The effect of silica fume in coconut shell concrete and examining bond through inverted metallurgic microscope

Abstract

The use of natural resources in concrete production makes environmental worry. To protect the natural resource one of the possible solutionsis to use different generated solid waste. Coconut shell is one of the agriculture waste which is been tried recently as coarse aggregate in concrete production. The cement is partially replaced with silica fume to reduce the emission of carbon dioxide (CO2). The silica fume was replaced from 5 to 25% in the increment of 5% both in a coconut shell and conventional concrete for the target strength of M25. Compressive strength of all these mixes was conducted at 3, 7, 28, 56, 90, 180 and 365 days for optimization of the percentage of silica fume to be used for its effective usage. It was observed that 10% replacement of silica fume gives higher strength compared to others. The other properties like flexural, split tensile and impact resistance strength were done for the optimized percentage of silica fume at the age of 3, 7 and 28 days. The inverted metallurgical microscope was used to inspect the interfacial transition zonebetween cement mortar and aggregates. This confirms the bonding layer is inversely proportional to its age.