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Construction of the Iowa Highway 60 Precast Prestressed Concrete Pavement Bridge Approach Slab Demonstration Project

Chapter 8. Summary and Recommendations


Summary

The bridge approach slab project on Highway 60 near Sheldon, Iowa, shown in figure 46, demonstrated one more application for PPCP. The primary objective of this demonstration project was to evaluate the viability of PPCP for bridge approach slab construction. Although this project was constructed on a new bridge, the design and construction details that were developed through this project lend themselves for approach slab reconstruction as well. The project helped to familiarize IADOT as well as local contractors and precast producers with this innovative construction technique. It also allowed IADOT to develop design details and construction procedures for precast approach slabs that may eventually be adopted as standards.

This project demonstrated some important features of PPCP:

  • Use of full-depth precast panels for bridge approach slabs.
  • Use of bi-directional post-tensioning in lieu of pretensioning.
  • Use of partial-width precast panels on a crowned pavement cross section.
  • Construction over a crushed stone aggregate base.

The project demonstrated the adaptability of the PPCP concept to a unique application. The design details and precast panel layout used for this project are adaptable to various approach slab lengths, widths, thicknesses, and skew angles. The concept can be used for full-width approach slab construction or partial-width (lane-by-lane) construction.

Recommendations for Future Implementation

The next step in bringing this construction technique into standard practice will be to use PPCP for reconstruction of an existing approach slab under traffic. This will bring additional considerations into play, such as staging construction and panel installation. Different precast panel configurations, as discussed in the previous chapter, may also be considered based on site constraints.

Reconstruction of existing approach slabs also requires consideration of the condition of the paving notch. A failed or poorly constructed paving notch will likely need to be replaced. IADOT is already addressing this need by developing details for a precast concrete paving notch that can be quickly bolted to the bridge abutment to replace the existing paving notch. This paving notch, used in conjunction with precast pavement panels, will provide IADOT with a long-term solution for rapid reconstruction of bridge approach slabs.

Figure 46. Photo. Finished north approach slab prior to opening to traffic.

Figure 46. Photo. Finished north approach slab prior to opening to traffic. A road-level view of the cleared and completed slab, with trucks seen in the distance.
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Updated: 04/07/2011

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United States Department of Transportation - Federal Highway Administration