Influence of Manufactured Sand on Fresh Properties, Strength Properties and Morphological Characteristics of Self-Compacting Coconut Shell Concrete

This research examines the fresh properties, strength performance, and morphological analysis of self-compacting coconut shell concrete (SCCSC) blended with crushed coconut shell and manufactured sand (M-sand). Crushed coconut shell (CS) was used as a coarse aggregate (CA), and M-sand replaced river sand (R-sand) at 25%, 50%, 75%, and 100%. The study focused on the workability characteristics, mechanical behavior, and microstructural analysis of SCCSC. Experiments were performed on fresh and mechanical characteristics, including slump flow diameter, T500 slump flow time, L-Box blocking ratio, V-funnel and a wet sieving stability test. Mechanical characteristics include compressive, split tensile, flexural, impact resistance and bond strength. Utilizing M-sand develops the mechanical performance of SCCSC. The morphological characteristics, using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and the X-ray diffraction (XRD) technique, were studied in this research work. The findings show that the addition of M-sand increases the concrete strength. The microstructural analysis demonstrates that adding different amounts of M-sand to SCCSC reduced the porosity and anhydrous cement percentage, although it increased calcium hydroxide and hydration products. The substitution of 100% M-sand at 28 days increased compressive strength by 3.79% relative to the reference SCCSC. Based on the findings, the mechanical strength of SCCSC containing M-sand significantly improved compared to the concrete with river sand.