The viscometric examination of cement pastes with interrupted helical impellers

The use of an interrupted helical impeller is known to prevent the occurrence of sedimentation during viscometric examination of cement pastes up to a water/cement ratio of 1·0. This feature is used to advantage in the study of time-dependent structural changes. Tests on high alumina cement pastes show that turbulence is likely to occur at Reynolds numbers exceeding 13 which leads to errors in the quantitative determination of yield stress and plastic viscosity. Guidance on the selection of an impeller for a particular cement paste is given so that flow is non-turbulent and quantitative analysis of the flow curves is justified.