Abstract
<title>Abstract</title> <p>This study investigated the suitability of using green banana peel ash (GBPA) (AAA group(, which is native to East Africa, as a partial replacement for cement in high-performance concrete (HPC). Green banana peels were collected, dried, and burned at a controlled temperature of 800°C to produce ash, which was then ground and sieved through a 75 µm sieve. The physical and chemical characteristics of GBPA were evaluated through particle size analysis, X-ray fluorescence (XRF), and X-ray diffraction (XRD) analyses. The XRF results showed that GBPA has pozzolanic characteristics, with a SiO₂ content of 47.9%, Al₂O₃ of 16.706%, and Fe₂O₃ of 5.294%. The physical properties revealed a specific gravity of 2.34 and a moisture content of 1.0%. Concrete mixes were prepared with GBPA replacing cement at 0% (control), 5%, 10%, 15%, and 20% by weight, maintaining a constant water-cement ratio of 0.30 and a total binder content of 450 kg/m³. A total of 110 specimens were cast and tested for compressive strength, splitting tensile strength, water absorption, and sorptivity at 7, 14, and 28 days of curing. The control mix achieved a compressive strength of 67.06 MPa at 28 days, while the 5% GBPA replacement exhibited good compressive strength in comparison with the control mix, achieving a maximum of 69.08 MPa at 28 days. Beyond 5%, a decline in compressive strength was observed: 10% substitution achieved 60.167 MPa, 15% achieved 39.55 MPa, and 20% achieved 33.314 MPa after 28 days of curing. Splitting tensile strength followed a similar trend, with the control achieving a maximum of 5.01 MPa at 28 days, while GBPA-modified mixes ranged from a highest of 5.22 MPa at 5% replacement to a lowest of 2.20 MPa at 20%. The durability results demonstrated that 5% GBPA replacement achieved the lowest water absorption (1.07%) and sorptivity (0.000064 mm/min⁰·⁵), comparable to the control mix. Higher GBPA replacements increased water absorption and sorptivity, reaching 1.47% and 0.0004 mm/min⁰·⁵ at 20% replacement. This indicates that low GBPA incorporation can maintain satisfactory durability performance while improving sustainability in HPC.The study concludes that 5% GBPA substitution resulted a satisfactory mechanical and durability properties compared to the control mix, and the characterization of GBPA showed pozzolanic properties close to the standard requirements.</p>