NOVELTY - A hydraulic binder comprises a source of calcium aluminate, calcium silicate, sulfate, and a source of reactive silica. The ingredients are present in such relative proportions that, upon hydration, both monosulfate and hydrated alumina are formed. USE - The binder is used for forming non-efflorescing cementitious bodies, e.g. roofing tiles, plates, cladding, and walls (claimed). ADVANTAGE - The hydraulic binder reduces or eliminates efflorescence while maintaining the physical properties of cementitious bodies at satisfactory levels. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method of forming a non-efflorescing cementitious body, comprising curing the hydraulic binder.