Author:

Keywords:

Optical fibre sensor, historical masonry, polarimetric setup, AE detection, damage monitoring

Abstract:

This paper presents the results of a study which focuses on the development of innovative monitoring techniques for historical masonry structures, based on Acoustic Emission (AE) detection with optical fibre sensors. In this study, for the first time, intrinsic optical fibre sensors are applied to detect AE in quasi-brittle construction materials such as masonry or concrete. For this purpose, a single mode optical fibre sensor (OFS) in a polarimetric setup is applied. Data acquisition, filtering and processing is performed in real-time. Optical fibre sensors were installed on a test wall and initial three-point bending tests were performed on small masonry samples to give a proof of concept and to calibrate the system. The optical fibres were embedded in the mortar joint or glued on the surface. Additionally, full-scale compression tests have been performed on masonry arches, while detecting crack initiation and growth both with optical fibre sensors and PZT transducers. Results indicate that damage due to crack initiation and growth in masonry can be detected with the optical fibre sensors. Although sensitivity to AE transients is less compared with PZT transducers, the results of the polarimetric OFS setup provide a good representation of the overall mechanical behaviour and crack growth within the masonry structure.