replaced by GFRP waste throughout both CW and FW test series (from 0% to 12%), the overall specific surface area of aggregates increases,while resin content is kept constant at 20% in weight in all formulations. The higher specific surface area of GFRP waste particles compared to sand particles, especially in the case of FW admixture, requires higher contents of binder matrix for a proper wetting and cohesive bonding of aggregates. This feature is believed to be the main reason for the observed inflexion points in the behaviour trend of the mortar materials (at approximately 8% in waste content for compression and 4% for bending).