Influence of Manganese Dioxide ( <scp> MnO ₂ </scp> ) Coated Oil Palm Empty Fruit Bunch Spikelet Fibers on the Physicochemical and Mechanical Properties of Fiber Cement Composites

ABSTRACT The use of natural fibers in cement‐based composites is increasingly encouraged as a sustainable alternative to synthetic fibers; however, their inherent hydrophilicity limits performance in fiber cement composites. In this study, manganese dioxide (MnO 2 )–coated oil palm empty fruit bunch (OPEFB) fibers were developed to reduce water uptake and enhance mechanical performance of fiber cement composites. The fibers were coated via a low‐temperature wet chemical process involving sequential treatment with manganese sulfate and potassium permanganate in an acidic medium, resulting in a visible color change from pale yellow to black. Scanning electron microscopy confirmed surface modification and coating deposition on the fibers. Water absorption tests showed a substantial reduction of 31.35% for coated fibers compared to uncoated fiber. Mechanical performance was evaluated through compressive strength testing, and statistical analysis was performed using two‐way analysis of variance (ANOVA) to assess the effects of curing duration (7, 14, and 28 days) and fiber content (0%–2.5%) on coated and uncoated composites. The ANOVA results revealed that curing duration, fiber content, and their interaction had highly significant effects on compressive strength ( p &lt; 0.0001), indicating that strength development is governed by the combined influence of both factors. Coated specimens consistently exhibited higher compressive strength than uncoated specimens at corresponding conditions, with a maximum strength of 6.12 MPa achieved at 28 days curing with 2.5% fiber, compared to 5.83 MPa for uncoated composites. The interaction effects further demonstrate that the beneficial influence of fiber coating becomes more pronounced at higher fiber contents and longer curing periods, confirming the effectiveness of MnO 2 coating in improving fiber–matrix interaction and overall composite performance.