High-activity multi-source solid waste-based cement admixture and preparation method thereof

Abstract

The invention belongs to the field of cement admixture preparation, and relates to a high-activity multi-source solid-waste-based cement admixture and a preparation method thereof.The high-activity multi-source solid-waste-based cement admixture is prepared from, by mass, 30-50 parts of steel slag, 20-30 parts of fly ash, 10-40 parts of blast furnace slag and 8-12 parts of desulfurized gypsum; the content ratio of alkaline oxide to acidic oxide in the solid waste-based cement admixture is close to 1, and SO3 is 5-8wt%; according to the invention, the respectively ground solid waste raw materials are scientifically compounded according to the characteristics of chemical composition complementation and activity mutual excitation, and the hydration activity of the cement admixture is greatly improved, so that the utilization efficiency of the cement admixture in a cement-based material is remarkably improved. According to the preparation method of the multi-source solid waste-based cement admixture provided by the invention, solid wastes such as steel slag, fly ash and desulfurized gypsum can be consumed on a large scale, the use of cement clinker in a traditional cementing material is reduced, and the low-carbon green development of the cement industry is promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of cement admixtures, and particularly relates to a high-activity multi-source solid waste-based cement admixture and a preparation method thereof. Background Art

[0002] Energy conservation, environmental protection and comprehensive utilization of solid waste resources have increasingly become the theme of the development of the times. On the one hand, as typical bulk industrial solid wastes, the production of steel slag, fly ash, desulfurized gypsum, etc. is huge, but the utilization rate is low. The accumulation of a large amount of solid waste not only occupies a large amount of land, but also causes serious pollution to the ecological environment. There is an urgent need for large-scale resource utilization of it; on the other hand, cement is a common building inorganic binder. The firing process of cement clinker not only consumes a large amount of fossil energy, but also emits a large amount of greenhouse gas CO2. As a high-energy-consuming and highly polluting industry, the green transformation and development of cement production are imminent.

[0003] Cement admixtures refer to auxiliary cementitious materials incorporated into cement clinker during the cement production process. The addition of cement admixtures can, on the one hand, greatly reduce the amount of cement clinker used. On the other hand, the active components in the cement admixtures will also participate in the cement hydration process, thereby greatly improving the mechanical properties of the cement. In addition, the addition of cement admixtures can also alleviate the hydration shrinkage of cement clinker to a certain extent and improve the stability of cement products. At present, common cement admixtures include blast furnace slag powder, fly ash, desulfurized gypsum, etc. However, due to problems such as low activity of the admixtures (the 28-day activity index is generally less than 95%), the addition amount of current cement admixtures is generally low, which is not conducive to the low-carbon and green development of the cement industry and also hinders the large-scale resource utilization of bulk industrial solid wastes. Summary of the Invention

[0004] The main purpose of the present invention is to overcome the deficiencies in the prior art and provide a high-activity multi-source solid waste-based cement admixture and a preparation method thereof. The present invention uses steel slag, blast furnace slag, fly ash, and desulfurized gypsum as raw materials, and prepares a high-quality multi-source solid waste-based cement admixture according to the complementary characteristics and mutual activation of activities of different raw material components. Compared with traditional single cement admixtures, the activity of the cement admixture of the present invention is significantly improved, thereby greatly increasing its incorporation amount in cement-based materials and promoting the further enhancement of the mechanical properties of cement.

[0005] The present invention is realized through the following technical solutions: A high-activity multi-source solid waste-based cement admixture, the composition of its raw materials and their mass ratios are: 30-50 parts of steel slag, 20-30 parts of fly ash, 10-40 parts of blast furnace slag, 8-12 parts of desulfurized gypsum; and, in the solid waste-based cement admixture, (CaO wt% + MgO wt%) : (SiO2 wt% + Al2O3 wt%) = 0.95-1.05, and SO3 is 5wt% - 8wt%.

[0006] The essence of the synergistic reaction of steel slag, fly ash, and blast furnace slag is an acid-base neutralization reaction, that is, the process in which acidic oxides such as SiO2 and Al2O3 react with basic oxides such as CaO and MgO in an aqueous solution to form calcium aluminosilicate hydrate (C-A-S-H) and magnesium aluminosilicate hydrate (M-A-S-H). In order to maximize the composite synergistic effect, the key to the component design of steel slag, fly ash, and blast furnace slag in the cement admixture is to adjust the ratio of the contents of CaO wt% and MgO wt% to the contents of SiO2 wt% and Al2O3 wt% to be as close to 1 as possible; and the role of desulfurized gypsum in the admixture is to provide SO4 at the initial stage of hydration 2- to form ettringite, thereby improving the early strength. Since the early strength of solid waste-based cement is generally lower than that of traditional cement, the dosage of desulfurized gypsum is appropriately increased so that the content of SO3 is 5% - 8%.

[0007] Furthermore, the raw materials of the solid waste-based cement admixture, namely steel slag, fly ash, blast furnace slag, and desulfurized gypsum, are all powder materials obtained after drying and grinding treatments.

[0008] Furthermore, the particle size of the steel slag is 0.3μm - 10μm, and the specific surface area ≥ 750m 2 / kg; the particle size of the fly ash is 0.5μm - 20μm, and the specific surface area ≥ 650m 2 / kg; the particle size of the blast furnace slag is 0.5μm - 20μm, and the specific surface area ≥ 600m 2 / kg, and the particle size of the desulfurized gypsum is 0.5μm - 40μm, and the specific surface area ≥ 550m 2 / kg.

[0009] Furthermore, the mass percentage of CaO in the steel slag is not less than 45wt%; the sum of the mass percentages of SiO2 and Al2O3 in the fly ash is not less than 65wt%; the mass percentage of CaO in the blast furnace slag is not less than 40wt%, and the mass percentage of SiO2 is not less than 30wt%; the mass percentage of CaSO4 in the desulfurized gypsum is not less than 85wt%.

[0010] A preparation method of a highly active multi-source solid waste-based cement admixture includes the following steps: S1. Raw material pretreatment: Thoroughly dry the steel slag, blast furnace slag, fly ash, and desulfurized gypsum, and then use a grinding device to grind and refine the raw materials respectively to obtain powder raw materials for later use; during the solid waste grinding and refinement process, the crystallization degree of solid waste particles decreases, and the activity is greatly improved. At the same time, due to the pore filling effect of small particles on the cement-based material, a denser structure of the cement-based material can be achieved to meet specific requirements; S2. Material mixing: Weigh the powder raw materials prepared in step S1 according to the raw material composition and mass ratio of the solid waste-based cement admixture, and then place them in a mixer and mix for 3 - 5 minutes to obtain a highly active multi-source solid waste-based cement admixture.

[0011] The beneficial effects of the present invention are as follows: By using a variety of solid wastes to compound and prepare the cement admixture, and rationally designing the raw material mix ratio according to the complementary chemical components and mutually stimulating activity characteristics of different solid wastes, the hydration activity of the solid waste-based cement admixture is greatly improved, the dosage in cement-based materials is significantly increased, the mechanical properties of cement-based materials are improved, and the resource utilization efficiency of industrial solid wastes is promoted. Description of the Drawings

[0012] Figure 1 It is the particle size distribution diagram of steel slag, blast furnace slag, fly ash and desulfurized gypsum in the specific embodiment. Specific Embodiment

[0013] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the present invention is not limited to the following embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0014] In this specific embodiment, steel slag, fly ash, blast furnace slag and desulfurized gypsum are used as raw materials, and steel slag, blast furnace slag, fly ash and desulfurized gypsum are all powdery materials obtained after drying and grinding. The particle size distribution of each raw material is as Figure 1 shown. After grinding, the particle size of steel slag is 0.3μm - 10μm, and the specific surface area ≥ 750m 2 / kg, and the mass percentage of CaO in steel slag is not less than 45wt%; the particle size of the fly ash is 0.5μm - 20μm, and the specific surface area ≥ 650m 2 / kg, and the sum of the mass percentages of SiO2 and Al2O3 in fly ash is not less than 65wt%; the particle size of the blast furnace slag is 0.5μm - 20μm, and the specific surface area ≥ 600m 2 / kg, and the mass percentage of CaO in blast furnace slag is not less than 40wt%, and the mass percentage of SiO2 is not less than 30wt%; the particle size of the desulfurized gypsum is 0.5μm - 40μm, and the specific surface area ≥ 550m 2 / kg, and the mass percentage of CaSO4 in desulfurized gypsum is not less than 85wt%.

[0015] A preparation method of a highly active multi-source solid waste-based cement admixture, comprising the following steps: S1. Raw material pretreatment: Thoroughly dry the steel slag, blast furnace slag, fly ash, and desulfurized gypsum, and then use grinding equipment to grind and refine the raw materials separately to obtain powder raw materials for subsequent use. During the grinding and refinement of solid waste, the crystallization degree of solid waste particles decreases, and the activity increases significantly. At the same time, due to the pore filling effect of small particles on cement-based materials, a denser structure of cement-based materials can be achieved to meet specific requirements. S2. Material mixing: This specific embodiment includes a total of five groups of embodiments, namely Embodiment 1 to Embodiment 5. Their compositions and mass percentages are shown in Table 1 below. Weigh the powder raw materials prepared in step S1 according to the raw material composition and mass ratio of the solid waste-based cement admixture in Table 1, and then place them in a blender and mix for 3 - 5 minutes to obtain a highly active multi-source solid waste-based cement admixture. The activity index tests were carried out on the highly active multi-source solid waste-based cement admixtures prepared in Embodiment 1 to Embodiment 5 respectively, and the test results are shown in Table 1 below.

[0016]

[0017] According to the activity index test results of the highly active multi-source solid waste-based cement admixtures prepared in Embodiment 1 to Embodiment 5 in Table 1, the 28-day activity index is 99% - 125%, far exceeding the currently commonly used commercially available S95 (activity index of 95%) grade mineral powder. Therefore, due to its high activity, the highly active multi-source solid waste-based cement admixture provided by the present invention can be used in high dosages in cement-based materials and enhance the mechanical properties of cement-based materials.

[0018] As mentioned above, the above is only the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claimed rights.

Claims

1. A high-activity multi-source solid waste-based cement admixture, characterized in that: The raw material composition and mass ratio of the solid waste-based cement admixture are as follows: 30-50 parts of steel slag, 20-30 parts of fly ash, 10-40 parts of blast furnace slag, and 8-12 parts of desulfurized gypsum; moreover, in the solid waste-based cement admixture, (CaO wt% + MgO wt%):(SiO2 wt% + Al2O3 wt%) = 0.95-1.05, and SO3 is 5wt%-8wt%.

2. The high-activity multi-source solid waste-based cement admixture according to claim 1, characterized in that: The raw materials of the solid waste-based cement admixture, namely steel slag, fly ash, blast furnace slag, and desulfurized gypsum, are all powder materials obtained after drying and grinding treatments.

3. The highly active multi-source solid waste-based cement admixture according to claim 1 or 2, wherein: The particle size of the steel slag is 0.3 μm to 10 μm, and the specific surface area is ≥ 750 m 2 / kg; the particle size of the fly ash is 0.5 μm to 20 μm, and the specific surface area is ≥ 650 m 2 / kg; the particle size of the blast furnace slag is 0.5 μm to 20 μm, and the specific surface area is ≥ 600 m 2 / kg, and the particle size of the desulfurized gypsum is 0.5 μm to 40 μm, and the specific surface area is ≥ 550 m 2 / kg.

4. A highly active multi-source solid waste-based cement admixture according to claim 3, characterized in that: The mass percentage of CaO in the steel slag is not less than 45wt%; the sum of the mass percentages of SiO2 and Al2O3 in the fly ash is not less than 65wt%; the mass percentage of CaO in the blast furnace slag is not less than 40wt%, and the mass percentage of SiO2 is not less than 30wt%; the mass percentage of CaSO4 in the desulfurized gypsum is not less than 85wt%.

5. A preparation method of a highly active multi-source solid waste-based cement admixture as described in claim 1, characterized in that, It includes the following steps: S1. Raw material pretreatment: Sufficiently dry the steel slag, blast furnace slag, fly ash, and desulfurized gypsum, and then use a grinding device to grind and refine the raw materials respectively to obtain powder raw materials for later use; S2. Material mixing: Weigh the powder raw materials prepared in step S1 according to the raw material composition and mass ratio of the solid waste-based cement admixture, and then place them in a mixer and mix for 3-5 minutes to obtain a highly active multi-source solid waste-based cement admixture.

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