The rheological properties (flow, fluidity, dynamic viscosity, stiffness rate) and hardening process (hydration, development of structure) of Portland - limestone cement (PLC) and Portland cement (PC) (strength class 42.5 R and N) pastes without and with superplasticizer (SP) based on synthetic polycarboxylatether (PCE) were investigated. It was found that limestone particles increase W/C and viscosity of cement pastes and reduction of water in plasticized pastes PCL is lower than in pastes PC. On the other hand, the fluidity of plasti cized cement pastes PCL is better and its thickening goes slower. The hydration and structure development in pastes PLC are going slower than in pastes PC. The impact of SP (when consistency of cement pastes is the same) on hydration process and hardening structure development of are going faster in plasticized cement pastes. The fineness of cements also has an influence on SP effect
