Cementitious formulations and their products with enhanced reactivity are provided. Formulations in certain embodiments may include at least one calcium source, a reactant and a filler in a hydrated environment, wherein the reactant, in one form, is crystalline silica that has been modified for reactivity. Enhancement of a reactant may include one or more modifications to its content, grind and/or the cement to silica ratio, as well as addition of one or more additives in the formulation, additives in the form of at least one alumina source, defoamer, catalyst and/or a clay.