ABSTRACT
ABSTRACT: Concrete can be modeled as three-phase particle composite where rigid particles are embedded in a continuous cement matrix. These two phases are separated by means of an interfacial transition zone (ITZ) with distinct properties. Depending on the particle density and/or ITZ-thickness percolation of the matrix phase or ITZ-phase may occur. The properties of either of these phases determine whether significant sub-critical crack growth can occur, and whether the tensile strength of the composite increases. Calculations have been carried out using a beam-lattice model originating from statistical physics. The analyses point to specific experiments that have partly been done, and that appear to confirm the predictions. A consequence of the distinct fracture behaviour below and above the percolation threshold relates to scaling. If sub-critical pre-peak micro-cracking does not occur, or in very mild form, Weibull scaling applies. On the other hand, when significant microcracking occurs, scaling will divert from classical Weibull behaviour.
