Assessing the Use of Cassava and Potato Ashes as Concrete Admixture

Abstract

Concrete is the most widely used construction material. This research investigated the potential of cassava peel ash (CPA) and potato peel ash (PPA) as supplementary cementitious materials (SCMs) for sustainable concrete production. Agricultural wastes were calcined (CPA at 246 °C for 180 min, PPA at 450 °C for 275 min), ground, and sieved to 45 µm. Chemical and mineralogical analyses (XRF, XRD) showed CPA contained 52.48% SiO₂, 19.65% Al₂O₃, and 7.12% Fe₂O₃, while PPA contained 49.82% SiO₂, 18.93% Al₂O₃, and 6.97% Fe₂O₃. The combined oxides exceeded ASTM C618’s 70% requirement, confirming pozzolanic suitability. Concrete mixes with 0%, 5%, 10%, and 15% replacement levels were tested for slump, density, compressive strength, and water absorption up to 28 days.

Results showed strength decreased with higher replacements but remained satisfactory at 5%: CPA and PPA (18.2 MPa) compared to 23.2 MPa for control. Density values ranged 2370–2435 kg/m³, while water absorption stayed below 5% at low levels, indicating good durability. Economically, CPA (₦1,500/kg) offered better performance, while PPA (₦1,000/kg) proved more cost-effective for non-structural use. The study concludes that ≤5% CPA or PPA replacement is optimal, promoting sustainable construction while reducing cement usage and agricultural waste.