Retarder matched with magnesia expansive agent and preparation method thereof

Abstract

The invention relates to a retarder matched with a magnesia expansive agent. The retarder comprises the components in percentage by mass as follows: 5%-10% of ammonium oxalate, 10%-20% of ammonium phosphate, 20%-30% of ammonium citrate, and the balance water. The invention further relates to a preparation method of the retarder. The retarder matched with the magnesia expansive agent can not only improve the initial fluidity of a cement paste mixed with the magnesia expansive agent, but also improve the fluidity keeping capacity of the cement paste after 60 min remarkably, and has an excellent retarding effect; and the retarder can retard the early-stage hydration of the magnesia expansive agent and improve the working performance of magnesium oxide concrete, and does not reduce the reaction activity of the magnesia expansive agent, so that the expansion performance of the magnesia expansive agent cannot be weakened. A preparation method of the retarder matched with the magnesia expansive agent has the characteristics that raw materials can be purchased conveniently, and the preparation process is simple and feasible, so that the retarder can be popularized and applied conveniently.

Description

technical field [0001] The invention belongs to the technical field of concrete admixtures, and in particular relates to a retarder compatible with a magnesium oxide expansion agent and a preparation method thereof. Background technique [0002] After the concrete is poured, due to the large amount of heat of hydration generated by the hydration of the cement, the temperature of the concrete rises, resulting in volumetric thermal expansion. After reaching the maximum temperature, as the heat dissipates to the external environment, the temperature will drop from the maximum value to a stable or quasi-stable value, and temperature shrinkage stress will be generated. When the shrinkage stress exceeds the ultimate tensile strength of concrete, it will lead to concrete cracking . In the construction of water conservancy and hydropower projects, the temperature shrinkage crack of mass concrete is one of the key factors affecting the quality and durability of the project. Chinese...

AI Technical Summary

Problems solved by technology

Obviously, when this retarder and magnesium oxide expansion agent are used in combination, the magnesium oxide expansion agent will lose its reactivity, resulting in a decrease in its expansion performance.

Moreover, the aluminum hydroxide disclosed in this patent is a relatively insoluble substance, which is easy to precipitate out of the mixed solution, which brings difficulties to use

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