Steel Fiber Reinforcement for Improved Structural Performance and Durability of 3D Printed Mortar in Marine Environments (2025-09)¶

This study investigates the influence of steel fiber reinforcement on the buildability, mechanical properties, and durability of 3D-printed mortar (3DPM) in marine environment. A mortar mix incorporating 0.75% steel fiber (by volume) was compared with a plain control mix. Experimental evaluations included compressive and flexural strength testing, buildability assessment (using 20 mm and 30 mm nozzles), and durability tests addressing water permeability, chloride ingress, and sorptivity. Results demonstrated that steel fibers enhanced compressive strength by 9.3–14.4% and flexural strength by 20.8–75.3%, while enabling stable printing of 500 mm structures with a 20 mm nozzle. However, fiber-reinforced specimens demonstrated increased chloride permeability and sorptivity with respect to plain mortar when cured in seawater and sulphate water. These findings confirm the potential of steel fibers as a viable solution for improving structural performance in 3D-printed concrete while highlighting the need for improved durability in severe environmental conditions.