Using Fiber Bragg Grating Sensors to Monitor Pavement Structures

Abstract

A new high-resolution temperature and strain sensor with fiber Bragg grating (FBG) technology was developed. The FBG sensor consists of a reference fiber grating and a grating pair scheme that could offer the potential of simultaneous measurement of strain and temperature for monitoring pavement structures. Experimental results showed that measurement errors of ±μ∈ and ±0.13°C for strain and temperature could be achieved, respectively. Feasible applications of this sensor for monitoring pavement structures were investigated. The reliability and long-term stability tests for this sensor were examined by mounting it on the surface of two kinds of specimens, asphalt and concrete, and several temperature cycles with a designed working temperature range up to 110°C were applied for at least 24 h. An electronic thermocouple and a long-period optical fiber grating (LPG) sensor with similar function were used to compare the performance. Small root-mean-squared temperature variations (better than 1°C) and excellent long-term stability (within 2%) were obtained. The maximum variations in temperature for 48 h were only 1.94% and 2.32% for asphalt and concrete specimens, respectively. Results indicated that although the performance of this FBG sensor was comparable with that of the conventional thermocouple, its long-term stability was four times better than its counterpart, the LPG sensor. This type of simple and low-cost fiber-optic sensor is expected to benefit the developments and applications of new paving materials, mix design procedures, or the enhancement of pavement management systems.