Statistical Analysis of the Impact of Chikoko Clay Source Variation on Concrete Strength Parameters

This study evaluates the impact of geographic source variation of Burnt Pulverized Chikoko (BPC) clay on the compressive strength characteristics of concrete Chikoko clay was sourced from Okrika (Rivers State) and Ogbia (Bayelsa State), both in the Niger Delta region of Nigeria, and processed through calcination into BPC. The material was incorporated as an admixture in concrete at varying proportions (0%, 5%, 10%, 15%, and 20%) using two mix ratios (1:1.5:3 and 1:2:4) with a constant water cement ratio of 0.5. Compressive strength was evaluated at curing ages of 7, 14, and 28 days. Results revealed distinct trends between the two sources: Okrika-sourced BPC significantly improved concrete strength, peaking at 32.89 MPa (15% admixture, 1:1.5:3 mix), while Ogbia clay showed optimal performance at lower dosages (5% - 10%) and declined thereafter. Two-way ANOVA confirmed that the clay source (p = 0.0033) and its interaction with BPC percentage (p = 0.0250) had statistically significant effects on strength development, while the BPC percentage alone was not uniformly significant (p = 0.1830). These findings emphasize that the pozzolanic performance of Chikoko clay is highly dependent on its mineralogical origin and dosage, underscoring the importance of source-specific characterization before use in structural applications. The study advocates for careful optimization of natural pozzolans based on location to ensure performance reliability in concrete production.