Magnified images of GFRP recyclates obtained by a high-resolution metallographic microscope (Fig. 6) also shows that the CW recyclates comprise a wide range of fibre lengths varying between 25 mm and few micrometres, whereas the maximum fibre length
of FW is about 5 mm; thus, CW has a higher reinforcing effect than FW. This feature generally leads to strengthening of the host material, provided strong interface bonding is ensured. In general terms and taking into account the distinct geometric characteristics of FW and CW recyclates, it can be stated that whereas FW acts more
like a filler extension for sand aggregates of modified mortar (leading to a less void-volume of resultant material), CW acts as an effective reinforcing material, promoting improved mechanical strength and less brittle behaviour of modified mortars.