Abstract: A glass fiber article having enhanced alkali resistance is described. The glass fiber has thereon a coating comprising zinc stearate and a film forming polymer with the coating being present in an amount of 1 to 60% by weight of solids based on weight of the glass fiber. The polymer is preferably initially in the form of a latex and is selected from the group consisting of acrylic terpolymers, vinyl acetate/ethylene copolymers, vinyl acetate/vinyl chloride/ethylene terpolymers, urethane polymers and epoxy polymers. The glass fiber is used at a rate of approximately 5% to 20% as reinforcing fiber in Portland cement and other alkaline cementitious composites. Such composites are also described, as is a method of imparting alkali resistance to glass fiber by applying such coating to the fiber.

Abstract: Alkali resistant glass articles are disclosed comprising glass fibers coated with zinc stearate. The coating will be present as 1 to 50, preferably 3 to 10, percent by weight of the coated fiber. The zinc stearate may be applied as a powder and converted to a coating by heating, or may be applied to the fibers from a water suspension.

Abstract: A process is described for the formation of fibrous insoluble calcium sulfate anhydrite, the fibers thereof having specified dimensions. A dilute aqueous suspension of gypsum and, if desired, a crystal habit modifier suitable for the formation of fibrous calcium sulfate hemihydrate, is first formed. The gypsum in this suspension is then converted to the fibrous hemihydrate by reaction in the presence of saturated steam at 120.degree. C to 155.degree. C for 0.5 to 2.5 hours, thereby forming fibrous calcium sulfate hemihydrate of the desired dimensions. The fibrous hemihydrate is thereafter calcined at 500.degree. C to 750.degree. C for 0.5 to 3.0 hours to convert the fibrous hemihydrate to fibrous insoluble calcium sulfate anhydrite having substantially the same crystalline shape and dimensions.

Abstract: A process is described for the formation of fibrous calcium sulfate hemihydrate, the fibers thereof having specified dimensions, wherein a dilute aqueous suspension of gypsum and, if desired, a crystal habit modifier is first formed. The gypsum in the suspension is then converted into fibrous hemihydrate by reaction in the presence of saturated steam at 120.degree. to 155.degree.C for 0.5 to 2.5 hours.