A nine-span reinforced concrete arch bridge built around 1927 needed extensive repairs. The deck expansion joints had failed, allowing water and salts to deposit on the top and faces of the piers. Transverse cracks allowed water to penetrate, which caused further damage from freeze-thaw cycles. Poor concrete
quality and inadequate consolidation contributed to the problem.

Non-destructive testing indicated that the arches had delamination and debonding at reinforcing bars, friable surfaces along the top, spalling, two full width traverse cracks on each span, and internal networks of cracks and voids.

Removal of the bridge was a viable option due to the extent of deterioration. Restoration using the vacuum injection/resin impregnation process, along with conventional concrete replacement in delaminated and spalled areas, was selected
instead.

Vacuum injection was used to repair visible surface cracks, particularly the two
full-width transverse cracks on each span, and the friable surfaces on the top of the arches. The cracks were cleaned and vacuum injected with a low viscosity resin that accounted for future thermal changes. The friable surfaces were solidified and sealed prior to the placement of the new deck slab.

Repairs were undertaken at a cost much lower than replacement and restoration only techniques, and the useful life of the structure was extended.

The case study was provided by Balvac Inc., a vacuum injection contractor located in East Aurora, NY