Abstract: A Cementatious admixture for use either as a mortar, cement or concrete when added to water comprising a hydraulic cement, such as Portland cement, in combination with presized inorganic filler particles having a maximum particle size of about 50 microns and in a predetermined relationship by weight to the Portland cement. The added water must also satisfy a relationship to the weight of hydraulic cement to provide thixotropy and nondilatency.