expansive cement, sulfoaluminate cement
A cement which when mixed with water forms a paste that tends to increase in volume, after setting, to a significantly greater degree than portland cement paste does; used to compensate for volume decrease due to shrinkage or to induce tensile stress in reinforcement. Classified as Type K: Contains anhydrous aluminosulfate burned simultaneously with a portland cement composition, or burned separately when it is to be inter-ground with portland cement clinker or blended with portland cement, calcium sulfate, and free lime. Type M: A mixture of portland cement, calcium aluminate cement, and calcium sulfate. Type S: A portland cement containing a large computed tricalcium aluminate content, modified by an excess of calcium sulfate above usual optimum content.