A lightweight coal gangue functional aggregate, its preparation method and application

Abstract

The present invention provides a lightweight coal gangue functional aggregate, a preparation method thereof, and an application thereof. The lightweight coal gangue functional aggregate of the present invention comprises coal gangue, fly ash, rice husk ash, and MnO₂. Among them, coal gangue, as the main raw material, realizes the resource utilization of solid waste and greatly reduces the production cost of lightweight aggregate from the raw material cost; fly ash is a corrective raw material used to adjust the ratio of the fluxing components and refractory components of the raw materials; the compounded rice husk ash and MnO₂ are used as pore-forming agents, which can increase the porosity of the lightweight aggregate. The lightweight coal gangue functional aggregate of the present invention has excellent properties such as lightweight, high strength, high water absorption, and slow water release. It can not only realize the large-scale utilization of solid waste, conform to the national green sustainable development strategy, but also make up for the shortage of natural lightweight aggregate resources, and at the same time realize the internal curing effect on UHPC, thereby reducing the early shrinkage and cracking of UHPC and improving the mechanical properties and durability of UHPC.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly relates to a lightweight coal gangue functional aggregate, a preparation method thereof, and an application thereof. Background Art

[0002] With the development direction of modern architecture towards high-rise, large-span, high-strength, high-durability and green sustainability, the importance of the research and application of ultra-high performance concrete (UHPC) has become increasingly prominent. However, due to the high dosage of cementitious materials, low water-binder ratio and dense design principle, UHPC has problems such as high density (2600 - 2800 kg / m 3 ), and large shrinkage (8.0×10 -4 ), etc., resulting in poor volume stability and prone to problems such as shrinkage cracking. In addition, due to the dense structure of UHPC, it is difficult for external moisture to penetrate into it. When the curing is insufficient in the early stage, the relative humidity inside UHPC decreases rapidly, making the problems of early water loss and cracking of UHPC structure particularly prominent. In order to solve the problem of easy shrinkage and cracking of UHPC while ensuring mechanical properties and durability, it is found through research that the performance of light aggregates in storing and releasing water stably can be utilized. As an internal curing material for UHPC, part of the water can be pre-introduced into the cementitious paste through pre-wetting, and the water is slowly released in the later stage of cement hydration, which can reduce or even eliminate the additional tensile pressure of capillaries, thereby reducing the self-drying of UHPC and ensuring the full progress of cement hydration in the later stage.

[0003] Light aggregates are the general term for light coarse aggregates with a bulk density less than 1100 kg / m 3 and light fine aggregates with a bulk density less than 1200 kg / m 3 . According to their sources, they can be divided into industrial waste light aggregates, natural light aggregates and artificial light aggregates. Due to the limitations in performance such as uneven texture and unqualified strength of industrial waste light aggregates and natural light aggregates, artificial light aggregates are mostly used in actual engineering applications. Traditional artificial light aggregates are prepared from natural materials such as shale and clay. However, with the continuous consumption and non-renewability of natural materials, it is an inevitable trend to use waste materials to replace natural materials in the production of light aggregates. At the same time, coal gangue is one of the largest industrial solid waste emissions in China at present. The large amount of piled-up coal gangue brings many inconveniences to social development and people's lives.

[0004] Based on the above problems, it is necessary to develop a lightweight coal gangue functional aggregate and a preparation method thereof. Summary of the Invention

[0005] In view of this, the present invention provides a lightweight coal gangue functional aggregate, a preparation method thereof, and an application thereof to solve or partially solve the technical problems existing in the prior art.

[0006] In the first aspect, the present invention provides a lightweight coal gangue functional aggregate, which comprises raw materials with the following mass fractions: 85-90% of coal gangue powder, 5-10% of fly ash, 0-3% of rice husk ash, and 0-3% of MnO₂.

[0007] Preferably, for the lightweight coal gangue functional aggregate, the particle size of the coal gangue powder is ≤150 μm and the specific surface area is ≥300 m 2 / kg; the mass content of SiO₂ in the coal gangue powder is 55-69%, the mass content of Al₂O₃ is 18-25%, and the total mass content of flux oxides is 13-20%. The flux oxides include Fe₂O₃, Na₂O, K₂O, MgO, and CaO.

[0008] Preferably, for the lightweight coal gangue functional aggregate, the particle size of the fly ash is ≤75 μm and the specific surface area is ≥340 m 2 / kg;

[0009] The mass content of SiO₂ in the fly ash is 50-60%, the mass content of Al₂O₃ is 15-22%, and the total mass content of flux oxides is 22-28%. The flux oxides include Fe₂O₃, Na₂O, K₂O, MgO, and CaO.

[0010] Preferably, for the lightweight coal gangue functional aggregate, the particle size of the rice husk ash is ≤75 μm and the specific surface area is ≥380 m 2 / kg.

[0011] In the second aspect, the present invention further provides a preparation method of the lightweight coal gangue functional aggregate, which is characterized by comprising the following steps:

[0012] Mix and stir the coal gangue powder, fly ash, rice husk ash, and MnO₂ to obtain a mixture;

[0013] Place the mixture in a granulator to granulate it into green balls;

[0014] After drying the green balls, roast, cool, and screen them to obtain the lightweight coal gangue functional aggregate.

[0015] Preferably, for the preparation method of the lightweight coal gangue functional aggregate, placing the mixture in a granulator to granulate it into green balls specifically includes:

[0016] Place the mixture in a granulator, control the rotation speed of the granulator at 50-60 r / min, and spray water onto the mixture while the granulator is rotating until the particle size of the green balls is ≤4.75 mm.

[0017] Preferably, in the method for preparing the lightweight coal gangue functional aggregate, in the step of drying the green balls, the drying temperature is 100-105°C and the drying time is 2-4 h.

[0018] Mix coal gangue powder, fly ash and rice husk ash, stir and then screen through a 80-120 mesh sieve to obtain a mixture.

[0019] Preferably, in the method for preparing the lightweight coal gangue functional aggregate, after drying the green balls, calcine, cool and screen to obtain the lightweight coal gangue functional aggregate, which specifically includes the following steps:

[0020] After drying the green balls, place them in a muffle furnace and heat from room temperature to 300-500°C at a temperature rise rate of 4-6°C / min and hold for 30-50 min, then heat to 1160-1200°C and hold for 50-70 min, and cool with the muffle furnace to room temperature, then screen to obtain the lightweight coal gangue functional aggregate.

[0021] Preferably, in the method for preparing the lightweight coal gangue functional aggregate, screen to a particle size of 0.15-4.75 mm to obtain the lightweight coal gangue functional aggregate.

[0022] In the third aspect, the present invention also provides an application of the above-mentioned lightweight coal gangue functional aggregate or the lightweight coal gangue functional aggregate prepared by the above-mentioned preparation method in the preparation of ultra-high performance concrete.

[0023] A lightweight coal gangue functional aggregate and a preparation method thereof according to the present invention have the following beneficial effects compared with the prior art:

[0024] 1) The lightweight coal gangue functional aggregate of the present invention replaces natural materials (such as shale and clay) with industrial solid waste coal gangue, which can not only save natural resources, make up for the shortage of natural lightweight aggregate resources, but also realize the high-value utilization of solid waste, and to a certain extent solve the environmental pollution problem caused by the large accumulation of coal gangue, thereby obtaining certain environmental and economic benefits.

[0025] 2) The present invention uses compounded rice husk ash and MnO2 as pore-forming agents to increase the porosity of the lightweight aggregate and form a uniformly distributed fine interconnected pore structure. The prepared lightweight coal gangue functional aggregate can be used as a good internal curing material for UHPC.

[0026] 3) The lightweight coal gangue functional aggregate prepared by the present invention has light weight (bulk density ≤ 1100 kg / m 3), with excellent properties of high strength (cylinder compressive strength ≥ 10 MPa), high water absorption (24-hour water absorption rate ≥ 15%), and slow-release water (containing a large number of fine interconnected pores below 100 nm), can effectively reduce the self-weight of UHPC, while achieving the internal curing effect on UHPC, reducing the early shrinkage and cracking of UHPC, and further improving the mechanical properties and durability of UHPC. Specific embodiments

[0027] The following will describe the technical solutions in the embodiments of the present invention in a clear and complete manner in combination with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0028] For a better understanding of the present invention rather than limiting the scope of the present invention, all numbers representing amounts, percentages, and other numerical values used in this application should be understood to be modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification and the appended claims are approximate values, which may vary according to the different desired properties to be obtained. Each numerical parameter should at least be regarded as obtained according to the reported significant figures and by the conventional rounding method.

[0029] It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments. In addition, in the description of this application, the term "including" means "including but not limited to". The various embodiments of the present invention may exist in a range form; it should be understood that the description in a range form is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present invention; therefore, it should be considered that the described 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. In addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0030] The embodiments of this application provide a lightweight coal gangue functional aggregate, including the following raw materials by mass fraction: 85 - 90% of coal gangue powder, 5 - 10% of fly ash, 0 - 3% of rice husk ash, and 0 - 3% of MnO₂.

[0031] In some embodiments, the particle size of the coal gangue powder ≤ 150 μm, and the specific surface area ≥ 300 m 2 / kg; The mass content of SiO2 in the coal gangue powder is 55-69%, the mass content of Al2O3 is 18-25%, and the total mass content of the flux oxides is 13-20%. Among them, the flux oxides include a mixture of Fe2O3, Na2O, K2O, MgO and CaO.

[0032] Specifically, coal gangue is a solid waste discharged during the coal mining process and the coal washing process. It is a black-gray rock with a lower carbon content and harder than coal, which is associated with the coal seam during the coal formation process. Its main components are Al2O3 and SiO2, and in addition, it also contains varying amounts of Fe2O3, CaO, MgO, Na2O, K2O, etc.

[0033] In some embodiments, the particle size of the fly ash ≤ 75 μm and the specific surface area ≥ 340 m 2 / kg; The mass content of SiO2 in the fly ash is 50-60%, the mass content of Al2O3 is 15-22%, and the total mass content of the flux oxides is 22-28%. Among them, the flux oxides include a mixture of Fe2O3, Na2O, K2O, MgO and CaO.

[0034] In some embodiments, the particle size of the rice husk ash ≤ 75 μm and the specific surface area ≥ 380 m 2 / kg.

[0035] The main component of the rice husk ash is silicon dioxide, followed by carbon, and there are also a small amount of metal oxides such as potassium oxide, sodium oxide, magnesium oxide and calcium oxide.

[0036] In some embodiments, MnO2 is of analytical purity with a purity of 85%.

[0037] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned lightweight coal gangue functional aggregate, comprising the following steps:

[0038] S1. Mix and stir the coal gangue powder, fly ash, rice husk ash and MnO2 to obtain a mixture;

[0039] S2. Place the mixture in a granulator to granulate it into green balls;

[0040] S3. After drying the green balls, roast, cool and screen them to obtain the lightweight coal gangue functional aggregate.

[0041] In some embodiments, placing the mixture in a granulator to granulate it into green balls specifically includes:

[0042] Place the mixture in a granulator, control the rotation speed of the granulator at 50-60 r / min, and spray water into the mixture while the granulator is rotating until the particle size of the green balls ≤ 4.75 mm.

[0043] Specifically, the uniformly stirred mixture is scattered into a rotating disk granulator, and the rotation speed is controlled at 50 - 60 r / min. While rotating, water is sprayed onto the mixture (the water spray nozzle of the used sprayer should not be too large, which is not conducive to ball formation). Wait until the rotating small balls gradually grow and finally reach the required particle size requirement (generally, select those with a diameter less than or equal to about 4.75 mm), and then take them out.

[0044] In some embodiments, in the step of drying the green balls, the drying temperature is 100 - 105 °C and the drying time is 2 - 4 h.

[0045] In some embodiments, coal gangue powder, fly ash, rice husk ash, and MnO₂ are mixed and stirred, and then sieved through a 80 - 120 mesh sieve to obtain a mixture.

[0046] In some embodiments, after drying the green balls, roasting, cooling, and screening are carried out to obtain the lightweight coal gangue functional aggregate. The specific steps are as follows:

[0047] After drying the green balls, place them in a muffle furnace and heat from room temperature to 300 - 500 °C at a temperature rise rate of 4 - 6 °C / min and hold for 30 - 50 min, then heat up to 1160 - 1200 °C and hold for 50 - 70 min, and then cool to room temperature (25 °C) with the muffle furnace, and screen to obtain the lightweight coal gangue functional aggregate.

[0048] In some embodiments, screen to a particle size of 0.15 - 4.75 mm to obtain the lightweight coal gangue functional aggregate.

[0049] The present invention provides a lightweight coal gangue functional aggregate and its preparation method. The lightweight coal gangue functional aggregate includes the following raw materials: coal gangue, fly ash, and rice husk ash. Among them, coal gangue, as the main raw material, realizes the resource utilization of solid waste, greatly reduces the production cost of lightweight aggregate from the raw material cost, thereby obtaining certain environmental and economic benefits; fly ash is a corrective raw material used to adjust the ratio of the flux component to the refractory component of the raw materials; rice husk ash and MnO₂ are used as pore-forming agents, which can increase the porosity of the lightweight aggregate. At the same time, the use of rice husk ash can solve the environmental pollution problem caused by agricultural waste. The lightweight coal gangue functional aggregate prepared by the present invention achieves the organic unity of light weight (bulk density ≤ 1100 kg / m 3 ), high strength (cylinder compressive strength ≥ 10 MPa), high water absorption (24 - hour water absorption rate ≥ 15%), and slow-release water (containing a large number of micro-connected pores below 100 nm). It can not only realize the large-scale utilization of solid waste, conform to the national green sustainable development strategy, but also make up for the shortage of natural lightweight aggregate resources. At the same time, it realizes the internal curing effect on UHPC, reduces the early shrinkage and cracking of UHPC, and further improves the mechanical properties and durability of UHPC.

[0050] Based on the same inventive concept, the present invention also provides an application of the above-mentioned lightweight coal gangue functional aggregate or the lightweight coal gangue functional aggregate prepared by the above-mentioned preparation method in the preparation of ultra-high performance concrete.

[0051] Specifically, the ultra-high performance concrete includes: 820 kg / m of cement 3 , 210 kg / m of silica fume 3 , 175 kg / m of fly ash 3 , 688 kg / m of lightweight coal gangue functional aggregate 3 , 217 kg / m of water 3 , 25.4 kg / m of water reducer 3 , 200 kg / m of steel fiber 3 .

[0052] The following further illustrates the lightweight coal gangue functional aggregate and its preparation method of the present application with specific examples. This part further illustrates the content of the present invention in combination with specific examples, but should not be construed as a limitation to the present invention. Unless otherwise specified, the technical means adopted in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment adopted in the present invention are conventional reagents, methods and equipment in the art.

[0053] Example 1

[0054] The embodiment of the present application provides a lightweight coal gangue functional aggregate, including raw materials with the following mass fractions: 88.2% of coal gangue powder, 9.8% of fly ash, 1% of rice husk ash, and 1% of MnO2.

[0055] Among them, the coal gangue powder is purchased from Huainan Dongchen Group Co., Ltd., with a particle size ≤ 150 μm, a specific surface area of 300 m 2 / kg, a SiO2 mass content of 58.91%, an Al2O3 mass content of 22.46%, and the total mass content of flux oxides (including the mixture of Fe2O3, Na2O, K2O, MgO and CaO) being 18.63%; the fly ash is purchased from Henan Yixiang New Material Technology Co., Ltd., with a particle size ≤ 75 μm, a specific surface area of 340 m 2 / kg, a SiO2 mass content of 56.2%, an Al2O3 mass content of 19.41%, and the total mass content of flux oxides (including the mixture of Fe2O3, Na2O, K2O, MgO and CaO) being 24.39%; the rice husk ash is purchased from a powerful supplier, LingShouXian JieLing Mineral Products Trading Co., Ltd., with a particle size ≤ 75 μm and a specific surface area of 380 m 2 / kg; the MnO2 is of analytical purity and is purchased from a powerful supplier, Tianmao Chemical Industry, with a purity of 85%.

[0056] The preparation method of the above-mentioned lightweight coal gangue functional aggregate is:

[0057] S1. Stir the coal gangue powder, fly ash, rice husk ash and MnO₂ in a powder mixer for 3 min, and then pass through a 100-mesh sieve to obtain a mixture.

[0058] S2. Place the mixture in a disk granulator, control the rotation speed at 55 r / min, and spray water into the mixture while the granulator is rotating. Wait until the rotating small balls gradually grow to the required particle size (particle size ≤ 4.75 mm) to obtain green balls.

[0059] S3. Dry the green balls in an oven at 105 °C for 4 h.

[0060] S3. Spread the dried green balls flat in a crucible and place it in a muffle furnace. Heat from room temperature to 400 °C at a temperature rise rate of 5 °C / min and hold for 30 min, then heat to 1160 °C and hold for 50 min, and then cool to room temperature with the muffle furnace. Screen the sintered lightweight aggregate cooled to room temperature through a standard sieve to obtain lightweight coal gangue functional aggregate with a particle size of 0.15 - 4.75 mm.

[0061] Example 2

[0062] This application example provides a lightweight coal gangue functional aggregate, including raw materials with the following mass fractions: 87.3% coal gangue powder, 9.7% fly ash, 2% rice husk ash, and 1% MnO₂.

[0063] Among them, the coal gangue powder is purchased from Huainan Dongchen Group, with a particle size ≤ 150 μm, a specific surface area of 300 m 2 / kg, a SiO₂ mass content of 58.91%, an Al₂O₃ mass content of 22.46%, and the total mass content of flux oxides (including a mixture of Fe₂O₃, Na₂O, K₂O, MgO and CaO) is 18.63%; the fly ash is purchased from Henan Yixiang New Material Technology Co., Ltd., with a particle size ≤ 75 μm, a specific surface area of 340 m 2 / kg, a SiO₂ mass content of 56.2%, an Al₂O₃ mass content of 19.41%, and the total mass content of flux oxides (including a mixture of Fe₂O₃, Na₂O, K₂O, MgO and CaO) is 24.39%; the rice husk ash is sourced from a powerful supplier, LingShou JieLing Mineral Products Trading Co., Ltd., with a particle size ≤ 75 μm and a specific surface area of 380 m 2 / kg; the MnO₂ is of analytical purity and is sourced from a powerful supplier, TianMao Chemical Industry, with a purity of 85%.

[0064] The preparation method of the above lightweight coal gangue functional aggregate is as follows:

[0065] S1. Stir the coal gangue powder, fly ash, rice husk ash and MnO₂ in a powder mixer for 3 min, and then pass through a 100-mesh sieve to obtain a mixture.

[0066] S2. Place the mixture in a disk granulator, control the rotation speed at 55 r / min, spray water into the mixture while the granulator is rotating, and wait for the rotating small balls to gradually grow to the required particle size (particle size ≤ 4.75 mm) to obtain green balls.

[0067] S3. Place the green balls in an oven at 105 °C and dry for 4 h.

[0068] S3. Spread the dried green balls flat in a crucible and place it in a muffle furnace. Heat from room temperature to 400 °C at a temperature rise rate of 5 °C / min and hold for 40 min, then heat to 1180 °C and hold for 60 min, and then cool to room temperature with the muffle furnace. Screen the sintered lightweight aggregate cooled to room temperature through a standard sieve to obtain lightweight coal gangue functional aggregate with a particle size of 0.15 - 4.75 mm.

[0069] Example 3

[0070] This application example provides a lightweight coal gangue functional aggregate, including raw materials with the following mass fractions: 87.3% coal gangue powder, 9.7% fly ash, 1% rice husk ash, and 2% MnO₂.

[0071] Among them, the coal gangue powder is purchased from Huainan Dongchen Group, with a particle size ≤ 150 μm, a specific surface area of 300 m 2 / kg, a SiO₂ mass content of 58.91%, an Al₂O₃ mass content of 22.46%, and the total mass content of fluxing oxides (including the mixture of Fe₂O₃, Na₂O, K₂O, MgO, and CaO) is 18.63%; the fly ash is purchased from Henan Yixiang New Material Technology Co., Ltd., with a particle size ≤ 75 μm, a specific surface area of 340 m 2 / kg, a SiO₂ mass content of 56.2%, an Al₂O₃ mass content of 19.41%, and the total mass content of fluxing oxides (including the mixture of Fe₂O₃, Na₂O, K₂O, MgO, and CaO) is 24.39%; the rice husk ash is sourced from a powerful supplier, LingShou County JieLing Mineral Products Trading Co., Ltd., with a particle size ≤ 75 μm, a specific surface area of 380 m 2 / kg; the MnO₂ is of analytical purity and is sourced from a powerful supplier, TianMao Chemical Industry, with a purity of 85%.

[0072] The preparation method of the above lightweight coal gangue functional aggregate is as follows:

[0073] S1. Stir the coal gangue powder, fly ash, rice husk ash, and MnO₂ in a powder mixer for 3 min, and pass through a 100 - mesh sieve to obtain a mixture.

[0074] S2. Place the mixture in a disk granulator, control the rotation speed at 55 r / min, spray water into the mixture while the granulator is rotating, and wait for the rotating small balls to gradually grow to the required particle size (particle size ≤ 4.75 mm) to obtain green balls.

[0075] S3. Place the green balls in an oven at 105 °C and dry for 4 h.

[0076] S3. Spread the dried green balls flat in a crucible and place them in a muffle furnace. Heat from room temperature to 400 °C at a temperature rise rate of 5 °C / min and hold for 50 min, then heat to 1200 °C and hold for 70 min, and then cool with the muffle furnace to room temperature. Screen the sintered lightweight aggregate cooled to room temperature through a standard sieve to obtain lightweight coal gangue functional aggregate with a particle size of 0.15 - 4.75 mm.

[0077] Example 4

[0078] The embodiment of the present application provides a lightweight coal gangue functional aggregate, including raw materials with the following mass fractions: coal gangue powder 86.4%, fly ash 9.6%, rice husk ash 3%, and MnO₂ 1%.

[0079] Among them, the coal gangue powder is purchased from Huainan Dongchen Group, with a particle size ≤ 150 μm, specific surface area 300 m 2 / kg, SiO₂ mass content 58.91%, Al₂O₃ mass content 22.46%, and the total mass content of flux oxides (including a mixture of Fe₂O₃, Na₂O, K₂O, MgO, and CaO) is 18.63%; the fly ash is purchased from Henan Yixiang New Material Technology Co., Ltd., with a particle size ≤ 75 μm, specific surface area 340 m 2 / kg, SiO₂ mass content 56.2%, Al₂O₃ mass content 19.41%, and the total mass content of flux oxides (including a mixture of Fe₂O₃, Na₂O, K₂O, MgO, and CaO) is 24.39%; the rice husk ash is sourced from a powerful supplier, LingShou County JieLing Mineral Products Trading Co., Ltd., with a particle size ≤ 75 μm, specific surface area 380 m 2 / kg; the MnO₂ is of analytical purity and is sourced from a powerful supplier, TianMao Chemical Industry, with a purity of 85%.

[0080] The preparation method of the above lightweight coal gangue functional aggregate is as follows:

[0081] S1. Stir the coal gangue powder, fly ash, rice husk ash, and MnO₂ in a powder mixer for 3 min, and pass through a 100 - mesh sieve to obtain a mixture.

[0082] S2. Place the mixture in a disk granulator, control the rotation speed at 55 r / min, spray water into the mixture while the granulator is rotating, and wait for the rotating small balls to gradually grow to the required particle size (particle size ≤ 4.75 mm) to obtain green balls.

[0083] S3. Place the green balls in an oven at 105 °C and dry for 4 h.

[0084] S3. Spread the dried green balls in a crucible and place it in a muffle furnace. Heat from room temperature to 500 °C at a temperature rise rate of 5 °C / min and hold for 30 min, then heat to 1140 °C and hold for 50 min, and then cool to room temperature with the muffle furnace. Screen the sintered lightweight aggregate cooled to room temperature through a standard sieve to obtain lightweight coal gangue functional aggregate with a particle size of 0.15 - 4.75 mm.

[0085] Example 5

[0086] The embodiment of the present application provides a lightweight coal gangue functional aggregate, including raw materials with the following mass fractions: coal gangue powder 86.4%, fly ash 9.6%, rice husk ash 1%, MnO₂ 3%.

[0087] Among them, the coal gangue powder is purchased from Huainan Dongchen Group, with a particle size ≤ 150 μm, specific surface area 300 m 2 / kg, SiO₂ mass content 58.91%, Al₂O₃ mass content 22.46%, and the total mass content of fluxing oxides (including the mixture of Fe₂O₃, Na₂O, K₂O, MgO and CaO) is 18.63%; the fly ash is purchased from Henan Yixiang New Material Technology Co., Ltd., with a particle size ≤ 75 μm, specific surface area 340 m 2 / kg, SiO₂ mass content 56.2%, Al₂O₃ mass content 19.41%, and the total mass content of fluxing oxides (including the mixture of Fe₂O₃, Na₂O, K₂O, MgO and CaO) is 24.39%; the rice husk ash is sourced from a powerful supplier, LingShou JieLing Mineral Products Trading Co., Ltd., with a particle size ≤ 75 μm, specific surface area 380 m 2 / kg; MnO₂ is of analytical purity and is sourced from a powerful supplier, TianMao Chemical Industry, with a purity of 85%.

[0088] The preparation method of the above lightweight coal gangue functional aggregate is as follows:

[0089] S1. Stir the coal gangue powder, fly ash, rice husk ash and MnO₂ in a powder mixer for 3 min, and pass through a 100-mesh sieve to obtain a mixture.

[0090] S2. Place the mixture in a disk granulator, control the rotation speed at 55 r / min, spray water into the mixture while the granulator is rotating, and wait for the rotating small balls to gradually grow to the required particle size (particle size ≤ 4.75 mm) to obtain green balls.

[0091] S3. Place the green balls in an oven at 105 °C and dry for 4 h.

[0092] S3. Spread the dried green balls flat in a crucible and place it in a muffle furnace. Heat from room temperature to 500 °C at a temperature rise rate of 5 °C / min and hold for 40 min, then heat to 1180 °C and hold for 60 min, and then cool to room temperature with the muffle furnace. Screen the sintered lightweight aggregate cooled to room temperature through a standard sieve to obtain lightweight coal gangue functional aggregate with a particle size of 0.15 - 4.75 mm.

[0093] Example 6

[0094] This application example provides a lightweight coal gangue functional aggregate, including raw materials with the following mass fractions: coal gangue powder 86.4%, fly ash 9.6%, rice husk ash 2%, MnO₂ 2%.

[0095] Among them, the coal gangue powder is purchased from Huainan Dongchen Group, with a particle size ≤ 150 μm, specific surface area 300 m 2 / kg, SiO₂ mass content 58.91%, Al₂O₃ mass content 22.46%, and the total mass content of flux oxides (including the mixture of Fe₂O₃, Na₂O, K₂O, MgO, and CaO) is 18.63%; the fly ash is purchased from Henan Yixiang New Material Technology Co., Ltd., with a particle size ≤ 75 μm, specific surface area 340 m 2 / kg, SiO₂ mass content 56.2%, Al₂O₃ mass content 19.41%, and the total mass content of flux oxides (including the mixture of Fe₂O₃, Na₂O, K₂O, MgO, and CaO) is 24.39%; the rice husk ash is sourced from a powerful supplier, LingShou JieLing Mineral Products Trading Co., Ltd., with a particle size ≤ 75 μm, specific surface area 380 m 2 / kg; MnO₂ is of analytical purity and is sourced from a powerful supplier, Tianmao Chemical Industry, with a purity of 85%.

[0096] The preparation method of the above lightweight coal gangue functional aggregate is as follows:

[0097] S1. Stir the coal gangue powder, fly ash, and rice husk ash in a powder mixer for 3 min, and pass through a 100-mesh sieve to obtain a mixture.

[0098] S2. Place the mixture in a disk granulator, control the rotation speed at 55 r / min, spray water into the mixture while the granulator is rotating, and wait for the rotating small balls to gradually grow to the required particle size (particle size ≤ 4.75 mm) to obtain green balls.

[0099] S3. Place the green balls in an oven at 105 °C and dry for 4 h;

[0100] S3. Spread the dried green balls in a crucible and place it in a muffle furnace. Heat from room temperature to 500 °C at a temperature rise rate of 5 °C / min and hold for 50 min, then heat to 1200 °C and hold for 70 min, and then cool to room temperature with the muffle furnace. Screen the sintered lightweight aggregate cooled to room temperature through a standard sieve to obtain lightweight coal gangue functional aggregate with a particle size of 0.15 - 4.75 mm.

[0101] Performance Test

[0102] Test the lightweight coal gangue functional aggregate prepared in Examples 1 - 6 above according to the national standard "Lightweight Aggregates and Their Test Methods - Part 2: Test Methods for Lightweight Aggregates" (GB / T 17431.2 - 2010). The results are shown in Tables 1 - 2 below.

[0103] Table 1 - Performance of Lightweight Coal Gangue Functional Aggregate Prepared in Different Examples

[0104]

[0105] Table 2 - Performance of Lightweight Coal Gangue Functional Aggregate Prepared in Different Examples

[0106]

[0107] It can be seen from Tables 1 - 2 that the bulk density of the lightweight coal gangue functional aggregate prepared in different examples < 1020 kg / m 3 , the apparent density < 2300 kg / m 3 , the water absorption rate > 15%, the cylinder compressive strength > 15 MPa, the porosity > 16.9%, achieving the organic unity of light weight, high strength, and high water absorption. And it contains a large number of uniformly distributed micro-connected pores below 100 nm inside, which can realize the excellent performance of slow-release water. It can be used as a good internal curing material to provide moisture for UHPC during the setting and hardening process, effectively maintaining the internal humidity of UHPC, reducing the shrinkage cracking phenomenon of UHPC caused by self-drying, and promoting the hydration reaction, thereby improving the mechanical properties, volume stability, and durability of UHPC.

[0108] Example 7

[0109] This application example provides a ultra-high performance concrete (UHPC), including the following raw materials: cement 820 kg / m 3 , silica fume 210 kg / m 3 , fly ash 175 kg / m 3 , lightweight coal gangue functional aggregate prepared in Example 5 688 kg / m 3, water 217 kg / m 3 , water reducer 25.4 kg / m 3 , steel fiber 200 kg / m 3 ;

[0110] Among them, the cement is Conch P·O 52.5 ordinary Portland cement; the silica fume is sourced from Sichuan Langtian Resources Comprehensive Utilization Co., Ltd., with a specific surface area of 18,200 m 2 / kg, the mass content of SiO2 is 95%, and the 28-day activity index is 110%; the fly ash is grade I fly ash produced by Henan Yixiang New Material Technology Co., Ltd., with a specific surface area of 340 m 2 / kg and a water demand ratio of 90 wt%; the water reducer is a polycarboxylate superplasticizer produced by Jiangsu Bote New Materials Co., Ltd.; the steel fiber is produced by a factory in Hengshui, Hebei, with a length of 13 mm, a diameter of 0.22 mm, 100% without fracture, and a tensile strength ≥ 2850 MPa; the water is ordinary tap water.

[0111] The preparation method of the above ultra-high performance concrete (UHPC) includes the following steps:

[0112] S1. Immerse 688 kg / m 3 lightweight coal gangue functional aggregate in water (completely submerging the lightweight coal gangue functional aggregate) until it reaches a saturated state to obtain pre-wetted aggregate;

[0113] S2. Dry-mix and stir 820 kg / m 3 cement, 210 kg / m 3 silica fume, and 175 kg / m 3 fly ash for 2 min, then add the pre-wetted aggregate from step S1 and stir for 3 min; then add 217 kg / m 3 water and 25.4 kg / m 3 water reducer and stir again for 10 min. Finally, add 200 kg / m 3 copper-plated steel fiber and continue to stir evenly. After molding, vibrating, and forming, cover the surface with an impermeable film for film curing. Demold after 1 day, and finally perform standard curing to obtain ultra-high performance concrete (UHPC).

[0114] Test the apparent density of the ultra-high performance concrete (UHPC) prepared in Example 7 to be 1960 kg / m 3 , the 28-day compressive strength reaches 130 MPa, and the autogenous shrinkage rate is as low as 260×10 -6 . It not only has the high strength of ordinary UHPC but also reduces the self-weight by 25% and the shrinkage by 60% compared with ordinary UHPC, achieving the organic unity of lightweight, high strength, and low shrinkage of UHPC.

[0115] Meanwhile, it should be noted that the apparent density of UHPC represents its bulk density. In addition to the lightweight coal gangue functional aggregate in its raw materials, there are also cement, silica fume, fly ash as these cementitious materials, water, water reducer and steel fiber. For example, the bulk density of cement is 1300 kg / m 3 , the bulk density of silica fume is 250 kg / m 3 , the bulk density of fly ash is 700 kg / m 3 . Therefore, even though the apparent density of the invented lightweight coal gangue functional aggregate is relatively high, its apparent density will decrease after being mixed with other low-bulk-density materials such as cementitious materials and water to prepare UHPC.

[0116] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A lightweight coal gangue functional aggregate, characterized in that The raw materials include the following mass fractions: 85 - 90% of coal gangue powder, 5 - 10% of fly ash, 1 - 3% of rice husk ash, and 1 - 3% of MnO₂; The particle size of the coal gangue powder is ≤ 150 μm, and the specific surface area is ≥ 300 m 2 / kg; the mass content of SiO2 in the coal gangue powder is 55 - 69%, the mass content of Al2O3 is 18 - 25%, and the total mass content of fluxing oxides is 13 - 20%. The fluxing oxides include Fe2O3, Na2O, K2O, MgO, and CaO; The particle size of the fly ash is ≤ 75 μm and the specific surface area is ≥ 340 m 2 / kg; The mass content of SiO₂ in the fly ash is 50 - 60%, the mass content of Al₂O₃ is 15 - 22%, and the total mass content of flux oxides is 22 - 28%. The flux oxides include Fe₂O₃, Na₂O, K₂O, MgO, and CaO; The particle size of the rice husk ash is ≤ 75 μm and the specific surface area is ≥ 380 m 2 / kg; The preparation method of the lightweight coal gangue functional aggregate includes the following steps: Mix and stir the coal gangue powder, fly ash, rice husk ash, and MnO₂ to obtain a mixture; Place the mixture in a granulator to granulate into green pellets; After drying the green pellets, roast, cool, and screen them to obtain the lightweight coal gangue functional aggregate.

2. A preparation method of the lightweight coal gangue functional aggregate as described in claim 1, characterized in that, Include the following steps: Mix and stir the coal gangue powder, fly ash, rice husk ash, and MnO₂ to obtain a mixture; Place the mixture in a granulator to granulate into green pellets; After drying the green pellets, roast, cool, and screen them to obtain the lightweight coal gangue functional aggregate.

3. The preparation method of the lightweight coal gangue functional aggregate according to claim 2, characterized in that, Placing the mixture in a granulator to granulate into green pellets specifically includes: Place the mixture in a granulator, control the rotation speed of the granulator at 50 - 60 r / min, and spray water into the mixture while the granulator is rotating until the particle size of the green pellets ≤ 4.75 mm.

4. The preparation method of the lightweight coal gangue functional aggregate according to claim 2, characterized in that, In the step of drying the green pellets, the drying temperature is 100 - 105 °C and the drying time is 2 - 4 h; Mix and stir the coal gangue powder, fly ash, and rice husk ash and then pass through a 80 - 120 mesh sieve to obtain a mixture.

5. The preparation method of the lightweight coal gangue functional aggregate according to claim 2, characterized in that, After drying the green pellets, roasting, cooling, and screening to obtain the lightweight coal gangue functional aggregate specifically includes the following steps: After drying the green pellets, place them in a muffle furnace and heat from room temperature to 300 - 500 °C at a temperature rise rate of 4 - 6 °C / min and hold for 30 - 50 min, then heat to 1160 - 1200 °C and hold for 50 - 70 min, cool with the muffle furnace to room temperature, and screen to obtain the lightweight coal gangue functional aggregate.

6. The preparation method of the lightweight coal gangue functional aggregate according to claim 5, characterized in that, Screen to a particle size of 0.15 - 4.75 mm to obtain the lightweight coal gangue functional aggregate.

7. Application of the lightweight coal gangue functional aggregate as described in claim 1 or the lightweight coal gangue functional aggregate prepared by the preparation method as described in any one of claims 2 - 6 in the preparation of ultra-high performance concrete.

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