The production of sewage sludge from waste water treatment plants is increasing all over the world due to raising of human needs; however, disposal of sewage sludge is yet a persistent question. This research work explores potential use of sewage sludge as a construction input material. Many studies have been conducted to determine the properties of both fresh and hardened concrete partially replaced fine aggregate with sewage sludge at normal temperature whereas the objective of this study is to investigate the behavior of concrete produced with fine aggregate being partially replaced with sewage sludge (SS) at elevated temperatures. The effect of intensity of elevated temperatures (300℃, 600℃ and 900℃), temperature exposure durations (1hr, 4hr, and 8hr), and various sewage sludge (SS) fine aggregate blending percentages (0%, 5%, 10%, and 15%) were investigated. During experimental test 120 concrete cylinders and 120 concrete cubes a total of 240 specimens were casted and tested to investigate behavior of concrete with fine aggregate replaced with sewage sludge at elevated temperature in the blast furnace. Physical and mechanical properties including mass loss, cracking and spalling, dry density, residual compressive strength, residual splitting tensile strength were determined after air cooling of concrete after heating in blaste furnace. Test results indicated that as the percentage replacement of sewage sludge increased the mass loss increased and the dry density decreased at constant temperature intensity and duration. The results also revealed that replacement of 5% sewage sludge as fine aggregate had greater residual compressive and split tensile strength than the normal concrete and up to 10% replacement the reduction in compressive and split tensile strength was not that much significant and beyond 10% sharp decrement was observed. It is a step forward in using waste materials as construction input ingridients by saving natural sand and promoting green environment and green construction.