Using fiber-optic sensing techniques to monitor behavior of transportation materials

Although not new to the communications or manufacturing area, fiber-optic sensors are only recently being applied to civil engineering structural evaluation. These sensors offer enormous potential within the transportation field to examine and characterize strain behavior in commonly used materials. Fiber-optic sensing research efforts conducted during the past 2 years on three materials relevant to the transportation industry are documented: portland cement concrete, steel, and asphalt concrete. Portland cement mortar beams were tested to determine the rate and magnitude of shrinkage. Impending fractures in steel structures may be avoided by real-time sensing, thereby minimizing potential safety problems. Steel beams were loaded to measure bending strains, as a precursor to beam crack detection. Finally the lateral strain behavior of axially loaded asphalt emulsion aggregate mixture (EAM) cylinders was studied. The EAM Poisson ratio was determined. Findings comparable with those calculated from theory, found in the literature, and obtained with traditional sensing techniques are presented. Whereas this fiber-optic sensing methodology offers great potential, the reliability and viability of this new measurement technique must be further assessed. This research advances the development and use of this innovative technology.