Optical fibre sensors for the measurement of concrete sample properties following exposure to freeze/thaw tests

In this work, a fibre Bragg grating (FBG)-based moisture sensor has been developed to test the porosity changes in a number of concrete samples when exposed to a series of different freeze/thaw cycles. The concrete samples produced specifically for the work have been analyzed under laboratory conditions using the sensor to monitor the changes in the rate of water ingress into the modified samples. The sensor works by monitoring the arrival of the moisture front at the centre of the cylindrical concrete samples when subjected to a simple water-bath test. The measurements were obtained by using a probe sensitive to the Bragg wavelength shift as a result of volumetric expansion of the moisture-sensitive polymer coated onto the FBG. This work is intended to show the feasibility of the use of the sensor developed to indicate the influence of freeze/thaw damage on the water absorption properties of concrete.