Fracture of plain and fiber-reinforced high strength mortar slabs with EA and ESPI monitoring

The failure of cement-based materials is associated with the development of a damaged zone in the form of a more or less large region of microcracking. The development and the evolution of the damaged zone is of fundamental importance in defining the mechanical response in terms of both structural behavior and peak strength. For geometrically similar beams of different sizes, this paper presents and discusses experimental evidence from interferometric measurements (ESPI) and locations of acoustic emission (AE) of the damaged zone development, at the peak load, in terms of shape and size. The cement-based materials had an aggregate/binder ratio of 1.5, a microsilica/binder ratio of 0.1 and a water binder ratio of 0.22. Beams made with (2% by volume) and without steel reinforcing microfibres were considered. It is shown that the size effects appear to be reduced in the fibre- reinforced materials.