Measurement of early-age strains in mortar specimens subjected to cyclic temperature

As well known, the volume change induced by environment temperature variation can lead to cracking at the surface of cementitious materials with low water-cement ratio. Thus, it can be said that there is a pressing need to reveal the early-age performance of cementitous materials in a variable environment temperature. Conventional thermocouple and strain gauge have been widely used for measuring temperature and strain in cementitious materials, respectively. However, conventional sensors have several limitations for measuring strain and temperature in cementitous materials such as too many cables for multipoint measurement, short circuit, and electromagnetic interference. Compared to conventional electrical strain gauge, fiber Bragg grating (FBG) has several inherent advantages including multiplexable, resistance to electromagnetic interference, and stable signal in long distance transmission. In this study, two lines mutiplexed with FBG strain and temperature sensors were fabricated and employed to measure the quasi-distributed strain and temperatures in mortar specimens subjected to cyclic temperature.