Macro to Micro: Rheology as a Probe for Microstructural Evolution in Clay-Water Systems

Abstract This paper illustrates the use of rheological measurements as probes for monitoring the evolution of the microstructure of Na-montmorillonite dispersions with changes in pore fluid salinity. A novel experimental setup is used to perform repeat rheological large amplitude oscillatory shear (LAOS) measurements on a single specimen, as the pore fluid’s salinity is increased through controlled injection of a NaCl brine. The increase in salinity is first associated with higher storage and loss moduli, greater intra-cycle non-linearity, and a broader range of intra-cycle rheological transitions. Beyond a certain brine dose, these trends are reversed. These results reflect the effect of the increased ionic strength on particle interactions and the resulting microstructure.