Experimental characterization of ETDR sensors for crack monitoring in concrete structures

A novel approach for health monitoring of civil infrastructural systems using electrical time domain reflectometry (ETDR) sensors has been established. In this paper, experimental characterization results obtained when a coaxial cable is used as an ETDR sensor to monitor cracks in reinforced concrete structures will be provided. The first part of the paper shows simulation of cracks due to high pressure on the sensor when it is embedded in concrete. The results show that as the pressure on the sensor increases, the ETDR technique was able to detect exactly the location on the sensor where the high pressure is applied. The technique is able to detect the crack location and magnitude of pressure to an application point in a harsh environment. Furthermore, the ETDR technique was able to distinctly detect the locations on the sensors when multiple compressive high-pressure forces were applied on the sensor within a spatial resolution of less than one inch. This multiple sensing ability confirms the ETDR sensing approach as a fully distributed sensing technique. The second part of the paper will show the simulated effect of high temperature on the sensor when embedded in concrete. The results show that the ETDR sensor is reliable and durable with significant increases in temperature variations.