Concrete contributes a very important role in the construction sector. Aggregates are the basic ingredients in concrete which will contribute about 60-70% of the total composition. Due to the highest demand for aggregates, it has resulted in over-exploitation of natural resources, hence it is very important to use alternative material. As we know fly ash and IOT are the largest wastes that have been producing in all over India and these are the best suitable alternative materials. In Karnataka state, Kudremukh iron ore company (KIOCL) produce a large amount of IoT waste and was deposited in the Lakya dam. The present study in undertaken to determine the fly ash and IOT characteristics using XRD and SEM analysis and also to determine the strength and durability of concrete made up of geopolymer coarse aggregate for M40 grade of concrete. The cubes of size 75x75x75 are prepared by mixing IoT and fly ash in proportion 70:30 respectively with varying molarity of alkaline activator as 4M, 6M, 8M, 10M & 12M. These cubes are crushed to obtain Geopolymer coarse aggregates and these aggregates are used in RCC structures to check the mechanical behavior and workability of concrete.