Studies on toughness of Hybrid Fibre-Reinforced cementitious composite beam

Abstract

Research works over the past three decades have clearly established the potential use of different fibre reinforcement for improving the flexural capacity as well as toughness of reinforced concrete members. The addition of fibres also helps to reduce the problems of congestion due to flexure and shear reinforcement at critical sections such as beam-column junctions. In the present study, thirty six numbers of fibre reinforced concrete prisms have been tested under quasi-static load according to ASTM C1609. Two types of steel fibres with hooked-end and two types of polymer fibres, namely polypropylene and polyester have been used. Different combinations of fibres and their volume fractions have been tried to arrive at the best possible combination from the point of view of toughness. The results of test on hybrid fibre reinforced cementitious composite beams show that though there is not much improvement in ultimate load carrying capacity; but there is tremendous change in ultimate displacement even after the first crack. The hybrid fibre reinforced cementitious composite beams have exhibited 10 to 15 times enhancement in toughness as compared to a similar plain concrete beam till failure. Since the results of testing show enhanced ductile behaviour before collapse of a structural element, appropriate combination of hybrid FRC (HyFRC) are strongly recommended for practical usage.