The partial replacement of sand aggregates by GFRP waste materials, up to 8% in total weight content, has an incremental effect on both flexural and compressive strengths of resultant PMs, regardless of the GFRP waste size grade. Increasing the amount of GFRP recyclates leads to progressive decrease in mechanical properties of admixed PMs, and above 12% waste content, loading capacities tend to drop below those of unmodified
PMs. The influence of GFRP waste content is more pronounced in compression than in bending, with turning points in the behaviour trends of these materials at 8% and 4% waste content, respectively.