Investigation of Deflection and Vibration Dynamics of Concrete and Bituminous Pavements Constructed Over Geofoam

Status:  Complete
Report Date:  01/01/2011

Summary:

Geofoam, an XPS polystyrene with a unit weight of 1 to 3 lb/ft.3, was used as embankment fill for Minnesota Trunk Highway (TH) 100 segment 3 (SP 2735-159) in 2000. It was also used at Technology Drive in 2002 to correct a slope failure that had occurred in a large embankment near a ramp. The TH 100 segment consisted of a 10 in. dowelled jointed plain concrete pavement (JPCP) and the Technology Drive section was a 7 in. bituminous pavement. Concerns about the vibration issues during and immediately after paving led to a retrofit of the sites with multi-depth deflectometers (MDD) and a two-year study of pavement response. The authors seasonally investigated flexible and rigid pavement response to Falling Weight Deflectometer (FWD) loads, loaded and calibrated snow and ice trucks through the MDDs, and a seismograph. This study compared seasonal deflection basins, elastic moduli, and dominant frequencies of flexible and rigid pavements built with Geofoam fill to their corresponding contiguous control sections built without Geofoam fill. The 3-ft. of granular fill above the 4 in. concrete cap covering the Geofoam compounded the process of layer moduli computations. The report concludes with interesting findings, particularly that the response of Geofoam pavements may exhibit higher deflections and vibration amplitudes and they are in a time series. However, these are not resonant vibrations that would require design changes from the current practice.

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