Micro- and macro-mechanical study of compressive behavior of expanded polystyrene geofoam

A series of uniaxial and triaxial compression tests was carried out in order to study micro-and macro-mechanical compressive behavior as well as some other mechanical properties of expanded polystyrene. Micromechanical behavior was analyzed by performing uniaxial compression tests on small cubic specimens. These tests were carried out using a load frame designed to be placed inside a scanning electron microscope. Using an automatic camera, micrographic sequences were taken during the loading process. These photographic sequences allowed the identification of the internal structure changes that occurred at different strain levels. Macro-mechanical behavior of expanded polystyrene (EPS) under compressive loading was investigated by means of triaxial tests on 10 cm-diameter specimens. Triaxial test results showed that the behavior was strongly influenced by EPS density, confining stress and displacement rate. Finally, based on the triaxial test results, a set of equations was proposed to estimate the compressive behavior of EPS and the accuracy of the equations was assessed by comparisons with experimental results.