Development of an eco-friendly high-strength lightweight concrete using pre-treated coconut shell aggregate and ground-granulated blast furnace slag

The effective utilization of agricultural and industrial wastes in construction not only mitigates disposal issues but also preserves precious natural resources. The main aim of this research was to develop an eco-friendly high strength lightweight concrete (HSLWC) by using pre-treated (grout coating) crushed coconut shells and ground granulated blast furnace slag (GGBFS). Untreated coconut shell aggregate (CSA) concrete was considered a control mix. Then, cement was partially replaced with GGBFS at varying levels of 5%, 10%, 15%, and 20% by weight in the control mix, and the optimum percentage replacement was found to be 10%. Furthermore, untreated CSA was replaced with pre-treated CSA to study the effect of pre-treatment on the fresh and mechanical properties of concrete. Pre-treated CSA concrete mix with 10% GGBFS replacement (T/10) achieved a compressive strength of 41.55 MPa, which is 6.76% higher than the control mix. The properties of concrete such as tensile strength, flexural strength, and modulus of elasticity, were also improved by utilizing pre-treated CSA. The findings in this study prove that grout coating is an effective CSA pre-treatment method that can considerably improve the characteristics of CSA concrete. From the carbon footprint analysis, T/10 and conventional concrete emits 0.393 tCO₂e/m³ and 0.410 tCO₂e/m³respectively. An eco-friendly, HSLWC can be produced by incorporating GGBFS and pre-treated CSA.