Abstract: A polymer-cement composite composition including an efflorescence-control agent and methods of making same. The composition comprises, by weight percent, about 40 to 50% inert, inorganic filler material, such as silica sand; about 12 to 23% latex preferably in aqueous suspension; about 20 to 25% cement, preferably hydraulic cement; about 7 to 13% reactive silica; and about 0.2 to 1% of an efflorescence-control agent, which is preferably diatomatious earth. The composition is preferably manufactured by simultaneously wet mixing the powdered and liquid components at medium intensity to form a thoroughly mixed batch of green body and de-airing the green body. The green body is then formed into the desired shape followed by curing and drying. The dried product may be further processed, for example by cutting or shaping the product or coating the product.