Effect of ion type and concentration on rheological properties of natural sodium bentonite dispersions at low shear rates

A contribution to understanding the rheological measurement, yielding mechanism and structural evolution of fresh cemented paste backfill

“…However, the Newtonian viscosity of the CPB interstitial solution at different pre-shear rates is maintained at 0.0068 Pa•s through flow sweep tests, indicating that the collisions frequency of Brownian particles may not change [35]. This is consistent with the results of ionic concentration, which is an important factor affecting the Newtonian viscosity of interstitial solution [77]. In addition, since the solid content or cement-tailings ratio is not changed in this study, the number density of Brownian particles (i.e., the number of Brownian particles in 1000 μm 3 [35]) in CPB system is fixed.…”

Surface Physicochemical Properties of Smectite‐Rich Fault Gouge: A Case Study of the Japan Trench Plate‐Boundary Fault

“…If the fault were filled with extremely low‐ionic‐strength fluid, such as ∼10 −3 M, then the strong EDL force would cause a large repulsive force to act between the particles (solid yellow line in Figure 4b). This strong EDL force is due to the far extension of the EDL around the particle (i.e., long Debye length), and when relative motion occurs between particles in such a state, the interaction between ionic clouds (e.g., overlapping and their distortions) occurs as a stronger viscous resistance force (i.e., the electroviscous effect; Montoro & Francisca, 2019; Rubio‐Hernández et al., 2004) and thus contribute to the suppression of fault sliding. In contrast, where salinity is high, as in the case of the Tohoku‐oki Fault, the interparticle energy is very low (solid red line in Figure 4b), and this may have contributed to a reduction in viscous resistance and thus facilitated fault slip.…”

“…This kind of microscopic force is described within the framework of DLVO (Derjaguin–Landau–Verwey–Overbeek) theory (Derjaguin & Landau, 1941; Verwey & Overbeek, 1948), which consists of repulsive electric double layer (EDL) forces and van der Waals attraction between clay particles. This framework, although classical, has been successfully applied to evaluate the stability of dispersion systems and their rheological parameters, such as yield stress (Otsuki, 2018) and viscosity (Duran et al., 2000; Montoro & Francisca, 2019). Therefore, the microscopic properties of clay particle surfaces, especially surface charge states, are also considered to be important for understanding fault behaviors.…”

Rheology and Sedimentation of Aqueous Suspension of Na-montmorillonite in the Very Dilute Domain

“…Continuous study for precise pH dependency will clarify this picture. In addition, further investigation for different chemical conditions (Penner D. and Lagaly G., 2001;Montoro M.A. and Francisca F.M., 2019), such as effect of divalent ions (Kobayashi S. and Adachi Y., 2008) and effect of organic substances (Wilkinson N. et al, 2017;Tombacz E. et al, 1998) will provide us very useful result for the consideration of natural colloid.…”