Underground utility vaults and pull boxes are frequently used by electrical utility companies. These concrete boxes (typically the size of a small room) are buried underground and provide a location to connect long segments of cables for electrical, telephone and fiber optics industries.
Access to utility vaults is normally provided through a manhole at the street level. Moisture is often entrapped in these vaults, resulting in corrosion of the side walls and the ceiling slab. This results in an unsafe condition for the traveling public that drive over these utility vaults. The limited access through manholes makes the use of repair with conventional materials such as steel and concrete challenging.
Our engineers can provide solutions utilizing carbon or glass FRP fabric. The design will consider the level of corrosion and the original strength of the wall and ceiling. The repair consists of protecting the cables inside the utility vault. Any major concrete spalls can be patched first. The carbon fabric is saturated outside on the street level and these sheets are passed through the manhole where the crew installs them on the ceiling and walls. In addition to strengthening the elements, the impervious FRP will prevent moisture penetration and thus will protect the concrete against future corrosion.
Features & Benefits:
1. Walls and ceiling can be repaired with FRP
2. Minimal increase in member size (typically ¼ inch (5mm))
3. Minimal disruption to street-level traffic
4. Repairs are fast and often completed in 1-2 days
5. Ideal for spot repair of only damaged areas
6. FRP will serve as moisture barrier to protect the walls and ceiling against future corrosion
7. Finished installation can be painted, making it hardly visible