Evaluating the Hydration of Cement Mortar Blended with Calcined Clay Using Piezoelectric-Based Sensing Technique

This paper aims to study the possibility of using piezoelectric-based patches to characterize the hydration of cement-based mortar mix blended with calcined clay (CC). An embedded piezoelectric-based sensor is used for monitoring for the early age as well as long-term hydration of binder paste. Progressive changes in hydration of mortar were studied in terms of admittance signatures recorded over a period of 28 days. This study examines the behavior of cement mortar with CC as partial replacement of cement at various substitution levels of 4–12%. 70.6 mm mortar cubes of 1:3 (cement:sand) were cast for the study. Setting time, compressive strength and hydration of cement-based mortar mix were studied on formulated binder paste. The experimental results with 6% replacement of cement showed maximum compressive strength as compared to other mixes, and similar trend of results has been noted by electromechanical impedance (EMI) technique. Delay in setting time and approximately linearly decrease in flow value have been observed with rising the percentage of CC replacement as cement in cast mortar mixes. To study the hydration of cement mortar mixes, signatures were recorded from 0 to 28 days on the prepared cubes of 70.6 mm with different percentages of CC. To relate the EMI spectra, statistical metrics such as root mean square deviation (RMSD) has been used for all cement mortar mixes. RMSD was found to be reasonably effective in estimating the hydration in terms of compressive strength gain of cement mortar over the time.