Flexible fiber reinforced composite rebar

Abstract

A flexible fiber reinforced composite rebar structure includes a plurality of continuous fibers embedded within a thermoplastic resin. The rebar structure has an elliptical cross sectional shape with an aspect ratio of about two to one and a twist with a twist pitch of about 30 cm. The thermoplastic resin matrix enables the rebar structure to be bent in the field by the application of heat to soften the structure and thereafter cooled to return to a rigid state.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority under 35 U.S.C. 119(e) and 37 C.F.R. 1.78(a)(4) based upon copending U.S. Provisional Application, Ser. No. 60 / 874,828 for FLEXIBLE REBAR, filed Dec. 14, 2006, which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]Concrete and other masonry or cementitious materials have high compressive strength but relatively low tensile strength. Thus, when concrete is employed as a structural material, it is conventional to incorporate reinforcing members to enhance the tensile strength of the structure. The reinforcing members are usually comprised of a rigid rod or bar, such as a steel rod or bar. Such reinforcing members are typically referred to as “rebar”. Unfortunately, steel and other metals are susceptible to oxidation. In addition, such materials are quite rigid prior to use so that the placement of such reinforcing members can be difficult and time-intensive. As a result, conventional meta...

AI Technical Summary

Benefits of technology

[0005]The present invention provides an improved composite reinforcement bar or rebar structure. The rebar structure is generally formed by continuous fibers embedded in a thermoplastic resin matrix to form a reinforcement bar. The bar is flattened to achieve a cross sectional aspect ratio greater than one to one. The bar is then twisted in a substantially helical manner. In one embodiment of the rebar structure, the bar has a substantially elliptical cross sectional shape with a cross sectional aspect ratio of about two to one and a twist pitch of about 30 centimeters. The matrix may be a thermoplastic resin such as polypropylene, and the fibers may be formed of glass. The thermoplastic resin matrix allows the matrix to be softened by the application of heat to thereby bend or flex the bar to desired shapes. The capability of being conveniently bent is also aided by the cross sectional shape and aspect ratio and by the twist applied to the bar. Once bent to a desired shape, the bar is allowed to cool and re-harden to a substantially rigid state.

Problems solved by technology

Concrete and other masonry or cementitious materials have high compressive strength but relatively low tensile strength.

Unfortunately, steel and other metals are susceptible to oxidation.

In addition, such materials are quite rigid prior to use so that the placement of such reinforcing members can be difficult and time-intensive.

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