The Effect of Alkali Treatment Concentrations on the Mechanical Properties of Ronier Fiber Reinforced Concrete

Abstract

This study experimentally investigates the effect of sodium hydroxide (NaOH) treatment on ronier fibers and their influence on the mechanical performance of concrete. With the growing demand for sustainable construction materials, natural fiber-reinforced concrete presents an attractive alternative to synthetic reinforcements. Ronier fibers, derived from the African Borassus aethiopum palm, possess high tensile strength, flexibility, and inherent alkali resistance, making them suitable for cementitious composites. In this study, fibers were treated with 1%, 3%, and 5% NaOH solutions and incorporated into concrete at a constant dosage of 1% by cement weight. Fiber tensile testing, Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FTIR) analyses were performed to assess the mechanical behavior, surface morphology, and chemical modifications prior to incorporation. Concrete mixes included a control, untreated fibers, and NaOH-treated fibers. Compressive, split tensile, and flexural strengths were evaluated at 7, 14, and 28 days using standard cube, cylinder, and beam specimens. The results showed that fiber inclusion caused a slight reduction in compressive strength, which increased with treatment concentration, whereas significant enhancements were observed in tensile and flexural performance. At 28 days, the split tensile strength increased by approximately 8% for untreated fibers and 19% for the 1% treated fibers, whereas the flexural strength improved by about 6% and 12.5%, respectively. Higher NaOH concentrations reduced the performance due to fiber degradation. Overall, the 1% NaOH treatment was identified as optimal, demonstrating the potential of ronier fiber-reinforced concrete for improved crack resistance and flexural capacity in sustainable and low-cost construction applications.