Effectiveness of recycled nylon fibers as reinforcing material in mortar

Disposing of waste fishing nets has been a major issue in the sea environment. Although the storage of such nets has not caused a serious safety hazard to date, it is important to find suitable recycling solutions. In this study, the authors investigate the utilization of recycled waste fishing nets in fiber-reinforced mortar and compare the mechanical properties of such mortar made with recycled waste fishing nets to those of mortar made with PVA (polyvinyl alcohol) short fibers. Two types of recycled nylon fiber were investigated: straight fiber and fiber with a knot at each end. The straight recycled nylon fibers were obtained by manually cutting waste fishing nets to the lengths of 20 mm, 30 mm, and 40 mm, and adding them to mortar at the volume ratios of 1.0%, 1.5%, and 2.0%. The 40-mm-long knotted fibers were added to mortar at the volume ratios of 0.5%, 0.75%, and 1.0%. The mechanical test results showed improvements in first-crack strength, toughness, and ductility for mortar reinforced with recycled nylon fibers. The addition of recycled nylon fibers improves first-crack strength more than that PVA fibers do. However, the compressive strength decreases with increase in fiber fraction, and decreases with increase in fiber aspect ratio.