A novel distributed fiber optic multi-parameter sensor for asphalt pavement monitoring: Design, fabrication, and performance characterization

This paper presents a novel distributed fiber optic sensor for simultaneous measurement of strain, temperature, and curvature in asphalt pavement monitoring. The sensor features a symmetric double-fiber configuration with a polycarbonate neutral layer, hot-melt adhesive, and a heat-shrinkable protective tube. The packaging process was systematically optimized using single fiber pull-out tests and in-situ OFDR monitoring. The optimal hot pressing parameters were identified as 160 °C temperature, 5.6 MPa pressure, and 1 N fiber tension, ensuring robust interfacial bonding and minimal internal strain. Comprehensive calibration tests were conducted for strain, temperature, and curvature. The sensor exhibits excellent linearity (R² > 0.99) with sensitivities of −0.0968 GHz/με, −1.6529 GHz/°C, and 351.13 GHz·m, respectively. The measurement ranges are ±12000 με, −30 to 60 °C, and 0–5 m⁻¹ . A multi-parameter decoupling method based on the superposition principle and a shape reconstruction algorithm using Frenet–Serret equations were developed. The sensor was embedded in asphalt mixture beams and validated through four-point bending tests, showing good agreement with FBG reference measurements and accurate deformation reconstruction. The results demonstrate that the proposed sensor, with its optimized packaging and comprehensive characterization, is a promising tool for multi-parameter monitoring in asphalt pavement health assessment.