SHEAR BEHAVIOR OF EXPANDED POLYSTYRENE GEOFOAM: AN EXPERIMENTAL INVESTIGATION
Volume Title: ICASGE2025
Paper ID : 1105-ICASGE-FULL
Authors
1Civil Engineering Department, Faculty of Engineering, Helwan University, Cairo, Egypt.
2Construction Research Institute, National Water Research Centre
3Reinforced Concrete Structures (RCS)
Abstract
Expanded polystyrene (EPS) geofoams have gained importance in geotechnical engineering applications since the 1960s. These materials serve multiple purposes, either as lightweight fill in structures such as embankments and bridge approaches or as compressible inclusions in retaining walls and culverts. In most of these applications, geofoams are installed either in direct contact with other geofoam blocks or with other construction materials. A key challenge in designing such systems is understanding how geofoams interact with other construction materials. This requires a thorough examination of the compressive and shear behavior of geofoam as well as the shear strength interfaces with other materials such as geofoam, soil, concrete, and steel. The aim of this study is to determine the shear strength parameters of EPS geofoam blocks with densities of 25, 30, and 35 kg/m³. To achieve this, multiple direct shear tests have been conducted, which provided vital information regarding material performance. The findings revealed a distinct relationship between density and shear behavior: a higher geofoam density corresponded to increased material cohesion and decreased internal friction angle. The study also investigated the interface shear strength between the EPS geofoam and other construction materials such as geofoam, soil, concrete, and steel. These experimental results provide valuable information for geotechnical engineers, allowing for more accurate analytical and numerical modeling of soil-EPS-structure interactions.
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