In this study, the effect of chemical and mineral admixtures, including superplasticizer, viscosity modifying agent (VMA), limestone powder and fly ash in different W/C on fluidity, viscosity, and stability of self-consolidating mortar is investigated and proper workability regions for the prepared mixtures are presented. The obtained results indicate that W/C is the most significant parameter influencing the rheological properties of cementitious mixtures, specially their stability. Furthermore, the maximum allowable W/C for preventing inhomogeneity could not be a fixed value for all the mixtures and should be adjusted for the target fluidity. On the other hand, using VMAs is an effective method for stabilizing self-consolidating mortars and preventing any kinds of instability while limestone powder and fly ash mainly affect bleeding and aggregate blockage. Besides, these mineral admixtures improved the fluidity of the mixtures to some extent.