Applications of a fiber optic crack sensor in concrete structures

Concrete structures deteriorate through the formation and propagation of cracks. Crack detection and monitoring is hence an effective means to assess the condition of structures for the development of appropriate maintenance schemes. For crack sensing in a concrete structure, the major challenge is that the exact crack location is often not known. If conventional point sensors are employed, the required number of sensors can become so high that the sensing scheme is no longer economically feasible. At HKUST, we have developed a novel fiber optic sensor that can detect and monitor cracks without prior knowledge of their locations. Moreover, a single fiber can be employed for the monitoring of multiple cracks. In this presentation, after describing the physical principle and fabrication techniques of the sensor, various applications of the sensor will be presented and illustrated with laboratory testing results. These will include monitoring of flexural crack under static and cyclic loading, detection and monitoring of multiple cracks, and crack sensing under restraint dimensional changes (due to shrinkage or thermal effects). Through these examples, the potential of the crack sensor for practical applications is demonstrated.