Crack detection in RC structural components using a collaborative data fusion approach based on smart concrete and large-area sensors

Abstract

Recent advances in the fields of nanocomposite technologies have enabled the development of highly scalable, low-cost sensing solution for civil infrastructures. This includes two sensing technologies, recently proposed by the authors, engineered for their high scalability, low-cost and mechanical simplicity. The first sensor consists of a smart-cementitious material doped with multi-wall carbon nanotubes, which has been demonstrated to be suitable for monitoring its own deformations (strain) and damage state (cracks). Integrated to a structure, this smart cementitious material can be used for detecting damage or strain through the monitoring of its electrical properties. The second sensing technology consists of a sensing skin developed from a flexible capacitor that is mounted externally onto the structure. When deployed in a dense sensor network configuration, these large area sensors are capable of covering large surfaces at low cost and can monitor both strain-and crack-induced damages. This work first presents a comparison of the capabilities of both technologies for crack detection in a concrete plate, followed by a fusion of sensor data for increased damage detection performance. Experimental results are conducted on a 50 50 5 cm3 plate fabricated with smart concrete and equipped with a dense sensor network of 20 large area sensors. Results show that both novel technologies are capable of increased damage localization when used concurrently.

Investigation of electrically isolated capacitive sensing skins on concrete to reduce structure/sensor capacitive coupling

“…The specimens were allowed to cure for at least seven days before testing since only strain is acquired during the test, and the strength of specimens is not of priority. No changes in the concrete/sensor capacitive coupling were noticed with specimens allowed to cure for up to 6 months [15,16]. In the exploratory stage of this study, more than 50 samples of concrete specimens were tested.…”

“…For example, experimental results from Yan et al [15] show that when an SEC sensor is attached to concrete, the measured strain values are significantly higher than anticipated. However, results by Yan et al [15], and Downey et al [16] show that when the exact amplitude of the signal is not considered significant but only the response to loading and damages is monitored, the general functionality of the SEC is not affected when used on concrete. The detection of crack formation can be inferred by monitoring an increase in the capacitance change of the SEC.…”

“…Of importance to this work are previous studies on the use of SEC for crack monitoring and detection; studies that investigate the use of SEC as strain sensing sheets on steel plates for crack detection report progressive data over the recent years [14]. The studies have also been extended to strain sensing on concrete [15,16].…”