In the current experimental study, fresh and hardened properties of high-volume ground granulated blast furnace slag blended cements were investigated. For this purpose, fifty-eight cement mortars satisfying minimum requirements of TS EN 197-1 were produced and nano calcite, nano SiO2 and nano Al2O3 were replaced by the cement up to a replacement level of 4% (which were 1%, 2%, 3% and 4%). First of all, the mechanical properties of mixtures were examined at the curing ages of 2, 7 and 28 days and then standard consistency and setting times of eight selected mixtures were determined. Test results showed that increase in the replacement level of slag was resulted in decrease in early age compressive strength. As a result of both seeding (nucleation) and chemical effect, decrease in setting time and enhancement in early age strength development of mixtures including nanomaterials were observed. Even though increase in replacement of nanomaterials resulted in a slight decrease in compressive strength of the mixtures, the best enhancements were obtained with the replacement level of 1%. As a result of this, minimum requirements of CEM III-C 32.5 were achieved in the mortars including CEM III-C type cement with a slag replacement level of 81% and modified by 1% of nanomaterial.