Exploring Metakaolin and Coconut Shells as Sustainable Alternatives in Concrete: Physical, Mechanical and Microstructural Properties

One of the most promising solutions to mitigate the depletion rate of non-renewable components in concrete is to partially or completely replace them with renewable plant-based alternatives.The main purpose of this study is to evaluate the synergistic effect of substituting cement with metakaolin and natural aggregate with coconut shells on concrete properties.The novelty of this research lies in the determination of the physical, strength and microstructural properties of varying concentrations of Meta Kaolin (MK) and a constant Coconut Shell Aggregate (CSA).Six groups of concrete test samples were designed and tested, which contained the control, CSA set at 10% with natural coarse aggregate and four different MK contents and constant CSA contents.The density, split tensile strength, compressive strength and microstructural properties were studied.The study found the highest split tensile strength of 3.32MPa, compressive strength of 32.45MPa and density of 2464kg/m 3 .There was a decrease in split tensile strength of 6.63-18.98%and compressive strength of 11.02-25.63%as the MK content increased as compared with with the control.The density of concrete decreased to 7.3% with an increase in the MK contents to 20%.Among the concrete with MK and CSA, the synergistic of 5% MK and 10% CSA showed the best physical and mechanical properties.An analysis of the microstructure of concrete with 5% MK and 10% CSA content exhibited a relatively compact microstructure and minimal internal porosity.The study concludes that the synergistic use of 5% MK and 10% CSA is feasible for concrete production.