LAUSR

Abstract Corrosion of reinforcement in concrete is one of the major causes for deterioration of concrete structures. This work presents an approach in the monitoring of concrete structures for damage induced by corrosion of steel in concrete using a lens-based plastic optical fiber (LPOF) strain sensor. The optical fiber sensor offers the advantage of being light weight, small in size, low-cost, immune to electromagnetic interference and it does not pose any spark hazard. The intensity-based optical fiber sensor used in this work consists of an emitter fiber, a ball lens, a receiving fiber and a light detector system. The light from the emitter fiber converges to focal point using the ball lens, before it enters the receiver fiber. A change in distance between the ball lens and the receiver fiber would lead to a change in the light intensity transmitted. The intensity change is correlated to the relative distance using a suitable calibration curve. Following the calibration of the sensor, it was used to monitor response of concrete members subjected to flexural loading. Subsequently, the sensor was tested for its ability to monitor corrosion of steel in concrete using an accelerated corrosion test set-up. The sensor shows promising results for detection of corrosion. The test results were used for identification of the corrosion propagation phase, which can be used for predicting the remaining service life of the structures. The optical fiber sensor strain readings were then correlated to the corrosion penetration depth to estimate the extent of damage during the corrosion of rebar. The test results show that it is possible to monitor concrete structures for damage due to flexural loading and corrosion of rebar using an intensity-based LPOF strain sensor.