VHPC Material Characterization and Recommendations for the Buffalo Branch Bridge Rehabilitation

Abstract

Adjacent box beam bridges are economical bridge systems for accelerated bridge construction. The box beams are constructed at precast plants and are traditionally connected by a shear key filled with grout. This system is ideal for short spans with low clearance restrictions. However, due to the grout deteriorating and debonding from the precast concrete in the shear key, reflective cracking propogates through the deck allowing water and chemicals to leak down into the joints. This can lead to the prestressing steel inside the precast member and the transverse tie steel corroding. This necessitates the bridge being rehabilitated or replaced which shortens the life-span of the bridge system and negates the economical value it had to begin with.

This research project aimed to design a rehabilitation plan for an adjacent box beam bridge with deteriorated joints using Very High Performance Concrete (VHPC). VHPC was chosen as an economical alternative to the proprietary Ultra High Performance Concrete (UHPC) and extensive material tests were performed. The results of the material testing of VHPC and grout revealed that VHPC had higher compressive and tensile strengths, a higher modulus of elasticity, gained strength faster, bonded better to precast concrete, was more durable over time, and shrank less than conventional grout.

The results of this research project were applied to rehabilitate the Buffalo Branch Bridge and further testing will be completed to determine the effectiveness of the rehabilitation.