Effect of Crushed Coconut Shell and Over Burnt Brick on the Mechanical Behaviour of Green Concrete as a Partial Replacement of Coarse Aggregate

Coarse aggregate (CA) is a major ingredient of the concrete, constituting around 60-75% of total concrete volume in a conventional mix design. The demand for CA is drastically growing, resulting in the diminishing of natural resources, and its extraction demands heavy machinery input, which triggers additional environmental issues. This research investigates the mechanical behavior of green concrete by partially substituting CA with wasted coconut shells (CS) and over-burnt bricks (OB). CS replaces at 5%, 10%, and 15% during the mix design, whereas OB substitutes at 20%, 25%, and 30%. Total 216 specimens were cast in the form of cubes, cylinders, and beams. It was observed that the workability and density of concrete decrease with increasing CS and OB. The compressive strength, split tensile strength, and flexural strength of the specimen decreased in both substitutes with the increasing amount of substituting materials when used individually. However, an increment is found in the mechanical behavior of green concrete when CS and OB were both used at 5% and 20% replacement, respectively. The study has multiple implications for casting eco-friendly or green concrete, such as the reuse of waste materials, reducing the carbon emissions obtained from the extraction of CA, and preserving the natural resources.