The observed experimental results, after through various investigations suggest and confirm that 10% and 25% blending of all the two fly ashes (LC and HC) in OPC (composites) when used with distilled water have higher strength than DW control. But blends with SW (25%) and with LC fly ash alone have higher strength than DW control. When 10%, 25% and 40% of OPC is replaced by fly ash, the net compressive strength of composites at 180days with both DW and SW. From all the three percentage of fly ash composites, 25% fly ash composites of LC fly ash gives a higher amount of hydration...