Assessment of the Interfacial Transition Zone
Percolation in Concrete

Daniel Rypl

Department of Mechanics
Faculty of Civil Engineering
Czech Technical University in Prague
Thákurova 7, 166 29 Prague, Czech Republic


Percolation threshold denotes the volume fraction of a particular phase of a composite material at which that phase goes from being disconnected to connected (or vice versa). Thus percolation is considered a critical factor affecting the transport properties of multiphase materials. In the case of concrete, the transport properties are strongly dependent on the interfacial transition zone (ITZ) which is a thin layer of cement paste next to aggregate particles. The percolation of ITZs in concrete is computationally not simple, as the geometry and topology of this phase is complex. In this paper, the assessment of ITZ percolation threshold is simulated for realistic shape and distribution of aggregate particles using the hard core - soft shell model, in which each randomly placed aggregate particle described in terms of the spherical harmonic expansion is surrounded by a shell of constant thickness representing the ITZ.