Sprayed concrete and preparation method thereof

Abstract

The invention relates to sprayed concrete and a preparation method thereof.The sprayed concrete is prepared from coarse aggregate, fine aggregate, a cementing material, water and an accelerator, the cementing material is prepared from tailing powder, and the coarse aggregate, the fine aggregate and the tailing powder are obtained through pretreatment of iron tailing waste rock; wherein the content of the coarse aggregate is 40 to 50 parts by weight, the content of the fine aggregate is 30 to 40 parts by weight, the content of the cementing material is 10 to 15 parts by weight, the content of the water is 6 to 9 parts by weight, and the content of the accelerator is 0.5 to 2 parts by weight. The sprayed concrete is prepared from the tailing barren rock, the cementing material, the water and the accelerator as raw materials, and resource utilization of solid wastes such as the tailing barren rock, the metallurgical slag and the desulfurized fly ash is achieved.

Description

Technical Field

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

[0002] Shotcrete is a method of spraying concrete, which is to mix cement, sand and stone evenly in a dry state, use compressed air to send it and the accelerator to the nozzle and mix it with pressurized water for spraying. At present, the shotcrete material in the existing technology is ordinary concrete with an accelerator added to make the concrete harden quickly, but the use of accelerators greatly increases the preparation cost. Concrete aggregates often use continuously graded natural sand and gravel, which are transported to mines with high demand, and the material cost and transportation cost are high.

[0003] At present, iron ore is being mined continuously, and a large amount of iron tailings and waste rock are piled up in the spoil dump, which not only occupies land, but also pollutes the environment and poses a safety hazard. Summary of the invention

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

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

[0006] Coarse aggregate, fine aggregate, cementitious material, water and quick-setting agent, the raw material of the cementitious material includes tailings powder, the coarse aggregate, the fine aggregate and the tailings powder are obtained by pre-treatment of iron tailings waste rock; wherein, in parts by weight,

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

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

[0009] The particle size of the fine aggregate is 0.5mm to 5mm continuous graded sand; and / or,

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

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

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

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

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

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

[0016] The performance indexes of the steel slag powder meet the requirements of first-class steel slag powder.

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

[0018] Optionally, the raw materials of the accelerating setting agent include: alumina clinker, refined slag powder and desulfurization ash; wherein, in parts 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 meets the following characteristics: specific surface area of ​​450m 2 / kg~500m 2 / kg, moisture content does not exceed 1%.

[0021] In a second aspect, the present application provides a method for preparing the shotcrete according to the first aspect, the method comprising:

[0022] Pre-treating the iron tailings waste rock 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] Stirring and mixing the first mixture, an accelerating setting agent and water to obtain a second mixture;

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

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] The shotcrete provided by the embodiment of the present application can obtain coarse aggregate, fine aggregate and tailings powder with different particle size distribution after pretreatment of iron tailings waste rock; coarse aggregate and fine aggregate can play the role of skeleton; cementitious material containing tailings powder with high activity can play the role of cementation, and exert the cementation characteristics of the cementitious material in combination with water, so as to cement the coarse aggregate and fine aggregate together; the accelerator can accelerate the solidification of liquid shotcrete and adhere to the construction surface, and reasonably design the content of coarse aggregate, fine aggregate, cementitious material, water and accelerator, and the compressive strength test results of the shotcrete can be obtained to be greater than 25MPa, reaching the level of shotcrete grade C25 or above. Therefore, the resource utilization of iron tailings waste rock is realized. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0030] Figure 1 The present invention is a schematic flow chart of a method for preparing shotcrete according to some embodiments of the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0032] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0033] In the present application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the specification of the present application, the terms "include", "comprise", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural.

[0034] Unless otherwise specified, various 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, the present application provides a shotcrete, wherein the raw materials of the shotcrete include:

[0036] coarse aggregate, fine aggregate, cementitious material, water and quick-setting agent, wherein the raw materials of the cementitious material include tailings powder,

[0037] The coarse aggregate, the fine aggregate and the tailings powder are obtained by pre-processing iron tailings waste rock; wherein, in parts by weight,

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

[0039] In the embodiment of the present application, the iron tailings waste rock can be pre-treated to obtain coarse aggregate, fine aggregate and tailings powder with different particle size distributions; the coarse aggregate and fine aggregate can play the role of a skeleton; the cementitious material containing tailings powder with higher activity can play a cementing role, and in combination with water, the cementitious properties of the cementitious material can be exerted to cement the coarse aggregate and the fine aggregate together; the accelerator can accelerate the solidification of liquid shotcrete and adhere to the construction surface, and by reasonably 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 25MPa, reaching the level of shotcrete grade C25 or above. Coarse aggregate and fine aggregate have different particle sizes. Fine aggregate is filled between coarse aggregate to fill the gaps, making the structure of the mixture dense. By adjusting the content of cementitious materials and aggregates, the mixture can have a certain strength grade. By adjusting the content of cementitious materials and water, the mixture can have a certain slurry ratio to meet the viscosity of the construction site and spray evenly. By adjusting the content of accelerator, the setting time of the mixture sprayed at the construction site can be controlled. Therefore, it can be understood that using tailings waste rock, cementitious materials, water and accelerator as raw materials to make shotcrete realizes the resource utilization of solid wastes such as tailings waste rock, metallurgical slag and desulfurization ash, reduces the use of natural sand and cement, and uses solid waste to replace part of the accelerator, thereby reducing the cost of shotcrete. While reducing energy consumption, it also reduces carbon dioxide emissions. The shotcrete produced in this way has stable performance and can meet the application needs in the fields of mine tunnel support, tunnel rock 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 accelerator can be 0.5 parts, 1.0 parts, 1.5 parts, 2 parts, etc.

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

[0041] The particle size of the fine aggregate is 0.5mm to 5mm continuous graded sand; and / or,

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

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

[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 the embodiment of the present application, the iron tailings waste rock is graded for utilization, and the coarse aggregate and fine aggregate are obtained by crushing and screening the iron tailings waste rock. The coarse aggregate is a continuously graded crushed stone with a particle size range of 5 to 10 mm, which meets the requirements of Class I building ballast index, and the fine aggregate is a continuously graded sand with a particle size range of 0.5 to 5 mm, which meets the requirements of Class I building sand index; the tailings powder can be obtained by grinding iron tailings powder with a particle size of less than 0.5 mm, and further mechanically stimulating 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 cementation and molding of the mixture. When the specific surface area is too large, it will increase the power consumption of grinding 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 cementation effect. Among the characteristics of tailings powder, the specific surface area can be 450m 2 / kg, 460m 2 / kg, 470m 2 / kg, 480m 2 / kg, 490m 2 / kg、500m 2 / kg, etc., 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. Relative to 100 parts by weight of the cementitious material, the tailings powder can be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, etc.

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

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

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

[0049] The performance indexes of the steel slag powder meet the requirements of first-class steel slag powder.

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

[0051] In the embodiment of the present application, cement can be silicate cement or ordinary silicate cement, the strength of cement is not less than 42.5 grade, slag powder is obtained by grinding blast furnace water-quenched slag, and the performance index of slag powder meets the requirements of S95 grade ore powder, and steel slag powder is obtained by grinding converter steel slag, and the performance index of steel slag powder meets the requirements of first-grade steel slag powder. Slag powder and steel slag powder replace a part of cement and have potential hydraulic cementing activity. Therefore, it can be understood that by mixing cement, slag powder, steel slag powder and tailings powder to form cementitious materials, steel slag, water slag and tailings are reasonably utilized, so that solid waste can be utilized as resources, the use of natural sand and cement is reduced, and the cost of shotcrete is reduced, while reducing energy consumption and reducing carbon dioxide emissions. For example, the cement content can be 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, etc., the slag powder content can be 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, etc., and the steel slag powder content can be 15 parts, 18 parts, 20 parts, 23 parts, 25 parts, etc.

[0052] In some embodiments, the raw materials of the accelerating setting agent include: alumina clinker, refined slag powder and desulfurized ash; wherein, in parts 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 meets the following characteristics: the specific surface area is 450m 2 / kg~500m 2 / kg, moisture content does not exceed 1%.

[0055] In the embodiment of the present application, the quick-setting agent can be an inorganic salt quick-setting agent, and the refined slag powder contains an early-setting component (calcium fluoroaluminate). The refined slag powder that meets the above characteristics has good activity. The refined slag powder and desulfurization ash replace a part of the alumina clinker and calcium oxide, etc. The desulfurization ash can be obtained by fine grinding of semi-dry desulfurization ash, mainly containing calcium hydroxide, calcium sulfite, calcium sulfate and calcium oxide, and the moisture content does not exceed 1%. Therefore, it can be understood that the quick-setting agent is prepared by mixing alumina clinker, refined slag and desulfurization ash, which reasonably utilizes the refined slag and desulfurization ash, so that solid waste can be recycled, the use of inorganic quick-setting agents such as alumina clinker is reduced, and the cost of shotcrete is reduced. While reducing energy consumption, it also reduces carbon dioxide emissions. Exemplarily, among the characteristics of the refined slag powder, the specific surface area can be 450m 2 / kg, 460m 2 / kg, 470m 2 / kg, 480m 2 / kg, 490m 2 / kg、500m 2 / kg, etc., and the moisture content can be 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 desulfurized ash can be 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, etc.

[0056] In a second aspect, the present application provides a method for preparing the shotcrete according to the first aspect, Figure 1 A schematic diagram of a process for preparing shotcrete according to some embodiments of the present application; see Figure 1 , the method comprising:

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

[0058] S2, stirring and mixing the coarse aggregate, the fine aggregate and the cementitious material containing the tailings powder to obtain a first mixture;

[0059] S3, stirring and mixing the first mixture, the accelerating agent and water to obtain a second mixture;

[0060] S4, spraying the second mixture to the construction site, and then curing to obtain sprayed concrete.

[0061] In an embodiment of the present application, the iron tailings waste rock is crushed and screened to obtain coarse aggregate and fine aggregate, and the iron tailings waste rock is further ground to obtain tailings powder; cement, slag powder, steel slag powder and tailings powder are mixed uniformly according to mass fractions to obtain cementitious material; the coarse aggregate, fine aggregate and cementitious material are stirred and mixed uniformly according to mass fractions to obtain a first mixture; alumina clinker, refined slag powder and desulfurization ash are mixed uniformly according to mass fractions 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 to the construction site, and the sprayed concrete is obtained after curing.

[0062] The preparation method of shotcrete is implemented based on the above-mentioned shotcrete. The specific raw material composition of the shotcrete can refer to the above-mentioned embodiment. Since the preparation method of shotcrete adopts part or all of the technical solutions of the above-mentioned embodiment, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be described one by one here.

[0063] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0064] Example 1

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

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

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

[0068] The performance indexes of slag powder meet the requirements of S95 grade slag powder; the performance indexes of steel slag powder meet the requirements of first grade steel slag powder.

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

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

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

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

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

[0074] First, the iron tailings waste rock is crushed and screened to obtain coarse aggregate, fine aggregate and iron tailings powder, and the iron tailings powder is ground to obtain tailings powder; then cement, slag powder, steel slag powder and tailings powder are mixed evenly according to weight fractions to obtain cementitious material; the coarse aggregate, fine aggregate and cementitious material are stirred and mixed according to weight fractions to obtain a first mixture; alumina clinker, refined slag powder and desulfurization ash are mixed evenly according to weight fractions 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 sprayed concrete is obtained after curing.

[0075] Example 2

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

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

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

[0079] The specific surface area of ​​tailings powder is 500m 2 / kg, and the activity index at 28 days was 73%.

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

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

[0082] Example 3

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

[0084] 44 parts of coarse aggregate, 30 parts of fine aggregate, 15 parts of cementitious material, 9 parts of water, and 2 parts of accelerating agent.

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

[0086] The specific surface area of ​​tailings powder is 470m 2 / kg, and the activity index at 28 days was 70%.

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

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

[0089] Comparative Example 1

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

[0091] 40 parts of coarse aggregate, 40 parts of fine aggregate, 14 parts of cementitious material, 6 parts of water, and no accelerator is added.

[0092] Comparative Example 2

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

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

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

[0096] Comparative Example 3

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

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

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

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

[0101] Table 1 Shotcrete performance test results

[0102]

[0103] It can be seen from the test results that the compressive strength test results of the shotcrete provided in the embodiments of the present application are all greater than 25MPa, reaching the level of shotcrete grade C25 or above. By comparing the experimental results of Example 1, Example 2 and Example 3, it can be seen that with the increase in the amount of accelerating setting agent, the setting time of the slurry is gradually shortened; with the increase in the amount of cementitious material, the compressive strength of the shotcrete is gradually increased. Comparative Example 1 shows that when the shotcrete is not equipped with an accelerating setting agent, the setting time is greatly prolonged, and the acceleration setting agent can improve the early compressive strength, but the 28d compressive strength decreases slightly; the specific surface area of ​​the tailings powder and the refined slag powder in Comparative Example 2 does not reach 450m 2 / kg index, hydration activity and rapid setting are not fully exerted, resulting in a decrease in the compressive strength of shotcrete at all ages and an extension of the setting time, affecting the construction performance of the shotcrete; Comparative Example 3 shows that cement and alumina clinker play a key role in cementitious materials and accelerating setting agents, which can ensure the stability of the compressive strength and setting time of the shotcrete.

[0104] Therefore, the shotcrete provided in the embodiment of the present application utilizes tailings and waste rock as aggregate and a large amount of solid waste to prepare cementitious materials and accelerators, which can save natural sand and gravel aggregates and cement, etc., can significantly reduce the cost of raw materials for engineering projects, and at the same time reduce carbon dioxide emissions. In addition, the environmental and social benefits generated by the application of the embodiment of the present application are greater than its economic benefits.

[0105] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will meet the widest range consistent with the principles and novel features applied for herein.

Claims

1. A shotcrete, characterized in that: The raw materials of the shotcrete include: coarse aggregate, fine aggregate, cementitious material, water and quick-setting agent, wherein the raw materials of the cementitious material include tailings powder, The coarse aggregate, the fine aggregate and the tailings powder are obtained by pre-processing iron tailings waste rock; wherein, in parts by weight, The content of the coarse aggregate is 40 to 50 parts, the content of the fine aggregate is 30 to 40 parts, the content of the cementitious material is 10 to 15 parts, the content of the water is 6 to 9 parts, and the content of the quick-setting agent is 0.5 to 2 parts.

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

3. The shotcrete according to claim 1, characterized in that: The tailings powder meets the following characteristics: specific surface area is 450m 2 / kg~500m 2 / kg, moisture content not exceeding 1%, and 28-day activity index not less than 65%.

4. The shotcrete according to claim 1, characterized in that: The tailings powder is 5 to 10 parts by weight relative to 100 parts by weight of the gelling material.

5. The shotcrete according to claim 1 or 4, characterized in that: The raw materials of the cementitious material also include cement, slag powder and steel slag powder.

6. The shotcrete according to claim 5, characterized in that: The strength of the cement is not less than grade 42.5; and / or, The performance index of the slag powder meets the requirements of S95 grade slag powder; and / or, The performance indexes of the steel slag powder meet the requirements of first-class steel slag powder.

7. The shotcrete according to claim 5, characterized in that: In the raw materials of the cementitious material, the content of the cement is 20 to 30 parts by weight, the content of the slag powder is 40 to 50 parts by weight, and the content of the steel slag powder is 15 to 25 parts by weight.

8. The shotcrete according to claim 1, characterized in that: The raw materials of the quick-setting agent include: alumina clinker, refined slag powder and desulfurized ash; wherein, by weight, 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.

9. The shotcrete according to claim 8, characterized in that: The refined slag powder meets the following characteristics: specific surface area is 450m 2 / kg~500m 2 / kg, moisture content does not exceed 1%.

10. A method for preparing shotcrete according to any one of claims 1 to 9, characterized in that: The method comprises: Pre-treating the iron tailings waste rock 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 a first mixture; Stirring and mixing the first mixture, an accelerating setting agent and water to obtain a second mixture; The second mixture is sprayed onto the construction site and then cured to obtain sprayed concrete.

Images