High-magnesia Portland cements: studies on cements prepared with reagent-grade chemicals

Abstract

Synopsis Several Portland cement clinkers containing up to 15% MgO have been prepared with reagent-grade chemicals, and the properties of cements made from them have been investigated. In particular, the effect of variations in composition, burning temperature and cooling conditions of the clinkers upon the autoclave expansion and strength of the corresponding cements has been examined in detail. It is not possible by controlling these factors alone to produce ‘sound’ (i.e. volume-stable) Portland cements having MgO percentages much above the present limits recommended by the Standards in different countries. The addition of a suitable reactive silicate material in finely divided form, e.g. pulverized-fuel ash, effectively stabilizes high-magnesia cements and these mixtures pass the ASTM test for soundness of Portland cements. Data on the autoclave expansion and mechanical strength of these mixtures of high-magnesia cement and pfa are presented.