Contribution of turbidimetry on the characterization of cement pastes bleeding

The aim of this paper is to examine the contribution of turbidimetry measurements on the characterization of cement pastes bleeding. In some cases (e.g. presence of superplasticizer), the bleed water becomes turbid due to finest particles dispersion and the boundary between the bleed water and the consolidated paste becomes difficult to detect. Turbiscan device allows detecting this boundary more accurately than traditional tests. The role of superplasticizer and solid volume fraction on bleeding is examined. The bleeding measurements highlight the role of superplasticizer on bleeding and its kinetics. The effect of superplasticizer may be explained by better dispersion leading to release of water trapped between agglomerates. Furthermore, the existence of critical volume fraction, above which no bleeding occurs, close to that corresponding to the appearance of contacts between particles is shown. Finally, using rheological measurements, the correlation between the yield stress and bleeding has been possible.