Glass fibre-based FRCM systems under mild temperature exposures

Fibre Reinforced Cementitious Matrix (FRCM) systems have been widely used as an effective method for retrofitting existing structures. However, their durability against environmental actions remains partially unsolved. A comprehensive experimental study was carried out to investigate the influence of different temperature levels on the mechanical properties of two FRCM systems. The first system was composed of a combination of aramid and glass fibres as reinforcing textile, while the second system was strengthened with glass fibres only. Tests were carried out on dry bundles and textiles, mortar prisms, FRCM coupons and single-lap direct shear specimens. A specific thermal procedure was developed and employed to control the conditioning and testing phases. To investigate the impact of temperature exposure on the tensile and bond behaviour of the FRCM systems, capacity retention rates were evaluated and, in general, a decreasing trend was registered in terms of peak axial stress vs temperature. In terms of tensile properties, a similar negative impact of temperature was registered for both systems, with capacity retention rates ranging between 60 % and 70 % at the highest temperature levels tested. In terms of bond behaviour, temperature variations can potentially trigger a change in the failure mode, which was more pronounced for the system containing only glass fibres, for which lower retention rates were recorded, with a maximum reduction to 50 % at the highest temperature. The obtained outcomes demonstrated how even mild temperatures can potentially affect the tensile strength of these systems as well as their bond capacity when applied on masonry substrates.