Acoustic Emission Characteristics of Cementitious Materials During Early Age Hydration

Abstract

Acoustic Emission (AE) testing was used to study the hydration process in cementitious materials during the first 18 h of setting. AE activity was monitored in fresh cement paste, mortar and concrete specimens. The specimens had a different mixture of composition. It was observed that the AE activity depended on the size of the aggregate present in the cementitious mixture. More AE signals were recorded during the setting process in specimens with the lower w/c ratio than for the higher one. Specimen cast with cement paste showed more AE activity compared to the larger coarse aggregate size (20 mm). The AE activity in fresh concrete is accredited to cavitation in the pores of cement paste during the hydration process and shrinkage. The AE activity showed a notable trend during the time of setting, based on which it was divided into three stages namely, before hydration, partial hydration and complete hydration. The occurrence and duration of these stages varied for cement paste, mortar and concrete. In this study, it was observed that if more AE signals are recorded during the hydration process, higher will be the strength gained by the same concrete in-situ.