Fracture properties of normal and lightweight high-strength concrete

This paper presents the results of a comparative study on the fracture properties of high-strength concrete (HSC) with normal aggregate (crushed limestone) and lightweight aggregate (sintered fly ash). The compressive strengths of the normal and lightweight HSC were about 115 and 90 MPa respectively. The fracture properties, namely the critical stress intensity factor (K_IC ^S) and critical crack tip opening displacement (CTODc) for the two-parameter model, and the fracture energy (G_F) for the fictitious crack model were examined. A three-point bending test on notched beams was carried out on specimens of varying sizes to examine the size effect on the measured properties andflexural behaviour. The experimental findings indicated that the K_IC ^S and G_F values of normal aggregate HSC were more size-sensitive than that of lightweight HSC while the CTOD_C of both types of HSC seemed to be size-independent, Compared with the normal aggregate HSC, the lightweight HSC had a considerably lower K_IC ^S but had a similar G_F and more ductile flexural behaviour.