Recovery stress of shape memory alloy wires induced by hydration heat of concrete in reinforced concrete beams

Abstract

The goal of this study is to investigate the prestressing effect of shape memory alloy bars in reinforced concrete beams; bars are prestressed by external force or recovery stress due to shape memory effect. The shape memory alloy bars are heated by hydration heat of concrete during curing to induce the shape memory effect. To achieve this goal, this study conducts bending tests of concrete beams reinforced by shape memory alloy bars as well as those reinforced by steel bars. The beams with shape memory alloy bars with recovery stress show the same or slightly larger flexural strength than those with shape memory alloy bars prestressed with external force. Thus, this study indicates that the recovery stress of shape memory alloy bars plays the same role as the prestressing force, and that the shape memory effect can be induced by hydration heat of concrete instead of heating by electronic resistance.