Role of magnesium acetate in hydration and carbonation of magnesium oxide-based cements

Abstract

MgO-based cements have the potential for low carbon binders especially when MgO is sourced from non‑carbonate minerals. Understanding the reaction kinetics and products formed are the keys to pave the way for these binders as construction materials. In this study, the influence of acetate on hydration and subsequent carbonation of reactive MgO is investigated. MgO hydrated in Mg-acetate solution of various concentrations (0 to 0.5 M) and CO2 cured afterward was characterized at different reaction times. Magnesium acetate in addition to enhancing the hydration kinetics modifies the morphology and crystallinity of the precipitated brucite. Acetate also influences the carbonate phases formed when samples are cured with CO2. Giorgiosite, a lesser-known hydrated magnesium carbonate, was formed in the presence of acetate, while the control specimens prepared with neat water produced nesquehonite. The findings reported here give insights into the use of organic additives in improving the reaction kinetics of MgO and the possibility to tune the formation pathways of different magnesium carbonates.