Abstract: Compositions of alkali activators useful in cement mixtures and concrete are described. The composition may include anhydrous sodium sulfate, a dispersant, a humectant, at least one additive, and water. Exemplary additives include rheology modifiers, de-foamers, biocide agents, surface tension agents (as synthetic additives or additives derived from naturally occurring sources), and combinations thereof. The composition may include about 20% by weight to about 80% by weight solids, based on the total weight of the composition, for example. Cement mixtures and concrete compositions are also described, as well as methods of preparing such compositions, cement mixtures, and concrete compositions.