Location and Width of Cracks in Concrete Pavement Overlays Monitored with Distributed Optical Fiber Sensor

In this study, commercial single mode optical fibers were applied as distributed sensors to detect cracks and measure crack widths in concrete overlay placed on top of an existing highway pavement. Full-size concrete panels (183 cm × 183 cm × 7.6 cm) were fabricated on a 3-mm thick porous fabric sheet as an interface between the concrete overlay and highway pavement in practice, and tested to failure under three-point loads. The optical fibers were first characterized at room temperature on a low capacity load frame up to 12,000 μe. They were then embedded into concrete panels to measure load-induced strains with a Neubrescope (Model 7020) based on the pulse pre-pump Brillouin optical time domain analysis (PPP-BOTDA), and locate and size multiple cracks from the directly measured strain distributions. The test results indicated that the distributed optical fiber sensors are a reliable and accurate tool for the monitoring of crack formation and early propagation in concrete pavement.