Performance Evaluation of Periwinkle Shell as Partial Replacement for Coarse Aggregate in Concrete Mix Strengthened by Conplast Sp430

This study investigates the performance evaluation of using periwinkle shells (Tympanotonus fuscatus) as a partial replacement for coarse aggregate in concrete mixes, with added Conplast SP430, to determine the physical properties, workability and durability, examine the mechanical proprieties of concrete mix and assess the optimal percentage replacement that balances sustainability and structural integrity. The method adopted was experimental and the concrete was mixed in a ratio of 1: 1.6: 3.8 and tested with 0%, 10%, 15%, 20%, and 25% replacement levels of periwinkle shell. The experimental program involved replacing granite with periwinkle shells at varying proportions (0%, 10%, 15%, 20%, and 25%) by weight and conducting a series of tests including slump test, bulk density, water absorption, aggregate crushing value (ACV), and compressive strength tests at different curing ages (7, 14, 21, and 28 days). Based on the results showed, the percentage of periwinkle shell increased at 0% replacement to 25% replacement, the slump value was 26mm to 41mm respectively, which falls within the very low to low workability range in the BS Code Slump classification, generally incorporating PS as coarse aggregate enhances the workability of concrete as evidenced by the increase in Slump Value with higher replacement, while water absorption increased from 1.23% (normal concrete) - 2.90% at 25% optimal replacement. However, concrete mixes with up to 10 - 15% replacement demonstrated compressive strengths at 28 days of 30.04N/mm2 - 30.40N/mm2 respectively, which were within acceptable limits for non-structural and lightweight applications. The inclusion of Conplast SP430 superplasticizer enhanced the mix’s performance by reducing water demand and improving consistency. The findings suggest that periwinkle shell is a viable, eco-friendly alternative aggregate, contributing to sustainable construction by minimizing environmental waste and reducing reliance on natural granite. The study concluded that a practical approach to waste management and costeffective construction in coastal and resource-constrained regions is highly recommended.