Corn Cob Ash and Palm kernel shell as partial replacement for cement and aggregate respectively in concrete

The sustainability of concrete constituents, particularly cement and coarse aggregates, is a growing concern. Research on using agricultural residues as alternatives has been explored but not fully exhausted, highlighting the need for further studies. This study investigates the viability of using Palm Kernel Shell (PKS) and Corn Cob Ash (CCA) as alternatives to coarse aggregate and Portland cement. A full factorial experimental design was adopted, including the elemental composition of materials, determination of concrete strength, and workability. Nine concrete mixes were designed, ranging from a control mix (S1) with no replacements to mixes (S2 to S9) with varying percentages of replacements at a 1:2:4 mix ratio and 0.65 water-cement ratio. Results revealed that strength increased as curing progressed from 7 to 28 days in all mixes, attaining a maximum strength of 16.44 N/mm² at 28 days. SEM-EDX analysis showed that corn cob ash contains elements like calcium (Ca), silicon (Si), and aluminum (Al) similar to those found in cement, supporting its potential as a viable partial replacement for cement. Compressive strength analysis on concrete samples demonstrated that as the percentage of replacement increased, there was a general reduction in strength across all mixes with S2, S3, S4 meeting required standard for a M15 concrete. Workability analysis using slump tests revealed variations from low to high workability rates. The study concludes that PKS and CCA can be viable alternatives in concrete production, offering a technical advantage and potential use in green building construction and sustainability initiatives.