Coal gangue-based graded ecological concrete and preparation method thereof
By designing the gradation of coal gangue aggregate and employing a segmented mixing process, combined with a cementing system of slag powder and carbide slag, a coal gangue-based graded ecological concrete that efficiently and synergistically utilizes multiple solid wastes was prepared. This solved the performance defects in the application of coal gangue aggregate and achieved excellent mechanical properties and durability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TAIYUAN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2026-03-20
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies have failed to effectively address the problems of loose and porous surface, high water absorption, and weak interfacial bonding between coal gangue aggregate and cement paste, resulting in low concrete strength and poor durability, and failing to efficiently utilize industrial solid wastes such as slag and carbide slag.
By designing the gradation of coal gangue aggregate and introducing slag powder and carbide slag into the cementing system, and using a segmented mixing process, concrete with excellent mechanical properties and good durability is prepared. Combined with allyl polyether high-efficiency water-reducing agent to improve interfacial bonding and gradation, the efficient synergistic utilization of various solid wastes is achieved.
It significantly improves the density and durability of concrete, realizes the efficient synergistic utilization of various solid wastes such as coal gangue, slag, and carbide slag, solves the performance defects in the application of coal gangue aggregate, and has excellent mechanical properties and volume stability, meeting the long-term use requirements of construction projects.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of solid waste resource utilization technology, specifically to a concrete with coal gangue as the main aggregate and industrial solid waste as the cementing component, and its preparation method, particularly to a coal gangue-based graded concrete and its preparation method. Background Technology
[0002] Coal gangue is a major solid waste generated during coal mining and washing. Its long-term storage not only occupies large amounts of land but also causes environmental pollution and ecological damage. Using coal gangue as aggregate in concrete is an important way to achieve its large-scale, high-value-added resource utilization. However, coal gangue aggregate has a loose and porous surface, high water absorption, and weak interfacial adhesion with cement paste. Direct use can easily lead to problems such as low concrete strength, poor durability, and poor volume stability, limiting its large-scale application.
[0003] Meanwhile, slag from the steel industry and calcium carbide slag from the chemical industry also face enormous storage pressure. These industrial solid wastes have certain potential cementitious activity, but the activity is low or the composition fluctuates greatly, making them ineffective when used alone. How to synergistically utilize coal gangue aggregate with industrial solid wastes such as slag and calcium carbide slag to prepare high-performance concrete is of great significance for promoting the green and sustainable development of the building materials industry.
[0004] While existing technologies include research on using coal gangue as concrete aggregate, such as Chinese patent documents "A method for preparing and applying ecological concrete based on waste coal gangue (Publication No.: CN108609986A)" and "A multi-component solid waste admixture for improving the strength of cement concrete and its preparation method (Publication No.: CN118637851A)," most of these studies have not systematically addressed the issues of weak interfacial bonding and gradation optimization, and have also given little consideration to the synergistic cementitious effect with low-activity solid wastes such as slag and carbide slag. Therefore, developing a concrete preparation method that can significantly improve the interfacial properties of coal gangue aggregate, optimize particle size distribution, and efficiently utilize various industrial solid wastes has become a pressing technical problem in this field. Summary of the Invention
[0005] To overcome the aforementioned technical problems, the present invention aims to provide a coal gangue-based graded ecological concrete and its preparation method. This method involves grading coal gangue aggregate and innovatively introducing slag powder and carbide slag into the cementitious system. Through a specific segmented mixing process, concrete with excellent mechanical properties, good durability, volume stability, and good workability is prepared, achieving efficient synergistic utilization of various solid wastes such as coal gangue, slag, and carbide slag.
[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, this application provides a coal gangue-based graded ecological concrete, comprising the following components by weight: 20-30 parts silicate cement, 10-15 parts calcium carbide slag, 10-15 parts slag powder, 10-15 parts coal gangue fine powder, 15-25 parts coal gangue medium aggregate, 15-25 parts coal gangue coarse aggregate, 1-3 parts activator, 0.6-1.0 parts allyl polyether high-efficiency water-reducing agent, and 20-25 parts deionized water; The allyl polyether high-efficiency water-reducing agent is prepared by the following steps: Add isopentenyl alcohol polyoxyethylene ether and sodium vinyl sulfonate to a four-necked flask equipped with a stirrer, thermometer, gas delivery tube, two constant-pressure dropping funnels, and a reflux condenser. Purge with nitrogen for protection, then add deionized water equal to 70% of the total water volume. Stir for 20-25 minutes at 80-82℃ and a stirring rate of 200-250 rpm. Then add ammonium persulfate to 15% of the total water volume of the deionized water and stir with a glass rod for 3-5 minutes. Pour the mixture into the first constant-pressure dropping funnel. Next, add acrylic acid and acrylic acid... Hydroxyethyl ester was added to 15% of the total water volume of deionized water and stirred with a glass rod for 3-5 minutes. The mixture was then poured into a second constant-pressure dropping funnel. The stopcocks of both constant-pressure dropping funnels were opened simultaneously, and the solution was added dropwise to the four-necked flask at a constant rate. The total dropping time was controlled to be 3.0-3.5 hours. During the dropping process, the temperature was maintained at 80-82°C. After the dropping was completed, the reaction conditions were kept unchanged, and the mixture was stirred and kept at the same temperature for 1.0-1.5 hours. The mixture was then allowed to cool naturally to room temperature and transferred to a dry and sealed plastic sample bottle to obtain an allyl polyether high-efficiency water-reducing agent.
[0007] In a preferred embodiment of the present invention, the ratio of isopentenyl polyoxyethylene ether, sodium vinyl sulfonate, deionized water, ammonium persulfate, acrylic acid, and hydroxyethyl acrylate is 40-50g: 0.8-1.0g: 120-150mL: 0.54-0.68g: 3.2-4.0g: 0.5-0.63g.
[0008] In a preferred embodiment of the present invention, the isopentenyl alcohol polyoxyethylene ether is of type TPEG-2400 and is produced by Jingzhou Yinjie Chemical Co., Ltd.
[0009] The coal gangue fine powder, coal gangue medium aggregate, and coal gangue coarse aggregate are prepared by the following steps: Step a1: Clean the mud and impurities adhering to the surface of the coal gangue, then place it in a constant temperature drying oven and dry it at a temperature of 60℃ for 2-4 hours. After drying, take it out and cool it to room temperature to obtain pretreated coal gangue. Step a2: The pretreated coal gangue is fed into the crushing equipment for graded crushing. After crushing, it is screened through a multi-stage standard sieve to obtain coarse coal gangue aggregate with a particle size of 10-20mm and medium coal gangue aggregate with a particle size of 2.36-4.75mm. Then, the coal gangue particles smaller than 2.36mm after screening are fed into the grinding equipment for fine grinding. After grinding, they are passed through a 0.075mm standard sieve, and the undersize material is collected to obtain fine coal gangue powder.
[0010] In a preferred embodiment of the present invention, the coal gangue is industrial-grade blocky coal gangue, provided by Yumei Bulk (Shanxi) Technology Co., Ltd.
[0011] Secondly, this application provides a method for preparing coal gangue-based graded ecological concrete, comprising the following steps: Step 1: Weigh out 20-30 parts by weight of silicate cement, 10-15 parts of calcium carbide slag, 10-15 parts of slag powder, 10-15 parts of coal gangue fine powder, 15-25 parts of coal gangue medium aggregate, 15-25 parts of coal gangue coarse aggregate, 1-3 parts of activator, 0.6-1.0 parts of allyl polyether high-efficiency water-reducing agent, and 20-25 parts of deionized water, and set aside. Step 2: Add the fine coal gangue powder to the mixer and add deionized water accounting for 40% of the total water volume. Mix for 30-60 seconds at a mixing speed of 30-45 r / min to obtain a slurry. Step 3: Add silicate cement, carbide slag, slag powder, activator, allyl polyether high-efficiency water-reducing agent and remaining deionized water to the slurry, and stir for 60-120 seconds at a stirring rate of 30-45 r / min to obtain cementitious mortar. Step 4: Add coal gangue aggregate to the cementitious mortar and stir for 30-50 seconds at a stirring speed of 30-45 r / min. Then add coal gangue coarse aggregate and continue stirring for 60-100 seconds to obtain concrete mixture. Step 5: Pour the concrete mixture into a standard test mold, vibrate to compact it, and cure it according to national standards at a temperature of 20℃ and a relative humidity of ≥95% until the specified age is reached to obtain coal gangue-based graded ecological concrete.
[0012] In a preferred embodiment of the present invention, the specific surface area of the slag powder in step one is not less than 400 m². 2 / kg, the specific surface area of carbide slag is not less than 350m² 2 / kg; the activator is a solid mixture of sodium hydroxide and calcium oxide in a dosage ratio of 1g:1g; the silicate cement is industrial-grade powdered silicate cement provided by Guangzhou Yaowei Building Materials Co., Ltd.; the carbide slag is industrial-grade powdered carbide slag provided by Zhengzhou Jinke Powder Materials Co., Ltd.; the slag powder is industrial-grade powdered slag powder provided by Fengfeng Mineral Products Processing Plant in Lingshou County, Hebei Province.
[0013] The beneficial effects of this invention are: This invention discloses a coal gangue-based graded ecological concrete and its preparation method. The coal gangue-based graded ecological concrete prepared using a segmented feeding and controlled-speed mixing process involves pre-mixing fine coal gangue powder into a slurry, followed by the sequential addition of cementitious materials and medium and coarse aggregates. This allows the cementitious mortar to fully coat and fill the gaps between aggregates at each level, optimizing the interfacial bonding between aggregates and the cementitious system. This significantly improves the internal density of the concrete, giving it excellent mechanical properties, volume stability, and comprehensive durability such as impermeability and carbonation resistance. It also allows the activator to fully function, and the micro-powder effect of the fine coal gangue powder activates the potential activity of the silicate cement-carbide slag-slag micro-powder composite cementitious system, ensuring rapid and stable strength development of the concrete. Simultaneously, this process achieves high-value utilization of coal gangue of all particle sizes in a large-scale, waste-free manner, effectively disposing of solid waste and reducing stockpiling pollution. Furthermore, the process is highly operable and easily industrialized.
[0014] In the preparation of coal gangue-based graded ecological concrete, an allyl polyether high-efficiency water-reducing agent was prepared. This allyl polyether high-efficiency water-reducing agent is a polycarboxylic acid-based high-efficiency water-reducing agent, prepared by free radical aqueous solution polymerization mechanism. Isopentenyl alcohol polyoxyethylene ether is used as the macromonomer, providing a long side chain structure, which is the main skeleton of the allyl polyether high-efficiency water-reducing agent. Acrylic acid provides carboxyl groups, providing adsorption groups, which can be adsorbed on the surface of cementitious material particles such as cement, slag, and coal gangue. Hydroxyethyl acrylate provides hydroxyl and ester groups, used to adjust the polymer's hydrophilicity-hydrophobicity balance, steric hindrance, and dispersion retention performance, improving the workability and slump retention of concrete. Sodium vinyl sulfonate provides sulfonic acid groups, enhancing the adsorption capacity and dispersion speed on the surface of cementitious material particles, improving the initial water-reducing effect. Ammonium persulfate is a thermally decomposable initiator, decomposing to generate free radicals, initiating the above unsaturated monomers to undergo a free radical copolymerization reaction, forming a comb-shaped polycarboxylic acid copolymer. Under nitrogen atmosphere, heating, and stirring conditions, isopentenyl alcohol polyoxyethylene ether, Sodium vinyl sulfonate, acrylic acid, and hydroxyethyl acrylate undergo free radical addition polymerization initiated by ammonium persulfate to generate a comb-shaped polycarboxylic acid allyl polyether high-efficiency water-reducing agent with a main chain containing carboxyl, sulfonic acid, and hydroxyl groups and long polyoxyethylene side chains. This allyl polyether high-efficiency water-reducing agent has a high water reduction rate, and its comb-shaped structure provides a strong steric hindrance effect, significantly dispersing cementitious material particles, reducing concrete water consumption, and improving system density and mechanical strength. It has excellent compatibility with industrial solid waste components such as coal gangue fine powder, slag powder, and carbide slag, and can effectively improve the problems of viscosity and uneven coating that easily occur in concrete under high solid waste content conditions. The hydroxyl and sulfonic acid groups introduced by hydroxyethyl acrylate and sodium vinyl sulfonate can play a synergistic role, enabling concrete to maintain excellent workability and slump retention for a longer period of time, meeting the needs of on-site construction. At the same time, the uniformly dispersed cementitious system can reduce internal defects and promote the dense development of hydration products, further improving the strength and long-term service performance of coal gangue-based concrete.
[0015] In the preparation of coal gangue-based graded ecological concrete, fine coal gangue powder, medium coal gangue aggregate, and coarse coal gangue aggregate were prepared. The medium and coarse aggregates were obtained by crushing and screening the coal gangue. The remaining portion was further ground in a mixer and then sieved to obtain fine coal gangue powder. The fine coal gangue powder, medium aggregate, and coarse aggregate form a continuous graded skeleton-filler system. The coarse aggregate serves as the core load-bearing skeleton, the medium aggregate fills the gaps between the coarse aggregate, and the fine powder fills the micropores and acts as a cementitious admixture, co-hydrating with cement, carbide slag, etc., thus optimizing the interface between the aggregate and the cementitious mortar. The surface bonding significantly improves the density of concrete, resulting in increased compressive strength, reduced drying shrinkage, and enhanced volume stability. The continuous gradation eliminates large interconnected pores within the concrete, fundamentally improving its impermeability, carbonation resistance, and freeze-thaw resistance. Furthermore, the hydration products of fine powder further fill the pores, continuously optimizing durability and meeting the long-term use requirements of building projects. This design not only solves the performance defects of using coal gangue as a single aggregate but also achieves high-value utilization of coal gangue across all particle sizes. At the same time, it endows the system with significant advantages from multiple dimensions, including concrete structure, mechanical properties, durability, and environmental benefits. Detailed Implementation
[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0017] Example 1:
[0018] This embodiment describes a method for preparing coal gangue-based graded ecological concrete, comprising the following steps: Step s1: Add 40g of isopentenyl alcohol polyoxyethylene ether (model TPEG-2400, produced by Jingzhou Yinjie Chemical Co., Ltd.) and 0.8g of sodium vinyl sulfonate to a four-necked flask equipped with a stirrer, thermometer, gas delivery tube, two constant pressure dropping funnels, and a reflux condenser. Purge with nitrogen for protection, add 84mL of deionized water, and stir for 20min at 80℃ and a stirring rate of 200r / min. Then add 0.54g of ammonium persulfate to 18mL of deionized water and stir with a glass rod for 3min. Pour... The solution was poured into the first constant-pressure dropping funnel. Then, 3.2 g of acrylic acid and 0.5 g of hydroxyethyl acrylate were added to 18 mL of deionized water and stirred with a glass rod for 3 min. The mixture was then poured into the second constant-pressure dropping funnel. The stopcocks of both constant-pressure dropping funnels were opened simultaneously, and the solution was added dropwise to the four-necked flask at a constant rate. The total dropping time was controlled to be 3.0 h. The temperature was maintained at 80 °C during the dropping process. After the dropping was completed, the reaction conditions were kept unchanged, and the mixture was stirred at the same temperature for another 1.0 h. The mixture was then allowed to cool naturally to room temperature and transferred to a dry and sealed plastic sample bottle to obtain an allyl polyether high-efficiency water-reducing agent. Step s2: Clean the surface of 100g of coal gangue (the coal gangue is industrial grade block coal gangue, provided by Yumei Bulk Coal Technology Co., Ltd., to remove the mud and impurities, then place it in a constant temperature drying oven and dry it at 60℃ for 2 hours. After drying, take it out and cool it to room temperature to obtain pretreated coal gangue. Step s3: The pretreated coal gangue is fed into the crushing equipment for graded crushing. After crushing, it is screened through a multi-stage standard sieve to obtain coarse coal gangue aggregate with a particle size of 10mm and medium coal gangue aggregate with a particle size of 2.36mm. Then, the coal gangue particles smaller than 2.36mm after screening are fed into the grinding equipment for fine grinding. After grinding, they are passed through a 0.075mm standard sieve, and the undersize material is collected to obtain fine coal gangue powder. Step s4: Design the concrete strength grade as C20, with a water-cement ratio of 0.45. Weigh out 20 parts by weight of silicate cement, 10 parts of carbide slag, 10 parts of slag powder, 10 parts of coal gangue fine powder, 15 parts of coal gangue medium aggregate, 15 parts of coal gangue coarse aggregate, 1 part of activator, 0.6 parts of allyl polyether high-efficiency water-reducing agent, and 20 parts of deionized water, and set aside. Step s5: Add the fine coal gangue powder to the mixer and add deionized water accounting for 40% of the total water volume. Mix for 30 seconds at a mixing speed of 30 r / min to obtain a slurry. Step s6: Add silicate cement (industrial-grade powdered silicate cement, provided by Guangzhou Yaowei Building Materials Co., Ltd.) and calcium carbide slag (industrial-grade powdered calcium carbide slag, provided by Zhengzhou Jinke Powder Materials Co., Ltd., with a specific surface area of not less than 350 m²) to the slurry. 2 / kg), slag powder (the slag powder is industrial grade powder, supplied by Fengfeng Mineral Products Processing Plant in Lingshou County, Hebei Province, with a specific surface area of not less than 400 m²). 2 / kg), activator (the activator is a solid mixture of sodium hydroxide and calcium oxide in a dosage ratio of 1g:1g), allyl polyether high-efficiency water-reducing agent and remaining deionized water, are stirred at a stirring rate of 30r / min for 60s to obtain cementitious mortar. Step s7: Add coal gangue aggregate to the cementitious mortar and stir for 30 seconds at a stirring rate of 30 r / min. Then add coal gangue coarse aggregate and continue stirring for 60 seconds to obtain concrete mixture. Step s8: Fill the concrete mixture into a standard test mold (100mm×100mm×100mm standard cube test mold), vibrate to compact it, and cure it according to the national standard at a temperature of 20℃ and a relative humidity of ≥95% until the specified age is reached to obtain coal gangue-based graded ecological concrete.
[0019] Example 2:
[0020] This embodiment describes a method for preparing coal gangue-based graded ecological concrete, comprising the following steps: Step s1: Add 50g of isopentenyl alcohol polyoxyethylene ether (model TPEG-2400, produced by Jingzhou Yinjie Chemical Co., Ltd.) and 1.0g of sodium vinyl sulfonate to a four-necked flask equipped with a stirrer, thermometer, gas delivery tube, two constant pressure dropping funnels, and a reflux condenser. Purge with nitrogen for protection, add 105mL of deionized water, and stir for 25min at 82℃ and a stirring rate of 250r / min. Then add 0.68g of ammonium persulfate to 22.5mL of deionized water, stir with a glass rod for 5min, and pour out the mixture. The solution was poured into the first constant-pressure dropping funnel, and then 4.0 g of acrylic acid and 0.63 g of hydroxyethyl acrylate were added to 22.5 mL of deionized water. The mixture was stirred with a glass rod for 5 min and then poured into the second constant-pressure dropping funnel. The stopcocks of both constant-pressure dropping funnels were opened simultaneously, and the solution was added dropwise to the four-necked flask at a constant rate. The total dropping time was controlled to be 3.5 h. The temperature was maintained at 82 °C during the dropping process. After the dropping was completed, the reaction conditions were kept unchanged, and the mixture was stirred at the same temperature for another 1.5 h. The mixture was then allowed to cool naturally to room temperature and transferred to a dry and sealed plastic sample bottle to obtain an allyl polyether high-efficiency water-reducing agent. Step s2: Clean the surface of 120g of coal gangue (the coal gangue is industrial grade block coal gangue, provided by Yumei Bulk Coal Technology Co., Ltd. in Shanxi) to remove the mud and impurities, then place it in a constant temperature drying oven and dry it at 60℃ for 4 hours. After drying, take it out and cool it to room temperature to obtain pretreated coal gangue. Step s3: The pretreated coal gangue is fed into the crushing equipment for graded crushing. After crushing, it is screened through a multi-stage standard sieve to obtain coarse coal gangue aggregate with a particle size of 20mm and medium coal gangue aggregate with a particle size of 4.75mm. Then, the coal gangue particles smaller than 2.36mm after screening are fed into the grinding equipment for fine grinding. After grinding, they are passed through a 0.075mm standard sieve, and the undersize material is collected to obtain fine coal gangue powder. Step s4: Design the concrete strength grade as C30, with a water-cement ratio of 0.48. Weigh out 30 parts by weight of silicate cement, 15 parts by weight of carbide slag, 15 parts by weight of slag powder, 15 parts by weight of coal gangue fine powder, 25 parts by weight of coal gangue medium aggregate, 25 parts by weight of coal gangue coarse aggregate, 3 parts by weight of activator, 1.0 part by weight of allyl polyether high-efficiency water-reducing agent, and 25 parts by weight of deionized water, and set aside. Step s5: Add the fine coal gangue powder to the mixer and add deionized water accounting for 40% of the total water volume. Mix for 60 seconds at a mixing speed of 45 r / min to obtain a slurry. Step s6: Add silicate cement (industrial-grade powdered silicate cement, provided by Guangzhou Yaowei Building Materials Co., Ltd.) and calcium carbide slag (industrial-grade powdered calcium carbide slag, provided by Zhengzhou Jinke Powder Materials Co., Ltd., with a specific surface area of not less than 350 m²) to the slurry. 2 / kg), slag powder (the slag powder is industrial grade powder, supplied by Fengfeng Mineral Products Processing Plant in Lingshou County, Hebei Province, with a specific surface area of not less than 400 m²). 2 / kg), activator (the activator is a solid mixture of sodium hydroxide and calcium oxide in a dosage ratio of 1g:1g), allyl polyether high-efficiency water-reducing agent and remaining deionized water, are stirred at a stirring rate of 45r / min for 120s to obtain cementitious mortar. Step s7: Add coal gangue aggregate to the cementitious mortar and stir for 50 seconds at a stirring rate of 45 r / min. Then add coal gangue coarse aggregate and continue stirring for 100 seconds to obtain concrete mixture. Step s8: Fill the concrete mixture into a standard test mold (100mm×100mm×100mm standard cube test mold), vibrate to compact it, and cure it according to the national standard at a temperature of 20℃ and a relative humidity of ≥95% until the specified age is reached to obtain coal gangue-based graded ecological concrete.
[0021] Comparative Example 1: Compared with Example 1, the cementitious material is only silicate cement (without carbide slag, slag powder, or coal gangue powder), and the mixing adopts a one-time feeding method (all raw materials are added and mixed at the same time). The proportions of other raw materials, aggregate treatment, and curing methods are all the same.
[0022] Comparative Example 2: Compared with Example 1, the coal gangue aggregate was not subjected to standardized pretreatment (it was directly crushed and screened without being washed and dried), and the mixing adopted a one-time feeding method. The proportions of other raw materials, the composition of cementitious materials, and the curing methods were all the same.
[0023] Comparative Example 3: Compared with Example 1, the coal gangue aggregate was not graded and was mixed with coarse aggregate and natural river sand. The proportions of other raw materials, composition of cementitious materials, mixing process and curing method were the same.
[0024] Comparative Example 4: Compared with Example 1, the self-made allyl polyether high-efficiency water-reducing agent was not used. Instead, a commercially available conventional naphthalene-based high-efficiency allyl polyether high-efficiency water-reducing agent (Shenyang Xingzhenghe Chemical, CAS No.: 36290-04-7) was used, with the same amount of solids content. The other raw material ratios, aggregate treatment, cementitious material composition, mixing process, and curing methods were all the same.
[0025] Performance testing: The test block preparation method, curing method and strength testing were in accordance with GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)"; the setting time was in accordance with GB / T 1346-2024 "Test Method for Standard Consistency Water Requirement, Setting Time and Soundness of Cement"; the performance of the coal gangue-based ecological concrete obtained in Examples 1 and 2 and Comparative Examples 1-4 was tested, and the compressive strength was tested at 3d, 7d and 28d, respectively. The test results are shown in Table 1 below.
[0026] Table 1: Test Results Summary Table
[0027] Referring to Table 1, based on the comparison between Examples 1 and 2 and Comparative Examples 1-4, it can be seen that the present invention significantly improves the comprehensive performance of concrete through surface modification of coal gangue aggregate, continuous gradation design, and synergistic use of slag / carbide slag auxiliary cementitious materials, combined with segmented mixing process. The method of the present invention effectively overcomes the technical difficulties of high water absorption and weak interface of coal gangue aggregate, and realizes the resource utilization of various solid wastes, with significant economic and social benefits.
[0028] The preparation method of this invention systematically solves the inherent defects of coal gangue as concrete aggregate by combining three technologies: continuous gradation of coal gangue particles, synergistic cementation of solid waste, and segmented mixing process.
[0029] The experimental results and comparative analysis jointly confirm that this method can stably produce high-quality concrete with good workability, mechanical properties that meet the standards, and stable volume. It has successfully realized the large-scale and high-value resource utilization of various solid wastes such as coal gangue, slag, and carbide slag, and has outstanding technological advancement, environmental benefits, and promotion and application value.
[0030] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0031] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.
Claims
1. A coal gangue-based graded eco-friendly concrete, characterized in that, Includes the following components by weight: 20-30 parts silicate cement, 10-15 parts calcium carbide slag, 10-15 parts slag powder, 10-15 parts coal gangue fine powder, 15-25 parts coal gangue medium aggregate, 15-25 parts coal gangue coarse aggregate, 1-3 parts activator, 0.6-1.0 parts allyl polyether high-efficiency water-reducing agent, and 20-25 parts deionized water; The allyl polyether high-efficiency water-reducing agent is prepared by the following steps: Isopentenyl polyoxyethylene ether and sodium vinyl sulfonate were added to a four-necked flask, followed by 70% of the total water volume of deionized water. The mixture was stirred, and then ammonium persulfate was added to 15% of the total water volume of deionized water. The mixture was stirred with a glass rod and poured into the first constant-pressure dropping funnel. Acrylic acid and hydroxyethyl acrylate were then added to 15% of the total water volume of deionized water. The mixture was stirred with a glass rod and poured into the second constant-pressure dropping funnel. The stopcocks of both constant-pressure dropping funnels were opened simultaneously, and the solution was added dropwise to the four-necked flask. The mixture was kept warm and stirred, and then cooled to obtain an allyl polyether high-efficiency water-reducing agent.
2. The coal gangue-based graded ecological concrete according to claim 1, characterized in that, The ratio of isopentenyl alcohol polyoxyethylene ether, sodium vinyl sulfonate, deionized water, ammonium persulfate, acrylic acid, and hydroxyethyl acrylate is 40-50g: 0.8-1.0g: 120-150mL: 0.54-0.68g: 3.2-4.0g: 0.5-0.63g.
3. The coal gangue-based graded ecological concrete according to claim 1, characterized in that, The fine coal gangue powder, medium coal gangue aggregate, and coarse coal gangue aggregate are prepared by the following steps: Step a1: Clean the coal gangue, then place it in a constant temperature drying oven to dry it. After drying, take it out and cool it to obtain pretreated coal gangue. Step a2: The pretreated coal gangue is fed into the crushing equipment for graded crushing. After crushing, it is screened through a multi-stage standard sieve to obtain coarse coal gangue aggregate with a particle size of 10-20mm and medium coal gangue aggregate with a particle size of 2.36-4.75mm. Then, the coal gangue particles smaller than 2.36mm after screening are fed into the grinding equipment for fine grinding. After grinding, they are passed through a 0.075mm standard sieve, and the undersize material is collected to obtain fine coal gangue powder.
4. A method for preparing coal gangue-based graded ecological concrete, characterized in that, The method for preparing coal gangue-based graded ecological concrete as described in any one of claims 1-3 includes the following steps: Step 1: Weigh out 20-30 parts by weight of silicate cement, 10-15 parts of calcium carbide slag, 10-15 parts of slag powder, 10-15 parts of coal gangue fine powder, 15-25 parts of coal gangue medium aggregate, 15-25 parts of coal gangue coarse aggregate, 1-3 parts of activator, 0.6-1.0 parts of allyl polyether high-efficiency water-reducing agent, and 20-25 parts of deionized water, and set aside. Step 2: Add the fine coal gangue powder to the mixer and add deionized water, which accounts for 40% of the total water volume. Stir to obtain a slurry. Step 3: Add silicate cement, carbide slag, slag powder, activator, allyl polyether high-efficiency water-reducing agent and remaining deionized water to the slurry, stir, and obtain cementitious mortar; Step 4: Add the coal gangue aggregate to the cementitious mortar and stir. Then add the coal gangue coarse aggregate and continue stirring to obtain the concrete mixture. Step 5: Pour the concrete mixture into a standard test mold, vibrate to compact it, and perform standard curing until the specified age to obtain coal gangue-based graded ecological concrete.
5. The method for preparing coal gangue-based graded ecological concrete according to claim 4, characterized in that, The specific surface area of the slag powder mentioned in step one is not less than 400 m². 2 / kg, the specific surface area of carbide slag is not less than 350m² 2 / kg.
6. The method for preparing coal gangue-based graded ecological concrete according to claim 4, characterized in that, The activator mentioned in step one is a solid mixture of sodium hydroxide and calcium oxide in a ratio of 1g:1g.