Glass fiber–reinforced polymer–packaged fiber Bragg grating sensors for ultra-thin unbonded concrete overlay monitoring

Abstract

The US Department of Transportation suggests a minimum thickness of 7 in (178 mm) to 8 in (203 mm) for unbonded concrete overlay. Thinner overlays driven by economic advantages have attracted worldwide attention. To prove the feasibility of thinner overlay, especially ultra-thin unbonded concrete overlays, robust overlay assessment techniques are demanded. In this article, glass fiber–reinforced polymer–packaged fiber Bragg grating sensors were developed and deployed to evaluate the early performance of fiber-reinforced unbonded concrete overlay with a thickness of 3 in (76 mm) placed on a 7.5-in (191-mm) concrete pavement, using a fabric interlayer as bond breaker. The early performance of the ultra-thin concrete overlay within a year was monitored and investigated, indicating the occurrence of transverse cracks located adjacent to the transverse cracks in the existing pavements. The numerical analysis and field experiments confirmed the accuracy and robustness of the fiber optic sensors, which showed their potential for further applications in concrete pavement monitoring.