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Abstract
In India, traditionally river sand is used as fine aggregate in concrete production. However, due to continuous exploitation of river sand, its availability has become scarce. Construction industry has started using alternate materials as fine aggregate. Out of which manufactured sand is one of the popularly used material as fine aggregate. Materials such as recycled concrete aggregate have issues of dumping and environmental pollution. These materials are viable alternatives for replacement of natural river sand. Recycled concrete, if used as coarse aggregate has problems of water absorption and reduction in strength. Hence, an attempt has been made in this research to use recycled concrete aggregate (RCA) as fine aggregate in concrete. Further, use of RCA as fine aggregate in concrete may reduce the compressive strength of concrete. Hence, it is proposed to use silica fume as a supplementary material in cement with Recycled Fine Aggregate (RFA) as fine aggregate. This study investigates the effect of silica fume and RFA on the mechanical characteristics of concrete mixtures. Mechanical properties and durability properties at 28 days are determined. Silica fume is added to cement in the range of 7.5% and 10% by weight of cement. Natural river sand is replaced with RFA (Recycled Fine Aggregate) in the range of 0%, 50%, 100% by weight of sand. From the study it is found that RFA could be used as alternative material for natural sand. However, as complete replacement of RFA reduces the strength of concrete, silica fume addition is mandatory. A minimum of 7.5% silica fume is required to prevent strength loss in concrete.