Iowa Department of Transportation
Brent Pharesbphares@iastate.edu email >
Bridge Research Engineer, BEC
About the research
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 was 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 Iowa State University (ISU) Bridge Engineering Center (BEC) performed full-scale laboratory testing of the proposed paving notch replacement system. The objective of the testing program was to verify the structural capacity of the proposed precast paving notch system and to investigate the feasibility of the proposed solution. This project describes the laboratory testing procedure and discusses its results.