Abstract
While distributed strain sensor has been advanced by the use of stimulated Brillouin scattering in optical fiber, fiber optic sensor has recently increased its application in civil engineering field. In this study, fiber optic sensor installation technique is developed, and it is experimentally proven that the sensor can contribute to strain monitoring for asphalt layer, which has a difficulty in embedding sensor because of its temperature-dependent behavior. Due to the softening of asphalt, the fact that the transferred stress from asphalt to sensor is drastically decreased over the transition temperature leads to low sensor sensitivity. To obtain both durability and sensitivity in asphalt over a wide range of temperature, several types of fiber optic sensor coated with resin materials are designed, fabricated, and evaluated for its basic performance. Through experiments on both prism specimens and a full-scale pavement with the developed sensor coated with polyester and polyethylene of 5 millimeters in total diameter, it can be stated that the sensor directly monitors asphalt behavior even if the temperature has been changed. Moreover, post-processing technique for measured strain distribution data is proposed toward global integrity monitoring.
