Numerical and Experimental Investigations of the Influence of Grain Size on the Compressibility of Sand–EPS Mixtures

In the past decade, there have been numerous investigations on the physical and mechanical properties of the lightweight composite materials. The application of the expanded polystyrene (EPS), which is a super lightweight material with very low density and potentially high compressibility, has been studied by many researchers. This paper presents experimental and numerical investigations on the compressibility of the sand–EPS mixtures. The influence of grain size variations on the compressibility of the composite samples was studied using the standard Casagrande oedometer apparatus in the laboratory. Moreover, a series of discrete element modeling (DEM) simulations were carried out to verify the results of the laboratory tests. Since it was aimed to elaborate on the behavior of completely rounded granules, steel pellets virtually representing the soil particles have been used in both the laboratory experiments and DEM simulations. The EPS beads were added to the steel pellets at 0%, 0.1%, 0.2%, 0.3%, 0.4% and 0.5% by weight. The results show that increasing the rigid grain size decreases the compressibility of the composite samples at low EPS contents. However, this impact becomes almost insignificant at very high EPS contents when rigid particles interaction is impeded.