In this study, supplementary cementing materials (SCM), such as nanosilica and microsilica, have been evaluated for optimal levels of replacement as a blending material in cement. The physical and chemical properties of these materials were first analyzed, then the properties of neat samples, mortar samples, and concrete samples were investigated. Mainly this study focused on the workability and compressive strength with different mixes at different ages of neat, mortar and concrete mixes. Test results obtained in this study indicate that up to 5% nanosilica and 10% of microsilica could be advantageously blended with cement without adversely affecting the strength. However, optimum levels of these materials are 1-3% of nanosilica and 3-8% of microsilica when we consider the strength of concrete.