River sand is the common form of fine aggregate used in the making of concrete mixture. To meet the high demand of river sand by the builders and construction industry in this fast urbanization age, river beds are mined for sand and it is depleted at a faster pace, which in turn causes substantial negative effect on our environment. So it is highly important to find alternative form of fine aggregates for meeting the large demand without distressing our ecosystem. Copper slag is one among various sustainable materials having a promising future as a substitute for river sand. This article presents a study on identifying the optimum percentage of copper slag to be used as a fine aggregate by partially replacing sand in the making of the concrete. Also, as part of durability aspects study, the impact of higher temperature of 200 °C, 400 °C, and 600 °C for 4 hours exposure time on concrete with optimum percentage of copper slag has been presented and has been compared with normal concrete. The results show that copper slag concrete has better resistance to strength loss and weight loss at a higher temperature of 200 °C, 400 °C in comparison with normal concrete, but at 600 °C copper slag concrete displays similar trends comparable to normal concrete. In the present experimental investigation, M30 concrete grade was used.