A novel electromechanical impedance–based model for strength development monitoring of cementitious materials

Abstract

Strength monitoring of early age concrete improves the efficiency of construction as it provides information on the optimum time for shoring removal and pre-stress transferring. Electromechanical impedance technique has been proven to be a useful tool for strength monitoring of cementitious materials. One of the key limitations of this technique is the lack of physical models, which resulted in strong reliance on statistical analysis tools to quantify the strength of structure being monitored. In this proof-of-concept study, a novel electromechanical impedance–based model with the potential of monitoring the strength of cementitious materials using the concept of Smart Probe is proposed. Instead of directly bonding a lead zirconate titanate patch on the host structure, a lead zirconate titanate was first surface-bonded on a pre-fabricated aluminum beam, which is termed Smart Probe. The Smart Probe was then partially embedded into cementitious materials for strength monitoring. The structural resonant frequencies of the Smart Probe can be identified from the conductance signatures measured from the lead zirconate titanate patch throughout the curing process and serve as strength indicator. By modeling the cementitious material as an elastic foundation supporting the Smart Probe, an analytical model was developed to predict the dynamic modulus of elasticity of cementitious materials based on the resonance frequency of the Smart Probe. Experimental study was carried out on a mortar slab specimen to verify the model and to investigate the performance of the Smart Probe. It was found that the dynamic modulus of elasticity of the host structure could be predicted from the conductance signatures using the proposed model. Compressive strength assessment was achieved by establishing an empirical relation with the dynamic modulus. The proposed electromechanical impedance–based model with Smart Probe is physically parametric in nature and shows high repeatability, which renders its superiority over the conventional statistical method–based electromechanical impedance technique for strength monitoring of cementitious materials.

Tension Force Estimation in Axially Loaded Members Using Wearable Piezoelectric Interface Technique

“…However, the direct attachment method of the PZT often influences the appearance of the monitored structure and causes difficulties in reconfiguration of the sensor in necessary cases [18,19]. An additional important issue is the repeatability of impedance signatures, which is dependent on the structural condition of the bonding layer and the surficial condition of the target surface [20]. To overcome these issues, Annamdas et al [18] developed an indirect attachment technique using a portable structure embedded with PZTs to indirectly acquire impedance signatures from a host structure.…”

Determining the Optimal Traffic Opening Timing Through an In-Situ NDT Method for Concrete Early Age Properties

“…They concluded that the post statistic treatment of real admittance could better reflect the compression gain of concrete than the imaginary admittance. Lu et al (2012) proposed a PZT based sensor called ''Smart Probe'' to improve the efficiency of monitoring the concrete properties. The Smart Probe was made by using the aluminum beam with the PZT bonded on the surface and partially embedded into concrete for measurement.…”

“…The other statistical models, including correlation coefficient deviation (CCD) Wang et al, 2014) and mean absolute percentage deviation (MAPD) (Lu et al, 2012;Narayanan et al, 2017;Wang & Zhu, 2011) are also proposed as a valid index on strength gain monitoring of concrete. In this research, MAPD and CCD indexes are also used.…”

A Review of the Piezoelectric Electromechanical Impedance Based Structural Health Monitoring Technique for Engineering Structures

“…Other studies related to concrete have also been active during the past several years as many authors applied the EMI technique for predicting concrete strength. Lu et al [ 67 ] proposed an idea of using ‘Smart Probe’ to monitor the strength development of cementitious materials. Dynamic modulus of elasticity of cementitious materials was predicted with the proposed analytical model where it showed good correlation with the compressive strength of the mortar.…”