Existing bleeding models are unable to explain fully the mechanism of bleeding as the effect of hydration reaction of cement is not considered. To understand the effect of hydration on bleeding, compressibility tests were first conducted for cement paste and mortar at different stages, but all within the first 120 min. Subsequently, bleeding tests were conducted for tall specimens, and, in addition to surface settlement, pore pressure and density profiles were also measured. A rheological model is proposed which can account for the effect of hydration on bleeding. This model is implemented in a self-weight consolidation bleeding model. A number of bleeding tests were conducted and the results were compared with the predictions. The good agreement shows that this model is able to explain the bleeding mechanism of cement paste and mortar, including the effect of hydration, better than previous models.