Pilot Study of Mechanical Waves Passing through Fine-Grained Cement Composite during the Early Hydration Process

Abstract

The aim of this paper is to present results of an experimental analysis focused on the mechanical waves passing through fine-grained materials, prepared from the CEM I 52.5 R Portland cement and the water coefficient w/c = 0.40, during the setting and hardening phase. In the experiment differences in the wave propagation in cement pastes and mortars were investigated. After mixing, both materials were poured into a cylindrical mould with the diameter of 75.0 ± 0.3 mm. These test specimens were then used to observe, in particular, the development of the amplitude of mechanical waves using a measuring setup which was composed for this purpose from the equipment of the Brno University of Technology. The results show that the time of „critical changes" in the internal structure of the material can be determined. These changes are related to the quality of the bonds of the particles in the internal structure which are reflected in the propagation of the mechanical waves within the material. It is also expected that the experimental analysis will help extend the knowledge of mechanical waves propagation in cement-based composite materials during setting.