Estimation of the Yield Stress of Cement Pastes from Electrical Resistivity Measurement

Abstract

This study proposes a continuous method for predicting the yield stress development from mixing until the final setting point. Samples prepared with water to cement ratios (w/c) of 0.3, 0.35 and 0.4 are tested using a vane in cup rheometer, a Vicat needle and a non contact electrical resistivity machine (NC-ERM). Times corresponding to the initial yield stress (ta), a dramatic increase in the yield stress (tb), a maximum torque reading on the rheometer (tc), an initial setting (td) and a final setting (te) on the yield stress-time (τ(t)-t) curve are correlated with the time at a point of inflexion (tP) on the bulk resistivity-time (ρ(t)-t) curve. A quantitative relationship developed between the yield stress and electrical resistivity shows a good agreement with experimental data.