Influence of Rheological Behavior of Mortar Matrix on Fresh Concrete Segregation and Bleeding

In this paper, the effect of water-binder ratio, sand ratio and high-range water reducer (HRWR) content on the rheological behavior of mortar formulated from concrete mixture was investigated by using a RheoCAD rheometer. The segregation of fresh concrete and hardened concrete was, respectively, measured by two different modified methods, coarse aggregate sieving-washing method and image processing method. The bleeding of fresh concrete was measured by two laser displacement sensors. The experimental results show that sand ratio and HRWR content have significant influences on yield stress whereas have little contribution to plastic viscosity. The segregation of concrete increases with the decrease of yield stress and is affected by plastic viscosity meanwhile. There is a weak relationship between bleeding rate and yield stress, but the bleeding rate decreases with the increase of plastic viscosity. Furthermore, it is convenient to analyze the degree of segregation and the distribution of coarse aggregate particles by image processing method and to real-timely monitor the bleeding and settlement of fresh concrete by laser displacement sensors.