International Journal of Scientific Research and Engineering Development

In this study, coarse aggregate was partially replaced with coconut shell, fine aggregate with rice husk ash, and cement with limestone powder to produce lightweight concrete (LWC). Concrete is one of the most widely used materials in the construction industry, with aggregates serving as a fundamental component. However, the large-scale extraction of natural rocks for aggregate production has raised serious environmental concerns. To address these issues and promote sustainable construction practices, this research investigates the use of alternative materials. Cement was replaced with limestone powder at a constant rate of 20%, fine aggregate with rice husk ash at varying proportions of 5%, 10%, 15%, 20%, and 25%, and coarse aggregate with coconut shell at replacement levels of 5%, 10%, 15%, 20%, and 25%. The mechanical properties evaluated included compressive strength, split tensile strength, and flexural strength. The addition of limestone powder improved both the workability and strength characteristics of the concrete. Moreover, the inclusion of coconut shell aggregate reduced the overall weight of the concrete, making it suitable for lightweight structural applications. The results indicated that the optimum strength was achieved with 10% coconut shell, 10% rice husk ash, and 20% limestone powder replacements.