| abstract |
An improved water-resistant cementitious composition and products made therefrom are provided by forming an aqueous cementitious slurry, as for example of calcined gypsum and adding to the slurry a composition in the form an aqueous emulsion of asphalt and wax, a minor proportion of polyvinyl alcohol and a minor proportion of a borate compound, that is, one having an anion comprising boron and oxygen, as for example borax. The slurry is set in conventional manner by heating and drying. The resulting product has a high degree of water-resistance while utilizing less asphalt and wax composition than required with conventional asphalt-wax emulsions thereby accomplishing a large savings in raw material costs. Additionally, the use of a small amount of the borate compound permits a smaller amount of the relatively expensive polyvinyl alcohol to be used without a reduction in the water-resistance of the final product. Alternatively, an amount of asphalt and wax composition may be utilized equal to or greater than that conventionally used, but obtaining a much greater degree of water-resistance. |