LAUSR

Abstract Assessment of degree of hydration of cement system at early age is an extremely important but challenging task. An effective- and non-invasive-technique for assessing the degree of hydration would be of great importance. In the present study, both passive and active acoustic emission (AE) technique is employed to capture and analyse the acoustic signals from the hydrating cement system till 72 h. Three different scales, namely, cement paste, mortar and concrete are investigated in the present study. Apart from the traditional AE parameter analysis, frequency content of the recorded signals in each hydration stage is analysed. Further, special attention is paid towards clustering the AE data into several types that reflect the different mechanisms which takes place during hydration. Based on the clustering results, the relationship between AE signals recorded and the mechanisms associated with hydration are emphasized. Further, discretised microstructure of cement system at different stages of hydration is developed for numerical studies. From the observations made during the experimental investigations and in-sights obtained from the numerical studies, the microstructure dependent wave characteristics is established. Attenuation factor as a function of propagating distance at various stages of hydration process is determined. The results show a reasonable correlation between the AE parameters and phase transition in the cement composites due to physical and chemical changes which occur during hydration.