Alkaline magnesium oxysulfate cement and preparation method thereof

Abstract

The invention relates to alkaline magnesium oxysulfate cement and a preparation method thereof. The alkaline magnesium oxysulfate cement is prepared from magnesium oxide, magnesium sulfate heptah, coal ash, core additives and water, wherein the core additives include a first core additive and a second core additive, and the first core additive is inorganic acid, and the second core additive is organic acid. The preparation method includes the steps: (1) dissolving the magnesium sulfate heptah in the water to prepare magnesium sulfate heptah solution; (2) weighing raw materials according to ratio; (3) adding the first core additive into the magnesium sulfate heptah solution; (4) sequentially adding the second core additive and the coal ash into the magnesium oxide, uniformly stirring the raw materials, adding the mixture into the magnesium sulfate heptah solution obtained in the step (3), and uniformly stirring the mixture and the solution to form cement paste. The completely hydrated alkaline magnesium oxysulfate cement is prepared, the hydrated phase of the magnesium oxysulfate cement is improved by leading in the core additives, a novel insoluble crystal whisker hydrated phase is generated, and further the strength, the flexibility and the water resistance of the novel insoluble crystal whisker hydrated phase are obviously superior to those of the magnesium oxysulfate cement.

Description

technical field [0001] The invention relates to the field of cement, in particular to a process for preparing alkaline magnesium oxysulfate cement by using magnesium desulfurization by-products and fly ash of coal-fired units. Background technique [0002] Magnesium oxysulfate cement is MgO-MgSO4 which is prepared by mixing active magnesium oxide and magnesium sulfate solution. 4 -H 2 O Aerohard cementitious material. Like magnesium oxychloride cement, it has the characteristics of light weight and fast gelation, but magnesium oxychloride cement overcomes the shortcomings of magnesium oxychloride cement such as moisture absorption, halogen return, and corrosion of steel bars. It has good temperature resistance, but its mechanical strength is much lower. Lower than magnesium oxychloride cement, and poor waterproof performance, these shortcomings limit its wide application. Therefore, improving the mechanical strength of magnesium oxysulfide cement is beneficial to the engi...

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Problems solved by technology

[0007] The invention provides a process for preparing alkaline magnesium oxysulfide cement by using magnesium sulfate heptahydrate, a by-product of magnesium oxysulfide desulfurization, and fly ash of coal-fired units. The process solves the problems of poor mechanical strength and water resistance of magnesium oxysulfide cement , and realized the full utilization of magnesium desulfurization waste liquid and power plant fly ash solid waste

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