Monitoring the mechanical properties of flyash incorporated cement composite using complimentary passive-active wave propagation techniques

For safe construction practise, it is important to monitor the hardening process of concrete during the construction stage itself. Moreover, with the increasing use of supplementary cement-based materials (SCM) in concrete construction which adversely alters (significantly delays) the setting and strength gain in concrete, it becomes highly imperative to closely monitor and examine the development of properties of cement composite in the structural system during hardening. In view of this, the present study investigates the efficacy of the non-invasive wave propagation methods employing Acoustic Emission (AE) and electromechanical impedance (EMI), through passive and active signatures, respectively, in monitoring the hardening process of just poured SCM incorporated cement system. Results showed that AE parameters combined with the frequency analysis could be able to qualitatively provide the information on the hardening process in cement mixtures made with varying levels of flyash replacements. AE results are further correlated with the properties such as stiffness of the material system obtained through EMI measurement and strength property. Correlations are found to be very consistent and will be helpful for continuous monitoring of strength and stiffness gain in cement composite during the construction stage, through non-invasive, non-destructive, in-situ technique combining AE and EMI.