Deformation measurements of mortars at early ages and of large concrete components on site by means of embedded fiber-optic microstrain sensors

The paper demonstrates the application of fiber-optic microstrain gages to steel components of prestressed and reinforced concrete structures in order to measure deformations caused by proof loads or induced by constraints during the hardening period of large concrete sections. The use of embedded micro sensors for assessment of volume changes of cementitious building materials at early ages, and corresponding deformations due to heat, shrinkage, etc. in matured mortars, is also discussed. A resolution of 0.01 mu epsilon was achieved. Theoretical aspects for the design of surface-mounted and embedded sensors are briefly addressed. We have investigated the behavior of embedded optical fibers, micro sensors and their coatings in cementitious mortars. Initial findings regarding the bond between sensor and the mortar matrix, as well as preferred coating materials, are presented. (C) 1997 Published by Elsevier Science Limited.