of the bentonite to the polycarboxylate superplasticizer is reduced, the total amount of the polycarboxylate superplasticizer actually playing a water-reducing role in the concrete mixture is increased, the fluidity of the concrete mixture is improved, and the construction performance of the shotcrete mixture is improved.

Description

Technical Field

[0001] This application relates to the field of building construction technology, and more specifically, to a shotcrete and its construction method. Background Technology

[0002] Shotcrete is a type of concrete formed by spraying a concrete mixture onto the surface of rock or concrete using a shotcrete machine. It is commonly used in the construction of thin-walled structures such as tunnel linings, building walls, and ceilings, as well as protective layers for steel structures. To ensure the continuity of the spraying process, shotcrete often requires a higher degree of fluidity than ordinary concrete.

[0003] One related technology involves shotcrete, the corresponding concrete mix of which is prepared from the following raw materials by weight: 150 parts cementitious material, 350 parts sand, 100 parts crushed stone, 4 parts water-reducing agent, 3 parts accelerator, and 30 parts synergist. It also contains diatomaceous earth, the amount of which is 0.2 times the sum of the weights of the water-reducing agent and synergist. The cementitious material is ordinary Portland cement with a strength grade of 42.5; the water-reducing agent is a polycarboxylate superplasticizer; the accelerator is an aluminum sulfate-based liquid alkali-free accelerator; the synergist consists of steel fiber, bentonite, and cyclodextrin, with a weight ratio of 100:300:1. This type of shotcrete requires mixing, grinding, and sieving diatomaceous earth, cyclodextrin, polycarboxylate superplasticizer, and bentonite to obtain a premix. The premix is ​​then mixed with the remaining components. The purpose is to improve the compatibility between the superplasticizer and the accelerator by grinding and modifying the superplasticizer, bentonite, and cyclodextrin with diatomaceous earth.

[0004] Regarding the aforementioned technologies, the inventors believe that the main component of bentonite is montmorillonite, which has a strong adsorption effect on the polyether side chains of polycarboxylate superplasticizers. When implementing the solutions in these technologies, if a polyether-type polycarboxylate superplasticizer is selected, bentonite will adsorb a large number of polycarboxylate superplasticizer molecules, reducing the number of polycarboxylate superplasticizer molecules that actually exert a water-reducing effect in the concrete mix. This leads to a decrease in the fluidity of the concrete mix and is detrimental to improving the workability of shotcrete mixes. Summary of the Invention

[0005] In related technologies, bentonite reduces the total amount of polycarboxylate superplasticizer that actually performs water-reducing effects in concrete mixes, leading to a decrease in the fluidity of the concrete mix. To improve this defect, this application provides shotcrete and its construction method.

[0006] In a first aspect, this application provides a shotcrete solution, which adopts the following technical solution:

[0007] A type of shotcrete, wherein the mixture comprises the following components: silicate cement, fine aggregate, coarse aggregate, accelerator, steel fiber, and premix. The premix is ​​obtained by mixing, grinding, and sieving diatomaceous earth, cyclodextrin, polycarboxylate superplasticizer, and modified bentonite. The modified bentonite is obtained by drying a mixture of bentonite and a modifying liquid to constant weight. The modifying liquid comprises polyethylene glycol and water, and the total amount of polyethylene glycol in the modifying liquid is 70-90% of the weight of bentonite.

[0008] By adopting the above technical solution, compared with related technologies, this application replaces bentonite with modified bentonite and uses diatomaceous earth, cyclodextrin, polycarboxylate superplasticizer, and modified bentonite in the production of premix. During the preparation of modified bentonite, because the modifying liquid contains polyethylene glycol, and the polyether segment structure of polyethylene glycol is similar to the side chain structure of polycarboxylate superplasticizer, polyethylene glycol can adsorb onto bentonite before it comes into contact with the polycarboxylate superplasticizer, occupying the adsorption sites of the bentonite. This makes it difficult for the modified bentonite to adsorb the polycarboxylate superplasticizer, improving the fluidity of the concrete mixture and helping to improve the construction performance of shotcrete mixtures.

[0009] Preferably, the total amount of polyethylene glycol in the modified liquid is 75-85% of the weight of bentonite.

[0010] By adopting the above technical solution, the amount of polyethylene glycol used was optimized, and the fluidity of the shotcrete mixture was significantly improved while saving polyethylene glycol.

[0011] Preferably, the modified bentonite is prepared according to the following method:

[0012] (1) Dry the bentonite to constant weight, then grind it for later use;

[0013] (2) Mix the bentonite obtained in step (1) with the modification liquid, stir for 2-3 hours and dry to constant weight to obtain modified bentonite.

[0014] By adopting the above technical solution, this application first removes moisture from the bentonite through drying and grinding, and then reduces the agglomeration of the bentonite through grinding. During the mixing process with the modifying liquid, the bentonite comes into contact with the polyether, achieving contact and adsorption of the polyether. After drying, the moisture in the modifying liquid is removed, thus obtaining the modified bentonite.

[0015] Preferably, the modified liquid comprises polyethylene glycol and polyether lubricating oil.

[0016] By adopting the above technical solution, both polyethylene glycol aqueous solution and polyether lubricating oil contain polyether compounds, which can be used to modify bentonite. When the unit price of polyethylene glycol increases, by recycling waste polyether lubricating oil and applying it to the production of modified bentonite, the waste polyether lubricating oil can be reused, which helps to reduce the production cost of modified bentonite.

[0017] Preferably, the average molecular weight of the polyethylene glycol is 600-1500.

[0018] By adopting the above technical solution, when the average molecular weight of polyethylene glycol is too low, the adsorption effect of bentonite on polyethylene glycol is limited, which is not conducive to reducing the adsorption of polycarboxylate superplasticizer by bentonite. Conversely, when the average molecular weight of polyethylene glycol is too high, the tortuosity of its molecular conformation increases significantly under the influence of water molecules, which is not conducive to the water-reducing effect of polycarboxylate superplasticizer in concrete mixtures. Within the preferred scope of this application, bentonite can relatively fully adsorb polyethylene glycol, and the conformation of polyethylene glycol has a relatively small impact on the water-reducing effect of polycarboxylate superplasticizer, which helps to improve the fluidity of shotcrete mixtures.

[0019] Preferably, the modified liquid also includes one of D-sorbitol, dipentaerythritol, and diethylene glycol.

[0020] By adopting the above technical solutions, the molecular structures of D-sorbitol, dipentaerythritol, and diethylene glycol are all similar to the side chain structures of polycarboxylate superplasticizers. Furthermore, the molecular weights of all three are much smaller than those of commercially available polyethylene glycol products. Therefore, they can penetrate into the interlayer of bentonite more easily than polyethylene glycol, reducing the adsorption of polycarboxylate superplasticizers by the bentonite interlayer and helping to improve the fluidity of shotcrete mixtures.

[0021] Preferably, in step (2) of preparing the modified bentonite, the mixture of bentonite and the modifying liquid is vacuum dried to obtain the modified bentonite.

[0022] By adopting the above technical solution, vacuum drying can not only remove moisture, but also promote the penetration of D-sorbitol, dipentaerythritol and diethylene glycol into the interior of bentonite through the negative pressure conditions under vacuum. This is beneficial for the adsorption of D-sorbitol, dipentaerythritol and diethylene glycol by bentonite, and helps to improve the fluidity of shotcrete mixture.

[0023] Preferably, the modified liquid further comprises sodium hydroxide, and the pH of the modified liquid is 8.5-10.5.

[0024] By adopting the above technical solution, this application uses sodium hydroxide to adjust the pH of the modified liquid, so that the pH of the modified liquid is close to that of the cement pore solution. Within this pH range, the silicon-oxygen bonds in the montmorillonite lattice are converted into silanol groups, and the aluminum-oxygen bonds are converted into aluminum alcohol groups. The silanol groups and aluminum alcohol groups have similar surface properties to polyethylene glycol, which promotes the adsorption of polyethylene glycol by bentonite, helps to reduce the adsorption of polycarboxylate superplasticizer by modified bentonite, and improves the fluidity of sprayed concrete.

[0025] Preferably, the modified liquid also includes alkaline silica sol.

[0026] By employing the above technical solution, the alkaline silica sol contains a large number of nano-sized silica particles. These silica particles have numerous silanol groups on their surface, which can adhere to and bind to the bentonite surface, increasing the silanol content on the bentonite surface. Simultaneously, the silanol groups on the silica particle surface that are not bound to the bentonite can adsorb free polyethylene glycol. Under the action of the alkaline silica sol, the number of adsorption sites on the bentonite surface increases, resulting in a denser distribution of polyethylene glycol on the bentonite surface. This helps reduce the adsorption of polycarboxylate superplasticizer on the modified bentonite surface, improving the fluidity of the shotcrete mixture.

[0027] Secondly, this application provides a method for constructing shotcrete, which adopts the following technical solution.

[0028] A method for applying shotcrete includes the following steps:

[0029] (1) Mix diatomaceous earth, cyclodextrin, polycarboxylate superplasticizer and modified bentonite, grind and sieve to obtain a premix;

[0030] (2) Mix the premix, quick-setting agent, coarse aggregate, fine aggregate, and silicate cement, add water and stir to obtain concrete mix;

[0031] (3) Spray the concrete mixture onto the working surface and then cure the concrete mixture to obtain sprayed concrete.

[0032] By adopting the above technical solution, this application first prepared the premix, then mixed the concrete mixture with the participation of the premix, and finally obtained shotcrete through spraying and curing. Since modified bentonite has difficulty adsorbing polycarboxylate superplasticizer, the total amount of polycarboxylate superplasticizer actually exerting its water-reducing effect in the concrete mixture is increased, thus improving the fluidity of the concrete mixture.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. This application prepares modified bentonite through adsorption between polyethylene glycol and bentonite, which reduces the adsorption of polycarboxylate superplasticizer by bentonite, increases the total amount of polycarboxylate superplasticizer that actually plays a water-reducing role in concrete mix, improves the fluidity of concrete mix, and helps to improve the construction performance of shotcrete mix.

[0035] 2. In this application, at least one of polyethylene glycol aqueous solution and polyether lubricating oil is preferred as a component of the modifying liquid. By using waste polyether lubricating oil, the modification of bentonite can also be achieved, and the cost is relatively low. In the case of rising polyethylene glycol prices, the production cost of modified bentonite can be reduced.

[0036] 3. The method of this application applies modified bentonite to the production of shotcrete, which increases the total amount of polycarboxylate superplasticizer that actually plays a water-reducing role in the concrete mix and improves the fluidity of the concrete mix. Detailed Implementation

[0037] The present application will be further described in detail below with reference to the embodiments, preparation examples and comparative examples. The raw materials involved in the present application can all be obtained commercially.

[0038] Preparation example of modified bentonite

[0039] The following explanation uses Preparation Example 1 as an example.

[0040] Preparation Example 1

[0041] In this preparation example, the modified solution is a 25% (w / w) aqueous solution of polyethylene glycol, and the average molecular weight of the polyethylene glycol is 500.

[0042] In this preparation example, the modified bentonite was prepared according to the following method:

[0043] (1) Dry the bentonite to constant weight in an oven at 105℃, then grind it and pass it through a 200-mesh sieve for later use.

[0044] (2) The bentonite obtained in step (1) and the modified liquid are mixed at a weight ratio of 1:2.8, stirred for 2.5 h and then dried at 105 °C to constant weight to obtain modified bentonite.

[0045] As shown in Table 1, the difference between preparation examples 1-5 is that bentonite and the modified liquid are mixed in different weight ratios.

[0046] Table 1 Bentonite: Modified Liquid

[0047]

[0048] As shown in Table 2, the difference between Preparation Examples 6-8 and Preparation Example 4 lies in the average molecular weight of polyethylene glycol.

[0049] Table 2 Average molecular weight of polyethylene glycol

[0050]

[0051] Preparation Example 10

[0052] The difference between this preparation example and preparation example 8 is that the modified liquid is prepared by mixing polyethylene glycol with an average molecular weight of 1500 and commercially available polyether lubricating oil and then adding water. The mass fraction of polyethylene glycol in the modified liquid is 10%, the mass fraction of polyether lubricating oil is 15%, and the model of polyether lubricating oil is ArChine Arcfluid PAG 50-A-20.

[0053] Preparation Example 11

[0054] The difference between this preparation example and preparation example 8 is that the modified solution is prepared by mixing polyethylene glycol with an average molecular weight of 1500 and D-sorbitol and then adding water. The mass fraction of polyethylene glycol in the modified solution is 25%, and the mass fraction of D-sorbitol is 5%.

[0055] Preparation Example 12

[0056] The difference between this preparation example and preparation example 11 is that D-sorbitol is replaced with dipentaerythritol at a molar ratio of 1:1.

[0057] Preparation Example 13

[0058] The difference between this preparation example and preparation example 11 is that the 1:1 molar ratio of D-sorbitol is replaced with diethylene glycol.

[0059] Preparation Example 14

[0060] The difference between this preparation example and preparation example 11 is that the mixture of bentonite and the modifying liquid is not dried, but is vacuum dried to constant weight to obtain modified bentonite.

[0061] Preparation Example 15

[0062] The difference between this preparation example and preparation example 8 is that the modified liquid also includes sodium hydroxide as a component. When preparing the modified liquid, the pH of the modified liquid is adjusted to 7.8 by using sodium hydroxide.

[0063] As shown in Table 3, the difference between Examples 15-19 is that the pH of the modified solution obtained after adjustment with sodium hydroxide is different.

[0064] Table 3 pH of the modified solution

[0065]

[0066] Preparation Example 20

[0067] The difference between this preparation example and preparation example 18 is that the modified solution is obtained by mixing polyethylene glycol with an average molecular weight of 1500 and alkaline silica sol with a water content (mass fraction of water) of 90% and a pH of 9, and then adjusting the pH of the mixture to 10.5 with sodium hydroxide.

[0068] In the modified solution of this preparation example, the mass fraction of polyethylene glycol is 25%.

[0069] Example

[0070] Examples 1-5

[0071] The following description uses Example 1 as an example.

[0072] Example 1

[0073] In this embodiment, the water-cement ratio of the shotcrete mixture is 0.4. In addition to water, the shotcrete mixture also includes the following components: 150 kg of silicate cement, 350 kg of fine aggregate, 100 kg of coarse aggregate, 3 kg of quick-setting agent, 4 kg of polycarboxylate superplasticizer, and in addition to the above components, it also includes steel fiber, modified bentonite, cyclodextrin and diatomaceous earth.

[0074] The polycarboxylate superplasticizer is a polyether-type polycarboxylate superplasticizer, the silicate cement is P.O42.5, the fine aggregate is natural river sand from the Ganjiang River, the coarse aggregate is crushed stone mined from Wuxue, Hubei, and the accelerator is SBT-1.

[0075] The modified bentonite was prepared according to the method of Preparation Example 1. The weight of the bentonite used in the preparation of the modified bentonite was 22.44 kg, the weight of the steel fiber was 7.48 kg, the weight of the cyclodextrin was 0.08 kg, and the weight of the diatomaceous earth was 6.8 kg.

[0076] In this embodiment, the sprayed concrete is applied according to the following steps:

[0077] (1) Mix diatomaceous earth, cyclodextrin, polycarboxylate superplasticizer and modified bentonite, grind and then pass through an 8000-mesh sieve to obtain a premix;

[0078] (2) Mix the premix, quick-setting agent, coarse aggregate, fine aggregate, and silicate cement, add water and stir to obtain concrete mix;

[0079] (3) Spray the concrete mixture onto the working surface and then cure the concrete mixture to obtain sprayed concrete.

[0080] As shown in Table 4, the main difference between Examples 1-20 lies in the different preparation examples used in the preparation methods of the modified bentonite.

[0081] Table 4 shows the preparation examples used in the preparation methods of modified bentonite.

[0082] sample Preparation Example sample Preparation Example Example 1 Preparation Example 1 Example 11 Preparation Example 11 Example 2 Preparation Example 2 Example 12 Preparation Example 12 Example 3 Preparation Example 3 Example 13 Preparation Example 13 Example 4 Preparation Example 4 Example 14 Preparation Example 14 Example 5 Preparation Example 5 Example 15 Preparation Example 15 Example 6 Preparation Example 6 Example 16 Preparation Example 16 Example 7 Preparation Example 7 Example 17 Preparation Example 17 Example 8 Preparation Example 8 Example 18 Preparation Example 18 Example 9 Preparation Example 9 Example 19 Preparation Example 19 Example 10 Preparation Example 10 Example 20 Preparation Example 20

[0083] Comparative Example

[0084] Comparative Example 1

[0085] This comparative example provides a shotcrete mixture with a water-cement ratio of 0.4. Besides water, the shotcrete mixture includes the following components: 150 kg of silicate cement, 350 kg of fine aggregate, 100 kg of coarse aggregate, 3 kg of accelerator, 4 kg of polycarboxylate superplasticizer, 7.48 kg of steel fiber, 22.44 kg of bentonite, 0.08 kg of cyclodextrin, and 6.8 kg of diatomaceous earth.

[0086] The sprayed concrete in this comparative example was applied according to the following steps:

[0087] (1) Mix diatomaceous earth, cyclodextrin, polycarboxylate superplasticizer and modified bentonite, grind and then pass through an 8000-mesh sieve to obtain a premix;

[0088] (2) Mix the premix, quick-setting agent, coarse aggregate, fine aggregate, and silicate cement, add water and stir to obtain concrete mix;

[0089] (3) Spray the concrete mixture onto the working surface and then cure the concrete mixture to obtain sprayed concrete.

[0090] Comparative Example 2

[0091] The difference between this comparative example and Comparative Example 1 is that diatomaceous earth is removed from the raw materials of the shotcrete.

[0092] Performance testing methods

[0093] The spread of the concrete mixtures in each embodiment and comparative example was tested according to the "GB / T 50080-2016 Standard for Test Methods of Performance of Ordinary Concrete Mixtures". Then, the ratio of the spread of the concrete in each embodiment and comparative example to the spread of the concrete in Comparative Example 1 was calculated. This ratio was defined as the relative spread. The results are shown in Table 5.

[0094] Table 5 Relative Expansion

[0095] sample Relative Expansion / % sample Relative Expansion / % Example 1 116.8 Example 12 129.7 Example 2 119.4 Example 13 129.9 Example 3 121.5 Example 14 132.6 Example 4 122.3 Example 15 130.9 Example 5 122.5 Example 16 132.2 Example 6 125.7 Example 17 133.5 Example 7 127.2 Example 18 133.8 Example 8 128.1 Example 19 133.9 Example 9 126.9 Example 20 137.9 Example 10 127.8 Comparative Example 1 100.0 Example 11 130.2 Comparative Example 2 102.7

[0096] Combining Examples 1-5 and Comparative Example 1 with Table 5, it can be seen that the relative spread measured in Examples 1-5 is greater than that in Comparative Example 1. This indicates that Examples 1-5, by modifying bentonite, reduced the adsorption of polycarboxylate superplasticizer by bentonite, increasing the total amount of polyether-type polycarboxylate superplasticizer that actually plays a water-reducing role in the concrete mix, thereby improving the fluidity of the concrete mix. Although the relative spread of Examples 1-5 also increased with the increase in the amount of modified liquid, the change was not linear. After optimization, after eliminating Examples 1 (with lower relative spread) and Example 5 (with a smaller increase in relative spread), the preferred total amount of polyethylene glycol in the modified liquid is 75-85% of the weight of bentonite (corresponding to a mixture of bentonite and modified liquid at a ratio of 1:(3.0-3.4)).

[0097] Combining Comparative Example 1 and Comparative Example 2 with Table 5, it can be seen that the relative extensibility of Comparative Example 2 is close to that of Comparative Example 1, indicating that diatomaceous earth is not the main reason why the flowability of the concrete mixture in Comparative Example 1 is lower than that in Examples 1-5.

[0098] Combining Examples 3 and 6-9 with Table 5, it can be seen that within the range of 500-1600, the relative fluidity first increases and then decreases with the increase of molecular weight, reaching a relatively high level at 1500. This indicates that when the average molecular weight of polyethylene glycol is below 600, the adsorption effect of bentonite on polyethylene glycol is limited, which is not conducive to reducing the adsorption of polycarboxylate superplasticizer by bentonite. However, when the average molecular weight of polyethylene glycol is above 1500, the tortuosity of its molecular conformation increases significantly under the influence of water molecules, which is not conducive to the water-reducing effect of polycarboxylate superplasticizer in concrete mixtures. When the average molecular weight of polyethylene glycol is in the range of 600-1500, bentonite can relatively fully adsorb polyethylene glycol, and the conformation of polyethylene glycol has a relatively small impact on the water-reducing effect of polycarboxylate superplasticizer, which helps to improve the fluidity of shotcrete mixtures.

[0099] As can be seen from Examples 8 and 10 and Table 5, the effect of polyether lubricating oil replacing polyethylene glycol in a certain proportion on the relative fluidity is small, indicating that polyether lubricating oil can be used to prepare modified bentonite.

[0100] Based on Examples 8, 11-13 and Table 5, it can be seen that D-sorbitol, dipentaerythritol, and diethylene glycol penetrate into the interlayer of bentonite more easily than polyethylene glycol, reducing the adsorption of polycarboxylate superplasticizer in the bentonite interlayer and helping to improve the fluidity of shotcrete mixtures.

[0101] As can be seen from Examples 11-13 and 14, and Table 5, the negative pressure conditions during the vacuum drying process are conducive to the full adsorption of D-sorbitol, dipentaerythritol, and diethylene glycol by bentonite, thereby improving the fluidity of the shotcrete mixture.

[0102] Based on Examples 8 and 15-19, and referring to Table 5, it can be seen that, based on Example 8, increasing the pH of the modified solution causes the silicon-oxygen bonds in the montmorillonite lattice to transform into silanol groups and the aluminum-oxygen bonds into aluminum alcohol groups. This promotes the adsorption of polyethylene glycol by bentonite within a certain range, helps reduce the adsorption of polycarboxylate superplasticizer by the modified bentonite, and improves the fluidity of the shotcrete. In Examples 15-19, the pH of Example 15 is below 8.5, resulting in relatively poor fluidity of the shotcrete. Example 19 shows almost no change compared to Example 18, indicating that the pH conditions of Example 18 are sufficient to promote the formation of silanol and aluminum alcohol groups on the bentonite surface. After optimization, when the pH of the modified solution is between 8.5 and 10.5, the fluidity of the shotcrete can be significantly improved while minimizing sodium hydroxide consumption.

[0103] As can be seen from Examples 18 and 20 and Table 5, the silanols provided by alkaline silica sol increase the number of adsorption sites on the bentonite surface, thus making the distribution of polyethylene glycol on the bentonite surface more dense. This helps to reduce the adsorption of polycarboxylate superplasticizer on the modified bentonite surface and improves the fluidity of the shotcrete mixture.

[0104] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A type of shotcrete, characterized in that, The shotcrete mixture comprises the following components: silicate cement, fine aggregate, coarse aggregate, quick-setting agent, steel fiber, and premix; the premix is ​​obtained by mixing diatomaceous earth, cyclodextrin, polycarboxylate superplasticizer, and modified bentonite, grinding, and sieving; the modified bentonite is prepared by the following method: (1) the bentonite is dried to constant weight and then ground for later use; (2) the bentonite obtained in step (1) is mixed with the modification liquid, stirred for 2-3 hours, and then dried to constant weight to obtain modified bentonite; the modified liquid comprises polyethylene glycol, sodium hydroxide, alkaline silica sol, and water, and also comprises one of D-sorbitol, dipentaerythritol, and diethylene glycol; the average molecular weight of the polyethylene glycol is 600-1500; the total amount of polyethylene glycol in the modified liquid is 70-90% of the weight of the bentonite; the pH of the modified liquid is 8.5-10.

5.

2. The shotcrete according to claim 1, characterized in that, The total amount of polyethylene glycol in the modified liquid is 75-85% of the weight of bentonite.

3. The shotcrete according to claim 2, characterized in that, The modified liquid comprises polyethylene glycol and polyether lubricating oil.

4. The shotcrete according to claim 1, characterized in that, In step (2) of preparing the modified bentonite, the mixture of bentonite and the modifying liquid is vacuum dried to obtain the modified bentonite.

5. The method for constructing shotcrete according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Mix diatomaceous earth, cyclodextrin, polycarboxylate superplasticizer and modified bentonite, grind and sieve to obtain a premix; (2) Mix the premix, quick-setting agent, coarse aggregate, fine aggregate, steel fiber and silicate cement, add water and stir to obtain concrete mix; (3) Spray the concrete mixture onto the working surface and then cure the concrete mixture to obtain sprayed concrete.

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