FRP Stay-in-Place Formworks for High Performance of Concrete Slabs

Abstract

Stay-in-Place (SiP) formworks obviate the transportation, placement, removal and storage requirements of conventional formworks. Fibre Reinforced Polymer SiPs (FRP-SiP) have additional advantages, such as corrosion resistance, high specific strength and durability. This paper discusses an experimental instigation consisting of two sets of slabs having varying span-to-depth ratios cast on an FRP-SiP. Control specimens with conventional steel bar reinforcements were also cast. Several treatments for improving interfacial bonds at the interface between concrete and FRP-SiP have been investigated. Cyclic flexural tests were performed to evaluate their structural performance. Load-displacement relationship and load capacity are presented. Failure envelopes and energy absorption capacity were evaluated. It was found that the load capacity of FRP-SiP was around 107% greater than the conventional steel rebar specimens. Bond treatment on the FRP-SiP specimens increased the load capacity by around 215% over the untreated specimens. The load-deflection behaviour and the failure modes of the FRP-SiP specimens were distinctly different from those of the conventional specimens. The flexure and shear provisions in American Concrete Institute Standards (ACI 440) were found to be conservative in comparison to the present results. This study demonstrates that FRP-SiPs improve both the structural performance and construction efficiency of concrete slabs, however, new standards would be necessary to be able to utilize their improved capacity.