A full-solid-waste concrete prefabricated part free of steam curing and a preparation method thereof

Abstract

The application belongs to the technical field of building materials and solid waste resource utilization, in particular to a non-autoclaved full-solid-waste concrete prefabricated part and a preparation method thereof. In the preparation method, 0.1wt%-10wt% of refining slag, 20wt%-30wt% of steel slag, 40wt%-60wt% of mineral slag and 15wt%-20wt% of industrial by-product gypsum are used to prepare cementitious materials, then 15wt%-20wt% of the cementitious materials, 75wt%-80wt% of aggregates and 5wt%-7wt% of water and water reducing agent are mixed and cast to form a test block, which is first subjected to standard curing for 2-6h, then subjected to temperature-controlled curing at 40 DEG C for 18-22h, and finally subjected to 28-day standard curing to obtain a C40 concrete prefabricated part. The raw materials of the concrete prefabricated part are derived from solid waste, which can reduce the production cost of the steel and building industry, and the economic and social environmental benefits are remarkable; the high-strength development can be realized without high-energy-consuming curing, and the concrete prefabricated part has low carbon and energy saving; the use of long-carbon-chain polycarboxylic acid water reducing agent improves the impermeability and frost resistance of the prefabricated part, and ensures that the prefabricated part has high strength and durability.

Description

Technical Field

[0001] This application belongs to the technical field of building materials and solid waste resource utilization, specifically a precast solid waste concrete component that does not require autoclaving and its preparation method. Background Technology

[0002] As a core product of industrialized construction, the quality, cost, and environmental performance of precast concrete components largely depend on the concrete materials used and their preparation and curing processes. Currently, the industry commonly uses silicate cement as the main cementing material for producing precast concrete components with strength grades of C40 and above, relying on high-temperature steam curing to accelerate cement hydration and shorten the demolding cycle to meet the production requirements of rapid turnover of precast components. However, this traditional material system and curing mode have the following significant drawbacks: 1. High energy consumption and large carbon emissions: The steam curing process requires a large amount of heat energy, usually from coal or gas, directly leading to huge energy consumption in the production process and generating significant carbon dioxide emissions, which contradicts the development concept of green building. 2. High material costs: Silicate cement itself is a high-energy-consuming and high-carbon-emission industrial product. Using it as the sole or main cementing material makes the material cost of precast components susceptible to fluctuations in cement market prices. 3. Insufficient utilization of solid waste resources: Traditional formulations have limited capacity for incorporating industrial solid waste (such as slag, fly ash, steel slag, etc.). Excessive solid waste content usually leads to slow early strength development of precast components, making it impossible to meet the strength requirements for rapid demolding without steam curing. This greatly limits the large-scale disposal of solid waste in the precast component field and wastes potential cementitious resources.

[0003] Therefore, developing a concrete preparation method based on all-solid waste cementitious materials, requiring no steam curing, and capable of stably producing high-performance precast components is an urgent technical challenge to be solved in order to reduce carbon emissions in the precast component industry, dispose of industrial solid waste, and achieve green and low-carbon buildings.

[0004] Patent CN118206335A discloses a method for preparing autoclaved concrete for prefabricated building components. This technology introduces self-heating components (iron powder, sodium chloride, and activated calcium oxide), heat-insulating and moisture-retaining components (expanded perlite powder), and setting-regulating components (stearic acid-coated calcium formate / aluminum sulfate) into a traditional concrete formula. It then employs a process of wrapping with plastic film and curing in a sealed, insulated box, utilizing the material's own heat of hydration and insulation to achieve autoclaving-free operation. Although this technology achieves the goal of "autoclaving-free," the material is essentially an improvement on the traditional cement-based concrete system. Its main cementitious material is still high-energy-consuming and high-carbon-emission silicate cement, and the self-heating and setting-regulating components are also chemical products. This approach fails to utilize large quantities of industrial solid waste such as slag, refining slag, and steel slag as the main cementitious material, thus limiting its environmental benefits. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a method for preparing precast concrete components made entirely from solid waste without steam curing. This technical solution utilizes the compounding and synergistic activation of various solid wastes, eliminating the need for steam curing. After casting, the components undergo 2-6 hours of standard curing, followed by 18-22 hours of temperature-controlled curing at 40℃. After demolding, a final standard curing is performed, resulting in precast concrete components with excellent workability, mechanical properties, and durability. This method not only maximizes the comprehensive utilization of refining slag but also achieves green, low-carbon, and resource-recycling processes in the precast concrete component preparation.

[0006] According to a first aspect of this application, this application provides a method for preparing precast solid waste concrete components without autoclaving, comprising the following steps: S1. Weigh the first raw material, which includes 0.1wt%~10wt% refining slag, 20wt%~30wt% steel slag, 40wt%~60wt% ore slag, and 15wt%~20wt% industrial by-product gypsum. Mix the refining slag, steel slag, ore slag, and industrial by-product gypsum and then grind them, or grind the refining slag, steel slag, ore slag, and industrial by-product gypsum separately in the first grinding and then mix them and grind them in the second grinding to obtain a cementitious material. S2. Weigh the second raw material, which includes 15wt%~20wt% of the cementitious material, 75wt%~80wt% of the aggregate, and 5wt%~7wt% of the water. Add the aggregate and water-reducing agent to the cementitious material and stir evenly. Then add the water and stir to obtain precast concrete. S3. The precast concrete is poured into shape, first subjected to standard curing for 2-6 hours, then subjected to temperature-controlled curing at 40℃ for 18-22 hours, and demolded after a total time of 24 hours to obtain the test block; S4. The test block is subjected to standard curing for a predetermined time to obtain a precast component.

[0007] Furthermore, the slag is granulated blast furnace slag powder conforming to GB / T18046-2008 "Granulated blast furnace slag powder for use in cement and concrete".

[0008] Furthermore, the main components of the industrial by-product gypsum include at least one of anhydrous calcium sulfate or calcium sulfate dihydrate.

[0009] Furthermore, the second grinding time is greater than 10 minutes.

[0010] Furthermore, the specific surface area of ​​the cementitious material is greater than 500 m². 2 / kg.

[0011] Furthermore, the aggregate includes at least one of natural sand, artificial sand, tailings, pebbles, crushed stone, or waste rock.

[0012] Furthermore, the aggregate consists of coarse aggregate and fine aggregate.

[0013] Furthermore, the mass ratio of the coarse aggregate to the fine aggregate is 1 to 1.5, the particle size of the coarse aggregate is greater than 5 mm and less than or equal to 10 mm, and the particle size of the fine aggregate is less than or equal to 5 mm.

[0014] Furthermore, the water-reducing agent is a polycarboxylate water-reducing agent, and the mass ratio of the water-reducing agent to the water is less than 0.3.

[0015] Furthermore, the carbon chain length of the carboxylic acid monomer in the polycarboxylic acid water-reducing agent is greater than or equal to 5.

[0016] Furthermore, when the predetermined time is 3 days, the compressive strength of the precast component is greater than or equal to 15 MPa, and when the predetermined time is 28 days, the compressive strength of the precast component is greater than or equal to 40 MPa.

[0017] Furthermore, prior to step S1, the first raw material is pretreated, including crushing, drying, and iron removal.

[0018] In the above technical solution, all solid raw materials are derived from industrial solid waste. The cementitious material, based on the traditional steel slag-blast furnace slag-desulfurized gypsum mix, incorporates refined slag components. Utilizing the potential hydraulic cementitious properties of the refined slag, the early-stage heat of hydration and setting time are increased. The use of polycarboxylate superplasticizers (especially long-chain polycarboxylate superplasticizers) enhances the stability between powder particles, thereby improving the density of the concrete, reducing the possibility of crack formation, and ultimately improving the concrete's impermeability and frost resistance. After mixing the raw materials to obtain concrete, standard curing followed by temperature-controlled curing at 40°C to obtain test blocks effectively avoids the steam expansion effect caused by the slow early hydration rate of the solid waste-based cementitious material. A fixed demolding time of 24 hours increases mold turnover and reduces mold management costs. This method allows for the production of all-solid-waste C40 concrete precast components without steam curing.

[0019] According to a second aspect of this application, this application provides a precast component of non-steam-cured solid waste concrete, which is prepared by the above-described method for preparing a precast component of non-steam-cured solid waste concrete.

[0020] This application proposes a steam-curing-free precast concrete component made entirely from solid waste and its preparation method, which produces the following beneficial effects: the raw materials of the precast concrete component are mainly derived from solid waste, realizing the large-scale high-value-added synergistic utilization of metallurgical solid waste and mining solid waste, which can reduce the production costs of the steel and construction industries, resulting in significant economic and social environmental benefits; high strength can be achieved without energy-intensive steam curing or oxygen autoclave treatment, truly realizing low-carbon and energy-saving; by using a long-chain polycarboxylate superplasticizer, a continuous and stable dispersion effect is provided, improving the impermeability and frost resistance of the precast concrete component, ensuring that the precast concrete component has high strength and durability. Detailed Implementation

[0021] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0022] This application provides a method for preparing precast solid waste concrete components without autoclaving, comprising the following steps: S1. Weigh the first raw material, which includes 0.1wt%~10wt% of refining slag, 20wt%~30wt% of steel slag, 40wt%~60wt% of ore slag, and 15wt%~20wt% of industrial by-product gypsum. Mix the refining slag, steel slag, ore slag, and industrial by-product gypsum and then grind them, or grind the refining slag, steel slag, ore slag, and industrial by-product gypsum separately in the first grinding and then mix them and grind them in the second grinding to obtain the cementitious material. S2. Weigh the second raw material, which includes 15wt%~20wt% cementitious material, 75wt%~80wt% aggregate, and 5wt%~7wt% water. Add the aggregate and water-reducing agent to the cementitious material and stir evenly. Then add water and stir to obtain precast concrete. S3. The precast concrete is poured into shape, and then standard curing is carried out for 2-6 hours. Then, temperature-controlled curing is carried out at 40℃ for 18-22 hours. The specimen is demolded after a total time of 24 hours to obtain the specimen. S4. The test block is cured for a predetermined time to obtain the precast component.

[0023] On the other hand, this application also provides a precast concrete component made using the above-mentioned method for preparing precast solid waste concrete components without autoclaving.

[0024] When the scheduled time is 3 days, the compressive strength of the precast component is greater than or equal to 15 MPa, and when the scheduled time is 28 days, the compressive strength of the precast component is greater than or equal to 40 MPa.

[0025] The technical solution of this application will be further described below with reference to specific embodiments. It should be noted that the refining slag, steel slag, mineral slag and industrial by-product gypsum used in the following embodiments and comparative examples have all undergone crushing, drying and iron removal treatment before use.

[0026] Example 1 The proportions of the second raw material and the water-reducing agent in this embodiment are shown in Table 1: Table 1 A method for preparing precast solid waste concrete components without autoclaving includes the following steps: S1. Weigh the first raw material. The components of the first raw material are: refining slag 2.5wt%, steel slag 27.5wt%, blast furnace slag 54wt%, and industrial by-product gypsum 16wt%. Grind the refining slag, steel slag, blast furnace slag, and industrial by-product gypsum separately, then mix them and grind them again to obtain a cementitious material. After the first grinding, the specific surface area of ​​the refining slag and blast furnace slag is 500 m². 2 / kg, the specific surface area of ​​steel slag and industrial by-product gypsum is 450m². 2 / kg, the specific surface area of ​​the cementitious material obtained from the second grinding is greater than 500m². 2 / kg; S2. Take the amount of cementitious material, coarse aggregate, fine aggregate, water-reducing agent and water in Table 1, add the aggregate and water-reducing agent to the cementitious material and mix evenly, then add water and mix to obtain precast concrete. S3. The precast concrete is poured into shape, first subjected to 4 hours of standard curing, then subjected to 20 hours of temperature-controlled curing at 40℃, and then demolded to obtain test blocks. S4. Perform standard curing on the test block to obtain the precast component.

[0027] Example 2 The proportions of the second raw material and the water-reducing agent in this embodiment are shown in Table 2: Table 2 A method for preparing precast solid waste concrete components without autoclaving includes the following steps: S1. Weigh the first raw material. The components of the first raw material are: 5 wt% refining slag, 25 wt% steel slag, 50 wt% ore slag, and 20 wt% industrial by-product gypsum. Grind the refining slag, steel slag, ore slag, and industrial by-product gypsum separately, then mix them and grind them again to obtain a cementitious material. After the first grinding, the specific surface area of ​​the refining slag and steel slag is 490 m². 2 / kg, the specific surface area of ​​slag is 500m² 2 / kg, the specific surface area of ​​industrial by-product gypsum is 450m². 2 / kg, the specific surface area of ​​the cementitious material obtained from the second grinding is greater than 500m². 2 / kg; S2. Take the amount of cementitious material, coarse aggregate, fine aggregate, water-reducing agent and water in Table 2, add aggregate and water-reducing agent to cementitious material and mix evenly, then add water and mix to obtain precast concrete. S3. The precast concrete is poured into shape, first subjected to 4 hours of standard curing, then subjected to 20 hours of temperature-controlled curing at 40℃, and then demolded to obtain test blocks. S4. Perform standard curing on the test block to obtain the precast component.

[0028] Example 3 The proportions of the second raw material and the water-reducing agent in this embodiment are shown in Table 3: Table 3 A method for preparing precast solid waste concrete components without autoclaving includes the following steps: S1. Weigh the first raw material. The components of the first raw material are: refining slag 7.5wt%, steel slag 22.5wt%, blast furnace slag 50wt%, and industrial by-product gypsum 20wt%. Mix the refining slag, steel slag, blast furnace slag, and industrial by-product gypsum, and then grind them to obtain a specific surface area of ​​550 m². 2 / kg of cementitious materials; S2. Take the amount of cementitious material, coarse aggregate, fine aggregate, water-reducing agent and water in Table 3, add aggregate and water-reducing agent to cementitious material and mix evenly, then add water and mix to obtain precast concrete. S3. The precast concrete is poured into shape, first subjected to 4 hours of standard curing, then subjected to 20 hours of temperature-controlled curing at 40℃, and then demolded to obtain test blocks. S4. Perform standard curing on the test block to obtain the precast component.

[0029] Comparative Example 1 The only difference between this comparative example and Example 1 is that the content of each component in the first raw material is 5wt% refining slag, 10wt% steel slag, 55wt% ore slag, and 30wt% industrial by-product gypsum.

[0030] Comparative Example 2 The only difference between this comparative example and Example 1 is that the content of each component in the first raw material is 20wt% refining slag, 20wt% steel slag, 45wt% ore slag, and 15wt% industrial by-product gypsum.

[0031] Comparative Example 3 The proportions of the second raw material and the water-reducing agent in this comparative example are shown in Table 4: Table 4 A method for preparing precast solid waste concrete components without autoclaving includes the following steps: S1. Weigh the first raw material. The components of the first raw material are: 5 wt% refining slag, 40 wt% steel slag, 40 wt% ore slag, and 15 wt% industrial by-product gypsum. Grind the steel slag, ore slag, and industrial by-product gypsum separately, then mix them and grind them again to obtain a cementitious material. After the first grinding, the specific surface area of ​​the steel slag and industrial by-product gypsum is 450 m². 2 / kg, the specific surface area of ​​slag is 500m² 2 / kg, the specific surface area of ​​the cementitious material obtained from the second grinding is greater than 500m². 2 / kg; S2. Take the amount of cementitious material, coarse aggregate, fine aggregate, water-reducing agent and water in Table 4, add aggregate and water-reducing agent to cementitious material and mix evenly, then add water and mix to obtain precast concrete. S3. The precast concrete is poured into shape, first subjected to 4 hours of standard curing, then subjected to 20 hours of temperature-controlled curing at 40℃, and then demolded to obtain test blocks. S4. Perform standard curing on the test block to obtain the precast component.

[0032] Comparative Example 4 The only difference between this comparative example and Example 3 is that the proportions of the second raw material and the water-reducing agent are shown in Table 5. Table 5 Comparative Example 5 The only difference between this comparative example and Example 1 is that the precast concrete was cast and cured at 20°C for 24 hours.

[0033] The compressive strength of the precast solid waste components without steam curing was tested after the test blocks of Examples 1-3 and Comparative Examples 1-5 were cured to the target age. The test results are shown in Table 7. Table 7 As shown in Table 1, the precast components prepared using samples 1-3 of this application exhibited compressive strengths greater than 18 MPa after 3 days of standard curing, and all exceeded 40 MPa after 28 days of standard curing, meeting the C40 standard. In contrast, the precast components prepared using samples 1-4 showed compressive strengths less than 40 MPa after 28 days of standard curing. Although the precast component of Comparative Example 5 exceeded 40 MPa after 28 days of standard curing, its compressive strength after 3 days of standard curing was only 12.17 MPa, requiring a longer curing time to reach the appropriate strength standard. This would increase curing costs and affect construction progress in actual production. Furthermore, the lower early strength makes the precast components more prone to water loss and cracking after conventional demolding, affecting not only construction performance but also durability and leading to serious engineering problems.

[0034] This application proposes a steam-curing-free precast concrete component made entirely from solid waste and its preparation method, which produces the following beneficial effects: the raw materials of the precast concrete component are mainly derived from solid waste, realizing the large-scale high-value-added synergistic utilization of metallurgical solid waste and mining solid waste, which can reduce the production costs of the steel and construction industries, resulting in significant economic and social environmental benefits; high strength can be achieved without energy-intensive steam curing or oxygen autoclave treatment, truly realizing low-carbon and energy-saving; by using a long-chain polycarboxylate superplasticizer, a continuous and stable dispersion effect is provided, improving the impermeability and frost resistance of the precast concrete component, ensuring that the precast concrete component has high strength and durability.

[0035] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for preparing precast solid waste concrete components without autoclaving, characterized in that, Includes the following steps: S1. Weigh the first raw material, which includes 0.1wt%~10wt% refining slag, 20wt%~30wt% steel slag, 40wt%~60wt% ore slag, and 15wt%~20wt% industrial by-product gypsum. Mix the refining slag, steel slag, ore slag, and industrial by-product gypsum and then grind them, or grind the refining slag, steel slag, ore slag, and industrial by-product gypsum separately in the first grinding and then mix them and grind them in the second grinding to obtain a cementitious material. S2. Weigh the second raw material, which includes 15wt%~20wt% of the cementitious material, 75wt%~80wt% of the aggregate, and 5wt%~7wt% of the water. Add the aggregate and water-reducing agent to the cementitious material and stir evenly. Then add the water and stir to obtain precast concrete. S3. The precast concrete is poured into shape, first subjected to standard curing for 2-6 hours, then subjected to temperature-controlled curing at 40℃ for 18-22 hours, and demolded after a total time of 24 hours to obtain the test block; S4. The test block is subjected to standard curing for a predetermined time to obtain a precast component.

2. The method for preparing precast solid waste concrete components without autoclaving according to claim 1, characterized in that, The slag is granulated blast furnace slag powder conforming to GB / T18046-2008 "Granulated blast furnace slag powder for use in cement and concrete".

3. The method for preparing precast solid waste concrete components without autoclaving according to claim 1, characterized in that, The main components of the industrial by-product gypsum include at least one of anhydrous calcium sulfate or calcium sulfate dihydrate.

4. The method for preparing precast solid waste concrete components without autoclaving according to claim 1, characterized in that, The specific surface area of ​​the cementitious material is greater than 500 m². 2 / kg.

5. The method for preparing precast solid waste concrete components without autoclaving according to claim 1, characterized in that, The aggregate includes at least one of natural sand, artificial sand, tailings, pebbles, crushed stone, or waste rock.

6. The method for preparing precast solid waste concrete components without autoclaving according to claim 1, characterized in that, The aggregate consists of coarse aggregate and fine aggregate.

7. The method for preparing precast solid waste concrete components without autoclaving according to claim 6, characterized in that, The mass ratio of coarse aggregate to fine aggregate is 1 to 1.5, the particle size of the coarse aggregate is greater than 5 mm and less than or equal to 10 mm, and the particle size of the fine aggregate is less than or equal to 5 mm.

8. The method for preparing precast solid waste concrete components without autoclaving according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate water-reducing agent, and the mass ratio of the water-reducing agent to the water is less than 0.

03.

9. The method for preparing precast solid waste concrete components without autoclaving according to claim 1, characterized in that, When the predetermined time is 3 days, the compressive strength of the precast component is greater than or equal to 15 MPa, and when the predetermined time is 28 days, the compressive strength of the precast component is greater than or equal to 40 MPa.

10. A precast solid waste concrete component that does not require steam curing, characterized in that, The precast component is prepared using the method for preparing precast solid waste concrete without autoclaving as described in any one of claims 1 to 9.

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