Fracture analysis of cement treated demolition waste using a lattice model

Fracture properties of cement treated demolition waste were investigated using a lattice model. In practice the investigated material is applied as a cement treated road base/subbase course. The granular aggregates used in this material were crushed recycled concrete and masonry. This results in six different types of phases in the mixture: recycled concrete, recycled masonry, mortar, interface between recycled concrete and mortar, interface between recycled masonry and mortar and interface between recycled concrete and masonry. In order to numerically analyze the fracture behavior of cement treated demolition waste, a cross section image of a cylindrical specimen (?150mm) for monotonic indirect tensile test (ITT) was digitized and processed to obtain a multiphase lattice image showing every individual phase. The mesh area used for the lattice model was 1 mm2. Simulation results show that when the simulated ITT loading direction varies on the image, the simulated indirect tensile strengths (ITS) have a larger scatter compared to the variation of experimental results of ITS in the laboratory. This indicates that the numerical simulation of cemented granular demolition waste using a 2D lattice model is strongly influenced by the loading direction on the simulated image. This should be because of high heterogeneity of the mixture, especially the arrangement of aggregates along the loading direction. With a model correlation factor 2, the average simulated ITS that is obtained under different loading directions on one image is comparable to the experimental ITS