Structural health monitoring of concrete cylinders using protected fibre optic sensors

Two kinds of sensor protection system for fibre optic sensors (FOS), an embedded type and a surface-mountable type, have been developed in the work described this paper. Extrinsic Fabry-Perot interferometric (EFPI) and fibre Bragg grating (FBG) sensors protected by the designed protection systems have been used to monitor the cure progress and structural health status of concrete cylinders. Experimental results indicate that the sensor protection systems for the FOS perform adequately and effectively in a concrete environment. The protected fibre optic sensors are suitable for achieving structural health monitoring in practice. It is also revealed that there is excellent correlation between the results obtained from the protected FOS and reference electrical resistance strain gauges.