Failure mechanism of normal and high-strength concrete with rice-husk ash

Mineral admixtures generally lead to a densification of the concrete internal structure. In this sense, the failure mechanism could be modified so that the concrete exhibits a more brittle behaviour. This paper discusses the effects of rice-husk ash (RHA) additions to concrete, based on analyses of the mechanical behaviour of normal and high-strength concrete. The stress-strain response in compression and load vs. CMOD (or deflection) in bending were analysed. It appears that the incorporation of RHA in concrete increases the strength, particularly for lower water/binder ratio concretes. The analysis of the failure mechanism indicates a tendency for more brittle failure behaviour in RHA concretes. For the same strength level, however, the energy of fracture was reduced no more than 10%, which is much smaller than the variations that may be produced by a change in the type or size of coarse aggregate.