Theoretical analysis of time-dependence and thixotropy of fluidity for high fluidity concrete

This paper deals with the time dependence of fluidity and thixotropy of high fluidity concrete containing polycarboxylate-based superplasticizer. Taking the effects of both hydration and physical flocculation of cement particles into consideration, the increases in apparent viscosity and Bingham constants with the elapsed time of the stationary state, and the time dependence of the apparent viscosity in agitated state, are theoretically investigated. Moreover, the effects of the number, peak value, and durations of applied stepwise stresses, etc., on the shape and the area surrounded by the hysteresis loop of shear rate versus shear stress are discussed quantitatively.