Rehabilitating Bridge Substructures

Part of the bridge piles were burned, corroded, and the concrete of some pier columns was hollowed out, damaged, and exposed.

In response to the corrosion of the piles and the problems of local concrete hollowing, damage, and exposed reinforcement in the pier columns, the damaged concrete was chiseled out and then reinforced with underwater FRP pile jackets.

The construction process is as follows:

(1) Surface treatment

Chisel away loose concrete from burnt areas such as hollow piers and exposed reinforcement, until the surface of fresh and solid concrete; Remove rust from corroded steel bars and apply epoxy steel bar rust inhibitor.

(2) Underwater FRP pile jackets installation

To repair the pier column, it is necessary to first unfold the fiberglass sleeve and wrap it around the pier column. In the most severely damaged area, the underwater FRP pile jackets extends 400-600mm upwards and downwards respectively, and in the intact area of the pile column, the underwater FRP pile jackets is spaced 50mm apart from the structural space.

(3) FRP pile jackets protection

Use fastening straps to temporarily fix the sleeve and anchor the FRP pile jackets joint with bolts. At the same time, internal support can be provided by tying cushion blocks or using expansion bolts on the housing to prevent the template from being concave.

(4) Bottom sealing

Seal the bottom of the FRP pile jackets with a compressible sealing strip.

(5) Grouting

Fill all gaps in the FRP pile jackets with cement-based grouting material to the top of the FRP pile jackets: add air entraining agent to the grouting material, with a content of 4%~6%.

(6) Top seal

Use cement-based grouting material to seal the top of the FRP pile jackets with a diagonal section to prevent moisture from being trapped on the top surface.