Gelation, shear-thinning and shear-thickening in cement slurries

The rheological behavior of cement slurries may be described in terms of a few elementary behaviors: the rapid formation of a gel, at rest; the collapse of this gel under a critical stress directly related to the strength of the interparticle forces; the progressive destruction of the gel fragments under moderate shear rate, with an increasingly shear-thinning behavior as the elementary particles gets smaller; the reconstruction, at high shear rate, of shear-resistant structures, probably as chains of grains at contact; complete jamming, possibly. We analyze the transition mechanisms from one step to the next one. We show how the addition of a dispersing agent favors shear- thickening at the expense of shear-thinning and how the control of the particle surface state and of interparticle friction restricts shear- thickening and the risk of jamming.