Influence of coconut shell grades as partial replacement of coarse aggregates on concrete properties

Abstract

Globally, the depletion of raw materials for concrete has become prevalent due to the rapid population growth. Coconut shells can be a cheap yet environmentally friendly solution as a partial replacement of coarse aggregate in concrete. In this research, the effect of coconut shell variable particles on concrete is investigated. The coconut shells were crushed in the laboratory using a mini jaw crusher, sieved to 5 to 14 mm and 5 to 20 mm, and used as a partial replacement for coarse aggregate in concrete mixes. To further understand the impact of coconut shell particles at variable grades on concrete, workability, density, compressive and splitting tensile strength, and water absorption properties were assessed. In comparison to the control concrete, five coarse aggregate replacement levels of 5 percent, 10 percent, 15 percent, 20 percent, and 25 percent of coconut shell particles (5-14 mm and 5-20 mm) were tested. The physical and mechanical properties of ordinary Portland cement, sand (fine aggregate), coarse aggregate, and coconut shell particles were all determined. A scanning electron microscope was used to better understand the surface structure of the coconut shell particles, and how these surfaces affect concrete when added. The workability investigation revealed a reduction in slump and compacting factor due to the significant addition of coconut shell particles (5-14 mm and 5-20 mm) into the concrete mixes. Thus, it was concluded that coconut shell particles (5-14 mm) had a significant impact on the density of concrete when compared to 5-20 mm and control concrete. The Slump, compacting factor, compressive, and splitting tensile strength were all lower in the coconut shell particles concrete than in the control concrete. Coconut shell concrete (CSC) absorbed more water after 28 days of curing than control concrete. Although coconut shell particles (5-14 mm) reduced concrete compressive and splitting tensile strength when compared to coconut shell particles (5-20 mm) and control, 5 percent partial coarse aggregate substitution with coconut shell particles was shown to be the optimal percentage after 7, and 28 days of curing. According to the findings captured in this research, the strength of coconut shell concrete is reduced due to the increased surface area because coconut shell particles have a specific gravity that is nearly three times that of coarse aggregate, batching was done by weight making coconut shell particles quantity more and the smoothness of the inner section which causes slip in concrete, while workability is increased due to the presence of micro small pores on the outer surface.