Application of DEM model to breakage and liberation behaviour of recycled aggregates from impact-breakage of concrete waste

For the recovery of aggregates from construction waste, the principle process is a separation of aggregates by breakage from the cement paste. In this study, a model based on DEM (discrete element method) was used to simulate the breakage behaviour of a block of concrete waste in repeated free fall tests. With 3D DEM model, 73 mm × 53 mm concrete block was modelled with macro-particles formed by a group of 970 spherical sub-particles and the sample block free fell 30 times from a 2 m height. The results of simulation were used to analyze the breakage characteristics of bonds between particles according to the number of free fall impacts. And, liberation ratio showed that high-quality recycled aggregates from concrete waste can be produced.