Application of inwardly directed prestressing pressure to concrete members

Abstract

Methods for forming prestressed concrete members wherein a pressure-containing casing is disposed around the outside surface of the concrete member and is spaced therefrom so that a cavity is formed between the casing and the outside surface of the concrete member. A pressurized medium is injected into the cavity between the casing and concrete member at a pressure sufficient to apply the required prestressed compressive force to the outside surface of the concrete member. The pressurized medium changes form by hardening or solidifying after injection. Examples of solid pressurized mediums include cement-like grouts and plastic, and epoxy resin materials. When the concrete member is cast within the casing so as to be in intimate contact with the casing the cavity is then formed by peeling the concrete member and casing away from each other as the pressurized medium is injected therebetween.

Dependencies are inferred from the claim text.