Authors: Davoud Ebrahimi Roland JM Pellenq Andrew J Whittle
Publish Date: 2016/06/21
Volume: 18, Issue: 3, Pages: 49-
Abstract
This paper proposes a novel methodology for understanding the mesoscale aggregation of clay platelets in water We use Molecular Dynamics simulations using the CLAYFF force fields to represent the interactions between two layers of Wyoming montmorillonite Nasmectite in bulk water The analyses are used to establish the potential of mean force at different spacings between the layers for edgetoedge and facetoface interactions This is accomplished by finding the change in free energy as a function of the separation distance between the platelets using thermodynamic perturbation theory with a simple overlap sampling method These nanoscale results are then used to calibrate the Gay–Berne GB potential that represents each platelet as a singlesite ellipsoidal body A coarsegraining upscaling approach then uses the GB potentials and molecular dynamics to represent the mesoscale aggregation of clay platelets at submicron length scale Results from mesoscale simulations obtain the equilibrium/jamming configurations for monodisperse clay platelets The results show aggregation for a range of clay platelets dimensions and pressures with mean stack size ranging from 3 to 8 platelets The particle assemblies become more ordered and exhibit more pronounced elastic anisotropy at higher confining pressures The results are in good agreement with previously measured nanoindentation moduli over a wide range of clay packing densities
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