Evaluation of a Precast, Post-Tensioned Bridge Paving Notch
Start date: 06/01/05
End date: 11/30/06
Sponsor(s): Iowa Department of Transportation
About the research
Abstract: Approach pavement settlement at the end of the bridge has been observed on a number of Iowa bridges. The failure of the bridge paving notch has been documented through previous investigation by the Iowa DOT as a contributing factor in this settlement. The conventional repair procedure for this problem consists of removing the deteriorated paving notch concrete while preserving as much of the existing reinforcing as possible. Wood forms are constructed, and a cast-in-place concrete paving notch is placed. Following sufficient curing of the new concrete, a replacement approach slab pavement is constructed.
The conventional replacement method requires that the bridge be taken out of service for an extended period of time, which disrupts the traveling public. The large number of bridges that exhibit the failing paving notch problem and, more importantly, their location on highly traveled roadways necessitate the development of a much more quickly-installed replacement method.
A rapid paving notch replacement is proposed that can be installed with a single overnight bridge closure. The proposed paving notch replacement consists of a precast concrete element that is connected to the rear of the abutment using high-strength post-tensioning rods and epoxy adhesive similar to that used in segmental bridge construction.
The proposed precast paving notch replacement requires a material that provides both high compressive and tensile strength. In addition, the location of the paving notch beneath an open expansion joint may subject the precast element to considerable chloride exposure during its life and therefore requires a material that is also highly resistant to chloride intrusion.
The research team will contact a manufacturer of ultra high performance concrete materials, which has both significant tensile and compressive strength with essentially zero permeability, such as Lafarge, regarding their willingness to contribute materials and fabrication of three specimens suitable for both laboratory and field testing. In order to ensure that a thorough laboratory testing program can be performed given the limited budget available, the research team will secure this contribution prior to proceeding with additional work.