A novel hybrid reinforcement of cement mortars using luffa and steel wool fibers

Considering the growing demand for more sustainable building materials, this study investigates the performance of hybrid cement mortars reinforced with luffa fibers (LF) and steel wool (SW) fibers manually prepared from commercially available luffa sponges and steel wool dish scrubs. A total of 34 mortar mixes were produced to examine the effects of fiber type, dosage, and length on water absorption, flexural strength, and compressive strength. Relative to the unreinforced control, fiber addition generally improved flexural performance, while compressive response depended strongly on the exact LF-SW proportion and the quality of fiber dispersion. The highest flexural strength was obtained for mix G-3, whereas mixes G-1 and G-2 produced the highest compressive strength; however, mix G-13 (1.75% luffa fibers and 0.50% steel wool fibers) provided the most balanced overall response, achieving 4.08 MPa in flexural strength and 26.36 MPa in compressive strength with low variability. Statistical analysis showed that compressive strength was more sensitive than flexural strength to the specific hybrid dosage, and response maps identified localized performance maxima at intermediate fiber combinations rather than at the highest total fiber contents. Failure observations and SEM analysis supported these trends byindicating that improved matrix continuity and reduced critical discontinuities were associated with more balanced mechanical behavior. Overall, the results show that hybridization of luffa and steel wool fibers can enhance mortar performance, but the benefit depends on achieving appropriate fiber proportioning, dispersion, and compaction. The proposed hybrid system therefore appears promising for cement mortar applications requiring a balance between strength and reduced water absorption.