Super-high ductility high-temperature-resistant coal gangue concrete and preparation method thereof

Abstract

The present application relates to the technical field of cement-based building materials, and particularly relates to a super-high ductility high-temperature-resistant coal gangue concrete and a preparation method thereof, wherein the recycled coal gangue is treated by a thermal activation technology, mixed with fibers, and then reinforced by modified calcium carbonate whiskers to improve the high-temperature resistance, and polyethylene glycol methacrylate and a thickening agent are used to ensure the workability of the concrete with the modified coal gangue and machine-made sand as the aggregate, so that a green low-carbon high-temperature-resistant high-ductility coal gangue concrete is prepared, which is conducive to the popularization and use of the coal gangue concrete in building structures.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cement-based building materials, and particularly relates to an ultra-high ductility high-temperature-resistant coal gangue concrete and a preparation method thereof. BACKGROUND

[0002] Coal is one of the important fossil energy, with the large-scale development and utilization of coal, the solid waste coal gangue discharged in the process of coal mining and coal washing is more and more. The large accumulation of coal gangue seriously pollutes the atmosphere, land and water source, and has hidden danger to the safety and environment of the surrounding area of the stacking area, and its resource utilization is imminent. Coal gangue is a complex mixture composed of sandstone and shale, and has large porosity, high content of needle-like particles, many edges and corners, and complex internal structure. Direct use of the original coal gangue to prepare concrete is prone to brittle fracture, easy to be damaged by high temperature, and often cannot meet the engineering requirements in ductility and compressive strength, which limits its application in some engineering.

[0003] Ultra-high ductile concrete (UHDC) as a new building material has a wide application prospect. Based on the design principle of micro mechanics, it usually uses cement, quartz sand and other materials as matrix, and uses fiber as reinforcing material to prepare, and has the characteristics of strain hardening and micro-crack cracking under load, and is a new type of high-performance concrete material with excellent deformation capacity. In the preparation process of UHDC, the high efficient bridging effect of fiber is utilized, and the micro and macro morphology of coal gangue is irregular, which is helpful to the dispersion of fiber and the interfacial adhesion between reinforcing fiber and matrix. However, simply combining ordinary coal gangue and cement-based composite material to prepare concrete will have a great negative impact on its performance.

[0004] Patent 1 (Chu Fengming, Zhao Lian, Chu Tian, A kind of full coal gangue high performance concrete and its preparation method, CN115710115A, 2023.02.24) discloses a full coal gangue high performance concrete preparation method. The invention uses composite powdery reinforcing agent, geopolymer admixture, and coal gangue material to prepare a concrete with high interfacial bonding strength and excellent compressive strength performance. The invention focuses on improving the compressive strength of concrete and fails to improve the toughness and tensile capacity of concrete, which is still relatively brittle. Patent 2 (Qin Qing, A fly ash geopolymer modified coal gangue concrete block and its preparation method, CN113845350A, 2021.12.28) discloses a fly ash geopolymer modified coal gangue concrete block preparation method. The invention uses coal gangue, fly ash and other solid waste to prepare a low-cost concrete block with good mechanical properties. However, its compressive strength can only reach 22.3MPa at most, and its flexural strength can only reach 2.3MPa at most. It does not improve the tensile deformation capacity and high temperature resistance of concrete, and still lacks in the efficient utilization of coal gangue. Our research group has previously studied high temperature resistant and high ductility concrete and applied for a patent CN116217182A. The invention mainly improves the high temperature resistance and high ductility of concrete by using special hybrid fibers and rubber particles. However, the hybrid fibers in this patent are no longer suitable for the super high ductility concrete of the invention which adds coal gangue and machine-made sand as aggregate. Therefore, other types of hybrid fibers and admixtures need to be explored to meet the needs of the material system of the invention. SUMMARY

[0005] To solve the problems in the prior art, the present invention provides a super high ductility and high temperature resistant coal gangue concrete and its preparation method. The invention uses thermal activation technology to process recycled coal gangue, mixes in fibers, and uses modified calcium carbonate whiskers to enhance its high temperature resistance, thereby preparing a green, low-carbon, high-ductility, and high-temperature-resistant coal gangue concrete, which is conducive to the popularization and use of coal gangue concrete in building structures.

[0006] Specifically, the super high ductility and high temperature resistant coal gangue concrete of the invention is composed of the following raw materials by weight: cement 300-450 parts, fly ash 190-260 parts, silica ash 170-220 parts, modified coal gangue 580-800 parts, machine-made sand 280-520 parts, water 160-230 parts, polyethylene fiber 10-20 parts, polypropylene fiber 1-10 parts, modified calcium carbonate whisker 30-65 parts, water reducing agent 3-8 parts, polyethylene glycol methacrylate 1-2 parts, and thickening agent 0.5-2 parts.

[0007] Preferably, the modified coal gangue preparation process is: calcining coal gangue at 700-800 DEG C, cooling, coarse crushing, primary screening, fine grinding, secondary screening, to obtain 5-15mm modified coal gangue.

[0008] The research of the present application shows that the concrete prepared by using the original coal gangue coarse aggregate is prone to brittle fracture, has low compressive strength, thicker and looser interface transition zone, and the number of irregular and porous particles increases, mainly because the impurities such as coal attached to the surface of the original coal gangue aggregate has a negative impact on the bonding performance between the cement matrix. The present application modifies the coal gangue by heat activation technology, and the carbon and organic matter in the modified coal gangue are effectively removed, and a large amount of amorphous SiO2 and Al2O3 is generated in the aggregate. During the curing process of the concrete, the amorphous substance on the surface of the aggregate reacts with Ca(OH)2 in the interface transition zone during the cement hydration process, to improve the pore structure of the cement-based material, and effectively improve the mechanical properties of the concrete.

[0009] The larger the particle size of the modified coal gangue is, the smaller the specific surface area is, and the amount of cement slurry required is reduced, and under certain workability and cement dosage conditions, the water consumption can be reduced to improve the strength of the concrete. From this aspect, the particle size should be slightly larger, but it is not the larger the better, the larger the particle size is, the greater the probability of internal cracking is, and the faster the particle sinking speed is during the mixing of the concrete, resulting in uneven distribution of particles in the concrete and reducing the strength. In the present application, the particle size is limited to be crushed to less than 15mm and the fine powder less than 5mm is removed. Moreover, the present application uses modified coal gangue as coarse aggregate, machine-made sand as fine aggregate, and adds a large amount of fibers and whiskers to prepare the concrete with poor workability. Therefore, the present application adds polyethylene glycol methacrylate and thickening agent to cooperatively improve the workability of the concrete, which has good effect.

[0010] Preferably, the modified calcium carbonate whisker preparation process is: adding calcium carbonate whisker into sodium hydroxide solution, constant temperature stirring, washing, drying, mixing with ethanol, deionized water and ammonia water, stirring, adding tetraethyl orthosilicate, and then deionized water washing, suction filtration and drying. More preferably, the mass concentration of sodium hydroxide solution is 5%, the constant temperature stirring temperature is 45 DEG C, and the drying temperature is 80 DEG C.

[0011] Preferably, the cement is Portland cement or ordinary Portland cement, and the strength grade is ≥42.5, more preferably, the initial setting time of the cement is 35min, and the final setting time is 3.5h.

[0012] Preferably, the fly ash is first-class fly ash, and the particle size range is 45-300um, and the specific surface area is ≥400m2 / kg.

[0013] Preferably, the silica fume has a specific surface area of ≥20000 m 2 / kg, and more preferably, the silica fume has an average particle size of 0.1 μm, a real density of 2.216 g·cm -3 , and a specific surface area of 20000 m 2 / kg.

[0014] Preferably, the machine-made sand has a water content of ≤0.2%, a maximum particle size of ≤2 mm, and a clay and powder content of ≤0.1%.

[0015] Preferably, the polyethylene fiber has a length of 12-36 mm, a diameter of 20-40 μm, an aspect ratio of ≥600, an elastic modulus of ≥100 GPa, and a tensile strength of ≥2800 MPa, and the polypropylene fiber has a length of 10-22 mm, a diameter of 20-30 μm, an aspect ratio of ≥600, an elastic modulus of ≥100 GPa, and a tensile strength of ≥800 MPa.

[0016] The polyethylene fiber and the polypropylene fiber are mixed and used as a reinforcing and toughening material, and the modified calcium carbonate whisker is used to improve the high-temperature resistance. The modified calcium carbonate whisker is a micron-scale fiber, and the efficient bridging between the mixed fiber and the whisker inhibits the generation and expansion of micro-cracks in the coal gangue concrete from the macro and micro perspectives, reduces the number of harmful pores in the super-high-ductility high-temperature-resistant coal gangue concrete, and refines the pore structure. Secondly, the mixed fiber, the whisker and the concrete bear the tensile stress through the adhesion and mechanical interlocking force, improve the bearing capacity of the concrete, and to some extent, can reduce the structure section size, prevent the intrusion of external moisture through crack resistance, improve the density of the cement matrix, and make the prepared concrete have higher compressive strength and tensile strength than the traditional coal gangue concrete.

[0017] The melting point of the polyethylene fiber is 108-126℃, and the melting point of the polypropylene fiber is 165-173℃. The mixed fiber will be melted at high temperature, providing a migration channel for water vapor in the super-high-ductility high-temperature-resistant coal gangue concrete structure, releasing the steam pressure in the component, effectively inhibiting the high-temperature burst phenomenon, and improving the high-temperature resistance of the coal gangue concrete. The polypropylene fiber has low energy consumption and slightly lower tensile strength, but has a lower elastic modulus. The polyethylene fiber has high tensile strength and tensile elastic modulus. The mixing of the two fibers is beneficial to improve the crack tolerance of the fiber, which is crucial for realizing the super-high-ductility, high durability and good crack control behavior of the coal gangue concrete. Moreover, the hydrophobic properties of the polyethylene fiber and the polypropylene fiber can significantly improve the supplementary residual energy during the fiber pull-out process, which helps to realize the strain hardening and multi-crack cracking of the super-high-ductility high-temperature-resistant coal gangue concrete.

[0018] The calcium carbonate whisker is modified to make more SiO2 adhere to the surface, SiO2 participates in the hydration reaction in the later stage to generate more C-S-H gel, the modified calcium carbonate whisker is tightly wrapped by the hydration product, the interface bonding between the modified calcium carbonate whisker and the cement matrix is increased, and the generation and expansion of microcracks in the hydration and hardening process of concrete are inhibited. In the application, the addition of the modified calcium carbonate whisker not only optimizes the pore size distribution of the cement matrix, but also reduces the number of harmful pores in the super-high ductility and high-temperature-resistant coal gangue concrete, and improves the compactness of the cement-based composite material matrix. In addition, the modified calcium carbonate whisker is high-temperature stable, can effectively reduce the reduction of high-temperature mechanical properties and strength failure of the super-high ductility and high-temperature-resistant coal gangue concrete due to the generation of water vapor escape channels caused by the melting of mixed fibers at high temperature, and the two work together to improve the high-temperature resistance of the super-high ductility and high-temperature-resistant coal gangue concrete.

[0019] Preferably, the water reducing agent is a polycarboxylic acid superplasticizer with a water reducing rate greater than 19%.

[0020] Preferably, the thickening agent is polyacrylamide.

[0021] The application also relates to a preparation method of the super-high ductility and high-temperature-resistant coal gangue concrete.

[0022] 1) The raw materials are weighed according to the weight parts;

[0023] 2) The cement and the modified coal gangue are uniformly stirred at a slow speed by using a stirrer;

[0024] 3) The machine-made sand, fly ash, silica fume, modified calcium carbonate whisker and water are added to the stirrer and stirred uniformly, and the water reducing agent and polyethylene glycol methacrylate are added and stirred at a slow speed;

[0025] 4) The thickening agent is added and stirred at a slow speed;

[0026] 5) The polyethylene fiber and the polypropylene fiber are slowly added to the stirrer, and then stirred at a slow speed and then at a fast speed to uniformly disperse the fibers, so that the concrete slurry is obtained;

[0027] 6) The concrete slurry is shaped, demolded and maintained, and the super-high ductility and high-temperature-resistant coal gangue concrete is obtained.

[0028] Preferably, the stirring speed of the slow stirring is 95-115 r / min, and the stirring speed of the fast stirring is 195-215 r / min.

[0029] Preferably, the slow stirring time is 1-3 min, and the fast stirring time is 2-4 min.

[0030] Preferably, the forming adopts vibration forming, more preferably, the vibration adopts bidirectional vibration mode in the vibration process, to ensure that the concrete obtains uniform mechanical properties in the vibration process. The vibration frequency in the vibration process is usually 50-70Hz, the vibration time is usually 2-3min, and appropriate moisture retention measures such as wet curing and covering protection are taken after forming and before demolding, to ensure the early strength and durability of the concrete.

[0031] Preferably, the curing adopts standard curing for 7-14d.

[0032] The present application has the following technical advantages:

[0033] 1) The mutual bridging between the mixed fibers and the whiskers in the present application inhibits the cracking of the super-high ductility and high-temperature-resistant coal gangue concrete from the macro and micro perspectives, and the compressive strength and tensile strength are higher than those of the traditional coal gangue concrete, the compressive strength at room temperature is usually above 50MPa, and the tensile strength is above 6MPa, which shows good performance compared with ordinary coal gangue and can meet the engineering requirements of high strength and high ductility.

[0034] 2) The addition of modified calcium carbonate whiskers in the present application can effectively reduce the decrease of high-temperature mechanical properties and strength failure of the coal gangue concrete due to the water vapor escape channel caused by the melting of the mixed fibers at high temperature. When the crack propagates to the surface of the whisker, more energy is consumed to overcome the friction between the whisker and the cement matrix interface, so that the coal gangue concrete shows good high-temperature resistance.

[0035] 3) The present application utilizes solid waste coal gangue to solve the environmental problems and safety hazards around the coal gangue pile, uses machine-made sand as fine aggregate, and uses polyethylene glycol methacrylate and thickening agent to improve the workability of the concrete, to prepare high-performance concrete, reduce cost, and be green, low-carbon, energy-saving and environment-friendly. DETAILED DESCRIPTION

[0036] The embodiments of the present application are described in detail below, and the embodiments are implemented on the premise of the technical scheme of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0037] The raw materials used in the embodiments are known and commercially available chemical raw materials unless otherwise specified.

[0038] Among them, the cement adopts P·O42.5 cement, and the fly ash adopts first-class fly ash.

[0039] The preparation process of the modified coal gangue is as follows: the coal gangue is calcined at 750℃ for 1h, cooled by a grate cooler, coarsely crushed, initially screened, finely ground, and secondarily screened, to obtain 5-15mm modified coal gangue.

[0040] The preparation process of the modified calcium carbonate whisker is as follows: calcium carbonate whisker is added into a 5% sodium hydroxide solution, stirred at 45°C, washed with deionized water, dried at 80°C, mixed with ethanol, deionized water and ammonia water, stirred, added with tetraethyl orthosilicate, continuously stirred, washed with deionized water, filtered, and dried at 80°C.

[0041] The concrete test piece is standard cured for 7 days.

[0042] Example 1

[0043] The ultrahigh ductility and high-temperature-resistant coal gangue concrete is composed of the following raw materials in parts by weight: cement 360 parts, fly ash 232 parts, silica ash 200 parts, modified coal gangue 720 parts, machine-made sand 286 parts, water 198 parts, polyethylene fiber 15 parts, polypropylene fiber 5 parts, modified calcium carbonate whisker 55 parts, polycarboxylate superplasticizer 3.5 parts, polyethylene glycol methacrylate 1.5 parts, and polyacrylamide 1 part.

[0044] After detection, the ultrahigh ductility and high-temperature-resistant coal gangue concrete has a compressive strength of 57.8 MPa, a tensile strength of 6.32 MPa, and a tensile strain capacity of 7.73% under normal temperature environmental conditions; after treatment at 200°C, the compressive strength is 45.8 MPa, the tensile strength is 4.18 MPa, the tensile strain capacity is 0.91%, the mass loss rate is 9.67%, and the test piece remains good integrity; after treatment at 400°C, the compressive strength is 34.7 MPa, the tensile strength is 1.92 MPa, the tensile strain capacity is 0.08%, the mass loss rate is 15.95%, and the test piece remains good integrity.

[0045] Example 2

[0046] The ultrahigh ductility and high-temperature-resistant coal gangue concrete is composed of the following raw materials in parts by weight: cement 350 parts, fly ash 222 parts, silica ash 200 parts, modified coal gangue 700 parts, machine-made sand 347 parts, water 192 parts, polyethylene fiber 11 parts, polypropylene fiber 3 parts, modified calcium carbonate whisker 45 parts, polycarboxylate superplasticizer 3.5 parts, polyethylene glycol methacrylate 1.2 parts, and polyacrylamide 1 part.

[0047] After detection, the ultrahigh ductility and high-temperature-resistant coal gangue concrete has a compressive strength of 53.2 MPa, a tensile strength of 5.65 MPa, and a tensile strain capacity of 5.73% under normal temperature environmental conditions; after treatment at 200°C, the compressive strength is 43.5 MPa, the tensile strength is 3.88 MPa, the tensile strain capacity is 1.25%, the mass loss rate is 9.48%, and the test piece remains good integrity; after treatment at 400°C, the compressive strength is 33.2 MPa, the tensile strength is 1.82 MPa, the tensile strain capacity is 0.12%, the mass loss rate is 15.87%, and the test piece remains good integrity.

[0048] Comparative Example 1

[0049] The concrete is composed of the following raw materials by weight: cement 360 parts, fly ash 232 parts, silica fume 200 parts, 5-15 mm coal gangue 720 parts, machine-made sand 286 parts, water 198 parts, polyethylene fiber 15 parts, polypropylene fiber 5 parts, modified calcium carbonate whisker 55 parts, polycarboxylic acid superplasticizer 3.5 parts, polyethylene glycol methacrylate 1.5 parts, and polyacrylamide 1 part.

[0050] It is detected that the compressive strength of the concrete under normal temperature environmental conditions is 43.4 MPa, the tensile strength is 4.32 MPa, and the tensile strain capacity is 4.83%; after 200℃ treatment, the compressive strength is 32.7 MPa, the tensile strength is 2.94 MPa, the tensile strain capacity is 0.67%, the mass loss rate is 13.65%, and the specimen remains good integrity; after 400℃ treatment, the compressive strength is 23.3 MPa, the tensile strength is 0.53 MPa, the tensile strain capacity is 0.04%, the mass loss rate is 20.48%, and the specimen has a slight explosion phenomenon.

[0051] Comparative Example 2

[0052] The concrete is composed of the following raw materials by weight: cement 360 parts, fly ash 232 parts, silica fume 200 parts, modified coal gangue 720 parts, machine-made sand 286 parts, water 198 parts, polyethylene fiber 15 parts, polypropylene fiber 5 parts, calcium carbonate whisker 55 parts, polycarboxylic acid superplasticizer 3.5 parts, polyethylene glycol methacrylate 1.5 parts, and polyacrylamide 1 part.

[0053] It is detected that the compressive strength of the concrete under normal temperature environmental conditions is 43.7 MPa, the tensile strength is 4.26 MPa, and the tensile strain capacity is 4.75%; after 200℃ treatment, the compressive strength is 31.8 MPa, the tensile strength is 2.85 MPa, the tensile strain capacity is 0.72%, the mass loss rate is 12.78%, and the specimen has a slight explosion phenomenon; after 400℃ treatment, the compressive strength is 22.4 MPa, the tensile strength is 0.63 MPa, the tensile strain capacity is 0.06%, the mass loss rate is 19.73%, and the specimen has an explosion phenomenon.

[0054] Comparative Example 3

[0055] The concrete is composed of the following raw materials by weight: cement 360 parts, fly ash 232 parts, silica fume 200 parts, modified coal gangue 720 parts, machine-made sand 286 parts, water 198 parts, polyethylene fiber 15 parts, polypropylene fiber 15 parts, polycarboxylic acid superplasticizer 3.5 parts, polyethylene glycol methacrylate 1.5 parts, and polyacrylamide 1 part.

[0056] The compressive strength of the concrete is 28.3 MPa under normal temperature environment, brittle failure occurs, and the test piece bursts after being treated at 200℃; the test piece bursts after being treated at 400℃.

[0057] Comparative Example 4

[0058] The concrete is composed of the following raw materials in parts by weight: cement 360 parts, fly ash 232 parts, silica fume 200 parts, coal gangue 720 parts, machine-made sand 286 parts, water 198 parts, polyethylene fiber 15 parts, polypropylene fiber 5 parts, steel fiber 55 parts, polycarboxylic acid superplasticizer 3.5 parts, polyethylene glycol methacrylate 1.5 parts, and polyacrylamide 1 part.

[0059] The concrete is segregated, the coal gangue sinks, the steel fiber is exposed, and the concrete cannot be shaped.

[0060] Comparative Example 5

[0061] The concrete is composed of the following raw materials in parts by weight: cement 360 parts, fly ash 232 parts, silica fume 200 parts, modified coal gangue 720 parts, machine-made sand 286 parts, water 198 parts, polyethylene fiber 15 parts, polypropylene fiber 5 parts, modified calcium carbonate whisker 55 parts, polycarboxylic acid superplasticizer 3.5 parts, and polyacrylamide 2.5 parts.

[0062] The concrete has poor workability, the fibers are not uniformly dispersed, and the shaped test piece is layered.

[0063] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A high-ductility, high-temperature resistant coal gangue concrete, characterized in that, It is composed of the following raw materials in parts by weight: 300-450 parts cement, 190-260 parts fly ash, 170-220 parts silica fume, 580-800 parts modified coal gangue, 280-520 parts manufactured sand, 160-230 parts water, 10-20 parts polyethylene fiber, 1-10 parts polypropylene fiber, 30-65 parts modified calcium carbonate whiskers, 3-8 parts water-reducing agent, 1-2 parts polyethylene glycol methacrylate, and 0.5-2 parts thickener; wherein the thickener is polyacrylamide. The modified coal gangue preparation process is as follows: calcining coal gangue at 700-800℃, cooling, coarse crushing, primary screening, fine grinding, and secondary screening to obtain 5-15mm modified coal gangue. The modified calcium carbonate whiskers are prepared as follows: calcium carbonate whiskers are added to sodium hydroxide solution, stirred at a constant temperature, washed, dried, mixed with ethanol, deionized water and ammonia, and then tetraethyl orthosilicate is added and stirred. After washing with deionized water, the mixture is filtered and dried to obtain the final product.

2. The ultra-high ductility, high-temperature resistant coal gangue concrete according to claim 1, characterized in that, The cement is silicate cement or ordinary silicate cement with a strength grade ≥42.

5.

3. The ultra-high ductility, high-temperature resistant coal gangue concrete according to claim 1, characterized in that, The fly ash is Grade I fly ash, with a particle size range of 45-300 μm and a specific surface area ≥400 m². 2 / kg.

4. The ultra-high ductility, high-temperature resistant coal gangue concrete according to claim 1, characterized in that, The specific surface area of ​​the silica fume is ≥20000m². 2 / kg.

5. The ultra-high ductility, high-temperature resistant coal gangue concrete according to claim 1, characterized in that, The manufactured sand has a moisture content of ≤0.2%, a maximum particle size of ≤2mm, and a mud and powder content of ≤0.1%.

6. The ultra-high ductility, high-temperature resistant coal gangue concrete according to claim 1, characterized in that, The polyethylene fiber has a length of 12-36 mm, a diameter of 20-40 μm, an aspect ratio ≥600, an elastic modulus ≥100 GPa, and a tensile strength ≥2800 MPa. The polypropylene fiber has a length of 10-22 mm, a diameter of 20-30 μm, an aspect ratio ≥600, an elastic modulus ≥100 GPa, and a tensile strength ≥800 MPa.

7. The ultra-high ductility, high-temperature resistant coal gangue concrete according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a water reduction rate greater than 19%.

8. The method for preparing ultra-high ductility high-temperature resistant coal gangue concrete according to any one of claims 1-7, characterized in that, Includes the following steps: 1) Weigh each raw material according to its weight percentage; 2) Mix the cement and modified coal gangue slowly and evenly using a mixer; 3) Add manufactured sand, fly ash, silica fume, modified calcium carbonate whiskers, and water to the mixer, stir evenly, add water-reducing agent and polyethylene glycol methacrylate and stir slowly. 4) Add thickener and stir slowly; 5) Slowly add polyethylene fibers and polypropylene fibers to the mixer, first stirring slowly and then stirring quickly to disperse the fibers evenly and obtain concrete slurry; 6) The concrete slurry is molded, demolded, and cured to obtain the final product.

9. The method for preparing ultra-high ductility, high-temperature resistant coal gangue concrete according to claim 8, characterized in that, The stirring speed for slow stirring is 95-115 r / min, and the stirring speed for fast stirring is 195-215 r / min.