Thixotropic behavior during shear of a fine-grained mud from Eastern Canada

The quantitative determination of the hysteresis loop area developed during viscometer tests on shear rate-shear stress reverse paths, has been used to describe the thixotropic behavior of a clayey mud under flow conditions. Tests were conducted for liquidity indexes between 1.8 and 4.0, and for six pore water salinities ranging from 0.1 to 30 g/l. Admitting that a low hysteresis loop area denotes a well-developed thixotropic behavior for a given liquidity index, the thixotropy of the slurry is likely to be more strongly marked for salinities greater than the flocculation threshold. At a constant salinity, the results also indicate the existence of a simple linear relationship between the hysteresis loop area and the yield stress and the viscosity of the slurry. The restrictions of this approach and the possible implications of a strengthening/softening process on mudflow kinematics are also discussed.