Shear behaviour of longitudinally reinforced self-compacting concrete beams

Abstract

Due to its unique composition, the mechanical properties and hence the structural performance of self-compacting concrete (SCC) may be significantly different from that of conventionally vibrated concrete (CVC). Since the coarse aggregate content in SCC is relatively smaller compared to that in CVC, there is concern that the aggregate interlock mechanism for resisting shear may be weaker in the former compared to the latter. An experimental investigation was carried out for a comparative appraisal of the shear strength of longitudinally reinforced SCC and CVC beams. A total of 18 beams with a constant shear span-to-depth ratio of 3.5 were tested under a four-point loading configuration until shear failure occurred. To ensure that shear failure preceded flexural failure, all the beams were intentionally over-reinforced with 3% tension reinforcement. The parameters for investigation included the type and the strength of concrete and the depth of the beams. The experimental results indicate that for the normal strength concrete, the ultimate shear strength of the SCC beams was lower than the CVC beams, whereas for high strength concretes no significant difference was observed between the shear strengths of SCC and CVC. The ultimate shear strength of both the SCC as well as CVC beams was found to be significantly influenced by beam size and lower shear strengths were obtained at higher beam depths. The shear strength equations in IS 456:2000 were found to give conservative predictions for both the SCC as well as the CVC beams.