This report provides a design guideline and recommended standard for geofoam applications in the design and construction of highway embankments. The guideline and standard will assist highway agencies in designing and constructing highway embankments using expandable polystyrene (EPS) blocks. Geofoam, a term referring to expanded polystyrene (EPS) blocks when used in embankment construction, is a super-lightweight soil substitute material. The first http://gulliver.trb.org/publications/nchrp/nchrp_rpt_529.pdfwidespread application of geofoam technology in highway construction was for insulation and pavement frost damage mitigation, but geofoam is now used in a broad variety of transportation-related applications. The use of geofoam in embankment construction avoids the problem of excessive settlements and affords benefits, including reduction of overburden pressure, reduction in the magnitude of ultimate settlement, and savings in construction time. Differential settlements between the approach fill and bridge abutments can also be reduced. Lateral pressure from approach fills on to abutments and wing walls can be lessened significantly with geofoam fill. Long-term maintenance requirements can be minimized, and ride quality of roads crossing swamps or bog areas can also be improved by the use of geofoam as fill. These applications call for the detailed analysis of the behavior of the geofoam under stresses that will develop during long-term use. Such analyses require knowledge of the material properties of the geofoam under service loads as well as models to predict geofoam behavior and embankment performance. There is a need for research to determine the behavior of geofoam under service loads in addition to the long-term performance of geofoam when used in embankment construction. This research will allow the development of a design guideline and material and construction standard for geofoam applications in the design and construction of highway embankments. This report may be accessed by Internet users at Under NCHRP Project 24-11, “Guidelines for Geofoam Applications in Embankment Projects,” the University of Illinois at Urbana-Champaign developed a design guideline and recommended material and construction standard for the use of geofoam as a super-lightweight fill in embankments and bridge approaches over soft ground. To develop the guideline and standard, it was necessary for the research team to first investigate the geotechnically relevant properties of block-molded EPS such as modulus, compressive strength, Poisson’s ratio, and interface shear resistance. It then developed a design methodology for geofoam embankments consisting of three different components: (1) pavement system design, (2) external stability evaluation, and (3) internal stability evaluation. Design charts and design examples were developed. Geofoam construction practices were investigated, and cost information was developed to assist designers in selecting an optimum design. (Author/publisher)
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