Ease of implementation of any sensor system must involve simple instrumentation techniques along with adequate adaptability to change in specimen configuration. The past decade has witnessed an exponential upsurge in applications of piezoelectric transducers in various fields of engineering and biotechnology, whereas sensor types has remained the same, narrowing its suitability in certain fields. The present research deals with development of two novel piezo sensor configurations namely the single clamp non-bonded sensor (SCNS) and re-useable bolted sensor (RBS). The sensor was developed to accommodate change in dimension and is tested on different specimens based on its design. Fundamentally, SCNS is developed for circular structures such as pipelines and RBS is developed for 2-D plates. Effectiveness of both sensors is tested by mounting it on a specimen based on its design. Damage sensitivity of the sensors was studied by analysing the conductance signatures extracted from the piezo patches based on electromechanical impedance (EMI) technique. Repeatability of less than 2% was observed in both cases. At different levels of damage created shifts in signatures is observed. A statistical index used to quantify the amount of shift showed a gradual increase in magnitude corresponding to increase in damage. Similar trends are observed in both sensor data making both sensors suitable for application. Through the damage sensitivity tests, SCNS and RBS its proved viability for application in field studies. However, it might be noted that all tests were conducted in controlled environments of temperature and pressure and negating its effects by application of correction factors must be carried out for field application.
Reinforced concrete (RC) is an economical, versatile and successful construction material as it can be moulded into a variety of shapes and finishes. In most cases, it is durable and strong, performing well throughout its service life. However, in some cases, it does not perform adequately due to various reasons, one of which is the corrosion of the embedded steel bars used as reinforcement. . Although the electro-mechanical impedance (EMI) technique is well established for damage detection and quantification of civil, mechanical and aerospace structures, only limited studies have been reported of its application for rebar corrosion detection in RC structures. This paper presents the recent trends in corrosion assessment based on the model derived from the equivalent structural parameters extracted from the impedance spectrum of concrete-rebar system using the lead zirconate titanate (PZT) sensors via EMI technique.