Compressive consolidation of strongly aggregated particle gels

TL;DR

This study uses 2D simulations to analyze how particle gels compress, revealing three distinct regimes and early structural changes, challenging traditional assumptions about fractal correlation loss during compression.

Contribution

It introduces a detailed simulation approach to understand the nonlinear compression behavior and structural evolution of particle gels, highlighting early fractal structure changes.

Findings

Identified three compression regimes: elastic, single-mode plastic, multi-mode plastic.

Observed early changes in fractal dimension and correlation length during compression.

Demonstrated that structural rearrangements occur earlier than predicted by existing models.

Abstract

The compressive yield stress of particle gels shows a highly nonlinear dependence on the packing fraction. We have studied continuous compression processes, and discussed the packing fraction dependence with the particle scale rearrangements. The 2D simulation of uniaxial compression was applied to fractal networks, and the required compressive stresses were evaluated for a wide range of packing fractions that approached close packing. The compression acts to reduce the size of the characteristic structural entities (i.e. the correlation length of the structure). We observed three stages of compression: (I) elastic-dominant regime; (II) single-mode plastic regime, where the network strengths are determined by the typical length scale and the rolling mode; and (III) multi-mode plastic regime, where sliding mode and connection breaks are important. We also investigated the way of losing the fractal correlation under compression. It turns out that both fractal dimension $D_{\mathrm{f}}$ and correlation length $\xi$ start to change from the early stage of compression, which is different from the usual assumption in theoretical models.