Central Composite Design for Enhancing the Compressive Strength of a Natural Lignocellulosic Fiber -Reinforced Concrete

This study evaluates the compressive strength performance of Nipa Palm Fibre Reinforced Concrete (NPFRC) as a sustainable alternative for low- to medium-strength construction. Using Central Composite Design, the research examined how varying fibre content and length influence compressive strength. NPFRC compressive strength ranged from 9.17 to 21.96 MPa, compared to 26.12 MPa for conventional concrete. Higher fibre content and length generally reduced strength due to poor workability, compaction, and increased porosity. Fibre dosage had a more significant impact than fibre length. Interaction plots revealed that fibre content and length had interdependent, not additive, effects on strength. Response Surface Methodology (RSM) optimized the mix design, identifying 0.5% fibre content and 34.25 mm fibre length as ideal, yielding a predicted strength of 20.98 MPa with 92.30% desirability. A confirmatory test recorded 19.87 MPa, a 5.58% deviation from the prediction, within acceptable limits. Although the optimized compressive strength does not meet structural-grade standards (ASTM and EN 206), the results demonstrate NPFRC’s potential for non-load-bearing and light structural applications. The study highlights the importance of fibre treatment, optimal proportioning, and quality control, reinforcing NPFRC’s viability in eco-friendly construction where moderate strength and sustainability are prioritized.