Dynamic Rheological Behavior of Low Water-to-binder Ratio Mortars under Large Amplitude Oscillatory Shear (LAOS)

Abstract

This work focuses on the dynamic rheological behavior of low water-to-binder ratio cement mortars blended with fly ash microspheres (FAM) or silica fume (SF). The initial slump flow of each group has been controlled at similar values by adjusting the superplasticizer dosages. With the help of a coaxial cylinder rheometer, the dynamic rheological behaviors of these mortars are investigated by frequency sweeping in the range of 0–2 Hz under large amplitude oscillatory shear (LAOS). Based on the systematical elaboration of dynamic rheological testing theory, the experimental data are processed according to Lissajous plot fitting to reveal the viscoelastic characteristics. The nonlinearity of response signals is further assessed with Fourier transform (FT) analysis. The parameters, storage modulus G', loss modulus G" and relative amplitude I3/I1 are proposed to clarify the influences of FAM and SF on the stability and energy consumption of local structures and nonlinearity of response torques. The hydration characteristics of various groups well confirmed the rheological phenomenon. This study is beneficial for the preparation and optimization of flow state concrete such as pumping concrete and self-compacting concrete.