Rheological properties of cementitious composites with and without nano-materials: A comprehensive review

Rheology is an effective and efficient indicator to characterize the flow properties of fresh concrete. Through rheology measurement, the influence of variations in constituents and mixing proportions on the fluidity of fresh concrete can be effectively evaluated. In the case of self-compacting concrete and 3D printed concrete, the user can predict and optimize the flowability of fluid concrete by controlling yield stress and viscosity. The rheology models have been proven to be an efficient tool to predict the fresh properties of cementitious composites. In most cases, fresh concrete follows Bingham's model. However, the special concrete combined with nano-materials requires certain modifications in the existing models. This paper presents a critical review of applicable rheological models based on flow curves as well as the viscosity equations of dense suspensions employed to characterize the flowability of cementitious materials in general. In addition to the governing variables included in the model formula, this review paper also highlights the effect of cement hydration, temperature, mixing methods, mixing sequence and time, vibration, pressure and air entrainment on rheology. Their respective effects can be potentially reflected and quantitatively evaluated by determining the values of the governing variables accordingly. The summary and discussions presented in this paper provide relevant information and knowledge on the rheological properties of the cementitious matrix with and without nano-modification and promote further research. © 2020