A lead-zinc metallurgical slag composite admixture for fabricated buildings and a preparation method thereof

Abstract

The application relates to the technical field of fabricated building materials, and particularly discloses a lead-zinc metallurgical slag composite admixture for fabricated buildings and a preparation method thereof. The lead-zinc metallurgical slag composite admixture for fabricated buildings provided by the application comprises 40-60 parts of desulfurized lead-zinc metallurgical slag, 20-40 parts of mineral powder, 3-6 parts of silane coupling agent modified bournonite and 2-4 parts of sodium hydroxide. The lead-zinc metallurgical slag contains a large amount of glass body which can be decomposed in an alkali environment, thereby improving the activity of the composite admixture and ensuring the strength and durability of the concrete; the mineral powder can participate in secondary hydration of the concrete, thereby reducing the hydration heat and improving the workability; the bournonite can be hydrated to generate magnesium hydroxide to produce expansion in the cement paste, thereby effectively preventing the shrinkage and cracking of the concrete; and the surface of the bournonite is modified by using the silane coupling agent, thereby improving the water repellency and durability of the material. The early strength of the fabricated building concrete can be improved by using the specific proportion of different raw materials.

Description

Technical Field

[0001] This invention relates to the field of prefabricated building materials technology, and in particular to a lead-zinc metallurgical slag composite admixture for prefabricated buildings and its preparation method. Background Technology

[0002] Metallurgical slag is a solid waste generated during the smelting of metal ores in the metallurgical industry. Its comprehensive utilization rate is less than 40%. The accumulation of this solid waste on land not only causes environmental and safety problems but also places a significant economic burden on enterprises. Therefore, the effective utilization of solid waste can solve various problems caused by improper disposal or storage of industrial solid waste, and is of great significance for achieving industrial upgrading and energy conservation and emission reduction.

[0003] With the increasing importance of prefabricated construction in the construction industry, the demand for high-performance prefabricated concrete is growing. In existing concrete technologies, admixtures have become a crucial component of high-performance concrete. Currently, to meet the early strength requirements of concrete and reduce curing and demolding time, concrete used in prefabricated buildings often employs low admixture dosages and high cement content to accelerate mold turnover. Although cement hydration is rapid, the intense hydration reaction generates heat, leading to excessively rapid internal temperature rise in large-volume concrete, significantly increasing the risk of cracking. Therefore, under the premise of meeting the later-stage strength and durability requirements of prefabricated concrete, developing a high-performance admixture that improves early strength, reduces heat of hydration, compensates for early hydration shrinkage, and enhances the bond between concrete and reinforcing steel has significant application prospects in the field of prefabricated concrete. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a lead-zinc metallurgical slag composite admixture for prefabricated buildings and its preparation method. The lead-zinc metallurgical slag composite admixture provided by this invention can replace a portion of cement, improving the early strength of concrete, reducing heat of hydration, compensating for early hydration shrinkage, and enhancing the bond between concrete and reinforcing steel, while ensuring the later-stage strength and durability of the prefabricated building concrete.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] A composite admixture of lead-zinc metallurgical slag for prefabricated buildings comprises the following raw materials in parts by weight: 40-60 parts of desulfurized lead-zinc metallurgical slag, 20-40 parts of mineral powder, 3-6 parts of silane coupling agent modified magnesia, and 2-4 parts of sodium hydroxide.

[0007] Compared to existing technologies, the lead-zinc metallurgical slag composite admixture for prefabricated buildings provided by this invention has a main chemical composition similar to that of natural ore. Furthermore, the mineral phase of the lead-zinc metallurgical slag contains a large amount of glassy substances, which can decompose in an alkaline environment to improve the activity of the composite admixture. However, the lead-zinc metallurgical slag has a high SO3 content, which can corrode cement after being used in concrete and also produces a large amount of expansion phase products, affecting the strength and durability of concrete. The desulfurized lead-zinc metallurgical slag ensures the strength and durability of the concrete. The mineral powder has pozzolanic properties, can participate in the secondary hydration of concrete, and significantly reduce the heat of hydration of concrete. It improves the workability of concrete; the main component of magnesia is magnesium oxide, which can hydrate in cement paste to generate magnesium hydroxide, causing expansion. This expansion can counteract the volume shrinkage caused by hydration of cementitious materials, temperature changes, and water loss during the setting and hardening process of concrete, effectively preventing concrete shrinkage cracking. It also exhibits good temperature stability and is inexpensive. Modifying the surface of magnesia with a silane coupling agent can generate an organic molecular layer on the surface of inorganic powders, changing the inorganic powders from hydrophilic to organic-philic, ensuring uniform dispersion of the filler, improving the material's water repellency, and enhancing the durability of concrete. Sodium hydroxide is an alkaline activator that dissolves in water and ionizes to release OH-. - Aluminosilicate glass in mineral powder and desulfurized lead-zinc metallurgical slag in OH - Under the action of the process, Si-O bonds and Al-O bonds break, forming silicon and aluminum oligomers, which are then dehydrated to obtain aluminosilicate gel, thus improving the activity of lead-zinc metallurgical slag composite admixtures for prefabricated buildings.

[0008] The combined use of different raw materials in this invention enables the lead-zinc metallurgical slag composite admixture for prefabricated buildings to exhibit filling benefits, morphological effects, and interfacial coupling effects in concrete. When desulfurized lead-zinc metallurgical slag, mineral powder, and silane coupling agent-modified magnesia are used in combination, the differences in particle size distribution, particle morphology, and mineral composition lead-zinc metallurgical slag composite admixture fill and interact with each other, reducing the porosity of the composite admixture and increasing its density. Simultaneously, the differences in specific surface area and structure of different raw materials increase the negative effect of water consumption. This invention, through specific proportions of different raw materials, optimizes the positive effects of the lead-zinc metallurgical slag composite admixture for prefabricated buildings and effectively controls its negative effects. Furthermore, the lead-zinc metallurgical slag composite admixture for prefabricated buildings enables the secondary utilization of lead-zinc metallurgical slag, reducing engineering costs and building carbon emissions.

[0009] Preferably, the specific surface area of ​​the desulfurized lead-zinc metallurgical slag is 500-550 m². 2 / kg.

[0010] The desulfurized lead-zinc metallurgical slag preferred in this invention contains a large number of spherical particles, which can fill the cement surface in the form of micro-aggregates, increasing the density of the concrete. During the concrete mixing process, these spherical particles can play a role similar to the micro-bead effect of fly ash, reducing the water demand of the lead-zinc metallurgical slag and effectively improving the workability of the concrete without changing the concrete mix proportions.

[0011] Preferably, the SO3 content in the desulfurized lead-zinc metallurgical slag is 4% to 5% by mass.

[0012] In this invention, the SO3 contained in the desulfurized lead-zinc metallurgical slag can react with water to generate sulfate ions, which combine with calcium aluminate hydrate (CAH), an early cement hydration product, to generate crystalline calcium sulfoaluminate hydrate (AFt). This compensates for the plastic shrinkage caused by water loss in concrete before hardening, making the reinforced concrete structure more compact, thereby further improving the early strength of concrete and the bond strength between concrete and steel reinforcement.

[0013] Preferably, the preparation process of the desulfurized lead-zinc metallurgical slag includes the following steps:

[0014] Lead-zinc metallurgical slag is mixed evenly with limestone powder and calcined at 750-800℃ to obtain desulfurized lead-zinc metallurgical slag.

[0015] It is worth noting that if the SO3 content in the lead-zinc metallurgical slag composite admixture used in prefabricated buildings is high, it will have a corrosive effect on cement after being used in concrete, and will also produce more expansion phase products, affecting the strength and durability of concrete. This invention uses limestone powder as a desulfurizing agent, whose main function is to absorb sulfur oxides released from flue gas or promote the decomposition of sulfur-containing substances. At the same time, it can lower the desulfurization temperature and reduce energy consumption. This invention involves calcination at a temperature of 750–800℃, achieving a desulfurization rate of 75%–80%, minimizing energy consumption while ensuring control of the SO3 content in the metallurgical slag.

[0016] For example, after calcination, the process further includes cooling and ball milling. The ball milling is performed until the residue on a 45μm square-hole sieve is less than 20%, and the specific surface area is greater than 500m². 2 / kg.

[0017] More preferably, the lead-zinc metallurgical slag is composed of the following components in weight percentage: SO3 14%–18%, Fe2O3 20%–25%, SiO2 20%–25%, CaO 12%–15%, Al2O3 8%–10%, ZnO 4%–6%, MnO 1%–2%, and other components 4%–5%.

[0018] For example, the other components mentioned above include PbO, BaO, P2O5, Cr2O3, etc.

[0019] More preferably, the specific surface area of ​​the limestone powder is 200-210 m². 2 / kg.

[0020] More preferably, the mass ratio of the lead-zinc metallurgical slag to the limestone powder is (8-12):1.

[0021] This invention maximizes the desulfurization effect by limiting the mass ratio of lead-zinc metallurgical slag to limestone powder.

[0022] More preferably, the calcination time is 20 to 30 minutes.

[0023] Preferably, the specific surface area of ​​the mineral powder is 420-480 m². 2 / kg.

[0024] More preferably, the mineral powder is S95 grade mineral powder with a specific surface area of ​​450-480 m². 2 / kg.

[0025] The mineral powder of this invention contains a large number of spherical glassy particles. Preferably, the fineness of the mineral powder is smaller than that of cement, which can fill the gaps between cement particles and exist in concrete as micro-aggregates, forming the densest packing and thus optimizing the micropore structure of concrete.

[0026] Preferably, the specific surface area of ​​the silane coupling agent-modified magnesia is 300–340 m². 2 / kg.

[0027] Preferably, the silane coupling agent in the silane coupling agent modified magnesia is γ-aminopropyltriethoxysilane.

[0028] Preferably, the preparation process of the silane coupling agent modified magnesia includes the following steps:

[0029] Step a: Dissolve the silane coupling agent in an alcohol solvent to obtain a modifier alcohol solution;

[0030] Step b: The modified alcohol solution is evenly sprayed onto the surface of magnesia, stirred, and calcined at 100-110°C to obtain silane coupling agent modified magnesia.

[0031] More preferably, the alcohol solvent is an aqueous solution of alcohol, and the volume ratio of water to alcohol is 1:(8-9).

[0032] More preferably, the alcohol solvent includes an aqueous solution of isopropanol or an aqueous solution of ethanol.

[0033] More preferably, the concentration of the silane coupling agent in the modifier alcohol solution is 22wt% to 28wt%.

[0034] More preferably, the mass ratio of the silane coupling agent to the magnesia is 1:(60-70).

[0035] More preferably, the stirring rate is 1300-1400 r / min and the stirring time is 20-30 min.

[0036] More preferably, the roasting time is 4 to 5 hours.

[0037] By limiting the preparation conditions of silane coupling agent modified magnesia, this invention can make the filler more uniformly dispersed, thereby further improving the water repellency of the material and the durability of concrete.

[0038] Preferably, the specific surface area of ​​the sodium hydroxide is 210–230 m². 2 / kg.

[0039] This invention provides a method for preparing a lead-zinc metallurgical slag composite admixture for prefabricated buildings, comprising the following steps:

[0040] S1, respectively prepared desulfurized lead-zinc metallurgical slag and silane coupling agent modified magnesia;

[0041] S2, Weigh each raw material according to the design ratio, and mix the desulfurized lead-zinc metallurgical slag, mineral powder, silane coupling agent modified magnesia and sodium hydroxide evenly to obtain a composite admixture of lead-zinc metallurgical slag for prefabricated buildings.

[0042] The present invention also provides a prefabricated building concrete, comprising the above-mentioned lead-zinc metallurgical slag composite admixture for prefabricated buildings.

[0043] Preferably, the prefabricated building concrete comprises the following raw materials in parts by weight: 270-300 parts cement, 180-200 parts lead-zinc metallurgical slag composite admixture for prefabricated buildings, 830-870 parts sand, 830-870 parts stone, 140-160 parts water, and 1-3 parts water-reducing agent.

[0044] The prefabricated concrete with lead-zinc metallurgical slag composite admixture provided by this invention has better workability, enabling the concrete to meet the requirements for various physical and mechanical properties and durability, with higher early strength. It also reduces the demolding time of prefabricated concrete, accelerates mold turnover, and improves work efficiency. By replacing part of the cement with the prefabricated concrete with lead-zinc metallurgical slag composite admixture, this invention reduces the heat of hydration, decreases cracks caused by shrinkage during concrete hydration reaction and temperature stress, and improves the reliability of prefabricated building components. The desulfurized lead-zinc metallurgical slag and mineral powder in the prefabricated concrete with lead-zinc metallurgical slag composite admixture act as micro-aggregates in the concrete, improving the compactness of the concrete and the bond strength between the concrete and reinforcing steel.

[0045] More preferably, the cement is ordinary Portland cement with a PO42.5 or higher.

[0046] More preferably, the sand has an apparent density of 2.2–3.0 g / cm³. 3 The manufactured sand has a mud content of 1.2% to 2.2%.

[0047] More preferably, the stone is continuously graded crushed stone with a particle size of 5.0 to 26.5 mm.

[0048] More preferably, the water-reducing agent is at least one of polycarboxylate superplasticizer or naphthalene-based water-reducing agent, with a solid content ≥35% and a water reduction rate ≥25%.

[0049] This invention also provides a method for preparing prefabricated building concrete, comprising the following steps:

[0050] Weigh each raw material according to the design ratio, mix cement, prefabricated building lead-zinc metallurgical slag composite admixture, sand, stone, water and water-reducing agent evenly, fill into the mold, demold after 18-24 hours, and cure for 27-29 days to obtain prefabricated building concrete.

[0051] Preferably, the standard curing temperature is 18–22°C and the relative humidity is 90%–100%. Attached Figure Description

[0052] Figure 1 The image shows the XRD pattern of the desulfurized lead-zinc metallurgical slag in Example 1 of this invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0054] The first aspect of this invention provides a composite admixture of lead-zinc metallurgical slag for prefabricated buildings, comprising the following raw materials in parts by weight: 40-60 parts of desulfurized lead-zinc metallurgical slag, 20-40 parts of mineral powder, 3-6 parts of silane coupling agent modified magnesia, and 2-4 parts of sodium hydroxide.

[0055] The synergistic effect of specific proportions of desulfurized lead-zinc metallurgical slag and mineral powder in this invention can optimize the positive effects of lead-zinc metallurgical slag composite admixtures for prefabricated buildings and effectively control the negative effects. The dosage of silane coupling agent modified magnesia is limited to 3-6 parts. Increasing the dosage can easily lead to concrete expansion and cracking, while decreasing the dosage will result in a poorer expansion effect. Appropriate addition of sodium hydroxide can promote the dissolution of the vitreous body and activate the activity of lead-zinc metallurgical slag composite admixtures for prefabricated buildings. However, excessive dosage will lead to harmful alkali-aggregate reactions inside the concrete, resulting in concrete cracking and spalling.

[0056] A second aspect of this invention provides a method for preparing a lead-zinc metallurgical slag composite admixture for prefabricated buildings, comprising the following steps:

[0057] S1, respectively prepared desulfurized lead-zinc metallurgical slag and silane coupling agent modified magnesia;

[0058] S2, Weigh each raw material according to the design ratio, and mix the desulfurized lead-zinc metallurgical slag, mineral powder, silane coupling agent modified magnesia and sodium hydroxide evenly to obtain a composite admixture of lead-zinc metallurgical slag for prefabricated buildings.

[0059] The third aspect of the present invention provides a prefabricated building concrete, comprising the following raw materials in parts by weight: 270-300 parts of cement, 180-200 parts of lead-zinc metallurgical slag composite admixture for prefabricated buildings, 830-870 parts of sand, 830-870 parts of stone, 140-160 parts of water, and 1-3 parts of water-reducing agent.

[0060] In the embodiments and comparative examples of this invention, the cement is PO42.5 ordinary Portland cement, and the 28-day compressive strength of the mortar is 52.4 MPa; the sand has an apparent density of 2.5–2.8 g / cm³. 3 The manufactured sand contains 1.5% to 2.0% mud; the stone is continuously graded crushed stone with a particle size of 5.0 to 26.5 mm; the water-reducing agent is a polycarboxylate high-efficiency water-reducing agent or a naphthalene-based water-reducing agent with a solid content ≥35% and a water reduction rate ≥25%.

[0061] A fourth aspect of this invention provides a method for preparing prefabricated building concrete, comprising the following steps:

[0062] Weigh each raw material according to the design ratio, mix cement, prefabricated building lead-zinc metallurgical slag composite admixture, sand, stone, water and water-reducing agent evenly, fill into the mold, demold after 18-24 hours, and cure for 27-29 days to obtain prefabricated building concrete.

[0063] To better illustrate the present invention, further examples are provided below.

[0064] Example 1

[0065] This embodiment provides a composite admixture of lead-zinc metallurgical slag for prefabricated buildings, which is composed of the following raw materials in parts by weight: 40 parts of desulfurized lead-zinc metallurgical slag, 20 parts of mineral powder, 3 parts of silane coupling agent modified magnesia, and 2 parts of sodium hydroxide.

[0066] The preparation method of the above-mentioned lead-zinc metallurgical slag composite admixture for prefabricated buildings includes the following steps:

[0067] S1, mix 40 parts of lead-zinc metallurgical slag with 5 parts of material with a specific surface area of ​​200 m² 2 Mix / kg of limestone powder evenly, place it in a muffle furnace, calcine at 750℃ for 30min, and cool to room temperature; then place it in a ball mill and ball mill until the residue on a 45μm square-hole sieve is greater than 20%, yielding a specific surface area of ​​505m². 2 / kg of desulfurized lead-zinc metallurgical slag. The lead-zinc metallurgical slag is composed of the following components by mass percentage: SO3 14%, Fe2O3 25%, SiO2 25%, CaO 15%, Al2O3 10%, ZnO 5%, MnO 2%, and other components 4%.

[0068] S2, dissolve γ-aminopropyltriethoxysilane in an aqueous isopropanol solution (the volume ratio of water to isopropanol is 1:8) to obtain a 22wt% modifier alcohol solution.

[0069] The above-mentioned modifier alcohol solution was uniformly sprayed onto the surface of magnesia (wherein the mass ratio of γ-aminopropyltriethoxysilane to magnesia was 1:60), stirred at a rate of 1300 r / min for 30 min, and calcined at 100℃ for 5 h to obtain a specific surface area of ​​300 m². 2 / kg of silane coupling agent modified magnesia.

[0070] It is worth noting that steps S1 and S2 are not in any particular order.

[0071] S3, weigh each raw material according to the design ratio, including the above-mentioned desulfurized lead-zinc metallurgical slag with a specific surface area of ​​430m³. 2 / kg of S95 grade mineral powder, the above-mentioned silane coupling agent modified magnesia, and a specific surface area of ​​210m² 2 / kg of sodium hydroxide is mixed evenly to obtain a composite admixture of lead-zinc metallurgical slag for prefabricated buildings.

[0072] Example 2

[0073] This embodiment provides a composite admixture of lead-zinc metallurgical slag for prefabricated buildings, which is composed of the following raw materials in parts by weight: 50 parts of desulfurized lead-zinc metallurgical slag, 30 parts of mineral powder, 4 parts of silane coupling agent modified magnesia, and 3 parts of sodium hydroxide.

[0074] The preparation method of the above-mentioned lead-zinc metallurgical slag composite admixture for prefabricated buildings includes the following steps:

[0075] S1, mix 50 parts of lead-zinc metallurgical slag with 5 parts of material with a specific surface area of ​​210 m² 2 Mix / kg of limestone powder evenly, place it in a muffle furnace, calcine at 780℃ for 25min, and cool to room temperature; then place it in a ball mill and ball mill until the residue on a 45μm square hole sieve is greater than 20%, yielding a specific surface area of ​​525m². 2 / kg of desulfurized lead-zinc metallurgical slag. The lead-zinc metallurgical slag is composed of the following components by mass percentage: SO3 16%, Fe2O3 24%, SiO2 24%, CaO 14%, Al2O3 9%, ZnO 6%, MnO 2%, and other components 5%.

[0076] S2, dissolve γ-aminopropyltriethoxysilane in an aqueous ethanol solution (water to ethanol volume ratio of 1:9) to obtain a 25wt% modifier alcohol solution.

[0077] The above-mentioned modifier alcohol solution was uniformly sprayed onto the surface of magnesia (wherein the mass ratio of γ-aminopropyltriethoxysilane to magnesia was 1:65), stirred at a rate of 1350 r / min for 25 min, and calcined at 105 °C for 4.5 h to obtain a specific surface area of ​​320 m². 2 / kg of silane coupling agent modified magnesia.

[0078] It is worth noting that steps S1 and S2 are not in any particular order.

[0079] S3, weigh each raw material according to the design ratio, including the above-mentioned desulfurized lead-zinc metallurgical slag with a specific surface area of ​​450m³. 2 / kg of S95 grade mineral powder, the above-mentioned silane coupling agent modified magnesia, and a specific surface area of ​​220m² 2 / kg of sodium hydroxide is mixed evenly to obtain a composite admixture of lead-zinc metallurgical slag for prefabricated buildings.

[0080] Example 3

[0081] This embodiment provides a composite admixture of lead-zinc metallurgical slag for prefabricated buildings, which is composed of the following raw materials in parts by weight: 60 parts of desulfurized lead-zinc metallurgical slag, 40 parts of mineral powder, 6 parts of silane coupling agent modified magnesia, and 4 parts of sodium hydroxide.

[0082] The preparation method of the above-mentioned lead-zinc metallurgical slag composite admixture for prefabricated buildings includes the following steps:

[0083] S1, mix 60 parts of lead-zinc metallurgical slag with 5 parts of slag with a specific surface area of ​​210 m² 2Mix / kg of limestone powder evenly, place it in a muffle furnace, calcine at 800℃ for 20min, and cool to room temperature; then place it in a ball mill and ball mill until the residue on a 45μm square hole sieve is greater than 20%, yielding a specific surface area of ​​550m². 2 / kg of desulfurized lead-zinc metallurgical slag. The lead-zinc metallurgical slag is composed of the following components by mass percentage: SO3 18%, Fe2O3 25%, SiO2 22%, CaO 15%, Al2O3 10%, ZnO 4%, MnO 1%, and other components 5%.

[0084] S2, dissolve γ-aminopropyltriethoxysilane in an aqueous ethanol solution (water to ethanol volume ratio of 1:8) to obtain a 28wt% modifier alcohol solution.

[0085] The above-mentioned modifier alcohol solution was uniformly sprayed onto the surface of magnesia (wherein the mass ratio of γ-aminopropyltriethoxysilane to magnesia was 1:70), stirred at a rate of 1400 r / min for 20 min, and calcined at 110℃ for 4 h to obtain a specific surface area of ​​340 m². 2 / kg of silane coupling agent modified magnesia.

[0086] It is worth noting that steps S1 and S2 are not in any particular order.

[0087] S3, weigh each raw material according to the design ratio, including the above-mentioned desulfurized lead-zinc metallurgical slag with a specific surface area of ​​480m³. 2 / kg of S95 grade mineral powder, the above-mentioned silane coupling agent modified magnesia, and a specific surface area of ​​230m² 2 / kg of sodium hydroxide is mixed evenly to obtain a composite admixture of lead-zinc metallurgical slag for prefabricated buildings.

[0088] Example 4

[0089] This embodiment provides a prefabricated building concrete, which is composed of the following raw materials in parts by weight: 270 parts of PO42.5 ordinary Portland cement, 180 parts of lead-zinc metallurgical slag composite admixture for prefabricated buildings in Example 1, 830 parts of sand, 830 parts of stone, 140 parts of water and 1 part of water-reducing agent.

[0090] The above-mentioned method for preparing prefabricated building concrete includes the following steps:

[0091] Weigh each raw material according to the design ratio, put cement, lead-zinc metallurgical slag composite admixture for prefabricated buildings, sand, stone, water and water-reducing agent into a concrete mixer and mix evenly. Fill the mold, demold after 1 day, and cure for 28 days under standard curing conditions (20±2℃, 95%±5% relative humidity) to obtain prefabricated building concrete.

[0092] Example 5

[0093] This embodiment provides a prefabricated building concrete, which is composed of the following raw materials in parts by weight: 290 parts of PO42.5 ordinary Portland cement, 190 parts of lead-zinc metallurgical slag composite admixture for prefabricated buildings according to Example 2, 850 parts of sand, 850 parts of stone, 150 parts of water and 2 parts of water-reducing agent.

[0094] The preparation method of the prefabricated building concrete described above is the same as that in Example 4, except that the raw materials are weighed according to the design proportions of this example.

[0095] Example 6

[0096] This embodiment provides a prefabricated building concrete, which is composed of the following raw materials in parts by weight: 300 parts of PO42.5 ordinary Portland cement, 200 parts of lead-zinc metallurgical slag composite admixture for prefabricated buildings according to Example 3, 870 parts of sand, 870 parts of stone, 160 parts of water and 3 parts of water-reducing agent.

[0097] The preparation method of the prefabricated building concrete described above is the same as that in Example 4, except that the raw materials are weighed according to the design proportions of this example.

[0098] Comparative Example 1

[0099] This comparative example provides a composite admixture of lead-zinc metallurgical slag for prefabricated buildings, which is composed of the following raw materials in parts by weight: 50 parts of desulfurized lead-zinc metallurgical slag, 30 parts of mineral powder, 4 parts of magnesia, and 3 parts of sodium hydroxide.

[0100] The preparation method of the above-mentioned lead-zinc metallurgical slag composite admixture for prefabricated buildings is similar to that in Example 2, except that the magnesia is not modified with a silane coupling agent. The specific steps are as follows:

[0101] S1, same as Example 2.

[0102] S2, weigh each raw material according to the design ratio, including the above-mentioned desulfurized lead-zinc metallurgical slag with a specific surface area of ​​450m³. 2 S95 grade mineral powder per kg, with a specific surface area of ​​320 m² 2 / kg of magnesia and a specific surface area of ​​220m² 2 / kg of sodium hydroxide is mixed evenly to obtain a composite admixture of lead-zinc metallurgical slag for prefabricated buildings.

[0103] Comparative Example 2

[0104] This comparative example provides a composite admixture of lead-zinc metallurgical slag for prefabricated buildings, which is composed of the following raw materials in parts by weight: 50 parts of desulfurized lead-zinc metallurgical slag, 30 parts of mineral powder, 4 parts of lithium slag, and 3 parts of sodium hydroxide.

[0105] The preparation method of the above-mentioned lead-zinc metallurgical slag composite admixture for prefabricated buildings is similar to that in Example 2, except that magnesia is replaced with lithium slag and no silane coupling agent modification is performed. The specific steps are as follows:

[0106] S1, same as Example 2.

[0107] S2, weigh each raw material according to the design ratio, including the above-mentioned desulfurized lead-zinc metallurgical slag with a specific surface area of ​​450m³. 2 S95 grade mineral powder per kg, with a specific surface area of ​​320 m² 2 / kg of lithium slag and a specific surface area of ​​220m² 2 / kg of sodium hydroxide is mixed evenly to obtain a composite admixture of lead-zinc metallurgical slag for prefabricated buildings.

[0108] Comparative Example 3

[0109] This comparative example provides a composite admixture of lead-zinc metallurgical slag for prefabricated buildings, which is composed of the following raw materials in parts by weight: 50 parts of lead-zinc metallurgical slag, 30 parts of mineral powder, 4 parts of silane coupling agent modified magnesia, and 3 parts of sodium hydroxide.

[0110] The preparation method of the above-mentioned lead-zinc metallurgical slag composite admixture for prefabricated buildings is similar to that in Example 2, except that the lead-zinc metallurgical slag is not desulfurized. The specific steps are as follows:

[0111] S1 is the same as step S2 in Example 2.

[0112] S2, weigh each raw material according to the design ratio, and weigh the raw material with a specific surface area of ​​525m². 2 / kg of lead-zinc metallurgical slag (mass composition same as in Example 2), with a specific surface area of ​​450m² 2 / kg of S95 grade mineral powder, the above-mentioned silane coupling agent modified magnesia, and a specific surface area of ​​220m² 2 / kg of sodium hydroxide is mixed evenly to obtain a composite admixture of lead-zinc metallurgical slag for prefabricated buildings.

[0113] Comparative Example 4

[0114] This comparative example provides a prefabricated building concrete, which is composed of the following raw materials in parts by weight: 290 parts of PO42.5 ordinary Portland cement, 190 parts of lead-zinc metallurgical slag composite admixture for prefabricated buildings according to Comparative Example 1, 850 parts of sand, 850 parts of stone, 150 parts of water and 2 parts of water-reducing agent.

[0115] The preparation method of the prefabricated building concrete described above is the same as that in Example 4, except that the raw materials are weighed according to the design proportions of this comparative example.

[0116] Comparative Example 5

[0117] This comparative example provides a prefabricated building concrete, which is composed of the following raw materials in parts by weight: 290 parts of PO42.5 ordinary Portland cement, 190 parts of lead-zinc metallurgical slag composite admixture for prefabricated buildings according to Comparative Example 2, 850 parts of sand, 850 parts of stone, 150 parts of water and 2 parts of water-reducing agent.

[0118] The preparation method of the prefabricated building concrete described above is the same as that in Example 4, except that the raw materials are weighed according to the design proportions of this comparative example.

[0119] Comparative Example 6

[0120] This comparative example provides a prefabricated building concrete, which is composed of the following raw materials in parts by weight: 290 parts of PO42.5 ordinary Portland cement, 190 parts of lead-zinc metallurgical slag composite admixture for prefabricated buildings (Comparative Example 3), 850 parts of sand, 850 parts of stone, 150 parts of water, and 2 parts of water-reducing agent.

[0121] The preparation method of the prefabricated building concrete described above is the same as that in Example 4, except that the raw materials are weighed according to the design proportions of this comparative example.

[0122] Comparative Example 7

[0123] This comparative example provides a prefabricated building concrete, composed of the following raw materials in parts by weight: 290 parts of PO42.5 ordinary Portland cement, 190 parts of concrete mineral admixtures, 850 parts of sand, 850 parts of aggregate, 150 parts of water, and 2 parts of water-reducing agent. The concrete mineral admixtures are commercially available Class II composite admixtures conforming to JG / T486-2015, composed of the following raw materials in parts by weight: 65 parts of fly ash and 125 parts of mineral powder.

[0124] The preparation method of the prefabricated building concrete described above is the same as that in Example 4, except that the raw materials are weighed according to the design proportions of this comparative example.

[0125] Comparative Example 8

[0126] This comparative example provides a prefabricated building concrete, which is composed of the following raw materials in parts by weight: 480 parts of PO42.5 ordinary Portland cement, 850 parts of sand, 850 parts of aggregate, 150 parts of water and 2 parts of water-reducing agent.

[0127] The preparation method of the prefabricated building concrete described above is the same as that in Example 4, except that the raw materials are weighed according to the design proportions of this comparative example.

[0128] Example of effect

[0129] The quality of the lead-zinc metallurgical slag composite admixtures for prefabricated buildings provided in Examples 1-3 and Comparative Examples 1-3 was tested. The fluidity ratio was determined according to the "Method for Determination of Flowability of Cement Mortar" (GB / T 2419-2016), the activity index was determined according to the "Method for Testing the Strength of Cement Mortar (ISO Method)" (GB / T 17671-2020), the sulfur trioxide content, loss on ignition, and chloride ion content were determined according to the "Cement Chemical Analysis Method" (GB / T 176-2017), and the specific surface area was determined according to the "Method for Determination of Specific Surface Area of ​​Cement - Blaine Method" (GB / T 8074-2008). The results are shown in Table 1. As can be seen from Table 1, the fluidity, sulfur trioxide content, and activity index of the lead-zinc metallurgical slag composite admixtures for prefabricated buildings provided by this invention all meet the technical indicators of the mineral admixture application technical specification in standard GB / T1003-2014, and can be used in green high-performance concrete.

[0130] Table 1. Quality test results of lead-zinc metallurgical slag composite admixtures for prefabricated buildings in Examples 1-3 and Comparative Examples 1-3.

[0131]

[0132]

[0133] Performance tests were conducted on the prefabricated building concrete provided in Examples 4-6 and Comparative Examples 4-8. The compressive strength of the concrete was determined according to the "Standard for Testing and Evaluation of Concrete Strength" (GB / T 50107-2010), the bond strength according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081-2019), and the 7-day autogenous shrinkage according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50082-2019). The results are shown in Table 2. As can be seen from Table 2, when the lead-zinc metallurgical slag composite admixture for prefabricated buildings provided by this invention is applied to prefabricated building concrete, all physical and mechanical properties and durability properties meet the requirements. It has good workability, higher early strength, and the compressive strength after 18 hours of demolding reaches the compressive strength after 24 hours of demolding in Comparative Example 8, greatly shortening the demolding time. The 7-day autogenous shrinkage rate is significantly better than that of the comparative examples, and the bond strength with the reinforcing steel at 28 days reaches 17.19 MPa. It can directly replace part of the cement in the production of prefabricated building concrete of different grades, and its comprehensive performance is significantly better than the concrete composite admixture in Comparative Example 7 and the ordinary Portland cement in Comparative Example 8.

[0134] Table 2 shows the performance test results of prefabricated building concrete in Examples 4-6 and Comparative Examples 4-8.

[0135]

[0136]

[0137] In summary, the lead-zinc metallurgical slag composite admixture for prefabricated buildings provided by this invention can directly replace a portion of cement in the production of prefabricated building concrete of different grades, and its overall performance is significantly superior to the comparative example. This invention utilizes lead-zinc metallurgical slag as a raw material, which not only saves production costs but also realizes the secondary utilization of metallurgical slag, maximizing benefits. This is of great significance for achieving industrial restructuring and protecting the ecological environment.

[0138] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite admixture of lead-zinc metallurgical slag for prefabricated buildings, characterized in that, The raw materials include the following parts by weight: 40-60 parts of desulfurized lead-zinc metallurgical slag, 20-40 parts of mineral powder, 3-6 parts of silane coupling agent modified magnesia, and 2-4 parts of sodium hydroxide; The preparation process of the desulfurized lead-zinc metallurgical slag includes the following steps: The lead-zinc metallurgical slag is mixed evenly with limestone powder and calcined at 750~800℃ to obtain desulfurized lead-zinc metallurgical slag. The lead-zinc metallurgical slag is composed of the following components in mass percentage: SO3 14%~18%, Fe2O3 20%~25%, SiO2 20%~25%, CaO 12%~15%, Al2O3 8%~10%, ZnO 4%~6%, MnO 1%~2%, and other components 4%~5%; The preparation process of the silane coupling agent modified magnesia includes the following steps: Step a: Dissolve the silane coupling agent in an alcohol solvent to obtain a modifier alcohol solution; Step b: The modified alcohol solution is evenly sprayed onto the surface of magnesia, stirred, and calcined at 100~110℃ to obtain silane coupling agent modified magnesia. The mass ratio of the silane coupling agent to the magnesite is 1:(60~70).

2. The lead-zinc metallurgical slag composite admixture for prefabricated buildings as described in claim 1, characterized in that, The SO3 content in the desulfurized lead-zinc metallurgical slag is 4%~5% by mass; and / or The silane coupling agent in the modified magnesia is γ-aminopropyltriethoxysilane.

3. The lead-zinc metallurgical slag composite admixture for prefabricated buildings as described in claim 1, characterized in that, The specific surface area of ​​the desulfurized lead-zinc metallurgical slag is 500~550m². 2 / kg; and / or The specific surface area of ​​the mineral powder is 420~480m². 2 / kg; and / or The specific surface area of ​​the silane coupling agent modified magnesia is 300~340 m². 2 / kg; and / or The specific surface area of ​​the sodium hydroxide is 210~230 m². 2 / kg.

4. The lead-zinc metallurgical slag composite admixture for prefabricated buildings as described in claim 1, characterized in that, The specific surface area of ​​the limestone powder is 200~210m². 2 / kg; and / or The mass ratio of the lead-zinc metallurgical slag to the limestone powder is (8~12):1; and / or The calcination time is 20-30 minutes.

5. The lead-zinc metallurgical slag composite admixture for prefabricated buildings as described in claim 1, characterized in that, The alcohol solvent is an aqueous solution of an alcohol, with a water-to-alcohol volume ratio of 1:(8~9); and / or The concentration of the silane coupling agent in the modified alcohol solution is 22wt%~28wt%; and / or The stirring rate is 1300~1400 r / min, and the time is 20~30 min; and / or The roasting time is 4-5 hours.

6. The preparation method of the lead-zinc metallurgical slag composite admixture for prefabricated buildings according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1, respectively prepared desulfurized lead-zinc metallurgical slag and silane coupling agent modified magnesia; S2, Weigh each raw material according to the design ratio, and mix the desulfurized lead-zinc metallurgical slag, mineral powder, silane coupling agent modified magnesia and sodium hydroxide evenly to obtain a composite admixture of lead-zinc metallurgical slag for prefabricated buildings.

7. A type of prefabricated building concrete, characterized in that, Includes the lead-zinc metallurgical slag composite admixture for prefabricated buildings as described in any one of claims 1 to 5.

8. The prefabricated building concrete as described in claim 7, characterized in that, The prefabricated building concrete comprises the following raw materials in parts by weight: 270-300 parts cement, 180-200 parts lead-zinc metallurgical slag composite admixture for prefabricated buildings, 830-870 parts sand, 830-870 parts stone, 140-160 parts water, and 1-3 parts water-reducing agent.

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