‘GFRP Waste Content’ is the most influential factor on compressive and flexural strength responses of modified mortars, contributing with 61% and 38%, respectively, to global variation. As stressed by response graphs of the main effect of ‘Waste content’ plotted in Figs. 4 and 5, the partial replacement of sand aggregates by GFRP recyclates, has a significant incremental effect on mechanical strengths of modified PMs for the lower replacement contents (4% and 8%), regardless GFRP waste type. However, distinct trends
were observed for the effect of waste admixture on mechanical performance depending on both the amount of waste addition and the mechanical response itself (compression or bending).