Ultimate compressive strain in lightweight aggregate concrete beams

Abstract

The major concern when using lightweight aggregate concrete (LWAC) in structural applications compared to normal weight concrete (NWC) is the more brittle post-peak behaviour and reduced ultimate strain, especially in compression. To investigate this six LWAC over-reinforced beams , with geometry 210-330x550x4500 mm, were subjected to four point bending with a constant moment zone of 1m between loading points. In this zone were varied main test parameters: the spacing of transverse reinforcement, amount of longitudinal compressive reinforcement and size of concrete cover. Strains were measured combining DIC, strain gauges and LVDTs. Five the tested beams showed ductile behaviour and ultimate compressive strain registered in the beams was in range 3.4-3.8‰. This indicate that standards underestimate ultimate compressive strain in LWAC structures from 30- 50%