Cracks monitoring in reinforced concrete structure with optical fibers patch

•Development of a patch based on a network of woven optical fibres;•Using light intensity in optical fibres to measure crack widths;•Structural health monitoring using fibre-optic patches;•Optimisation of fibre optic patches for civil engineering applications;•Use of lateral degradation of optical fibres for the development of displacement sensors. In the context of the necessity to monitor civil engineering structures in order to prevent incidents, this paper presents the performance of an innovative optical fibers patch sensor. The patch comprises a tissue containing an optical fiber network. The sensor is attached to the concrete surface and capable of detecting opening cracks in the order of 0.01 mm with good precision, thus satisfying the regulatory limits. The sensor is capable of precisely following the evolution of the crack, including cyclic changes in crack width. The procedure presented in this paper includes a preliminary investigation into the influence of the fibers’ diameter and the density of fibers in the patch, as well as the method of attachment to the concrete’s surface with the objective of identifying an optimal sensor configuration. Subsequently, a series of laboratory tests were conducted on reinforced concrete samples of varying dimensions. Comparisons and verifications of measurements of optical fiber patch sensors are conducted via Digital Image Correlation process. The conclusions of this paper permit the consideration of the use of this novel sensor on and within real reinforced concrete structures.