Lightweight high-strength self-compacting concrete and preparation method thereof

Abstract

The application discloses a kind of lightweight high-strength self-compacting concrete and preparation method thereof, belong to concrete material technical field, the lightweight high-strength self-compacting concrete of the present application includes water, cement, mineral powder, fly ash, modified coal gangue aggregate, machine-made sand and naphthalenesulfonic acid / polycarboxylic acid system water reducing agent;The modified coal gangue aggregate is obtained by polymeric fluorine liquid activation full-grade aggregate;The polymeric fluorine liquid is obtained by polyethylene glycol, acrylic acid and perfluoroalkyl vinyl ether comonomer reaction in turn.This application prepared concrete is formed by full-grade aggregate, doped efficient water reducing agent, finally under the premise of ensuring lightweight, with high-strength and self-compacting property.Wherein, polyethylene glycol and acrylic acid are esterified first, then free radical polymerization occurs with perfluoromethyl vinyl ether, and then polymeric fluorine liquid is formed.Full-grade aggregate is coated by polymeric fluorine liquid, and then modified coal gangue aggregate is obtained.

Description

Technical Field

[0001] This invention belongs to the field of concrete materials technology, specifically a lightweight, high-strength self-compacting concrete and its preparation method. Background Technology

[0002] Accelerating the development of waste recycling is a key part of promoting the conservation and utilization of natural resources and exploring new development strategies. Using porous aggregates prepared from industrial solid wastes such as coal gangue to replace traditional ceramsite helps advance the greening of materials science. This involves large-scale utilization of industrial waste residues to replace natural aggregates. It can reduce dependence on natural resources and reduce the negative environmental impact of solid waste.

[0003] However, recycled aggregate concrete differs significantly from ordinary concrete in terms of mechanical properties: firstly, recycled aggregates have uneven gradation and contain defects such as fine voids; secondly, recycled aggregates have weak bonding with mortar, low strength, and high water absorption. This is particularly relevant for super high-rise buildings. Lightweight concrete has specific requirements regarding density, strength, and pumpability. If recycled aggregate is used as the aggregate in the concrete, it will affect the density and strength of the concrete, failing to meet the requirements.

[0004] For example, patent application CN118239733A discloses a high-performance coal gangue lightweight aggregate concrete and its preparation method. The raw materials for the lightweight aggregate concrete include silicate cement, mineral admixtures, graded ceramsite, and additives. Alkali slag and graded ceramsite can be incorporated into the concrete through internal wetting... The release of moisture as the temperature decreases helps to slow down the decrease in internal moisture of the concrete, thereby reducing concrete shrinkage.

[0005] Patent application CN113788652A discloses a high-flowability, lightweight, high-strength concrete. The concrete raw materials include cement, silica fume, lightweight sand, glass microspheres, fly ash, water-reducing agent, and viscosity reducer. The addition of spherical hollow glass microspheres and viscosity reducers can improve the flowability of the concrete. However, the doping of hollow glass microspheres reduces the strength of the prepared concrete. Therefore, how to utilize coal gangue waste to prepare lightweight, high-strength, and high-density concrete is an urgent technical problem to be solved.

[0006] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a lightweight, high-strength self-compacting concrete and its preparation method, which solves the technical problems of low strength and poor compaction in coal gangue-based recycled aggregate concrete in the prior art.

[0008] The objective of this invention can be achieved through the following technical solutions: A lightweight, high-strength self-compacting concrete comprises, by weight, 160-260 parts water, 340-350 parts cement, 20-40 parts mineral powder, 80-200 parts fly ash, 760-780 parts modified coal gangue aggregate, 0-150 parts manufactured sand, and 0.01105-0.012 parts naphthalenesulfonic acid / polycarboxylate superplasticizer; The modified coal gangue aggregate is obtained by activating fully graded aggregate with polyfluorinated liquid; the polyfluorinated liquid is obtained by reacting polyethylene glycol, acrylic acid and perfluoroalkyl vinyl ether comonomer in sequence.

[0009] Furthermore, the preparation method of the modified coal gangue aggregate includes the following steps: A1. Coal gangue is crushed in batches to form aggregates with particle size distributions of 0-3mm, 3-5mm, 5-8mm and 14mm, forming fully graded aggregates. A2, toluene, 95-98 wt% sulfuric acid solution, polyethylene glycol and acrylic acid are mixed and heated to 90-95°C. The reaction is carried out at this temperature for 4-5 hours. Then, perfluoroalkyl vinyl ether comonomer is added, potassium persulfate solution is added dropwise, and polymerization is continued at 65-75°C. Toluene is extracted and the product is discharged to obtain polyfluorinated liquid. A3. Mix the polyfluorinated liquid and fine aggregate evenly, and heat and activate at 60-65°C for 1-2 hours to obtain modified fine aggregate; mix the polyfluorinated liquid and coarse aggregate evenly, and heat and activate at 60-65°C for 1-2 hours to obtain modified coarse aggregate. The modified fine aggregate and modified coarse aggregate are considered to form modified coal gangue aggregate.

[0010] Further, in step A1, the mass ratio of aggregates with particle size distributions of 0-3mm, 3-5mm, 5-8mm and 14mm is 248:128.5-309:0-385.5:0-205.

[0011] Further, in step A2, the ratio of toluene, concentrated sulfuric acid, polyethylene glycol, acrylic acid, perfluoroalkyl vinyl ether comonomer and potassium persulfate solution is 100mL:1-3mL:20-40g:5-15mL:20-30g:3-5mL, and the concentration of potassium persulfate solution is 3-5wt%.

[0012] Furthermore, the perfluoroalkyl vinyl ether comonomer is any one of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, perfluoropropyl vinyl ether, and perfluorobutyl vinyl ether.

[0013] Furthermore, in step A3, the mass ratio of polyfluorinated liquid to fully graded aggregate is 2-4:1.

[0014] Furthermore, the preparation method of the naphthalenesulfonic acid / polycarboxylate superplasticizer includes the following steps: Naphthalene and 98% wt concentrated sulfuric acid are mixed and heated to 170-180°C for sulfonation reaction for 3-4 hours. Then toluene diisocyanate is added to form a mixture. The mixture is reacted at 80-90°C for 1-2 hours, then a polycarboxylate superplasticizer is added, and the reaction is continued at this temperature for 1-2 hours to obtain naphthalene sulfonic acid / polycarboxylate superplasticizer.

[0015] Furthermore, the ratio of naphthalene, concentrated sulfuric acid, toluene diisocyanate, and polycarboxylate superplasticizer is 50-70g:80-100g:17-34g:3-5g; the polycarboxylate superplasticizer is obtained by free radical copolymerization of acrylic acid, styrene, methyl methacrylate, ethyl methacrylate, and maleic anhydride.

[0016] As another aspect of the present invention, a method for preparing lightweight, high-strength self-compacting concrete includes the following steps: S1, water, cement, mineral powder, fly ash, modified coal gangue aggregate, manufactured sand and naphthalene sulfonic acid / polycarboxylate superplasticizer are added to a mixer and mixed evenly to obtain concrete; S2. Before the concrete arrives at the construction site, it should be rotated at 10 r / min and then mixed at 200-300 r / min for 20-30 seconds to form a concrete mixture. The concrete mixture should be poured into the mold, cast into shape, and then sprayed with water for wet curing. The wet curing time should be ≥7 days.

[0017] The present invention has the following beneficial effects: 1. Coal gangue is crushed and used as cement aggregate to replace ceramsite; the crushed coal gangue forms aggregate with a continuous particle size, thus forming a fully graded aggregate. Polyethylene glycol and acrylic acid are first esterified, and then undergo free radical polymerization with perfluoromethyl vinyl ether to form a polyfluorinated liquid. The polyfluorinated liquid coats the entire... Graded aggregates are then used to obtain modified coal gangue aggregates. Polyfluorinated liquid can form a polymer protective film on the surface of the aggregates, and the polyfluorinated liquid has good compatibility with water-reducing agents, cement, etc., which can prevent the aggregates from separating from the cement paste.

[0018] 2. The polycarboxylate superplasticizer used in this invention is specifically MAS polycarboxylate superplasticizer, obtained by copolymerization of acrylic acid, styrene, methyl methacrylate, ethyl methacrylate, and maleic anhydride. Modifying the polycarboxylate superplasticizer with the nucleophilic addition product of sulfonated naphthalene and toluene diisocyanate can further enhance its water-reducing effect. The naphthalene sulfonic acid / polycarboxylate superplasticizer can dissociate to form sulfonic acid groups, thereby dispersing cement particles due to electrostatic repulsion. Furthermore, the amide group, as a reactive group, can undergo hydrolysis in the alkaline environment of concrete, continuously replenishing the water-reducing agent concentration lost due to cement particle hydration and adsorption. As a highly efficient water-reducing agent, the above-mentioned polycarboxylate superplasticizer can effectively reduce the water-cement ratio and improve the self-compacting properties of the prepared concrete.

[0019] 3. Adding appropriate amounts of mineral powder and fly ash to the prepared concrete helps to increase the apparent density and bulk density of the concrete; continuously graded aggregates can further enhance the bulk density of the prepared concrete. Furthermore, this invention further enhances the strength of the prepared concrete by controlling the water-cement ratio. During construction, the synthesized concrete is consistently mixed at a low speed; and during the curing stage, it is consistently wet-cured, thereby better promoting the complete completion of the cement hydration reaction and improving its compactness. Ultimately, the concrete prepared by this invention has the advantages of high density, lightweight, and high strength. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0021] The performance indicators of the ceramsite (coal gangue used in Examples 1-3 of this invention) are as follows:

[0022] The mineral powder used in Examples 4-6 of this invention is S95 grade mineral powder purchased from Shanghai Baotian New Building Materials Co., Ltd.; the fly ash used in Examples 4-6 of this invention is Grade II finely ground powder purchased from Shanghai Fuchen New Materials Co., Ltd.; the manufactured sand used in Examples 4-6 of this invention is medium sand, specifically Fujian Mawei sand, with a fineness modulus of 2.6-2.9, a powder content ≤7.0%, and an apparent density ≤2600kg / m3; the MAS polycarboxylate superplasticizer used in Examples 4-6 of this invention is purchased from Shanghai Construction Engineering Building Materials Technology Group Co., Ltd., and is obtained by copolymerization of acrylic acid, styrene, methyl methacrylate, ethyl methacrylate, and maleic anhydride; wherein the mass ratio of acrylic acid, styrene, methyl methacrylate, ethyl methacrylate, and maleic anhydride is 20:2.7:5:4.5:7.5; the mixer used in Examples 4-6 of this invention is produced and supplied by the Jungong Road mixing plant under Shanghai Caijiu Technology Co., Ltd.

[0023] Example 1: This example provides a method for preparing modified coal gangue aggregate for lightweight, high-strength self-compacting concrete, comprising the following steps: A1. Coal gangue is crushed in batches to form aggregates with particle size distributions of 0-3mm, 3-5mm, 5-8mm, and 14mm, respectively. The aggregates of different particle sizes are collected separately. The mass ratio of the aggregates with particle size distributions of 0-3mm, 3-5mm, 5-8mm, and 14mm is 248:257:257:0, which is the prepared fully graded aggregate.

[0024] A2. Add 100 mL of toluene solvent to the polymerization reactor, then add 1 mL of 95-98 wt% sulfuric acid solution dropwise. Next, add 20 g of polyethylene glycol (relative molecular mass 1000) and 5 mL of acrylic acid. Heat the polymerization reactor to 90°C and react at this temperature for 4 hours, which is considered the completion of the reaction. Then add 20 g of perfluoromethyl vinyl ether to the polymerization reactor, followed by 3 mL of 3 wt% potassium persulfate solution dropwise over 10 minutes. Continue polymerization at 65°C, then remove the toluene solvent from the polymerization reactor using a vacuum pump. Discharge the product to obtain polyfluorinated fluoride solution.

[0025] A3. Mix polyfluorinated liquid and fully graded aggregate at a solid-liquid ratio of 2:1, heat to 60°C for 1 hour to activate, and the resulting modified coal gangue aggregate is obtained.

[0026] Example 2: This example provides a method for preparing modified coal gangue aggregate for lightweight, high-strength self-compacting concrete, comprising the following steps: A1. Coal gangue is crushed in batches to form aggregates with particle size distributions of 0-3mm, 3-5mm, 5-8mm, and 14mm, respectively. The aggregates of different particle sizes are collected separately. The mass ratio of the aggregates with particle size distributions of 0-3mm, 3-5mm, 5-8mm, and 14mm is 248:128.5:385.5:0, which is the prepared fully graded aggregate.

[0027] A2. Add 100 mL of toluene solvent to the polymerization reactor, then add 2 mL of 96 wt% concentrated sulfuric acid catalyst dropwise. Next, add 30 g of polyethylene glycol (relative molecular mass 1000) and 10 mL of acrylic acid. Heat the polymerization reactor to 92°C and react at this temperature for 4.5 hours, which is considered the reaction complete. Then add 25 g of perfluoroethyl vinyl ether to the polymerization reactor, followed by 4 mL of 4 wt% potassium persulfate solution dropwise over 15 minutes. Continue polymerization at 70°C, then remove the toluene solvent from the polymerization reactor using a vacuum pump. Discharge the product to obtain polyfluorinated fluoride liquid.

[0028] A3. Polyfluorinated liquid and fully graded aggregate are mixed at a solid-liquid ratio of 3:1 and heated to 62°C for 1.1 hours to activate, which is the prepared modified coal gangue aggregate.

[0029] Example 3: This example provides a method for preparing modified coal gangue aggregate for lightweight, high-strength self-compacting concrete, comprising the following steps: A1. Coal gangue is crushed in batches to form aggregates with particle size distributions of 0-3mm, 3-5mm, 5-8mm, and 14mm, respectively. The aggregates of different particle sizes are collected separately. The mass ratio of the aggregates with particle size distributions of 0-3mm, 3-5mm, 5-8mm, and 14mm is 248:309:0:205, which is the prepared fully graded aggregate.

[0030] A2. Add 100 mL of toluene solvent to the polymerization reactor, then add 3 mL of 98 wt% concentrated sulfuric acid catalyst dropwise. Next, add 40 g of polyethylene glycol (relative molecular mass 1000) and 15 mL of acrylic acid. Heat the polymerization reactor to 95°C and react at this temperature for 5 hours, which is considered the reaction complete. Then add 30 g of perfluorobutyl vinyl ether to the polymerization reactor, followed by 5 mL of 5 wt% potassium persulfate solution dropwise over 20 minutes. Continue polymerization at 75°C, and then remove the toluene solvent from the polymerization reactor using a vacuum pump. Discharge the material to obtain polyfluorinated liquid.

[0031] A3. Polyfluorinated liquid and fully graded aggregate are mixed at a solid-liquid ratio of 4:1 and heated to 65°C for 2 hours to obtain modified coal gangue aggregate.

[0032] Example 4: This example provides a method for preparing lightweight, high-strength self-compacting concrete, including the following steps: S1. Add 50g of naphthalene to a reactor, heat to 120°C, then slowly add 80g of 98%wt concentrated sulfuric acid while stirring. Heat the reactor to 170°C and carry out a sulfonation reaction for 3 hours. After the sulfonation reaction, cool the reactor to 90°C, then add 17g of toluene diisocyanate to the reactor to obtain a mixture. Continue reacting the mixture at 80°C for 1 hour to form an intermediate. Add 3g of MAS-type polycarboxylate superplasticizer to the reactor and continue reacting at this temperature for 1 hour. Then discharge the product to obtain naphthalene sulfonic acid / polycarboxylate superplasticizer.

[0033] S2. According to the weight ratio, add 160 parts water, 350 parts PII52.5 cement, 40 parts mineral powder, 80 parts fly ash, 760 parts modified coal gangue aggregate prepared in Example 1, 150 parts manufactured sand, and 0.012 parts sulfonic acid / polycarboxylate superplasticizer to a mixer and mix thoroughly to obtain concrete raw materials. Before mixing, the moisture content of the modified coal gangue aggregate needs to be tested. To ensure a water-cement ratio of 0.33, the amount of water added can be adjusted as needed.

[0034] S3. When the prepared concrete raw materials are transported to the production site by mixer truck, the mixing drum needs to maintain a rotation speed of 10 r / min to control the concrete from segregation and stratification after it arrives at the pouring location, and to ensure the slump spread required for on-site construction. When the mixer truck arrives at the pouring site, the mixing drum should be rotated at 200 r / min for 20 seconds to form a concrete mixture. The concrete mixture is then fed into the pump truck's receiving hopper. The time from the end of mixing to the pouring of the concrete mixture should not exceed 180 minutes. If more than 180 minutes have passed, the slump and spread of the concrete mixture must be tested. After pouring and molding, it should be covered and water-cured promptly. The wet curing time is 7 days, ultimately producing lightweight, high-strength self-compacting concrete.

[0035] Example 5: This example provides a method for preparing lightweight, high-strength self-compacting concrete, including the following steps: S1. Add 60g of naphthalene to a reactor, heat to 125°C, then slowly add 90g of concentrated sulfuric acid while stirring. Heat the reactor to 175°C and carry out a sulfonation reaction for 3.5 hours. After the sulfonation reaction, cool the reactor to 95°C, then add 26g of toluene diisocyanate to the reactor to obtain a mixture. Continue reacting the mixture at 85°C for 1.3 hours to form an intermediate. Add 4g of MAS-type polycarboxylate superplasticizer to the reactor and continue reacting at this temperature for another 1.3 hours. Then discharge the product to obtain naphthalene sulfonic acid / polycarboxylate superplasticizer.

[0036] S2. According to the weight ratio, add 260 parts water, 350 parts PII52.5 cement, 20 parts mineral powder, 200 parts fly ash, 780 parts modified coal gangue aggregate prepared in Example 2, and 0.0105 parts naphthalenesulfonic acid / polycarboxylate superplasticizer to a mixer and mix thoroughly to obtain the lightweight, high-strength self-compacting concrete. Before mixing, the moisture content of the modified coal gangue aggregate needs to be tested. To ensure a water-cement ratio of 0.34, the amount of water added can be adjusted as needed.

[0037] S3. When the prepared concrete raw materials are transported to the production site by mixer truck, the mixing drum needs to maintain a low rotation speed of 100 r / min to control the concrete from segregation and stratification after it arrives at the pouring location, and to ensure the slump spread required for on-site construction. When the mixer truck arrives at the pouring site, the mixing drum should be rotated at a high speed of 220 r / min for 22 seconds to form a concrete mixture. The concrete mixture is then fed into the pump truck's receiving hopper. The time from the end of mixing to the pouring of the concrete mixture should not exceed 180 minutes. If more than 180 minutes have passed, the slump and spread of the concrete mixture must be tested. After pouring and molding, it should be covered and water-cured promptly. The wet curing time is 7 days, ultimately producing lightweight, high-strength self-compacting concrete.

[0038] Example 6: This example provides a method for preparing lightweight, high-strength self-compacting concrete, including the following steps: S1. Add 70g of naphthalene to a reactor, heat to 130°C, then slowly add 100g of concentrated sulfuric acid while stirring. Heat the reactor to 180°C and carry out a sulfonation reaction for 4 hours. After the sulfonation reaction is complete, cool the reactor to 100°C, then add 34g of toluene diisocyanate to the reactor to obtain a mixture. Continue reacting the mixture at 80°C for 2 hours to form an intermediate. Add 5g of MAS-type polycarboxylate superplasticizer to the reactor and continue reacting at this temperature for 2 hours. Then discharge the product to obtain naphthalene sulfonic acid / polycarboxylate superplasticizer.

[0039] S2. According to the weight ratio, add 160 parts water, 340 parts PII52.5 cement, 20 parts mineral powder, 120 parts fly ash, 760 parts modified coal gangue aggregate prepared in Example 3, 150 parts manufactured sand, and 0.012 parts naphthalenesulfonic acid / polycarboxylate superplasticizer to a mixer and mix thoroughly to obtain concrete raw materials. Before mixing, the moisture content of the modified coal gangue aggregate needs to be tested. To ensure a water-cement ratio of 0.66, the amount of water added can be adjusted as needed.

[0040] S3. When the prepared concrete raw materials are transported to the production site by mixer truck, the mixing drum needs to maintain a low rotation speed of 10 r / min to control the concrete from segregation and stratification after it arrives at the pouring location, and to ensure the slump spread required for on-site construction. When the mixer truck arrives at the pouring site, the mixing drum should be rotated at a high speed of 300 r / min for 30 seconds to form a concrete mixture. The concrete mixture is then fed into the concrete hopper. The time from the end of mixing to the pouring of the concrete mixture should not exceed 180 minutes. If more than 180 minutes have passed, the slump and spread of the concrete mixture must be tested. After pouring and molding, the concrete should be covered and water-cured promptly. The wet curing time is 7 days, ultimately producing lightweight, high-strength self-compacting concrete.

[0041] Comparative Example 1 The difference between this comparative example and Example 6 is that, in preparing the modified coal gangue aggregate, step A2 specifically involves: 100 mL of toluene solvent was added to the polymerization reactor, followed by 3 mL of 98 wt% concentrated sulfuric acid catalyst, then 40 g of polyethylene glycol (relative molecular mass of 1000) and 15 mL of acrylic acid. The polymerization reactor was heated to 95°C and reacted at this temperature for 5 hours. The reaction was then considered complete and the product was discharged to obtain a polymer solution.

[0042] At this point, the prepared polyfluorinated liquid is replaced with an equal mass of polymer solution.

[0043] Comparative Example 2 The difference between this comparative example and Example 6 is that, in the preparation of modified coal gangue aggregate, in step A1, 3-5 mm aggregate replaces all the fine aggregate of the same mass; and aggregate with a particle size distribution of 14 mm replaces all the coarse aggregate of the same mass.

[0044] Comparative Example 3 The difference between this comparative example and Example 6 is that step S1 is omitted, and the prepared naphthalene sulfonic acid / polycarboxylic acid water-reducing agent is replaced with an equal mass of MAS-type polycarboxylic acid-based high-efficiency water-reducing agent.

[0045] Performance testing: The lightweight, high-strength self-compacting concrete prepared in Examples 4-6 and Comparative Examples 1-3 were molded and cured at 22°C for 28 days with a curing humidity of 95% to obtain the prepared lightweight, high-strength self-compacting concrete test blocks.

[0046] 1. In accordance with GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", the initial slump, 3-hour spread, initial void time and 3-hour void time of the lightweight and high-strength self-compacting concrete specimens prepared in Examples 4-6 and Comparative Examples 1-3 were tested sequentially.

[0047] 2. In accordance with GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", the dry apparent density of the lightweight and high-strength self-compacting concrete specimens prepared in Examples 4-6 and Comparative Examples 1-3 were tested sequentially.

[0048] 3. In accordance with GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", the 7-day compressive strength of the lightweight and high-strength self-compacting concrete specimens prepared in Examples 4-6 and Comparative Examples 1-3 were tested sequentially.

[0049] The specific test results are shown in Table 1.

[0050]

[0051] Data Analysis: Initial spread and 3-hour spread are important parameters for determining the fluidity of the prepared self-compacting concrete. The initial cavitation time and 3-hour cavitation time of the cement are used to characterize the flow rate and cohesiveness of the prepared self-compacting concrete, thereby evaluating its pumpability. The concrete prepared in Examples 4-6 of this invention exhibits good fluidity, characterized by high initial spread and 3-hour spread values. In Comparative Example 1, a polymer solution without perfluoromethyl vinyl ether was used instead of the prepared polyfluorinated liquid to coat the fully graded aggregate, thus reducing the fluidity of the concrete prepared in Comparative Example 1. Therefore, the initial spread, 3-hour spread, initial cavitation time, and 3-hour cavitation time values ​​of the self-compacting concrete prepared in Comparative Example 1 were all reduced.

[0052] Furthermore, based on on-site observations, the lightweight, high-strength self-compacting concrete prepared in Example 1 was relatively loose; the lightweight, high-strength self-compacting concrete prepared in Example 2 was relatively compact with many air bubbles; and the lightweight, high-strength self-compacting concrete prepared in Example 3 was mostly compact with many air bubbles.

[0053] The lightweight, high-strength self-compacting concrete prepared in Examples 4-6 of this invention exhibits high dry apparent density and short-term compressive strength, thus significantly reducing the self-weight of buildings or structures. In Comparative Example 2, when preparing modified coal gangue aggregate, coarse and fine aggregates of specific diameters were used instead of continuous, fully graded aggregates, increasing porosity between aggregates and resulting in a low dry apparent density. In Comparative Example 3, an unmodified MAS-type polycarboxylate superplasticizer was used instead of the prepared naphthalenesulfonic acid / polycarboxylate superplasticizer. The modified polycarboxylate superplasticizer contains multiple reactive groups, which can accelerate hydration and improve the self-compactness of concrete. Therefore, the dry apparent density and compressive strength of the concrete prepared in Comparative Example 3 were significantly reduced.

[0054] The above description is merely an example and illustration of the structure 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 structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0055] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" 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.

[0056] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A lightweight, high-strength self-compacting concrete, characterized in that, It includes, by weight, 160-260 parts water, 340-350 parts cement, 20-40 parts mineral powder, 80-200 parts fly ash, 760-780 parts modified coal gangue aggregate, 0-150 parts manufactured sand, and 0.0105-0.012 parts naphthalenesulfonic acid / polycarboxylate superplasticizer; The method for preparing the modified coal gangue aggregate includes the following steps: A1. Coal gangue is crushed in batches to form aggregates with particle size distributions of 0-3mm, 3-5mm, 5-8mm and 14mm, respectively. The mass ratio of the aggregates with particle size distributions of 0-3mm, 3-5mm, 5-8mm and 14mm is 248:128.5-309:0-385.5:0-205. A2, toluene, 95-98 wt% sulfuric acid solution, polyethylene glycol and acrylic acid are mixed and heated to 90-95℃. The reaction is carried out at this temperature for 4-5 hours. Then, perfluoroalkyl vinyl ether comonomer is added, potassium persulfate solution is added dropwise, and polymerization is continued at 65-75℃. Toluene is extracted and discharged to obtain polyfluorinated liquid. A3. Mix the polyfluorinated liquid and aggregate evenly, and heat and activate at 60-65℃ for 1-2 hours to form modified coal gangue aggregate; The preparation method of the naphthalenesulfonic acid / polycarboxylic acid water-reducing agent includes the following steps: Naphthalene and 98% wt concentrated sulfuric acid are mixed and heated to 170-180℃ for sulfonation reaction for 3-4 hours. Then, toluene diisocyanate is added to form a mixture. The mixture is reacted at 80-90℃ for 1-2 hours, and then a polycarboxylate superplasticizer is added. The reaction is continued at this temperature for 1-2 hours to obtain naphthalene sulfonic acid / polycarboxylate superplasticizer. The ratio of naphthalene, concentrated sulfuric acid, toluene diisocyanate and polycarboxylate superplasticizer is 50-70g:80-100g:17-34g:3-5g. The polycarboxylate superplasticizer is obtained by free radical copolymerization of acrylic acid, styrene, methyl methacrylate, ethyl methacrylate and maleic anhydride.

2. The lightweight, high-strength self-compacting concrete according to claim 1, characterized in that, In step A2, the ratio of toluene, concentrated sulfuric acid, polyethylene glycol, acrylic acid, perfluoroalkyl vinyl ether comonomer, and potassium persulfate solution is 100mL:1-3mL:20-40g:5-15mL:20-30g:3-5mL, and the concentration of potassium persulfate solution is 3-5wt%.

3. The lightweight, high-strength self-compacting concrete according to claim 2, characterized in that, The perfluoroalkyl vinyl ether comonomer is any one of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, perfluoropropyl vinyl ether, and perfluorobutyl vinyl ether.

4. The lightweight, high-strength self-compacting concrete according to claim 2, characterized in that, In step A3, the mass ratio of polyfluorinated liquid to aggregate is 2-4:

1.

5. The method for preparing lightweight, high-strength self-compacting concrete according to any one of claims 1-4, characterized in that, Includes the following steps: S1, water, cement, mineral powder, fly ash, modified coal gangue aggregate, manufactured sand and naphthalene sulfonic acid / polycarboxylate superplasticizer are added to a mixer and mixed evenly to obtain concrete; S2. Before the concrete arrives at the construction site, it is always rotated at 10 r / min, and then stirred at 200-300 r / min for 20-30 seconds to form a concrete mixture. The concrete mixture is poured into the mold, cast into shape, and sprayed with water for wet curing. The wet curing time is ≥7 days, and finally lightweight and high-strength self-compacting concrete is obtained.

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