Instantaneous monitoring the early age properties of cementitious materials using PZT-based electromechanical impedance (EMI) technique

The use of piezoelectric materials based Electromechanical Impedance (EMI) technique for monitoring the hydration of cementitious materials has caught much attention recently. However, very few literatures have explored the feasibility of using this method on monitoring the stiffness development and compressive strength gain at the very early age properties (4th-8th h) of cementitious materials. This research serves as a comprehensive study to verify the reliability of using lead zirconate titanate (PZT) based EMI method in monitoring the compressive strength gain and elastic modulus of mortar at both very early age (4th-8th h) and early age (1st, 3rd, and 7th day). Extensive experiments and data analysis have been done on ten different mixes with various water-to-cement ratio and Type I & III cement. The EMI signatures are measured for each sample at the period of interest, and post-processed with three statistic model including the root mean square deviation (RMSD), correlation coefficient deviation (CCD), and mean absolute percentage deviation (MAPD) as indices. To examine the correlation and linearity between the compressive strength/elastic modulus obtained via conventional cubic testing using ASTM C109 and the EMI indices, a linear least square regression analysis is performed. As the authors postulated, all the mixes display a good linear correlation of R-2. Among all three statistical indices, RMSD index is proved as the most accurate statistical index on strength gain monitoring of cementitious materials. The results indicated the feasibility of using piezoelectric-based EMI method for monitoring the cementitious material's strength gain at very early age, regardless the concrete mix design. (C) 2019 Elsevier Ltd. All rights reserved.