Influence of palm fruit stalk fibre length variation on the properties of fibre-reinforced composite concrete

This study investigates the influence of palm fruit stalk fibre (PFSF) length on the properties of fibre-reinforced cementitious composites (FRCC). Fibres of 30, 60, 90, 120, and 150 mm length were incorporated at a constant volume fraction of 0.5%. Specimens were tested for workability, density, water absorption, compressive strength, splitting tensile strength, flexural strength, and abrasion resistance. Results demonstrate that a 30 mm fibre length optimally enhances performance, yielding the highest mechanical strengths (16.94 N/mm2 compressive, 2.09 N/mm2 split tensile, 4.91 N/mm2 flexural) and the lowest water absorption (2.99%). Fibre lengths exceeding 90 mm reduced mechanical properties due to fibre clumping and poor dispersion. While a 90 mm length provided the highest workability (58 mm slump), longer fibres significantly reduced it. Statistical analysis indicated a strong, significant negative correlation between fibre length and mechanical strength (r = − 0.886, p < 0.05), with fibre length accounting for 78% of the observed strength variation (R2 = 0.78). Elemental and scanning electron microscopy (SEM) analyses confirmed improved fibre-matrix bonding in composites with shorter fibres, evidenced by compositional changes indicative of calcium-silicate-hydrate (C–S–H) formation. The findings establish 30 mm as the optimal PFSF length for producing enhanced, sustainable Fibre-Reinforced Cementitious Composite (FRCC). Accordingly, the findings of this study are intended for non-structural and low-load construction applications, such as pavements, architectural panels, partitions, and secondary concrete elements.