Self-weight consolidation of kaolinite suspensions in deionized water measured by Nuclear Magnetic Resonance — experiments and modeling

Abstract

In this article, we study the self-weight consolidation behavior of kaolinite suspensions with different concentrations in deionized water using nuclear magnetic resonance (NMR). NMR enables the direct assessment of density distributions and pore size within the consolidating suspensions. The results show that electrochemical conditions (pH and ionic strength), arising from ion leaching from the kaolinite, influence the consolidation dynamics, in agreement with previous studies. The evolution of the density profile over time is interpreted using a large-strain consolidation model based on the Gibson–Merckelbach formulation. The model is implemented in both Eulerian and Lagrangian frameworks, allowing a comparison between these two approaches. A key observation from the NMR measurements is that the solid volume fraction reaches a maximum value at the base of the column. This behavior is not captured by the classical Merckelbach–Kranenburg constitutive model, highlighting its limitations in highly compacted regimes. To account for this effect, a simple modification based on a reduction in permeability is introduced. This modification can be interpreted as a hydraulic limitation, as it leads to vanishing fluid fluxes and prevents further densification. The comparison between experimental and numerical results shows that this approach improves the agreement with the measured density profiles. In addition, the model captures the main trends of the pore size distribution measured by NMR, although some discrepancies remain in magnitude. Overall, the combined experimental–numerical approach provides new insight into the applicability and limitations of Gibson–Merckelbach consolidation models for fine-grained suspensions.