Abstract: A method and composition are provided for making a finished concrete structure having a water-impervious surface. A particulate composition of a paraffin wax material, glyceryl fatty-acid esters, and stearic or palmitic acid is added to the aggregate phase and mixed in a wet hydraulic Portland cement mixture. The resultant slurry is then poured and cured. The surface of the cured structure is thereafter heated as by solarization under black pigmented polyethylene sheets to cause the wax particles to melt and invade capillary and other interstices in the surface region of the concrete structure, thereby rendering said structure impervious to the infusion of water and water solubles.