A viscoelastic-plastic behaviour analysis of expanded polystyrene under compressive loading: Experiments and modelling

Generally, when soil has poor properties (unstable or compressible soils) i t is possible to use EPS foam in road construction, because this material h as low density. In this case, it is necessary to investigate the mechanical properties of EPS. In this work, an experimental study and modelling inves tigation were performed in order to determine the EPS mechanical behaviour under compressive loading. The experimental results show that the global compression behaviour of EPS is characterised by three stages. The linear elastic stage is defined by an initial tangent modulus E* followed by a non-linear elastic part. The seco nd stage, which is described by a plateau, is characterised by a stress thr eshold sigma (s)*. Finally, the densification stage corresponds to large co mpressive strains when the material of the cell walls is entirely compresse d. Globally, the apparent density of EPS plays an important role. In fact, whe n the density increases 'Young's modulus and threshold stress increase, but the densification strain decreases. A phenomenological mechanical model is verified in order to simulate the EP S viscoelastic-plastic behaviour under compressive loading. This model, whi ch is based on a super-position of viscoelastic and elastic-plastic behavio ur, introduces six parameters determined by an identification technique. Th e results obtained in terms of the stress-strain curves are in a good agree ment with the experimental data. Using "Castem 2000" finite element software, the numerical simulations were achieved in order to describe the mechanical behaviour of the EPS material . This shows that it is possible to use numerical simulation in order to co mpute EPS structure used in road laying.