The rheology of Portland cement pastes

Experiments with a rotation viscometer on the structural breakdown of Portland cement/water pastes are described. Hysteresis curves are shown and an empirical equation T = T E + ( T 0 - T E ) exp (- Bt ) for the decay of torque T with time t , at constant rate of shear, is given. The equation is also derived theoretically by assuming that the "excess torque" is proportional to the number of linkages existing, and it is shown that the predicted dependence of B on the rate of shear is approximately fulfilled by the experimental results.