Mechanical Performance of Coconut Fibre Reinforced Bio-Concrete
1,2*Ajagbe, W. O., 1Ajayi, M. T., 2Adebiyi, A.Y., and 3Ganiyu A. A.
1Department of Civil Engineering, University of Ibadan, Ibadan, Nigeria
2Department of Civil Engineering, Lead City University, Ibadan, Nigeria
3Department of Civil Engineering, British University of Bahrain, Saar 527, Bahrain
DOI: 10.36108/laujoces/6202.61.0190
Abstract
Fibre reinforced bio-concrete entails cementitious mixes that incorporate discrete reinforcing fibres with a bacteria precursor to trigger microbially induced calcite precipitation (MICP) for autonomous crack repair. This study investigates the influence of coconut fibre reinforcement on the mechanical performance of bio-concrete, with emphasis on flexural strength and split tensile strength, alongside an assessment of aggregate quality to ensure reliable mix performance. Well-graded fine and coarse aggregates satisfying
BS EN 12620 requirements were used, with aggregate properties confirming suitability for structural concrete. The coarse aggregate exhibited a low aggregate crushing value of 12.24%, indicating high resistance to crushing and ensuring that aggregate failure did not govern concrete performance. Bioconcrete specimens were produced with varying coconut fibre contents (0%, 0.5%, 1.0%, and 1.5%) and tested for splitting tensile and flexural strength at curing ages of 7, 14, and 28 days. The results revealed that the incorporation of 0.5% coconut fibre yielded the highest flexural and split tensile strengths at all curing ages, achieving maximum values of 5.2 MPa and 2.6 MPa, respectively, at 28 days. These improvements were attributed to effective crack-bridging action and enhanced stress redistribution provided by the fibres, resulting in improved ductility and delayed crack propagation. However, higher fibre contents (≥1.0%) led to a reduction in strength due to fibre agglomeration, increased porosity, and poor matrix continuity. The findings demonstrate that coconut fibre can serve as an effective and sustainable reinforcement in bio-concrete when used at an optimal dosage. A fibre content of 0.5% was identified as the threshold for maximising mechanical performance without compromising matrix integrity. This study highlights the potential of coconut fibre reinforced bio-concrete as a durable and environmentally friendly material for structural applications.
Keywords: Coconut Fibre, Bio-concrete, Crack Healing, Flexural Strength, Tensile Strength.