Currently, the construction industry in developing countries like Ethiopia is booming at a faster growth rate due to an ever-increasing population and urbanization. The industry uses concrete as the main input. Thus, it increases the demand for aggregates which constitutes around 60 to 75% of concrete volume. To satisfy concrete demand natural resources like natural sand are depleting and river beds are eroded due to mining of natural sand. On the other hand, construction and demolition wastes disturb the environment due to different construction and demolition activities in the industry like master plan change, destruction of building due to its service life, destruction of cubes from a laboratory, and destruction due to different natural disasters. Nowadays practically construction and demolition wastes are used as landfills. Thus, in this study RCFA from concrete cubes at a laboratory was used to check the suitability of RCFA for concrete production as a partial replacement of natural sand. A mix of C - 25 concrete was prepared with 0%, 10%, 20%, 30%, 40%, 50%, and 100% replacement of natural sand by RCFA with and without admixture. Thirteen series of mixes and 117 cubes were prepared and the suitability of produced concrete was checked by using slump and compressive strength tests. Here the 0% replacement concrete was used as a control mix. The workability of mixes without admixture increases as the replacement ratio of RCFA increases and vice versa for mixes with admixture. The compressive strength of concrete was tested at the ages of 3rd, 7th, and 28th days and the result shows that, the compressive strength of concrete decreases as the replacement ratio of RCFA increases. Even if there is a decrease in compressive strength as replacement ratio of RCFA increases, it is possible to replace NS up to 20% without an admixture and up to 50% with an admixture for the production of C-25 concrete without a significant compressive strength loss from the control mix. The outcome of the research suggests that using alternative materials for concrete production is very essential in the present construction scenario for sustainability and the preservation of natural resources.