‘GFRP Waste Type’ factor also has a significant influence on mechanical strength of modified PMs, contributing with 12% and 17% to the global variation of compressive and flexural strength responses, respectively. As shown in response graphs of Figs. 4 and 5
regarding the main effect of this factor, PMs modified with CW clearly show improved mechanical behaviour over FW admixed mortars. This feature is also highlighted in response graphs of interaction effects and is more pronounced regarding compressive
than flexural behaviour. In general, the addition of CW recyclates leads to higher increases in loading capacities than homologous amounts of FW admixtures. For GFRP waste contents of 4% and 8% respectively, increases of 16.0% and 22.3% on average mechanical properties of CW admixed formulations were found, compared with increases of 8.3% and 1.3% on homologous values of FW trial formulations (the average increases of mechanical properties are computed as average increases of compressive plus flexural strengths). Moreover, for 12% waste addition, FW test series even shows a decrease of 8.7% on mechanical properties with regard to the control formulation, whereas for the CW12 trial formulation they remained higher. While focusing only on the waste type effect, the results clearly show that 4% and 8% in waste content addition constitute the turning points in the trend of the behaviour of these materials for, respectively, FW and CW based formulations(either in bending or in compression). The higher sensitivity of FW admixed mortars to increasing amounts of GFRP waste might be explained, once again, by the distinct specific surface areas and geometric characteristics of CW and FW recyclates (FW admixtures, with finer particles, require higher contents of resin binder
to attain the same level of wetting).