Effects of confinement on the stress-strain behavior of EPS geofoam

EPS geofoam blocks underlying compacted soil and structural loads become subjected to multi-axial loading. Effects of confining pressure on the stress-strain behavior of EPS geofoam have been investigated in previous studies. Some studies found increases in confining stress lead to corresponding decreases in both modulus and compressive strength. Increasing confining stress has also been reported to result in higher compressive strength. Regardless of the sense and attributed significance of the effects of confinement on EPS geofoam behavior, the implied effects on performance are generally not considered in practice. A series of triaxial compression tests was conducted on EPS geofoam of different densities and over a range of confining pressures. Results from the investigation indicate increases in confinement lead to decreases in yield stress and post-yield compressive resistances, depending on the EPS density and range of confining pressures. The sense and practical significance of confining stress effects are discussed. An approach for incorporating the more significant effects of confining stress on EPS geofoam behavior is considered.