Shear capacity of lightweight concrete beams without shear reinforcement

The main disadvantages of lightweight aggregate concrete (LWAC) compared with normal weight concrete are its brittleness at the material level in compression and the risk of uncontrolled crack propagation. The brittleness of concrete is characterized by its sensitivity to stress concentrations and rapid crack/fracture development. This paper presents results from an experimental investigation with Stalite as the lightweight aggregate. The main goals were to investigate beams subjected to shear and to compare these results with previous experimental work. Four lightweight concrete beams without shear reinforcement were tested in four-point bending. The main test parameter was the shear span length to effective height ratio (a/d). The shear loads of all beams at diagonal cracking and at failure were plotted as a function of the a/d ratio and compared with previous results. Small specimens were also tested to find the compressive strength, splitting tensile strength, Young’s modulus, and fracture energy. The beams tested did not show brittle behaviour. After the formation of shear diagonal cracks, the beams were able to resist increased loading. In general, the beams were more ductile than expected. The results obtained during this testing show that this type of LWAC has almost the same behaviour as normal weight concrete.