For several years the Kansas Department of Transportation (KsDOT) was faced with shear cracks in the concrete girders of two-girder reinforced concrete bridges. A technique that would repair the cracks and increase the girder's shear capacity was needed. Post reinforcement, a repair method that does both of these things, was developed and is now used by the KsDOT. It consists of the following four steps:
- Seal all cracks in the girder with a silicone sealant.
- Vacuum drill 1-inch-diameter clean, dust-free holes at a 45-degree angle to the deck near the girder center-line in the pattern specified in the engineering plans.
- Pump epoxy into the drilled holes and into cracks intercepted by these holes.
- Insert a #6, Grade 60 rebar cut 3 inches short of full hole depth into each hole.
If the bridge deck is badly deteriorated, it can be repaired by applying a thin bonded concrete overlay, once the epoxy for the post reinforcement has fully set. The air-entrained overlay concrete must have a minimum of 625 pounds of portland cement per cubic yard and a water-cement ratio of no more than 0.40. Slump must not exceed 3/4 inch. The overlay is generally placed 2 1/4 inches thick over the entire prepared deck, though it will be thicker where it fills in the depressions left by the removal of unsound concrete.
