Pavement Condition Monitoring of Ultra-Thin Unbonded Concrete Overlay Using Fiber Reinforced Polymer Packaged Fiber Bragg Grating Sensors

Abstract

Concrete overlay has been long used as a promising and cost-effective approach for pavement repair compared to an entire pavement replacement. To ensure the quality and durability of the concrete overlay, US Department of Transportation (USDOT) suggests a minimum thickness of 5~6 inches for concrete overlay. For a cost benefit, thinner concrete overlays with sufficient strength are continuously investigated and a practical application of thinner concrete overlays needs field performance evaluation, which demands reliable infrastructure sensors. Traditional electrical sensors such as strain gauges and vibration wires, showed high electromagnetic interference (EMI), relatively short life cycle, and need corrections due to temperature variations and lead wires/connections are degraded by high humidity in the pavement environment. These disadvantages limit their reliability for long-term pavement performance monitoring. Optical Fiber Bragg grating (FBG) sensors, with unique advantages of compactness, immunity to EMI and moisture, capability of quasi-distributed sensing, and having a long life cycle, could be a potential candidate for long-term concrete overlay performance evaluation. However, the FBG sensors suffer from their fragile nature of glass materials to survive the concrete overlay construction process. In this study, to enhance the durability of the FBG sensors, glass fiber reinforced polymer (GFRP) is used to package material. The GFRP packaged FBG (GFRP-FBG) sensors are further applied to evaluate the performance of ultra-thin concrete overlay of 3 inches in thickness using fiber reinforced concrete materials, at MnROAD facility, Minnesota DOT (MnDOT). The design of the GFRP-FBG sensors, their field layout, field test setup, and data analysis are discussed in this paper. The performance of the ultimate thin concrete overlay in the first few months of service was evaluated accordingly. Upon validation, the GFRP-FBG sensors can be further applied for condition monitoring of any types of concrete pavements to assist in pavement maintenance.