Functional material for wet shotcrete and preparation method thereof

Abstract

The invention relates to the field of concrete, in particular to a functional material for wet shotcrete and a preparation method thereof.The functional material is formed by compounding a carbonaceous material and MoS2 and is selected from one or more of a reduced graphene oxide / MoS2 composite material, a single-walled carbon nanotube / MoS2 composite material and a multi-walled carbon nanotube / MoS2 composite material; the mass fraction of the functional material in the wet shotcrete is 0.3%-0.5%. The MoS2 and the carbonaceous material are compounded for use, so that the agglomeration structure of the carbonaceous material such as reduced graphene oxide, single-walled carbon nanotubes and multi-walled carbon nanotubes is reduced, the filling of gaps is further improved, and the mechanical property of the sprayed concrete is improved.

Description

Technical Field

[0001] The invention relates to the field of concrete, and in particular to a functional material for wet shotcrete and a preparation method thereof. Background Art

[0002] With the continuous deepening of underground engineering, the application of shotcrete technology in the fields of tunnel and mine support is becoming more and more extensive. This technology is favored for its fast construction speed, low cost and remarkable effect. Especially in the excavation of deep mines, the requirements for support materials are getting higher and higher, which has prompted shotcrete to continuously improve the quality of spraying, enhance mechanical strength and extend durability. In order to adapt to more demanding engineering conditions, the formula and construction technology of shotcrete are being continuously optimized to meet the urgent demand for high-performance support materials in deep underground engineering.

[0003] At present, the mechanical properties of shotcrete are improved mainly through the following aspects to optimize the selection of raw materials: using high-strength cement, reasonable aggregate matching and high-quality fine aggregate, all of which help to improve the mechanical properties of shotcrete; determining the best ratio of cement, aggregate and water through experiments to ensure the strength and workability of concrete; the reasonable use of admixtures such as accelerators, water reducers, air entraining agents, viscosity regulators, etc. can improve the rheological properties of shotcrete and the mechanical properties after hardening. Adding steel fibers or organic fibers to shotcrete can significantly improve its tensile strength and toughness. By using low-cement castables (LCC) and ultra-low cement castables (ULCC), the amount of cement can be reduced and the mechanical properties and durability of concrete can be improved.

[0004] In recent years, domestic and foreign scholars have made some research on carbon nanomaterials to enhance the mechanical properties of cement, such as MWCNTs, but the performance effect needs to be further improved. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a functional material for wet shotcrete and a preparation method thereof, which is achieved by the following technical scheme: A functional material for wet shotcrete, the functional material being a composite of a carbonaceous material and MoS2, and being selected from one or more of a reduced graphene oxide / MoS2 composite material, a single-walled carbon nanotube / MoS2 composite material, and a multi-walled carbon nanotube / MoS2 composite material; The mass fraction of the functional material in the wet shotcrete is 0.3% to 0.5%.

[0006] Reduced graphene oxide, single-walled carbon nanotubes, and multi-walled carbon nanotubes are filled in the cement matrix in a spatial network structure, which reduces the porosity of the cement matrix. By compounding with MoS2, the agglomeration of reduced graphene oxide, single-walled carbon nanotubes, and multi-walled carbon nanotubes is reduced, and the filling of the voids is further improved, thereby improving the mechanical properties of the shotcrete. Furthermore, the preparation method of MoS2 is: dissolving Na2MoO4 and C2H5NS in deionized water, stirring at room temperature, reacting at 200~260°C, washing the precipitate, and drying it.

[0007] The present invention also provides a method for preparing a functional material for wet spraying concrete, characterized in that the functional material is selected from a reduced graphene oxide / MoS2 composite material, and the preparation method thereof is as follows: MoS2 and reduced graphene oxide are added to deionized water, stirred evenly, heated at 180°C for reaction for 24 hours, and the precipitate is washed with deionized water and ethanol respectively, and dried to obtain the obtained material. The carbon content in the reduced graphene oxide is ≥75 wt.%, and the nitrogen content is 5 wt.%, and the oxygen content is <22 wt.%. The functional material is selected from a single-walled carbon nanotube / MoS2 composite material, and the preparation method thereof is as follows: MoS2 and single-walled carbon nanotubes are added to deionized water, stirred evenly, heated at 180°C for reaction for 24 hours, and the precipitate is washed with deionized water and ethanol respectively, and dried to obtain the obtained material. The single-walled carbon nanotube has an average diameter of 2 nm, a length of 3 μm, and a surface area of ​​≥700 m2 / g. The functional material is selected from a multi-walled carbon nanotube / MoS2 composite material, and the preparation method thereof is as follows: MoS2 and multi-walled carbon nanotubes are added to deionized water, stirred evenly, heated at 180°C for reaction for 24 hours, and the precipitate is washed with deionized water and ethanol respectively, and dried to obtain the multi-walled carbon nanotube. The outer diameter of the multi-walled carbon nanotube is 6-13nm, the length is 2.5-20μm, and the surface area is ≥220 m2 / g.

[0008] The soil-ash ratio in the shotcrete is fixed at 0.45, the cement content is fixed at 400 kg per cubic meter, and the mass ratio of cement, sand and gravel in the shotcrete is 1:2.25:2.

[0009] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention reduces the agglomeration structure of carbonaceous materials such as reduced graphene oxide, single-walled carbon nanotubes, and multi-walled carbon nanotubes by combining MoS2 with carbonaceous materials, further improves the filling of voids, and improves the mechanical properties of shotcrete. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The illustrative embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0011] Example 1 This embodiment provides a functional material for wet shotcrete.

[0012] The functional material for wet shotcrete is a reduced graphene oxide / MoS2 composite material, and its preparation method comprises the following steps: Step S1: 2 mmol Na2MoO4 and 10 mmol C2H5NS (thioacetamide) were dissolved in 30 mL deionized water and stirred at room temperature for 1 h. After stirring, the mixture was transferred to a reaction kettle and heated in an oven at 240 ° C for 24 h. After the reaction was completed, the precipitate was filtered and washed with water and ethanol several times. The washed precipitate was dried at 40 ° C for 24 hours to obtain MoS2; Step S2: Take 10 g of MoS2 obtained in step S1, and then take 3 g of reduced graphene oxide, add them to 600 mL of deionized water and stir for 1 hour, transfer them to a reactor, heat and react in an oven at 180°C for 24 hours, wash the obtained precipitate with deionized water and ethanol three times respectively, and dry it at 40°C for 24 hours to prepare a reduced graphene oxide / MoS2 composite material.

[0013] The functional materials of wet shotcrete prepared were added to the shotcrete according to different mass percentages for performance testing. The soil-ash ratio in the shotcrete was fixed at 0.45, the cement content was fixed at 400kg per cubic meter, and the mass ratio of cement, sand and gravel was 1:2.25:2, which met the national standards GB500886-2015 and JGJ-55-2011. The concrete test sample was a cube cut after spraying, with a size of 100mm×100mm×400mm; the concrete was cut into blocks 24 hours after the concrete was sprayed, and cured at a constant temperature of 25℃ and a relative humidity of 96% for 1d, 3d, 7d, and 28d, respectively, and then the compressive strength and splitting tensile strength of the concrete test blocks were measured. The test results are shown in Tables 1 and 2.

[0014] Table 1 Compressive strength test Table 2 Splitting tensile strength test This embodiment provides a functional material for wet shotcrete The functional material for wet shotcrete is a single-walled carbon nanotube / MoS2 composite material, and its preparation method comprises the following steps: Step S1: 2 mmol Na2MoO4 and 10 mmol C2H5NS were dissolved in 30 mL deionized water and stirred at room temperature for 1 h. After stirring, the mixture was transferred to an oven and heated at 240 ° C for 24 h. After the reaction was completed, the precipitate was filtered and washed with water and ethanol several times. The washed precipitate was dried at 40 ° C for 24 hours to obtain MoS2; Step S2: Take 10g of MoS2 obtained in step S1, and then take 3g of reduced graphene oxide, add them to 600mL of deionized water and stir for 1h, transfer to an oven, heat and react at 180°C for 24h, wash the obtained precipitate with deionized water and ethanol three times respectively, and dry at 40°C for 24h to prepare a single-walled carbon nanotube / MoS2 composite material The functional materials of wet shotcrete prepared were added to the shotcrete in different mass percentages for performance testing. The soil-ash ratio in the shotcrete was fixed at 0.45, the cement content was fixed at 400 kg per cubic meter, and the mass ratio of cement, sand and gravel was 1:2.25:2, which met the national standards GB500886-2015 and JGJ-55-2011. The concrete test sample was a cube cut after spraying, with a size of 100 mm × 100 mm × 400 mm; the concrete was cut into blocks 24 hours after the concrete was sprayed, and cured at a constant temperature of 25 ° C and a relative humidity of 96% for 1d, 3d, 7d, and 28d, respectively, and then the compressive strength and splitting tensile strength of the concrete test blocks were measured. The test results are shown in Tables 3 and 4.

[0015] Table 3 Compressive strength test Table 4 Splitting tensile strength test Example 3 This embodiment provides a functional material for wet shotcrete The functional material for wet shotcrete is a multi-walled carbon nanotube / MoS2 composite material, and its preparation method comprises the following steps: Step S1: 2 mmol Na2MoO4 and 10 mmol C2H5NS were dissolved in 30 mL of deionized water and stirred at room temperature for 1 h. After stirring, the mixture was transferred to an oven and heated at 240 ° C for 24 h. After the reaction was completed, the precipitate was filtered and washed with water and ethanol several times. The washed precipitate was dried at 40 ° C for 24 hours to obtain MoS2; Step S2: Take 10g of MoS2 obtained in step S1, and then take 3g of reduced graphene oxide, add them to 600mL of deionized water and stir for 1h, transfer to an oven, heat and react at 180°C for 24h, wash the obtained precipitate with deionized water and ethanol three times respectively, and dry at 40°C for 24h to prepare a multi-walled carbon nanotube / MoS2 composite material The prepared functional materials of wet shotcrete were added to the shotcrete in different mass percentages for performance testing. The soil-ash ratio in the shotcrete was fixed at 0.45, the cement content was fixed at 400 kg per cubic meter, and the mass ratio of cement, sand and gravel was 1:2.25:2, which met the national standards GB500886-2015 and JGJ-55-2011. The concrete test sample was a cube cut after spraying, with a size of 100 mm × 100 mm × 400 mm; the concrete was cut into blocks 24 hours after the concrete was sprayed, and cured at a constant temperature of 25 ° C and a relative humidity of 96% for 1d, 3d, 7d, and 28d, respectively, and then the compressive strength and splitting tensile strength of the concrete test blocks were measured. The test results are shown in Tables 5 and 6.

[0016] Table 5 Compressive strength test Table 6 Splitting tensile strength test It can be seen from Tables 1 to 6 in Examples 1 to 3 that the addition of reduced graphene oxide / MoS2 composite materials, single-walled carbon nanotubes / MoS2 composite materials, and multi-walled carbon nanotubes / MoS2 composite materials in shotcrete has a certain degree of influence on the compressive strength and splitting tensile strength of concrete at different curing stages. Among them, when the addition amount of reduced graphene oxide / MoS2 composite materials is 0.1% to 0.3%, the compressive strength at 28 days is significantly improved, exceeding 40Mpa.

Claims

1. A functional material for wet shotcrete, characterized in that: The functional material is a composite of a carbonaceous material and MoS2, and is selected from one or more of a reduced graphene oxide / MoS2 composite material, a single-walled carbon nanotube / MoS2 composite material, and a multi-walled carbon nanotube / MoS2 composite material; The mass fraction of the functional material in the wet shotcrete is 0.3% to 0.5%.

2. The functional material for wet shotcrete according to claim 1, characterized in that: The preparation method of MoS2 is as follows: dissolving Na2MoO4 and C2H5NS in deionized water, stirring at room temperature, reacting at 200-260°C, washing the precipitate, and drying to obtain the MoS2.

3. A method for preparing a functional material for wet shotcrete according to claim 2, characterized in that: The functional material is selected from reduced graphene oxide / MoS2 composite material, and its preparation method is: MoS2 and reduced graphene oxide are added to deionized water, stirred evenly, heated to react at 180°C for 24 hours, and the precipitate is washed with deionized water and ethanol respectively, and then dried to obtain the obtained material.

4. The method for preparing a functional material for wet shotcrete according to claim 3, characterized in that: The reduced graphene oxide has a carbon content of ≥75 wt. %, a nitrogen content of 5 wt. %, and an oxygen content of <22 wt. %.

5. The method for preparing a functional material for wet shotcrete according to claim 2, characterized in that: The functional material is selected from single-walled carbon nanotube / MoS2 composite material, and its preparation method is: MoS2 and single-walled carbon nanotubes are added to deionized water, stirred evenly, heated at 180°C for reaction for 24 hours, and the precipitate is washed with deionized water and ethanol respectively, and then dried to obtain the obtained material.

6. The method for preparing the functional material for wet shotcrete according to claim 5, characterized in that: The single-walled carbon nanotubes have an average diameter of 2 nm, a length of 3 μm, and a surface area of ​​≥700 m2 / g.

7. The method for preparing a functional material for wet shotcrete according to claim 2, characterized in that: The functional material is selected from multi-walled carbon nanotube / MoS2 composite material, and its preparation method is: MoS2 and multi-walled carbon nanotubes are added to deionized water, stirred evenly, heated at 180°C for reaction for 24 hours, and the precipitate is washed with deionized water and ethanol respectively, and then dried to obtain the obtained material.

8. The method for preparing a functional material for wet shotcrete according to claim 7, characterized in that: The multi-walled carbon nanotubes have an outer diameter of 6-13 nm, a length of 2.5-20 μm, and a surface area of ​​≥220 m2 / g.

9. The functional material for wet shotcrete according to claim 1, characterized in that: The soil-ash ratio in the shotcrete is fixed at 0.45, and the fixed cement content per cubic meter is 400 kg.

10. The functional material for wet shotcrete according to claim 9, characterized in that: The mass ratio of cement, sand and gravel in the shotcrete is 1:2.25:2.

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