Discrete Element Modelling of Monotonic Compression Tests in an Idealised Asphalt Mixture

ABSTRACT Discrete Element Modelling (DEM) has been used to simulate constant strain rate tests on an idealised asphalt mixture containing approximately single-sized sand particles under monotonic compressive loading. Results have been compared to a range of constant strain-rate compressive tests to failure that have been undertaken in the laboratory. The internal geometry of the idealised asphalt mixture has been reproduced in PFC-3D and internal damage (cracking) in the material was modelled by allowing bond breakage between adjacent particles. Elastic contact properties have been used to investigate the effect of random variations in internal sample geometry, the distribution of bond strengths between adjacent particles and the coefficient of friction between particles where the bond has broken on the stress-strain behaviour. A simple viscoelastic Burger's model was introduced to give time dependent shear and normal (tensile) contact stiffnesses and an elastic contact has been assumed for the compressive normal contact stiffness. To reduce the computation time, the effect of scaling the viscosities in the Burger's model to simulate slower strain rates has been investigated. Results from the model compared well to the experimental data. KEYWORDS: Idealised Asphalt MixtureMonotonic CompressionDemStress-Strain ResponseBond Breakage