Effect of Coconut Shell Size Variation on the Physical and Mechanical Properties of Concrete

Abstract

Concrete is the second most used material in the world after water. Approximately ten billion tons of concrete are produced every year. It is expected that the demand for concrete will continue to increase in the future. Due to the huge amount of concrete produced daily which consumes natural resources and has negative effects on the environment, it has become necessary to minimize environmental effects per ton. This research investigates the use of coconut shells as a substitute for coarse aggregates in concrete, specifically looking at how this substitution affects the physical and mechanical of the concrete characteristics. In this study, crushed coconut shell aggregates of different sizes:12.5-9.5mm, 19-12.5mm, 25-19mm, and 37.5-25 mm, were utilized for concrete, making up 10% by weight of the overall coarse aggregate. The aggregate impact value of the coconut shells was determined according to IS 2386 (Part IV). The physical and mechanical properties were determined according to British Standards. The study found that concrete containing 12.5 – 9.5mm coconut shells sizes exhibited superior performance in terms of compressive and tensile strengths, compared to 37.5 – 25mm coconut shells. The 28th-day compressive strength of the crushed coconut shell concrete ranged between 12.81 N/mm² and 13.40 N/mm², while the tensile strength ranged from 1.01 N/mm² to 1.25 N/mm². Water absorption varied between 4.577% and 5.542%, and density ranged from 2128.33 kg/m³ to 2165.33 kg/m³. Notably, 12.5 – 9.5mm crushed coconut shells offered improved workability, density, and strength, making them suitable for lightweight concrete applications. Coconut shell concrete is a feasible alternative to conventional aggregates, particularly for sustainable construction practices. Physical and mechanical properties of concrete partially replaced with coconut shell size variation at different percentages on a large scale are recommended for future research.