Electromechanical impedance (EMI) based lead zirconate titanate (PZT) is an effective sensor to ensure the safety of structure. In civil engineering community, Reinforced Concrete (RC) structure is one of the most familiar engineering structures. Hence, it is very important to monitor the health of structure. In this paper, a new approach of structural health monitoring using embedded PZT in host structure is proposed. There are several issues while embedding PZT inside RC structure which are examined during study. This paper presents two experimental studies on lab sized concrete beams. First implementation was carried out with different methods of embedment of PZT and its sensitivity study when the host structure was subjected to damage. The second implementation was verified in terms of conductance sensitivity of embedded Smart Aggregate (SMAG) in varying orientation i.e. horizontal (0?) and vertical (90?) after embedding in RC beam. The electrical conductance and susceptance signatures of different embedded PZT transducers were measured and damage index was calculated by using Root Mean Square Deviation Method.

Around the world, health monitoring of concrete structure has been playing an important role in the development of civil engineering. Structural Health Monitoring (SHM) is a process of monitoring the present condition of engineering structures. Many techniques for SHM have been reported in recent years. Moreover, there are several conflicts while monitoring health of concrete structure. This paper presents a new approach of health monitoring of structure based on electromechanical impedance (EMI) technique using embedded PZT sensors.

Earlier several authors have also proposed the SHM by using PZT Smart Aggregate sensors. Shanker [1] proposed the experimental study on embedded PZT as a Smart Aggregate sensor by using EMI technique. A simple low cost experimental technique was developed to extract the experimental strain mode shapes of the structure directly by using a surface bonded and embedded PZT sensor. It was found that damage ranging from incipient to near failure (severe) can be located and quantified by using the EMI technique and the experimental mode shapes with desired accuracy. Annamdas et al. [2] proposed a method of embedding PZT sensor in concrete for monitoring concrete. The implementation was verified on various lab sized concrete cubes and the observations were examined by statistical analysis. Wang et al. [3] proposed a health monitoring method based on EMI measurements, which used the electromechanical coupling property of embedded PZT transducers. Khante and Gedam [4] experimentally monitored the health of RC structure by embedding indigenously prepared PZT based smart aggregate in two phases i.e. for healthy and damaged state of RC specimen. Dumoulin et al. [5] studied crack propagation in a reinforced concrete beam by using PZT sensor. Two different types of excitation signals were used (pulse and chirp) and the resulting waves were recorded on the receivers. Based on these signals, different damage indicators were investigated and compared. Kaur et al. [6] investigated the integrity of the low-cost EMI technique and the global vibration technique for health assessment. Fourteen CVS were embedded inside a RC beam, while casting, to obtain the first curvature mode shape of the RC beam. A mode shape curvature based algorithm was adopted for damage detection and severity assessment. Song et al. [7] proposed the smart aggregates as a multifunctional tool for health monitoring. A damage index based on the wavelet packet analysis was used to determine the structural health status. Negi et al. [8] oriented PZT patches in different configuration in host structure. Visalakshi and Bhalla [9] proposed a comparison between the sensing capabilities of surface bonded and embedded piezoceramic (PZT) patches in corrosion assessment for RC structures. Accelerated corrosion tests were performed on RC specimens, and the statistical index and the equivalent parameters were compared for the two types of sensor configurations. B. Xu et al. [10] proposed a PZT based active interface debonding defect detection approach for multi-chamber Steel Reinforced Concrete (SRC) columns and validated experimentally with an irregular multi-chamber SRC specimen. A number of embedded piezo-based functional elements (EPFEs) installed close to the steel plates and piezoelectric ceramic (PZT) patches bonded on the surface of the steel plates were used as actuators and sensors respectively. Based on the amplitude of the measurement of the PZT patches under sinusoidal excitations and the wavelet packet energy under sweep sinusoidal signals, the interface debonding defects was detected successfully. Zhu et al. [11] presented the design and fabrication processes of EMI sensors embedded into concrete structures. Based on the electrical admittance and strain measurements, the health statuses of the continuous rigid frame bridge was monitored and evaluated successfully in the construction and operation stages by using a root-Mean-Square Deviation (RMSD) index. Gupta et al. [12] discussed a newly developed approach for detecting and quantifying corrosion of steel bars utilizing a piezoelectric ceramic (PZT) patch surface bonded on the rebar employing equivalent structural parameters using the Electro-Mechanical Impedance (EMI) technique.

By using conventional and EMI techniques, a lot of experimental and analytical work has been done by many researchers for health monitoring of structures. Electro-me- chanical impedance technique is considered more reliable and convenient for structural health monitoring. In previous studies, a limited experimental work using embedded PZT was carried out on the structures. Hence, in this paper, an attempt is made to study preparation of indigenous embedded SMAG and the feasibility of EMI technique for in situ SHM. This research article presents EMI approach using a new variant of the embedded SMAG for non-destructive monitoring of concrete structures. The conductance and susceptance signatures acquired over input frequency range are the basis for assessing the health of real-life RC structures.