Modified solid waste doped self-compacting low-carbon concrete and preparation method thereof

Abstract

The invention relates to the technical field of building materials, in particular to modified solid waste doped self-compacting low-carbon concrete and a preparation method thereof. The self-compacting low-carbon concrete is prepared from the following raw material components: cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water and a polycarboxylic acid high-performance water reducing agent, the modified solid waste slurry is obtained by mixing solid waste mixed powder with water and modifying with a modifier in sequence; the modified solid waste aggregate is obtained by sequentially performing low-concentration hydrochloric acid solution soaking treatment, interface reinforcing agent rinsing modification treatment and drying treatment on solid waste mixed aggregate. By modifying and optimizing the solid waste, optimizing the mix proportion of the solid waste self-compacting concrete and preparing the special admixture for the solid waste self-compacting low-carbon concrete, the solid waste can stably play a role in the concrete, so that the mechanical property and durability of the concrete are improved, and the rheological property of the concrete can meet the requirements of the self-compacting concrete; according to the scheme, the low-carbonization effect can be achieved through waste utilization.

Description

Technical Field

[0001] The present application relates to the technical field of building materials, and in particular to a self-compacting low-carbon concrete mixed with modified solid waste and a preparation method thereof. Background Art

[0002] Concrete is one of the core basic materials for building a great country. It is also the largest building material in the world so far. It is the most widely used and largest man-made material in the national economy and people's livelihood. The carbon emissions of concrete mainly come from cement, which accounts for a high proportion of cementitious materials, has a large amount of use, and has high carbon emissions. The most important issue in the world at present is to deal with climate change.

[0003] At present, the low carbonization of concrete is mainly focused on the reuse of solid waste materials, and carbon emissions are reduced by introducing solid waste materials to replace cement and natural materials such as sand and gravel. However, during use, due to the complex composition of solid waste, the performance of solid waste concrete is difficult to stably control. Most solid waste concrete is only used in non-structural parts and ordinary concrete, and is rarely used in special concrete, especially self-compacting concrete.

[0004] To solve the above problems, the use of cement and natural aggregates can be reduced by adding solid waste powder to replace part of the cement, and solid waste aggregates to replace natural aggregates, so as to reduce the carbon emissions of self-compacting concrete. However, as can be seen from the above, conventional solid waste powders are all industrial by-products, and their composition is easily changed, resulting in large differences in their performance, and most of their potential activity is lower than that of cement, which can easily cause performance loss. In addition, solid waste aggregates have a high water absorption rate, and the surface slurry layer is not uniform, which can easily form interface defects in concrete, resulting in a decrease in concrete performance. Therefore, the use of solid waste powders and aggregates in the preparation of self-compacting concrete will have an adverse effect on the performance of concrete. For example, the performance of the mixture cannot meet the requirements of self-compacting concrete, the amount of water reducer required increases, and the mechanical properties and durability of the concrete are insufficient to meet the requirements.

[0005] Therefore, how to prepare solid waste self-compacting low-carbon concrete and ensure that its mixture performance, mechanical properties and durability meet the requirements of self-compacting concrete is the technical problem that technical personnel in this field are committed to solving. Summary of the invention

[0006] In order to solve the problems of the prior art mentioned in the above background technology, the present application provides a self-compacting low-carbon concrete added with modified solid waste, and its technical solution is as follows: The self-compacting low-carbon concrete with modified solid waste provided in the present application includes the following raw material components: cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water and polycarboxylic acid high-performance water reducing agent; the modified solid waste slurry is obtained by mixing solid waste mixed powder with water and modifying it with a modifier in sequence; wherein the solid waste mixed powder includes two or more combinations of solid waste powder with an average particle size of 2 μm, solid waste powder with an average particle size of 3 μm, solid waste powder with an average particle size of 7 μm, solid waste powder with an average particle size of 10 μm, and solid waste powder with an average particle size of 20 μm; the components of the modifier include one or more combinations of graphene dispersion, carbon nanotube dispersion, and nano-silicon dioxide suspension; the modified solid waste aggregate is obtained by soaking the solid waste mixed aggregate in a low-concentration hydrochloric acid solution, rinsing and modifying it with an interface enhancer, and drying it in sequence; wherein the interface enhancer is one or more combinations of silicone, water-based resin, silicate enhancer, and acrylic enhancer.

[0007] In some embodiments, the solid waste mixed aggregate includes, by weight, 34 to 40 parts of solid waste aggregate with a particle size of 0 mm to 2.5 mm (excluding 0 mm), 4 to 11 parts of solid waste aggregate with a particle size of 2.5 mm to 5 mm, 11 to 33 parts of solid waste aggregate with a particle size of 5 mm to 10 mm, and 22 to 44 parts of solid waste aggregate with a particle size of 10 mm to 20 mm; the mass concentration of the hydrochloric acid solution is 0.05% to 1%.

[0008] In some embodiments, the preparation process of the modified solid waste slurry is: first, the solid waste powder raw material is subjected to mechanical grinding to obtain solid waste powder with different average particle size ranges, and then the solid waste powder with different average particle size ranges are mixed to obtain the solid waste mixed powder; the solid waste mixed powder is mixed with water and stirred evenly; finally, a modifier is added and stirred evenly to obtain a modified solid waste slurry; wherein the weight ratio of the solid waste mixed powder, the water and the modifier is: (80~100): (50~70): (3~7); the components of the solid waste powder include two or more combinations of mineral powder, fly ash, ceramic polishing powder, glass powder and limestone powder.

[0009] In some embodiments, the preparation process of the modified solid waste aggregate is as follows: the construction solid waste is first crushed and shaped to obtain solid waste aggregates of different particle size ranges, and the solid waste aggregates of different particle size ranges are mixed to form a solid waste mixed aggregate; the solid waste mixed aggregate is added to a low concentration hydrochloric acid solution to remove some cement particles remaining on the surface of the aggregate; then filtered, washed with water, and dried in sequence to obtain a primary treated solid waste mixed aggregate; the primary treated solid waste mixed aggregate is rinsed and modified with an interface enhancer, and finally dried to obtain the modified solid waste aggregate.

[0010] In some embodiments, the components of the solid waste powder are composed of mineral powder, fly ash, and ceramic polishing powder; the solid waste mixed powder is composed of solid waste powder with an average particle size of 2 μm, solid waste powder with an average particle size of 7 μm, and solid waste powder with an average particle size of 10 μm, mixed in a weight ratio of 4:3:3.

[0011] In some embodiments, the raw material components include, by weight: 220 to 260 parts of cement, 220 to 260 parts of modified solid waste slurry, 20 to 40 parts of silica fume, 1700 to 1750 parts of modified solid waste aggregate, 65 to 80 parts of water, and 4 to 6 parts of high-performance water reducing agent.

[0012] In some embodiments, the cement is one of P·O 42.5R cement, P·0 42.5 cement, and P·II 42.5 cement.

[0013] In some embodiments, the silica fume is silicon powder modified by a silane coupling agent, and its silicon dioxide content is 90% to 95%, and its bulk density is 250 kg / m 3 ~300kg / m 3 , loss on ignition is 1% to 4%, 7d activity index is 105% to 110%, specific surface area is 19000m 2 / kg~23000 m 2 / kg.

[0014] In some embodiments, the high-performance water-reducing agent is compounded from a polycarboxylic acid comprehensive water-reducing concentrate, a shrinkage-reducing agent, a retarder, a slump-retaining agent, cellulose, a regulator, an air-entraining agent and water in a weight ratio of (240-280): (330-500): (10-20): (20-50): (5-10): (1-3): (0.5-1): (200-330), and has a solid content of 17% to 22%, a water reduction rate of 28% to 33%, and a 28d compressive strength ratio of 143% to 150%.

[0015] High-performance water-reducing agent has a strong dispersing effect on cementitious materials, can significantly adjust the workability of concrete, enhance the interfacial adhesion between concrete paste and aggregate, improve the paste strength, and reduce concrete shrinkage.

[0016] The present application also provides a method for preparing the self-compacting low-carbon concrete with modified solid waste as described above, which comprises the following preparation steps: weighing cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water, and high-performance water reducer according to the formula; stirring and mixing the first part of water and silica fume evenly to obtain slurry A; stirring and mixing the modified solid waste slurry and slurry A evenly to obtain slurry B; stirring and mixing cement and slurry B evenly to obtain slurry C; stirring and mixing the second part of water, high-performance water reducer and slurry C evenly to obtain slurry D; pouring the modified solid waste aggregate into slurry D, stirring and mixing evenly to obtain a self-compacting concrete mixture; the mixture is solidified and formed to obtain self-compacting low-carbon concrete with modified solid waste.

[0017] In some embodiments, the preparation method includes the following preparation steps: weighing cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water, and high-performance water reducer according to the formula; pouring the first part of water and silica fume into a mixer, stirring and mixing evenly, the stirring time is 20s to 40s, and obtaining slurry A; stirring and mixing the modified solid waste slurry and slurry A evenly, the stirring time is 10s to 20s, and obtaining slurry B; stirring and mixing cement and slurry B evenly, the stirring time is 10s to 20s, and obtaining slurry C; the second part of water and high-performance water reducer Mix evenly with slurry C for 15s to 30s to obtain slurry D; pour the modified solid waste aggregate into slurry D, mix evenly for 60s to 90s to obtain a self-compacting concrete mixture; wherein the fluidity of the mixture is controlled between 650mm and 700mm; the mixture is solidified and formed to obtain self-compacting low-carbon concrete with modified solid waste; wherein the sum of the first part of water and the second part of water is the total amount of water, and the weight ratio of the first part of water to the second part of water is 2:1.

[0018] Compared with the existing technology, this application has the following technical effects: The present application provides a self-compacting low-carbon concrete with modified solid waste, which optimizes solid waste by modification, optimizes the mix ratio of solid waste self-compacting concrete and configures special admixtures for solid waste self-compacting low-carbon concrete, so that modified solid waste slurry and modified solid waste aggregate can effectively and stably play a role in concrete, so as to improve the mechanical properties and durability of concrete, and ensure that the rheological properties of concrete can meet the requirements of self-compacting concrete. The present application applies solid waste powder and aggregate to self-compacting concrete, so as to make use of waste and achieve a low-carbon effect. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] The present application provides a method for preparing self-compacting low-carbon concrete by adding modified solid waste: The preparation method comprises the following preparation steps: According to the formula, cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water and high-performance water reducing agent are weighed; the mixing water is divided into two parts according to the weight ratio of 2:1, and the first part of water with a large amount and silica fume are poured into the mixer, stirred and mixed evenly, and the stirring time is 20s to 40s to obtain slurry A; the modified solid waste slurry and slurry A are stirred and mixed evenly, and the stirring time is 10s to 20s to obtain slurry B; cement and slurry B are stirred and mixed evenly, and the stirring time is 10s to 20s to obtain slurry C; the remaining second part of water, high-performance water reducing agent and slurry C are stirred and mixed evenly, and the stirring time is 15s to 30s to obtain slurry D; the modified solid waste aggregate is poured into the slurry D, stirred and mixed evenly, and stirred for 60s to 90s to obtain a self-compacting concrete mixture; wherein the fluidity of the mixture is controlled between 650mm and 700mm; the mixture is solidified and formed, and the self-compacting low-carbon concrete with modified solid waste is obtained. Among them, the formula of concrete: Calculated by weight, the raw material components include 220 to 260 parts of cement, 220 to 260 parts of modified solid waste slurry, 20 to 40 parts of silica fume, 1700 to 1750 parts of modified solid waste aggregate, 65 to 80 parts of water, and 4 to 6 parts of high-performance water reducing agent.

[0021] Among them, modified solid waste slurry: The modified solid waste slurry is obtained by mixing solid waste powder with water and modifying it with a modifier in sequence. The preparation process is as follows: (1) firstly subjecting the solid waste powder raw material to mechanical grinding to obtain solid waste powders with different average particle size ranges, and then mixing the solid waste powders with different average particle size ranges to obtain the solid waste mixed powder; Wherein, the components of the solid waste powder include two or more combinations of mineral powder, fly ash, ceramic polishing powder, glass powder, and limestone powder; the solid waste mixed powder includes two or more combinations of solid waste powder with an average particle size of 2 μm, solid waste powder with an average particle size of 3 μm, solid waste powder with an average particle size of 7 μm, solid waste powder with an average particle size of 10 μm, and solid waste powder with an average particle size of 20 μm. Preferably, the solid waste mixed powder is formed by mixing solid waste powder with an average particle size of 2 μm, solid waste powder with an average particle size of 7 μm, and solid waste powder with an average particle size of 10 μm in a weight ratio of 4:3:3.

[0022] It should be noted that solid waste powder is recycled waste, which is a mixture of fine powders such as mineral powder, fly ash, ceramic polishing powder, glass powder, and limestone powder, and there is no clear restriction on the formula ratio. For example, mineral powder, fly ash, and ceramic polishing powder can be mixed in a weight ratio of (30-50): (20-30): (30-40).

[0023] (2) Mixing the solid waste mixed powder with water and stirring evenly; finally adding a modifier and stirring evenly to obtain a modified solid waste slurry.

[0024] The components of the modifier include one or more combinations of graphene dispersion, carbon nanotube dispersion, and nano-silicon dioxide suspension; the weight ratio of the solid waste mixed powder, the water and the modifier is: (80-100): (50-70): (3-7).

[0025] Among them, modified solid waste aggregates: The modified solid waste aggregate is obtained by sequentially soaking the solid waste mixed aggregate in a low-concentration hydrochloric acid solution, washing and modifying with an interface enhancer, and drying. The preparation process is as follows: (1) The construction solid waste is first crushed and shaped to obtain solid waste aggregates with different particle size ranges, and the solid waste aggregates with different particle size ranges are mixed to form solid waste mixed aggregates; Among them, the solid waste mixed aggregate includes, by weight, 34 to 40 parts of solid waste aggregate with a particle size of 0 mm to 2.5 mm, 4 to 11 parts of solid waste aggregate with a particle size of 2.5 mm to 5 mm, 11 to 33 parts of solid waste aggregate with a particle size of 5 mm to 10 mm, and 22 to 44 parts of solid waste aggregate with a particle size of 10 mm to 20 mm.

[0026] (2) adding the solid waste mixed aggregate into a low concentration hydrochloric acid solution to remove some cement particles remaining on the surface of the aggregate; then filtering, washing and drying in sequence to obtain a primary treated solid waste mixed aggregate; wherein the mass concentration of the hydrochloric acid solution is 0.05% to 1%.

[0027] (3) The solid waste mixed aggregate treated initially is rinsed and modified with an interface enhancer, and finally naturally dried for 7 to 15 days to obtain the modified solid waste aggregate; wherein the interface enhancer is one or more combinations of organic silicon, water-based resin, silicate enhancer, and acrylic enhancer.

[0028] It should be noted that: Construction solid waste generally refers to the discarded concrete blocks obtained after house demolition and some aggregates obtained after crushing (some concrete slurry will adhere to the surface of the aggregate, so the key to the acid impregnation step in the modification process is to remove these attached slurries).

[0029] During the impregnation treatment with low-concentration hydrochloric acid solution, the amount of hydrochloric acid solution used can be sufficient to impregnate the solid waste mixed aggregate without excessive restrictions.

[0030] During the interfacial enhancer rinsing and modification process, the amount of interfacial enhancer used can be sufficient to fully contact and rinse the initially treated solid waste mixed aggregate, without excessive restrictions.

[0031] The present application also provides the formulas of the embodiments and comparative examples as shown in Table 1 (unit: parts by weight): Table 1

[0032] Specifically, the embodiments and comparative examples provided in this application and the preparation process of the comparative examples are as follows: Example 1 In this embodiment, the raw materials include, by weight: 260 parts of cement, 220 parts of modified solid waste slurry, 20 parts of silica fume, 1750 parts of modified solid waste aggregate, 80 parts of water, and 4.5 parts of high-performance water reducing agent.

[0033] 1. The preparation method of the modified solid waste slurry comprises the following specific steps: (1) Mechanically grinding a variety of solid waste powder raw materials to produce solid waste powders with different particle size ranges, and then mixing the solid waste powders with different particle size ranges to form solid waste mixed powder; The components of the solid waste powder include mineral powder, fly ash and ceramic polishing powder, and the weight ratio of the three is 45:20:35. The solid waste mixed powder is made by mixing solid waste powders with average particle sizes of 2μm, 7μm and 10μm in a weight ratio of 4:3:3.

[0034] (2) Mix the solid waste powder with water and stir until evenly mixed for 20 minutes; (3) Pour in the modifier, stir evenly for 45 minutes, and let stand for use. The modifier is a carbon nanotube dispersion, specifically GTCO 301. The weight ratio of the solid waste mixed powder, water and modifier is 90:56:4.

[0035] 2. The preparation method of the modified solid waste aggregate comprises the following specific steps: (1) Construction solid waste is first crushed and shaped to prepare solid waste aggregates of various particle sizes, and the solid waste aggregates of various particle sizes are mixed to form solid waste mixed aggregates. The solid waste mixed aggregates are made by mixing solid waste aggregates with particle sizes ranging from 0mm to 2.5mm, 2.5mm to 5mm, 5mm to 10mm, and 10mm to 20mm in a weight ratio of 40:10:19:38.

[0036] (2) Pour the solid waste mixed aggregate into a low concentration hydrochloric acid solution to simply remove some of the cement particles remaining on the surface of the aggregate, and then filter, wash and dry; the concentration range of the hydrochloric acid solution is 0.1%.

[0037] (3) The aggregate is then placed in a mesh barrel, rinsed and modified with an interface enhancer, and finally dried naturally for 7 days to obtain modified solid waste aggregate. The interface enhancer is an organic silicon enhancer, specifically R06.

[0038] 3. Other raw materials The cement is Runfeng P·O 42.5 cement, with a 28d compressive strength of 47.1MPa and a 28d flexural strength of 8.9MPa; The silica fume is a silicon powder modified by a silane coupling agent, with a silicon dioxide content of 94% and a bulk density of 265 kg / m 3 , loss on ignition is 1.6%, 7d activity index is 107%, specific surface area is 19300m 2 / kg.

[0039] The high-performance water-reducing agent is compounded from polycarboxylic acid comprehensive water-reducing concentrate, shrinkage-reducing agent, retarder, slump-retaining agent, cellulose, regulator, air-entraining agent and water in a weight ratio of 240:350:10:25:5:2:0.6:300. Specifically, it is Point-50SCS of KZJ New Materials Group Co., Ltd.

[0040] It has a strong dispersing effect on cementitious materials, can significantly adjust the workability of concrete, enhance the interface bonding between concrete paste and aggregate, improve paste strength, and reduce concrete shrinkage. Its solid content is 19%, water reduction rate is 28%, and 28d compressive strength ratio is 145%.

[0041] The method for preparing self-compacting low-carbon concrete with modified solid waste comprises the following preparation steps: 1. Weigh each raw material component: weigh cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water, and high-performance water reducing agent according to a certain weight proportion; 2. Divide the mixing water into two parts according to the ratio of 2:1, pour the larger amount of water into the mixer first, then pour the silica fume into it, and stir for 30 seconds to obtain slurry A; 3. Mix the modified solid waste slurry and slurry A evenly, stirring for 20 seconds to obtain slurry B; 4. Mix cement and slurry B evenly for 20 seconds to obtain slurry C; 5. Evenly mix the remaining small amount of water and high-performance water reducing agent with slurry C and stir for 20 seconds to obtain slurry D; 6. Pour the modified solid waste aggregate into slurry D and stir for 90 seconds to obtain a self-compacting concrete mixture, the fluidity of which is controlled between 650 mm and 700 mm; 7. Part of the mixture obtained is used for mixture performance testing, and the remaining part is molded to test mechanical and durability properties. Molding method: Pour it directly into a fixed mold without vibration or tamping, and scrape the surface to make it smooth. After standard curing for 28 days, test its various properties.

[0042] Example 2 In this embodiment, the raw material composition includes, by weight: 240 parts of cement, 240 parts of modified solid waste slurry, 30 parts of silica fume, 1750 parts of modified solid waste aggregate, 70 parts of water, and 5.4 parts of high-performance water reducing agent.

[0043] 1. The preparation method of the modified solid waste slurry comprises the following specific steps: (1) Mechanically grinding a variety of solid waste powder raw materials to produce solid waste powders with different particle size ranges, and then mixing the solid waste powders with different particle size ranges to form solid waste mixed powder; The components of the solid waste powder include mineral powder, fly ash and ceramic polishing powder, and the weight ratio of the three is 50:20:30. The solid waste mixed powder is made by mixing solid waste powders with average particle sizes of 2μm, 7μm and 10μm in a weight ratio of 4:3:3.

[0044] (2) Mix the solid waste powder with water and stir until evenly mixed for 20 minutes; (3) Pour in the modifier, stir evenly for 45 minutes, and let stand for use. The modifier is a carbon nanotube dispersion, and the specific selection is the same as in Example 1. The weight ratio of the solid waste mixed powder, water and modifier is 90:56:4.

[0045] 2. The preparation method of the modified solid waste aggregate comprises the following specific steps: (1) Construction solid waste is first crushed and shaped to prepare solid waste aggregates of various particle sizes, and the solid waste aggregates of various particle sizes are mixed to form solid waste mixed aggregates. The solid waste mixed aggregates are made by mixing solid waste aggregates with particle sizes ranging from 0mm to 2.5mm, 2.5mm to 5mm, 5mm to 10mm, and 10mm to 20mm in a weight ratio of 40:10:19:38.

[0046] (2) Pour the solid waste mixed aggregate into a low concentration hydrochloric acid solution to simply remove some of the cement particles remaining on the surface of the aggregate, and then filter, wash and dry; the concentration range of the hydrochloric acid solution is 0.1%.

[0047] (3) The aggregate is then placed in a grid barrel, rinsed and modified with an interface enhancer, and finally dried naturally for 7 days to obtain modified solid waste aggregate. The interface enhancer is an organic silicon enhancer, and the specific selection is the same as in Example 1.

[0048] 3. Other raw materials The cement is Runfeng P·O 42.5 cement, with a 28-day compressive strength of 47.1 MPa and a 28-day flexural strength of 8.9 MPa; the silica fume is a silicon micropowder modified by a silane coupling agent, with a silicon dioxide content of 94% and a bulk density of 265 kg / m 3 , loss on ignition is 1.6%, 7d activity index is 107%, specific surface area is 19300m 2 / kg.

[0049] The high-performance water reducer is compounded from a polycarboxylic acid comprehensive water-reducing mother liquid, a shrinkage-reducing agent, a retarder, a slump-retaining agent, cellulose, a regulator, an air-entraining agent and water, and the weight ratio is 240:350:10:25:5:2:0.6:300. The specific water reducer is selected in accordance with Example 1. It has a strong dispersing effect on cementitious materials, can significantly adjust the workability of concrete, enhance the interface bonding force between concrete paste and aggregate, and improve the paste strength and reduce concrete shrinkage. It has a solid content of 19%, a water reduction rate of 28%, and a 28d compressive strength ratio of 145%.

[0050] The method for preparing self-compacting low-carbon concrete with modified solid waste comprises the following preparation steps: 1. Weigh each raw material component: weigh cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water, and high-performance water reducing agent according to a certain weight proportion; 2. Divide the mixing water into two parts according to the ratio of 2:1, pour the larger amount of water into the mixer first, then pour the silica fume into it, and stir for 30 seconds to obtain slurry A; 3. Mix the modified solid waste slurry and slurry A evenly, stirring for 20 seconds to obtain slurry B; 4. Mix cement and slurry B evenly for 20 seconds to obtain slurry C; 5. Evenly mix the remaining small amount of water and high-performance water reducing agent with slurry C and stir for 20 seconds to obtain slurry D; 6. Pour the modified solid waste aggregate into slurry D and stir for 90 seconds to obtain a self-compacting concrete mixture; 7. Part of the mixture obtained is used for mixture performance testing, and the remaining part is molded to test mechanical and durability properties. Molding method: Pour it directly into a fixed mold without vibration or tamping, and scrape the surface to make it smooth. After standard curing for 28 days, test its various properties.

[0051] Example 3 In this embodiment, the raw materials include, by weight: 220 parts of cement, 260 parts of modified solid waste slurry, 40 parts of silica fume, 1750 parts of modified solid waste aggregate, 65 parts of water, and 6 parts of high-performance water reducing agent.

[0052] 1. The preparation method of the modified solid waste slurry comprises the following specific steps: (1) A variety of solid waste powder raw materials are first mechanically ground to produce solid waste powders with different particle size ranges, and the solid waste powders with different particle size ranges are mixed to form solid waste mixed powder; wherein the components of the solid waste powder include mineral powder, fly ash, and ceramic polishing powder, and the weight ratio of the three is 40:20:40. The solid waste mixed powder is formed by mixing solid waste powders with average particle sizes of 2μm, 7μm, and 10μm in a weight ratio of 4:3:3.

[0053] (2) Mix the solid waste powder with water and stir until evenly mixed for 20 minutes; (3) Pour in the modifier, stir evenly for 45 minutes, and let stand for use. The modifier is a carbon nanotube dispersion, and the specific selection is the same as in Example 1. The weight ratio of the solid waste mixed powder, water and modifier is 90:56:4.

[0054] 2. The preparation method of the modified solid waste aggregate comprises the following specific steps: (1) Construction solid waste is first crushed and shaped to prepare solid waste aggregates of various particle sizes, and the solid waste aggregates of various particle sizes are mixed to form solid waste mixed aggregates. The solid waste mixed aggregates are made by mixing solid waste aggregates with particle sizes ranging from 0mm to 2.5mm, 2.5mm to 5mm, 5mm to 10mm, and 10mm to 20mm in a weight ratio of 40:10:19:38.

[0055] (2) Pour the solid waste mixed aggregate into a low concentration hydrochloric acid solution to simply remove some of the cement particles remaining on the surface of the aggregate, and then filter, wash and dry; the concentration range of the hydrochloric acid solution is 0.1%.

[0056] (3) The aggregate is then placed in a grid barrel, rinsed and modified with an interface enhancer, and finally dried naturally for 7 days to obtain modified solid waste aggregate. The interface enhancer is an organic silicon enhancer, and the specific selection is the same as in Example 1.

[0057] 3. Other raw materials The cement is Runfeng P·O 42.5 cement, with a 28d compressive strength of 47.1MPa and a 28d flexural strength of 8.9MPa; The silica fume is a silicon powder modified by a silane coupling agent, with a silicon dioxide content of 94% and a bulk density of 265 kg / m 3 , loss on ignition is 1.6%, 7d activity index is 107%, specific surface area is 19300m 2 / kg.

[0058] The high-performance water reducer is compounded from a polycarboxylic acid comprehensive water-reducing mother liquid, a shrinkage-reducing agent, a retarder, a slump-retaining agent, cellulose, a regulator, an air-entraining agent and water, and the weight ratio is 240:350:10:25:5:2:0.6:300. The specific water reducer is selected in accordance with Example 1. It has a strong dispersing effect on cementitious materials, can significantly adjust the workability of concrete, enhance the interface bonding force between concrete paste and aggregate, and improve the paste strength and reduce concrete shrinkage. It has a solid content of 19%, a water reduction rate of 28%, and a 28d compressive strength ratio of 145%.

[0059] The method for preparing self-compacting low-carbon concrete with modified solid waste comprises the following preparation steps: 1. Weigh each raw material component: weigh cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water, and high-performance water reducing agent according to a certain weight proportion; 2. Divide the mixing water into two parts according to the ratio of 2:1, pour the larger amount of water into the mixer first, then pour the silica fume into it, and stir for 30 seconds to obtain slurry A; 3. Mix the modified solid waste slurry and slurry A evenly, stirring for 20 seconds to obtain slurry B; 4. Mix cement and slurry B evenly for 20 seconds to obtain slurry C; 5. Evenly mix the remaining small amount of water and high-performance water reducing agent with slurry C and stir for 20 seconds to obtain slurry D; 6. Pour the modified solid waste aggregate into slurry D and stir for 90 seconds to obtain a self-compacting concrete mixture; 7. Part of the mixture obtained is used for mixture performance testing, and the remaining part is molded to test mechanical and durability properties. Molding method: Pour it directly into a fixed mold without vibration or tamping, and scrape the surface to make it smooth. After standard curing for 28 days, test its various properties.

[0060] Comparative Example 1 The only difference between Comparative Example 1 and Example 3 is that in Comparative Example 1, the weight of the modified solid waste slurry in Example 3 is replaced by conventional mineral admixtures and water. The sum of the weights of the conventional mineral admixtures and water is 260 parts. According to Example 3, the solid content of the modified solid waste slurry is 90 / 150, so the weight ratio of the conventional mineral admixture and water is set to 90:60, that is, 156 parts of conventional mineral admixtures and 104 parts of water.

[0061] Among them, the conventional mineral admixture is the same powder as the solid waste slurry before grinding in Example 3, that is, the various solid waste powders before mechanical grinding in the modified solid waste slurry preparation step (1) of Example 3 are used as the conventional mineral admixture in Comparative Example 1, and other conditions remain unchanged.

[0062] Comparative Example 2 The difference between this comparative example 2 and example 3 is that in comparative example 2, the modified solid waste aggregate of example 3 is replaced by solid waste aggregate of double particle size range, and other conditions remain unchanged.

[0063] The solid waste aggregate in the dual particle size range is specifically a mixture of 0 mm to 5 mm solid waste aggregate and 10 mm to 20 mm solid waste aggregate in a weight ratio of 50:57. The source of the solid waste aggregate in the dual particle size range is the same as that in Example 3. The same batch of construction solid waste as that in Example 3 is crushed and shaped in step (1) to prepare solid waste aggregate of the required particle size.

[0064] Comparative Example 3 The only difference between Comparative Example 3 and Example 3 is that in Comparative Example 3, the modified solid waste aggregate in Example 3 is replaced with an equal amount of ordinary aggregate, and other conditions remain unchanged.

[0065] Among them, ordinary aggregates are machine-made sand and crushed stone, and the specific weight ratio of the two is 50:57. Among them, the machine-made sand is medium sand in the second zone with a fineness of 2.5, and the crushed stone is a continuously graded crushed stone of 5mm to 20mm.

[0066] Comparative Example 4 The only difference between Comparative Example 4 and Example 3 is that in Comparative Example 4, the modified solid waste slurry of Example 3 is replaced by unmodified solid waste slurry, that is, the mixture of solid waste mixture and water obtained in step (2) of preparing the modified solid waste slurry of Example 3 is used to replace the modified solid waste slurry in Example 3, and other conditions remain unchanged.

[0067] Comparative Example 5 The difference between this comparative example and Example 3 is that in the step (1) of preparing the modified solid waste slurry, solid waste powder with a single average particle size (average particle size of 10 μm) is selected by weight to replace the solid waste mixed powder formed by mixing three solid waste powders with different particle size ranges in Example 3, and then the modified solid waste slurry is obtained by mixing with water and modifying with a modifier in the same manner as in Example 3, and the other steps and conditions remain unchanged.

[0068] The solid waste powder component formula of this comparative example is consistent with that of Example 3, and mineral powder, fly ash, and ceramic polishing powder are mixed in a specific ratio. The only difference between this comparative example and Example 3 is that the solid waste powder is not mixed in a specific ratio of three particle size ranges.

[0069] Comparative Example 6 The difference between this comparative example and Example 3 is that in the step (1) of preparing the modified solid waste aggregate, a solid waste mixed aggregate prepared by mixing 0 mm to 5 mm solid waste aggregate and 10 mm to 20 mm solid waste aggregate in a weight ratio of 50:57 is selected to replace the solid waste mixed aggregate prepared by mixing four kinds of solid waste aggregates with different particle size ranges in Example 3 by equal weight, and then the modified solid waste aggregate is obtained by soaking in a low concentration hydrochloric acid solution, washing and modifying with an interface enhancer, and drying in the same manner as in Example 3, and the other steps and conditions remain unchanged.

[0070] The source of the solid waste aggregate components in this comparative example is the same as that in Example 3. The solid waste from the same batch as in Example 3 is crushed and shaped in step (1) to prepare solid waste aggregates of the desired particle size. The only difference between this comparative example and Example 3 is that the solid waste mixed aggregate is not a compound of four specific particle size ranges.

[0071] It should be noted that: Comparative Examples 1 to 6 change and replace the raw materials (especially solid waste slurry and solid waste aggregate) on the basis of Example 3, in order to keep the expansion degree of the concrete mixture of the comparative example at the same level as that of Example 3 (i.e., the same initial state) in the final test for the convenience of horizontal performance comparison, it is necessary to adjust the amount of water reducer in Comparative Examples 1 to 6. This is to compare the performance difference between the comparative example and the example with solid waste slurry and solid waste aggregate as variables, so as to explore the influence of the variable design of solid waste slurry and solid waste aggregate on the performance of concrete, rather than introducing the amount of water reducer as a variable.

[0072] Performance tests of the products obtained in the embodiments and comparative examples: The concrete prepared in the above examples and comparative examples was tested for performance according to the standards T / CECS 203-2021 "Technical Specifications for Application of Self-Compacting Concrete", GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete" and GB / T 50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete". The results are shown in Table 2: Table 2

[0073] In Table 2, the slump, expansion, expansion time, and J-ring height difference are the properties of fresh self-compacting concrete mixtures; 28d represents the compressive strength and chloride ion migration coefficient of concrete after 28 days of standard curing.

[0074] From the test results in Table 2, we can see that: From the test results of Examples 1 to 3, it can be seen that as the amount of modified solid waste slurry increases, the amount of cement decreases, and the amount of water reducer needs to be increased so that its fluidity meets the requirements of self-compacting concrete, which means that the modified solid waste slurry is easier to absorb water than cement, resulting in a decrease in its fluidity. As the amount of modified solid waste slurry increases, the expansion time increases, and the height difference of the J ring decreases, indicating that the viscosity of the slurry is slightly improved, the gap passability is enhanced, and it is more conducive to the movement of aggregates in narrow spaces. As the amount of modified solid waste slurry increases, the mechanical properties and durability of self-compacting concrete are also enhanced. This is not only the effect of the modified solid waste slurry, but also the effect of silica fume in improving performance.

[0075] Embodiments 1 to 3 of the present application optimize solid waste by modifying it, and optimize the mix ratio of solid waste self-compacting concrete and configure special admixtures for solid waste self-compacting low-carbon concrete, so that the modified solid waste slurry and modified solid waste aggregate can effectively and stably play a role in concrete, thereby improving the mechanical properties and durability of concrete, and ensuring that the rheological properties of concrete can meet the requirements of self-compacting concrete.

[0076] Compared with Example 3, while maintaining similar expansion, the amount of high-performance water-reducing agent in Example 1 is reduced, but the compressive strength and durability are reduced, indicating that the modified solid waste slurry of the present application is easier to absorb admixtures and water through the refinement effect of physical grinding; the solid waste powder of the present application through physical grinding and modification improves the cohesiveness of concrete, and the slurry can more effectively promote the rolling of aggregates, and has a great effect on the strength of concrete and the resistance to chloride ion penetration. Among them, when the amount of water-reducing agent in Comparative Example 1 is kept consistent with that in Example 3, the slump is 235mm, the expansion is 740mm, the expansion time is 2.6s, and the J-ring height difference is 34mm; the 28d compressive strength and chloride ion migration coefficient are 47.6MPa and 5.2×10 -12 m 2 / s. The results show that under the same dosage, the mixture of Comparative Example 1 segregates and cannot meet the performance requirements of self-compacting concrete. Therefore, it is necessary to control its workability by reducing the dosage of high-performance water-reducing agent.

[0077] Comparative Example 2 Compared with Example 3, Comparative Example 2 only uses solid waste aggregates in the double particle size range, and the waste aggregates are not modified, which has a greater impact on the fluidity of the concrete. It is necessary to increase the amount of high-performance water-reducing agent to improve the fluidity. The reason is that the unmodified solid waste aggregates have strong water absorption and will absorb part of the concrete water, resulting in a decrease in the amount of water used by the powder and an increase in the viscosity of the concrete. The solid waste aggregates in the double particle size range have a large stacking porosity and poor gap permeability. However, the present application can effectively improve its gap permeability and enhance the rheology of self-compacting concrete by combining multiple medium-sized aggregates. And the solid waste aggregates treated by the modification in the present application significantly improve the strength and durability of the concrete. The reason is that by pickling, the weak cement layer on the surface of the aggregate is removed, the transition zone range of the new and old mortar is reduced, and the generation of internal cracks is reduced. Then, through the action of the organosilicon reinforcing agent, it can penetrate into the interior of the solid waste aggregate, enhance the strength of the aggregate, and form an external film to reduce the water absorption rate of the solid waste aggregate and ensure the stability of the water consumption.

[0078] Comparative Example 3 Compared with Example 3, Comparative Example 3 does not use waste, but ordinary aggregates with continuous grading of 5mm to 20mm. The various properties measured by the waste utilization scheme (especially Example 3) of this application are close to those of the modified solid waste aggregate, indicating that the modification effect of the scheme of this application is better, which can reduce the water absorption of solid waste aggregates and improve the strength of aggregates, making it close to the performance of ordinary aggregates. Although the traditional scheme of using ordinary aggregates has good comprehensive performance, it uses ordinary aggregates, which cannot reduce carbon emissions by waste utilization compared to this application, and the raw material cost is relatively high.

[0079] Compared with Example 3, Comparative Example 4 uses unmodified solid waste slurry, and the main difference in performance is that the compressive strength and chloride ion migration coefficient of Comparative Example 4 are worse, indicating that the modifier modification treatment adopted in this application can optimize the internal slurry pore structure, block the chloride ion transmission channel, and improve the strength and durability of self-compacting concrete.

[0080] Compared with Example 3, the modified solid waste slurry prepared in Comparative Example 5 using solid waste powder of a single particle size has different performances mainly in that the J-ring height difference becomes larger, the compressive strength decreases, and the resistance to chloride ion penetration becomes worse. The single particle size powder cannot be effectively combined with cement, and the grading curve of the formed cementitious material shows a single peak, which affects the overall performance of the concrete.

[0081] Compared with Example 3, Comparative Example 6 uses double-size modified solid waste aggregates, and the main differences in their performance are in the J-ring height difference and compressive strength. The mixture of double-size aggregates is prone to aggregate accumulation, and the slurry cannot effectively promote the dispersion and advancement of the aggregates, resulting in a decrease in the performance of the self-compacting concrete. Specifically, the J-ring height difference exceeds the specified range, and the compressive strength and durability of the concrete are both deteriorated.

[0082] Compared with Comparative Example 2, the modified aggregate has a significantly lower water absorption rate and various properties are optimized, indicating that it has an improvement effect on self-compacting concrete. In summary, compared with the prior art, the method for preparing a high-bonding anti-fouling and drag-reducing coating for a titanium alloy substrate provided in the present application includes the following design concepts and beneficial effects: Design concept: The present application scheme takes the dual modification of solid waste powder and aggregate as the core, and prepares various types of solid waste powder by physical grinding to obtain micro powders of various particle size ranges for combination to achieve the best stacking effect, and then uses water as a medium to make it into a slurry state, reducing the aggregation caused by excessively fine particles, and further improving its uniformity. Finally, it is combined with a modifier to optimize its pore structure, reduce the generation of large pores and interconnected pores, and improve the mechanical properties and durability of concrete; This application scheme further modifies construction solid waste to obtain modified solid waste aggregates, and uses crushing and shaping methods to strengthen the roundness of waste aggregates, improve the interface between aggregates and slurry, promote the coordinated movement of aggregates and slurry, increase their fluidity and gap pass rate, and form an optimal 5mm-20mm continuous grading with a variety of single-particle combination modes, reduce the void ratio of aggregates, and increase density. During the crushing process of construction solid waste, part of the cement slurry adheres to the surface of the aggregate, forming a weak layer, which reduces the performance of the concrete. The amount of cement on the surface of the aggregate is reduced by pickling, and then the surface of the aggregate is hardened by interface reinforcement, and penetrates into the interior of the aggregate, reducing the water absorption rate of the aggregate and enhancing the stability and performance of the aggregate. This application applies solid waste powder and aggregate to self-compacting concrete, turning waste into treasure and achieving a low-carbon effect.

[0083] Beneficial effects: The present application provides a self-compacting low-carbon concrete with modified solid waste added thereto, which effectively solves the problem of large carbon emissions from concrete by adding modified solid waste powder and modified solid waste aggregate. More significantly, the modified solid waste can effectively and stably play a role in concrete to effectively improve the mechanical properties and durability of concrete. Finally, by optimizing the mix ratio of solid waste self-compacting concrete and configuring special admixtures for solid waste self-compacting low-carbon concrete, it can be ensured that the rheological properties of concrete meet the requirements of self-compacting concrete.

[0084] It should be noted that: Unless otherwise specified, “~” is used herein to indicate a numerical range, and the range indicated by this expression includes two endpoint values.

[0085] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments of the present invention, but are not intended to limit the present invention. Those skilled in the art may make adaptive adjustments within the scope of the present invention.

[0086] In addition, unless otherwise specified, the raw materials used may also be conventional commercial products in the art, or prepared by conventional methods in the art; that is, the reagents and instruments used in this embodiment are not indicated with information such as the manufacturer, and are all conventional products that can be purchased on the market.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-compacting low-carbon concrete with modified solid waste, characterized in that: The raw material components include cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water and polycarboxylic acid high-performance water reducing agent; The modified solid waste slurry is obtained by sequentially mixing solid waste powder with water and modifying it with a modifier; The solid waste mixed powder includes two or more combinations of solid waste powder with an average particle size of 2 μm, solid waste powder with an average particle size of 3 μm, solid waste powder with an average particle size of 7 μm, solid waste powder with an average particle size of 10 μm, and solid waste powder with an average particle size of 20 μm; the components of the modifier include one or more combinations of graphene dispersion, carbon nanotube dispersion, and nano-silicon dioxide suspension; The modified solid waste aggregate is obtained by sequentially treating solid waste mixed aggregate by soaking it in a low-concentration hydrochloric acid solution, washing and modifying it with an interface enhancer, and drying it; wherein the interface enhancer is a combination of one or more of silicone, water-based resin, silica enhancer, and acrylic enhancer.

2. The self-compacting low-carbon concrete with added modified solid waste according to claim 1, characterized in that: In parts by weight, the solid waste mixed aggregate includes 34 to 40 parts of solid waste aggregate with a particle size of 0 mm to 2.5 mm, 4 to 11 parts of solid waste aggregate with a particle size of 2.5 mm to 5 mm, 11 to 33 parts of solid waste aggregate with a particle size of 5 mm to 10 mm, and 22 to 44 parts of solid waste aggregate with a particle size of 10 mm to 20 mm; wherein the solid waste aggregate with a particle size of 0 mm to 2.5 mm does not include solid waste aggregate with a particle size of 0 mm; The mass concentration of the hydrochloric acid solution is 0.05% to 1%.

3. The self-compacting low-carbon concrete with added modified solid waste according to claim 1, characterized in that: The preparation process of the modified solid waste slurry is as follows: Firstly, the solid waste powder raw material is subjected to mechanical grinding to obtain solid waste powders with different average particle size ranges, and then the solid waste powders with different average particle size ranges are mixed to obtain the solid waste mixed powder; The solid waste mixed powder is mixed with water and stirred evenly; finally, a modifier is added and stirred evenly to obtain a modified solid waste slurry; The weight ratio of the solid waste mixed powder, the water and the modifier is: (80-100): (50-70): (3-7); the components of the solid waste powder include two or more combinations of mineral powder, fly ash, ceramic polishing powder, glass powder and limestone powder.

4. The self-compacting low-carbon concrete with added modified solid waste according to claim 1, characterized in that: The preparation process of the modified solid waste aggregate is as follows: The construction solid waste is first crushed and shaped to obtain solid waste aggregates with different particle size ranges, and the solid waste aggregates with different particle size ranges are mixed to form solid waste mixed aggregates; The solid waste mixed aggregate is added into a low concentration hydrochloric acid solution to remove some cement particles remaining on the surface of the aggregate; and then filtered, washed with water, and dried in sequence to obtain a primary treated solid waste mixed aggregate; The solid waste mixed aggregate initially treated is rinsed and modified with an interface enhancer, and finally dried to obtain the modified solid waste aggregate.

5. The self-compacting low-carbon concrete with added modified solid waste according to claim 1, characterized in that: The solid waste powder is composed of mineral powder, fly ash and ceramic polishing powder; The solid waste mixed powder is formed by mixing solid waste powder with an average particle size of 2 μm, solid waste powder with an average particle size of 7 μm, and solid waste powder with an average particle size of 10 μm in a weight ratio of 4:3:

3.

6. The self-compacting low-carbon concrete with added modified solid waste according to claim 1, characterized in that: By weight, the raw material components include: 220 to 260 parts of cement, 220 to 260 parts of modified solid waste slurry, 20 to 40 parts of silica fume, 1700 to 1750 parts of modified solid waste aggregate, 65 to 80 parts of water, and 4 to 6 parts of high-performance water reducing agent.

7. The self-compacting low-carbon concrete with added modified solid waste according to claim 1, characterized in that: The cement is one of P·O 42.5R cement, P·0 42.5 cement and P·II 42.5 cement; The silica ash is silicon powder modified by silane coupling agent, with a silicon dioxide content of 90% to 95% and a bulk density of 250 kg / m 3 ~300kg / m 3 , loss on ignition is 1% to 4%, 7d activity index is 105% to 110%, specific surface area is 19000m 2 / kg~23000 m 2 / kg.

8. The self-compacting low-carbon concrete with added modified solid waste according to claim 1, characterized in that: The high-performance water-reducing agent is compounded by polycarboxylic acid comprehensive water-reducing mother liquor, shrinkage-reducing agent, retarder, slump-retaining agent, cellulose, regulator, air-entraining agent and water in a weight ratio of (240-280): (330-500): (10-20): (20-50): (5-10): (1-3): (0.5-1): (200-330), and has a solid content of 17%-22%, a water reduction rate of 28%-33%, and a 28d compressive strength ratio of 143%-150%.

9. A method for preparing self-compacting low-carbon concrete with modified solid waste as claimed in any one of claims 1 to 8, characterized in that: The method comprises the following preparation steps: Weigh cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water, and high-performance water reducing agent according to the formula; The first portion of water and silica fume are stirred and mixed evenly to obtain slurry A; The modified solid waste slurry and slurry A are stirred and mixed evenly to obtain slurry B; The cement and slurry B are stirred and mixed evenly to obtain slurry C; The second portion of water, the high performance water reducing agent and the slurry C are stirred and mixed uniformly to obtain slurry D; Pour the modified solid waste aggregate into slurry D, stir and mix evenly to obtain a self-compacting concrete mixture; The mixture is solidified and formed to obtain self-compacting low-carbon concrete added with modified solid waste.

10. The method for preparing self-compacting low-carbon concrete with modified solid waste according to claim 9, characterized in that: The method comprises the following preparation steps: Weigh cement, modified solid waste slurry, silica fume, modified solid waste aggregate, water, and high-performance water reducing agent according to the formula; Pour the first part of water and silica fume into a mixer, stir and mix evenly for 20s to 40s to obtain slurry A; The modified solid waste slurry and slurry A are stirred and mixed evenly for 10s to 20s to obtain slurry B; Stir cement and slurry B evenly for 10s to 20s to obtain slurry C; The second part of water, high performance water reducing agent and slurry C are stirred and mixed uniformly for 15s to 30s to obtain slurry D; Pour the modified solid waste aggregate into slurry D, stir and mix evenly, stir for 60s to 90s, and obtain a self-compacting concrete mixture; wherein the fluidity of the mixture is controlled between 650mm and 700mm; The mixture is solidified and formed to obtain self-compacting low-carbon concrete added with modified solid waste; The sum of the first part of water and the second part of water is the total amount of water, and the weight ratio of the first part of water to the second part of water is 2:1.

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