Piezoelectric EMI–Based Monitoring of Early Strength Gain in Concrete and Damage Detection in Structural Components

Knowledge about the strength gain of reinforced concrete structures facilitates speedy and accurate decision making in formwork removal and transfer of prestressing forces for prestressed concrete. In the current study, a set of two smart aggregates embedded in concrete cubes have been investigated for their suitability in evaluating the strength gain during the initial curing regime, through electromechanical impedance (EMI) signatures. Correlation of EMI signature from these embedded smart aggregates with progressive strength loss is also established. Different statistical metrics have been evaluated to quantify the variations between the reference and modified states. A relation between root-mean-square deviation (RMSD) and strength parameter is developed, which potentially could be used for arriving at the characteristic strength gain. The novelty is the proposed serial/parallel connected multisensor configuration with a cluster of lead zirconate titanate (PZT) sensors to monitor early-stage characteristics and later-stage strength evolution under a large-scale sensor deployment scenario. The experimental investigation on PZT-bonded concrete shear wall looked for variations in EMI signature under crack opening conditions. Experimental studies on PZT-bonded metal structures have also been carried out to study the variation in modal density characteristics and the effect of low-frequency vibration on the resulting EMI signature.