  Differential shrinkage in particulate quasi-brittle materials causes
microcracking which reduces durability in these materials by increasing their
mass transport properties. A hydro-mechanical three-dimensional periodic
network approach was used to investigate the influence of particle and specimen
size on the specimen permeability. The particulate quasi-brittle materials
studied here consist of stiff elastic particles, and a softer matrix and
interfacial transition zones between matrix and particles exhibiting nonlinear
material responses. An incrementally applied uniform eigenstrain, along with a
damage-plasticity constitutive model, are used to describe the shrinkage and
cracking processes of the matrix and interfacial transition zones. The results
showed that increasing particle diameter at constant volume fraction increases
the crack widths and, therefore, permeability, which confirms previously
obtained 2D modelling results. Furthermore, it was demonstrated that specimen
thickness has, in comparison to the influence of particle size, a small
influence on permeability increase due to microcracking.
