Added advantages in using a fiber Bragg grating sensor in the determination of early age setting time for cement pastes

A fiber Bragg grating (FBG) sensor was used to monitor the early age curing temperatures of cement paste. Additional advantages in using the sensor were highlighted. The FBG was inscribed by a Continuous Wave 244 nm argon ion laser in the photosensitivity fiber. The fabricated FBG was calibrated from room temperature to 105 degrees C. In this temperature range, the FBG was found to be good in terms of both the sensitivity and linearity which were around 9 pm/degrees C and 99.9%, respectively. A host specimen with ratio of Portland cement, sand and water of 800, 500, and 275 ml by volume was used in the experiment. Results showed that the FBG could determine the initial and the final early age setting times. The initial early age setting time for the cement paste was about 5 h and the final early age setting time was about 14 h after casting. (C) 2013 Published by Elsevier Ltd.