Fractal dimensions of cement-based composites after mechanical comminution

The paper reports about the comminution of cementitious composites in a laboratory jaw breaker. Two samples of cement paste, one mortar sample, one lightweight concrete sample, and samples of four standard concrete mixtures were investigated. Water-cement ratio and maximum aggregate size were varied. Based on sieve analysis, the fractal dimensions of the fragment samples were estimated. The fractal dimensions varied in a range between D-F = 1.90 and 2.22, whereas the lower value belonged to the mortar specimen. Materials with failed through a single, dominant fracture propagation mode could be approximated suitably with a one-parameter fractal model. Other mixtures could better be modelled with a bi-linear procedure. (C) 2012 Elsevier B.V. All rights reserved.