Expanded polystyrene (EPS) Geofoam has long been used as a geotechnical lightweight and durable alternative material to typical backfills, significantly reduces the loads imposed on underlying soils, and intend to solve engineering challenges. The main problem of using the locally available Geofoam is the non-availability of various material properties. There is also a shortage in the design parameters that should be driven based on information from verified models. In this study, a comprehensive laboratory testing program on the local EPS Geofoam was planned to accurately measure the modulus of elasticity, Poisson's ratio, shear and compressive strength parameters, and interface properties such as foam-soil and foam-concrete. The measurements acquired from laboratory tests were used as input for a finite element (FE) analysis by utilizing the hardening constitutive equations to model the behavior of Geofoam. The FE model was successfully calibrated to accurately capture the actual behavior of Geofoam with different interfaces, which can be utilized for future investigation for various engineering problems.