A shotcrete and a method for producing the same

Abstract

The application relates to a shotcrete and a preparation method thereof, raw materials of the shotcrete comprising coarse aggregate, fine aggregate, cementitious material, water and quick-setting agent, raw materials of the cementitious material comprising tailing powder, the coarse aggregate, the fine aggregate and the tailing powder being obtained by iron tailing waste rock pretreatment; wherein the content of the coarse aggregate is 40-50 parts by weight, the content of the fine aggregate is 30-40 parts by weight, the content of the cementitious material is 10-15 parts by weight, the content of the water is 6-9 parts by weight, and the content of the quick-setting agent is 0.5-2 parts by weight. The shotcrete is prepared by using tailing waste rock, cementitious material, water and quick-setting agent as raw materials, and resource utilization of solid wastes such as tailing waste rock, metallurgical slag and desulfurization ash is realized.

Description

Technical Field

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

[0002] Shotcrete is a type of concrete applied using the spraying method. It involves mixing cement, sand, and aggregate in a dry state, then using compressed air to deliver the mixture, along with an accelerator, to a nozzle where it is mixed with pressurized water and sprayed onto the surface. Currently, existing shotcrete technologies use ordinary concrete with added accelerators to accelerate hardening. However, the use of accelerators significantly increases preparation costs. Furthermore, the concrete aggregates are often continuously graded natural sand and gravel, transported to mines with high demand, resulting in high material and transportation costs.

[0003] Currently, with the continuous mining of iron ore, a large amount of iron tailings waste rock has been piled up in the spoil heaps, which not only occupies land but also pollutes the environment and poses safety hazards. Summary of the Invention

[0004] This application provides a shotcrete and its preparation method to solve the following technical problem: how to realize the resource utilization of iron tailings waste rock.

[0005] In a first aspect, this application provides a shotcrete, the raw materials of which include:

[0006] The mixture comprises coarse aggregate, fine aggregate, cementitious material, water, and a quick-setting agent. The cementitious material is derived from tailings powder. The coarse aggregate, fine aggregate, and tailings powder are obtained through pretreatment of iron tailings waste rock. The composition is as follows: (parts by weight)

[0007] The coarse aggregate content is 40 to 50 parts, the fine aggregate content is 30 to 40 parts, the cementitious material content is 10 to 15 parts, the water content is 6 to 9 parts, and the quick-setting agent content is 0.5 to 2 parts.

[0008] Optionally, the coarse aggregate is 5mm to 10mm continuously graded crushed stone; and / or,

[0009] The fine aggregate has a particle size of 0.5 mm to 5 mm, which is continuously graded sand; and / or,

[0010] The tailings powder is obtained by grinding iron tailings powder with a particle size of less than 0.5 mm.

[0011] Optionally, the tailings powder meets the following characteristics: specific surface area of ​​450 m². 2 / kg~500m 2 / kg, moisture content not exceeding 1%, and activity index not less than 65% after 28 days.

[0012] Optionally, the tailings powder is 5 to 10 parts by weight relative to 100 parts by weight of the cementitious material.

[0013] Optionally, the raw materials for the cementitious material may also include cement, slag powder, and steel slag powder.

[0014] Optionally, the cement has a strength of not less than grade 42.5; and / or,

[0015] The performance indicators of the slag powder meet the requirements of S95 grade slag powder; and / or,

[0016] The performance indicators of the steel slag powder meet the requirements of Grade I steel slag powder.

[0017] Optionally, in the raw materials of the cementitious material, the content of cement is 20 to 30 parts by weight, the content of slag powder is 40 to 50 parts, and the content of steel slag powder is 15 to 25 parts.

[0018] Optionally, the raw materials for the accelerator include: alumina clinker, refined slag powder, and desulfurization ash; wherein, by weight,

[0019] The content of alumina clinker is 40 to 50 parts, the content of refined slag powder is 30 to 40 parts, and the content of desulfurization ash is 10 to 20 parts.

[0020] Optionally, the refined slag powder satisfies the following characteristics: specific surface area of ​​450 m². 2 / kg~500m 2 / kg, moisture content not exceeding 1%.

[0021] Secondly, this application provides a method for preparing the shotcrete described in the first aspect, the method comprising:

[0022] Iron tailings waste rock is pre-treated to obtain coarse aggregate, fine aggregate and tailings powder;

[0023] The coarse aggregate, the fine aggregate, and the cementitious material containing the tailings powder are stirred and mixed to obtain a first mixture.

[0024] The first mixture, the quick-setting agent, and water are stirred and mixed to obtain the second mixture;

[0025] The second mixture is sprayed onto the construction site and then cured to obtain shotcrete.

[0026] The technical solutions provided in this application have the following advantages compared with the prior art:

[0027] The shotcrete provided in this application embodiment utilizes pretreated iron tailings waste rock to obtain coarse aggregate, fine aggregate, and tailings powder with different particle size distributions. The coarse and fine aggregates act as a skeleton, while the cementitious material containing highly active tailings powder acts as a binder. In combination with water, the cementitious material exerts its binding properties, thus binding the coarse and fine aggregates together. An accelerator accelerates the solidification and adhesion of the liquid shotcrete to the construction surface. By rationally designing the content of coarse aggregate, fine aggregate, cementitious material, water, and accelerator, the compressive strength test results of this shotcrete are all greater than 25 MPa, reaching a shotcrete grade of C25 or higher. Therefore, the resource utilization of iron tailings waste rock is achieved. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic flowchart of a method for preparing sprayed concrete according to some embodiments of this application. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0033] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Here, A and B can be singular or plural.

[0034] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0035] In a first aspect, this application provides a shotcrete, the raw materials of which include:

[0036] The mixture comprises coarse aggregate, fine aggregate, cementitious material, water, and a quick-setting agent, wherein the raw material for the cementitious material includes tailings powder.

[0037] The coarse aggregate, the fine aggregate, and the tailings powder are obtained from the pretreatment of iron tailings waste rock; wherein, by weight,

[0038] The coarse aggregate content is 40 to 50 parts, the fine aggregate content is 30 to 40 parts, the cementitious material content is 10 to 15 parts, the water content is 6 to 9 parts, and the quick-setting agent content is 0.5 to 2 parts.

[0039] In this embodiment, iron tailings waste rock, after pretreatment, can yield coarse aggregate, fine aggregate, and tailings powder with different particle size distributions. The coarse and fine aggregates can act as a skeleton. The cementitious material containing highly active tailings powder can act as a binder, and when combined with water, it exerts its binding properties, thereby binding the coarse and fine aggregates together. The accelerator can accelerate the solidification and adhesion of liquid shotcrete to the construction surface. By rationally designing the content of coarse aggregate, fine aggregate, cementitious material, water, and accelerator, the compressive strength test results of the shotcrete can be obtained to be greater than 25 MPa, reaching the level of shotcrete grade C25 or above. Coarse and fine aggregates have different particle sizes. Fine aggregates fill the gaps between coarse aggregates, making the mixture dense. Adjusting the content of cementitious materials and aggregates allows the mixture to achieve a certain strength grade. Adjusting the content of cementitious materials and water allows the mixture to have a specific slurry ratio, meeting the viscosity requirements for adhesion at the construction site and ensuring uniform spraying. Adjusting the content of the accelerator allows control over the setting time of the mixture at the construction site. Therefore, it is understandable that using tailings waste rock, cementitious materials, water, and accelerators as raw materials to produce shotcrete achieves resource utilization of solid waste such as tailings waste rock, metallurgical slag, and desulfurization ash, reducing the use of natural sand and cement. Replacing some of the accelerator with solid waste reduces the cost of shotcrete, lowers energy consumption, and reduces carbon dioxide emissions. Furthermore, the shotcrete produced in this way has stable performance and can meet the application needs in fields such as mine roadway support, tunnel rock mass reinforcement, and slope protection. For example, the content of coarse aggregate can be 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, etc.; the content of fine aggregate can be 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, etc.; the content of cementitious material can be 10 parts, 12 parts, 14 parts, 15 parts, etc.; the content of water can be 6 parts, 8 parts, 9 parts, etc.; and the content of quick-setting agent can be 0.5 parts, 1.0 parts, 1.5 parts, 2 parts, etc.

[0040] In some embodiments, the coarse aggregate is 5mm to 10mm continuously graded crushed stone; and / or,

[0041] The fine aggregate has a particle size of 0.5 mm to 5 mm, which is continuously graded sand; and / or,

[0042] The tailings powder is obtained by grinding iron tailings powder with a particle size of less than 0.5 mm.

[0043] In some embodiments, the tailings powder has the following characteristics: a specific surface area of ​​450 m². 2 / kg~500m 2 / kg, moisture content not exceeding 1%, and activity index not less than 65% after 28 days.

[0044] In some embodiments, the tailings powder is 5 to 10 parts by weight relative to 100 parts by weight of the cementitious material.

[0045] In this embodiment, iron tailings waste rock is graded and utilized. Coarse and fine aggregates are obtained from the iron tailings waste rock through crushing and screening. The coarse aggregate is continuously graded crushed stone with a particle size range of 5-10 mm, meeting the requirements of Class I construction ballast. The fine aggregate is continuously graded sand with a particle size range of 0.5-5 mm, meeting the requirements of Class I construction sand. Tailings powder can be obtained by grinding iron tailings powder with a particle size of less than 0.5 mm, further mechanically activating the activity of the iron tailings powder. The tailings powder meets the above characteristics and can have good activity. Controlling the specific surface area of ​​the tailings powder has good hydration activity, which is beneficial to the cementing and forming of the mixture. When the specific surface area is too large, it will increase the grinding power consumption and increase the processing cost. When the specific surface area is too small, it will reduce the hydration activity of the tailings powder and fail to achieve a good cementing effect. Among the characteristics of the tailings powder, the specific surface area can be 450 m². 2 / kg, 460m 2 / kg, 470m 2 / kg, 480m 2 / kg, 490m 2 / kg, 500m 2 The moisture content can be 1%, 0.9%, 0.8%, 0.7%, etc., and the 28-day activity index can be 65%, 66%, 67%, 68%, 69%, etc. The tailings powder can be 5, 6, 7, 8, 9, 10 parts by weight, etc., relative to 100 parts by weight of the cementitious material.

[0046] In some embodiments, the raw materials for the cementitious material also include cement, slag powder, and steel slag powder.

[0047] In some embodiments, the cement has a strength of not less than grade 42.5; and / or,

[0048] The performance indicators of the slag powder meet the requirements of S95 grade slag powder; and / or,

[0049] The performance indicators of the steel slag powder meet the requirements of Grade I steel slag powder.

[0050] In some embodiments, the raw materials of the cementitious material, by weight, contain 20 to 30 parts of cement, 40 to 50 parts of slag powder, and 15 to 25 parts of steel slag powder.

[0051] In this embodiment, the cement can be silicate cement or ordinary silicate cement, with a strength of not less than 42.5 grade. The slag powder is obtained by grinding blast furnace water-quenched slag, and its performance indicators meet the requirements of S95 grade slag powder. The steel slag powder is obtained by grinding converter steel slag, and its performance indicators meet the requirements of first-grade steel slag powder. The slag powder and steel slag powder replace a portion of the cement and possess potential hydraulic cementitious activity. Therefore, it can be understood that by mixing cement, slag powder, steel slag powder, and tailings powder to produce a cementitious material, steel slag, water slag, and tailings are rationally utilized, enabling the resource utilization of solid waste, reducing the use of natural sand and cement, and lowering the cost of shotcrete. This reduces energy consumption and carbon dioxide emissions. For example, the content of cement can be 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, etc., the content of slag powder can be 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, etc., and the content of steel slag powder can be 15 parts, 18 parts, 20 parts, 23 parts, 25 parts, etc.

[0052] In some embodiments, the raw materials for the accelerator include: alumina clinker, refined slag powder, and desulfurization ash; wherein, by weight,

[0053] The content of alumina clinker is 40 to 50 parts, the content of refined slag powder is 30 to 40 parts, and the content of desulfurization ash is 10 to 20 parts.

[0054] In some embodiments, the refined slag powder has the following characteristics: a specific surface area of ​​450 m². 2 / kg~500m 2 / kg, moisture content not exceeding 1%.

[0055] In this embodiment, the accelerator can be an inorganic salt-based accelerator. The refined slag powder contains an early-setting component (calcium fluoroaluminate). Refined slag powder meeting the above characteristics exhibits good activity. The refined slag powder and desulfurization ash replace a portion of the alumina clinker and calcium oxide. The desulfurization ash can be obtained by finely grinding semi-dry desulfurization ash, mainly containing calcium hydroxide, calcium sulfite, calcium sulfate, and calcium oxide, with a moisture content not exceeding 1%. Therefore, it can be understood that by mixing alumina clinker, refined slag, and desulfurization ash to prepare the accelerator, the refined slag and desulfurization ash are rationally utilized, enabling the resource utilization of solid waste, reducing the amount of inorganic accelerators such as alumina clinker used, and lowering the cost of shotcrete. This reduces energy consumption and carbon dioxide emissions. For example, the specific surface area of ​​the refined slag powder can be 450 m². 2 / kg, 460m 2 / kg, 470m 2 / kg, 480m 2 / kg, 490m 2 / kg, 500m 2 / kg, etc., with moisture content of 1%, 0.9%, 0.8%, 0.7%, etc. The content of alumina clinker can be 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, etc.; the content of refined slag powder can be 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, etc.; and the content of desulfurization ash can be 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, etc.

[0056] Secondly, this application provides a method for preparing the shotcrete described in the first aspect. Figure 1 This is a schematic flowchart illustrating a method for preparing sprayed concrete according to some embodiments of this application; please refer to [link / reference]. Figure 1 The method includes:

[0057] S1. Pre-treat the iron tailings waste rock to obtain coarse aggregate, fine aggregate and tailings powder;

[0058] S2. The coarse aggregate, the fine aggregate, and the cementitious material containing the tailings powder are stirred and mixed to obtain a first mixture.

[0059] S3. Stir and mix the first mixture, the quick-setting agent, and water to obtain the second mixture;

[0060] S4. The second mixture is sprayed onto the construction site and then cured to obtain sprayed concrete.

[0061] In this embodiment, iron tailings waste rock is crushed and screened to obtain coarse aggregate and fine aggregate. The iron tailings waste rock is further ground to obtain tailings powder. Cement, slag powder, steel slag powder and tailings powder are mixed evenly according to the mass ratio to obtain cementitious material. Coarse aggregate, fine aggregate and cementitious material are stirred and mixed evenly according to the mass ratio to obtain a first mixture. Aluminum clinker, refined slag powder and desulfurization ash are mixed evenly according to the mass ratio to obtain an accelerator. The first mixture is stirred and mixed with the accelerator and water to obtain a second mixture. The second mixture is sprayed onto the construction site and cured to obtain shotcrete.

[0062] The method for preparing this sprayed concrete is based on the above-described sprayed concrete. The specific raw material composition of the sprayed concrete can be referred to the above embodiments. Since the method for preparing this sprayed concrete adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0063] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0064] Example 1

[0065] A shotcrete comprising the following components by weight: 40 parts coarse aggregate, 40 parts fine aggregate, 13.5 parts cementitious material, 6 parts water, and 0.5 parts quick-setting agent.

[0066] The cementitious material is made from the following raw materials in parts by weight: 20 parts cement, 50 parts slag powder, 25 parts steel slag powder, and 5 parts tailings powder.

[0067] The cement is silicate cement, and its strength grade is 42.5.

[0068] The performance indicators of the slag powder meet the requirements of S95 grade slag powder; the performance indicators of the steel slag powder meet the requirements of Grade I steel slag powder.

[0069] Tailings powder is obtained by grinding iron tailings and has a specific surface area of ​​450 m². 2 / kg, with a moisture content of 1%, and an activity index of 65% after 28 days.

[0070] The quick-setting agent is an inorganic salt quick-setting agent, composed of 50 parts alumina clinker, 30 parts refining slag powder and 20 parts desulfurization ash.

[0071] Refined slag powder is obtained by grinding refined slag powder, with a specific surface area of ​​450 m². 2 / kg, with a moisture content of 1%.

[0072] The desulfurization ash is obtained by fine grinding of semi-dry desulfurization ash, and mainly contains calcium hydroxide, calcium sulfite, calcium sulfate and calcium oxide, with a moisture content of 1%.

[0073] A method for preparing shotcrete includes the following steps:

[0074] First, the iron tailings waste rock is crushed and screened to obtain coarse aggregate, fine aggregate, and iron tailings powder. The iron tailings powder is then ground to obtain tailings powder. Next, cement, slag powder, steel slag powder, and tailings powder are mixed evenly according to their mass proportions to obtain a cementitious material. The coarse aggregate, fine aggregate, and cementitious material are then stirred and mixed evenly according to their mass proportions to obtain a first mixture. Aluminum clinker, refined slag powder, and desulfurization ash are then mixed evenly according to their mass proportions to obtain an accelerator. The first mixture is then stirred and mixed with the accelerator and water to obtain a second mixture. The second mixture is sprayed onto the construction site and cured to obtain shotcrete.

[0075] Example 2

[0076] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is as follows:

[0077] 50 parts coarse aggregate, 32 parts fine aggregate, 10 parts cementitious material, 7 parts water, and 1 part quick-setting agent.

[0078] The cementitious material is made from the following raw materials in parts by weight: 30 parts cement, 40 parts slag powder, 20 parts steel slag powder, and 10 parts tailings powder.

[0079] The specific surface area of ​​tailings powder is 500 m². 2 / kg, with an activity index of 73% after 28 days.

[0080] The quick-setting agent is an inorganic salt quick-setting agent, composed of 50 parts alumina clinker, 40 parts refining slag powder and 10 parts desulfurization ash.

[0081] The specific surface area of ​​refined slag powder is 500 m². 2 / kg.

[0082] Example 3

[0083] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is as follows:

[0084] 44 parts coarse aggregate, 30 parts fine aggregate, 15 parts cementitious material, 9 parts water, and 2 parts quick-setting agent.

[0085] The cementitious material is made from the following raw materials in parts by weight: 25 parts cement, 45 parts slag powder, 23 parts steel slag powder, and 7 parts tailings powder.

[0086] The specific surface area of ​​tailings powder is 470 m². 2 / kg, with an activity index of 70% after 28 days.

[0087] The quick-setting agent is an inorganic salt quick-setting agent, composed of 50 parts alumina clinker, 35 parts refining slag powder and 15 parts desulfurization ash.

[0088] The specific surface area of ​​refined slag powder is 480m². 2 / kg.

[0089] Comparative Example 1

[0090] Comparing Comparative Example 1 and Example 1, the difference between Comparative Example 1 and Example 1 is as follows:

[0091] 40 parts coarse aggregate, 40 parts fine aggregate, 14 parts cementitious material, 6 parts water, no quick-setting agent added.

[0092] Comparative Example 2

[0093] Comparing Comparative Example 2 with Example 1, the difference between Comparative Example 2 and Example 1 is as follows:

[0094] The specific surface area of ​​tailings powder is 400 m². 2 / kg.

[0095] The specific surface area of ​​refined slag powder is 380m². 2 / kg.

[0096] Comparative Example 3

[0097] Comparing Comparative Example 3 with Example 1, the difference between Comparative Example 3 and Example 1 is as follows:

[0098] The cementitious material is made from the following raw materials in parts by weight: 70 parts slag powder, 25 parts steel slag powder, and 5 parts tailings powder.

[0099] The quick-setting agent is an inorganic salt quick-setting agent, composed of 80 parts of refining slag powder and 20 parts of desulfurization ash.

[0100] The setting time was tested according to Appendix D of the standard "Accelerating Agent for Shotcrete" (GB / T35159-2017), which specifies the method for determining the setting time of neat cement paste with accelerating agent. The mechanical properties of concrete were tested according to the method of "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081-2019), and the specimens were cured in a standard curing environment to the corresponding test age. The compressive strength values ​​of the specimens at hardening ages of 1d, 7d, and 28d were tested. The test results are shown in Table 1.

[0101] Table 1. Test results of shotcrete performance

[0102]

[0103] The test results show that the compressive strength of the shotcrete provided in this application is greater than 25 MPa, reaching the level of shotcrete grade C25 or above. A comparison of the experimental results of Examples 1, 2, and 3 shows that with the increase of the accelerator dosage, the setting time of the cement paste gradually shortens; with the increase of the cementitious material dosage, the compressive strength of the shotcrete gradually increases. Comparative Example 1 shows that without an accelerator, the setting time of the shotcrete is significantly prolonged; the addition of an accelerator can improve the early compressive strength, but the 28-day compressive strength decreases slightly. In Comparative Example 2, the specific surface area of ​​the tailings powder and refined slag powder did not reach 450 m². 2 The index of / kg indicates that the hydration activity and quick-setting properties are not fully utilized, resulting in a decrease in compressive strength and a prolongation of setting time at all ages of shotcrete, which affects the workability of shotcrete. Comparative Example 3 shows that cement and alumina clinker play a key role in cementitious materials and quick-setting agents, which can ensure the stability of compressive strength and setting time of shotcrete.

[0104] Therefore, the shotcrete provided in this application uses tailings waste rock as aggregate and a large amount of solid waste to prepare cementitious materials and quick-setting agents, which can save natural sand and gravel aggregates and cement, significantly reduce the raw material cost of engineering projects, and reduce carbon dioxide emissions. Moreover, the environmental and social benefits generated by applying this application are greater than its economic benefits.

[0105] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be satisfied with the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A type of shotcrete, characterized in that, The raw materials for the shotcrete are: The mixture comprises coarse aggregate, fine aggregate, cementitious material, water, and a quick-setting agent, wherein the raw material for the cementitious material includes tailings powder. The coarse aggregate, the fine aggregate, and the tailings powder are obtained from the pretreatment of iron tailings waste rock; wherein, by weight, The coarse aggregate content is 40-50 parts, the fine aggregate content is 30-40 parts, the cementitious material content is 10-15 parts, the water content is 6-9 parts, and the quick-setting agent content is 0.5-2 parts. The cementitious material is composed of tailings powder, cement, slag powder, and steel slag powder; wherein the specific surface area of ​​the tailings powder is 450 m². 2 / kg~500m 2 / kg, moisture content not exceeding 1%, 28-day activity index not less than 65%; the strength of the cement not less than grade 42.5; the performance indicators of the slag powder meet the requirements of grade S95 slag powder; the performance indicators of the steel slag powder meet the requirements of grade 1 steel slag powder, and the tailings powder is 5 to 10 parts by weight relative to 100 parts by weight of the cementitious material. The quick-setting agent is composed of alumina clinker, refined slag powder, and desulfurization ash; the specific surface area of ​​the refined slag powder is 450 m². 2 / kg~500 m 2 / kg, moisture content not exceeding 1%.

2. The shotcrete according to claim 1, characterized in that, The coarse aggregate is 5mm~10mm continuously graded crushed stone; and / or, The fine aggregate has a particle size of 0.5mm to 5mm and is continuously graded sand; and / or, The tailings powder is obtained by grinding iron tailings powder with a particle size of less than 0.5 mm.

3. The shotcrete according to claim 1, characterized in that, Of the raw materials of the cementitious material, by weight, the content of cement is 20 to 30 parts, the content of slag powder is 40 to 50 parts, and the content of steel slag powder is 15 to 25 parts.

4. The shotcrete according to claim 1, characterized in that, The raw materials for the accelerator include, by weight, The content of alumina clinker is 40-50 parts, the content of refining slag powder is 30-40 parts, and the content of desulfurization ash is... 10 to 20 servings.

5. A method for preparing sprayed concrete according to any one of claims 1 to 4, characterized in that, The method includes: Iron tailings waste rock is pre-treated to obtain coarse aggregate, fine aggregate and tailings powder; The coarse aggregate, the fine aggregate, and the cementitious material containing the tailings powder are stirred and mixed to obtain... First mixture; The first mixture, the quick-setting agent, and water are stirred and mixed to obtain the second mixture; The second mixture is sprayed onto the construction site and then cured to obtain shotcrete.

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