Use of EPS Geofoam for support of a bridge

In much of reported geofoam applications in roadway construction, innovative uses featured approach fills and light weight embankments below rigid or flexible pavement structures. This paper describes a bridge construction that represents a marked departure from conventional practice. EPS geofoam was used to support pre-stressed concrete box beams and composite concrete deck of a single span bridge. The bridge is a replacement of a shorter, steel-girder single-span bridge on spread footings across Oatka Creek in Warsaw, NY. Criteria for the new bridge included a larger span and increased load and hydraulic capacities. Soil borings showed very weak strata extend to large depths, initially suggesting the need for deep foundations to support the new bridge. As an alternative to piles, excavation and replacement of the underlying soil with EPS geofoam was selected to provide a compensated foundation system. This paper describes the construction and post-construction performance monitoring of the bridge. The instrumentation included stress cells, settlement plates, and piezometers. Heat dissipation in the thick early strength concrete of the abutment slabs was monitored, and was inferred as the source of thermally-induced creep. Periodic surveys of the roadway profile were also taken. Subsequent to completion, the bridge and the approaches were inundated during a period of intense rainfall, and successfully withstood the uplift due to buoyancy. Following 10 years of service, the bridge continues to be rated with the highest NYSDOT bridge performance ranking in 2012.