GB580960A - Improvements in reinforced concrete bodies and method of producing same - Google Patents

Abstract

580,960. Reinforced concrete. BILLNER, K. P. June 24, 1943, No. 10235. Convention date, June 17, 1942. [Class 20 (iv)] A method of stressing a reinforcing element 12 in a body 10 of concrete consists in surrounding the element with a zone or coating which is softened by the application of heat, thermally expanding the element with respect to the body cooling the element, and applying at least a portion of the contracting force of the element to produce compressive stresses in the body. In Fig. 1 the body 10 has a reinforcement 12 coated at 14 with a material of low melting point, such as a thermoplastic material, sulphur, or low melting metals or alloys. The ends of the reinforcement are screw-threaded and are fitted with nuts 16 and washers 20. When the concrete has set an electric current is passed through the reinforcement, the current being sufficient to soften the coating 14. The heat expands the reinforcement and the nuts 16 are advanced sufficiently to produce the required compressive stress on the concrete when it cools. In a modification, Fig. 2 (not shown) the concrete body and its reinforcements are curved. In the case of cylindrical bodies the ends 28, Fig. 4, of the reinforcing rings are enlarged, the enlargements being located within a recess 30 in the outer face of the cylinder. When the reinforcement is heated a clip 32 having bifurcated ends is clipped over the ends 28 to enable the reinforcement partially to contract. The recess 30 is subsequently fitted with dry packed concrete 33. In a modification, Fig. 3 (not shown) the reinforcement for a tube is in the form of oppositely wound helices the ends of which have enlargements to receive clips 32.