Comprehensive evaluation of sustainable Musa acuminata stems fiber–fly ash ecohybrid composites: Chemical, mechanical, thermal, and durability performance

Sustainable ecohybrid composites derived from agricultural and industrial waste offer a promising route toward environmentally friendly engineering materials. This study systematically investigates the composition-dependent mechanical, thermal, moisture-resistance, and microstructural performance of banana stem fiber (BFs)–fly ash (FA) ecohybrid composites fabricated by hot-press molding. Five FA/BFs volume-fraction ratios were investigated: 0/40, 35/5, 25/15, 20/20, and 40/0. Reinforcement composition strongly influenced the multifunctional performance of the composites. The composite containing 40 vol% BFs exhibited the highest tensile strength (26.47 ± 0.20 MPa) and flexural strength (56.16 ± 0.50 MPa), whereas the highest impact strength (647 ± 17.61 kJ/m 2 ) was obtained for MF35 containing 35 vol% FA and 5 vol% BFs. Water absorption after 24 h increased from 1.20% to 4.28% with increasing BFs content. TGA showed residual masses ranging from 30.43% to 38.83%, indicating the contribution of FA to thermal stability. SEM observations revealed that fiber–matrix adhesion, filler dispersion, and microstructural defects influenced composite performance. Overall, the results demonstrate distinct trade-offs between BFs and FA, highlighting reinforcement composition as a key parameter governing the multifunctional behavior of the ecohybrid system. These composites show potential for sustainable non-load-bearing building components.