The Effect of Mgo Admixture on Cement Pastes and Mortars

摘要

One of the principal components of cement, limestone is usually not found in pure form. Limestones contain some MgCO3 and small amounts of silica, iron oxide, alumina, sulfur, and alkalis. When baked at 900oC, CaCO3 decomposes to form CaO and MgO. MgO in portland cement is an oxide that might adversely affect cement paste and concrete properties. A large amount of MgO might lead to cracks and fractures in concrete as a result of expansion due to hydration. This study investigated the effect of magnesium oxide (MgO) on cement pastes and mortars both experimentally and based on literature review. MgO was added into cement pastes and mortars with rates of 0%, 5%, 10% and 15% in weight and XRD, SEM-EDS images, chemical analyses, and compressive strengths of paste samples on the 2nd, 7th and 28th days were examined. In the study, the most suitable compressive strength was obtained from 10% MgO-added cement pastes and mortars.