Mechanical properties of concrete with seashell waste as partial replacement of cement and aggregate

Abstract

Seashell is a very hard and protective outer layer produced by an animal that lives in the sea. Empty seashells are mostly found in the shore and collected as waste by beachcombers. This marine by-product can be used as partial replacement of coarse aggregate and cement in concrete. This paper describes the potential use of seashell powder and seashell waste as cement and aggregate replacement in concrete, to produce a greener concrete. This study also focused on the effect of seashell powder and aggregate in concrete with respect to compressive, split tensile and flexural strength after 7, 28, 56 and 90 days of curing the concrete specimen. The three different replacements of cement by seashell powder (5%, 10% and 15%) and replacement of coarse aggregate by seashell aggregate (10%, 20% and 30%) was used in mix proportion with w/c ratio of 0.5. The mechanical properties of seashell concrete were compared with control mix specimen of M25 grade of concrete. It was found that replacement of cement and coarse aggregate by seashell products enhances the compressive strength by 30 %, at the later age (after 90 days of curing) and thus enable proper utilisation of these seashell waste as sustainable material for the concrete. The 5% seashell powder and 10 % seashell aggregate replacement mix is the optimum percentage of replacement in the concrete. Therefore, this study recommends replacing cement with 5% seashell cement and 10% seashell aggregate.