Effects of hygrothermal ageing on the mechanical behavior of conventional composites and bio-composites intended for structural reinforcement ; Influence du vieillissement hygrothermique sur le comportement mécanique de composites conventionnels ou biosourcés destinés au renforcement de structures

International audience ; In the context of ageing infrastructures, structural reinforcement by externally bonded fibre reinforced polymers offers a reliable solution for the rehabilitation of structures. Nevertheless, some questions remain concerning the long-term sustainability of these reinforcements and their environmental impact. This study, which is part of the MICRO project funded by the National Research Agency (ANR), aims to study the effect of hygrothermal ageing on the mechanical performance of traditional carbon/epoxy composites and an innovative composite system with a reduced environmental footprint. This bio-sourced system, which was specifically developed as part of this project, consists of a bio-epoxy matrix reinforced with flax fibres. The design of experiment consisted in subjecting both types of composite laminates, as well as concrete slabs reinforced with these two systems, to different accelerated ageing conditions under six combinations of temperature and relative humidity. Samples were also subjected to natural ageing in the external environment, in order to compare ageing kinetics under accelerated and natural conditions. The mechanical properties of composites were then periodically characterized by tensile tests, interlaminar shear tests and short beam 3-point-bending tests, while the interface concrete/composite was evaluated by pull-off tests. In addition, physico-chemical tests were systematically carried out to identify possible microstructural modifications or degradation of the composites during the various ageing processes. ; Face au vieillissement du parc d’infrastructures, le renforcement structural par collage externe de matériaux composites s’impose comme une solution de choix pour la réhabilitation des ouvrages. Néanmoins, certaines questions restent posées quant à la durabilité à long terme de ces renforcements et à leur impact sur l’environnement. Dans ce contexte, cette étude réalisée dans le cadre du projet MICRO financé par l'Agence nationale de la recherche, vise à ...