A Study on the Fracture of Cementitious Materials in Terms of the Rate of Acoustic Emissions in the Natural Time Domain

A novel approach for describing the acoustic activity in brittle structural materials while they are loaded mechanically at levels close to those causing macroscopic fracture is proposed. It is based on the analysis of the rate of acoustic emissions in terms of the Natural Time concept. Experimental data from protocols with either intact or notched beams, made of cementitious materials, subjected to three-point bending are analyzed. It is concluded that in case the acoustic activity is described with the aid of the F-function in the Natural Time domain, its evolution is governed by a power law, independently of geometrical details and the type of the loading scheme. It appears that the onset of validity of this law provides an interesting pre-failure indicator.