One of the most recent strengthening techniques of masonry structures involves fibre-reinforced polymer (FRP) grids as internal reinforcement of mortar plasters to produce what is normally referred to as Composite Reinforced Mortar (CRM) systems. The behaviour of such systems relies on the performance of the FRP grids which in turn depends on the properties of their constituents (fibres and resin).

By comparing results of tensile tests at different displacement rates on glass fibre yarns, the effects of the strain history on the strengths exhibited by such products is here investigated. Further tensile tests were then performed on glass FRP grids made of the same previously analysed yarns in their warp direction and the influence of the displacement rates again studied.

The analysis of the results of the performed experimental activity allows studying the influence of strain rates on the mechanical properties and failure behaviour of both yarns and their relative composites, and to investigate how the weaving process and, therefore, the geometry of the glass FRP grids, influence their final mechanical behaviour.