Waterproof Magnesia Binder for Composite Materials

Abstract

The paper presents a study of structure formation during the hardening of a new water resistant hydraulic magnesium cement. Improvement of water resistance and the manifestation of hydraulic properties in magnesium cement are associated with the use of a fundamentally new mixing liquid involving a magnesium bicarbonate solution. Use of this solution makes possible for the magnesium composition to harden not only in air, but also in water. The Coefficient of resistance is 1.0–1.8. When mixing the magnesium cement with an aqueous solution of magnesium bicarbonate, the main products of hardening are magnesium hydroxide and magnesium hydrocarbonates. The increase of the hydrocarbon phase contributes to the strengthening characteristics of magnesia compositions. Magnesium hydrocarbonates are insoluble in water, which provides the increased water resistance of magnesia compositions and the opportunity to harden and gain strength in water.

Effect of Molar Ratios and Curing Conditions on the Moisture Resistance of Magnesium Oxychloride Cement

“…This is due to its chloride content and lower alkalinity than conventional concrete binders (Wei et al 2018). It is also susceptible to moisture which causes transformation of its main phases and a subsequent loss of strength (Deng 2003;Mitina et al 2016;Wang et al 2019). Despite these issues MOC has many niche applications including grinding wheels, lightweight wall panels, floor tiles and decorative panels (Aiken et al 2020(Aiken et al , 2021Chau and Li 2008;Li and Chau 2008;Wøhler Nielsen et al 2019;Zhou and Li 2012).…”