Application of Epoxy Resins in Tunnel Lining Concrete Repair

Concrete lining in a large diameter tunnel spillway damaged by cavitation erosion caused by variable high flows up to 20,000 cfs was repaired by use of bonded concrete, and epoxy bonded epoxy mortar. Epoxy bonded epoxy mortar was used to make the repairs except in the damaged areas of large volume. The repair area to receive epoxy mortar was prepared by bushhammering, chipping, or sandblasting. The surfaces of the concrete were made completely dry. Seeping hairline cracks were rendered dry by chemical grouting. Air and concrete temperature was maintained at about 60° F by a heating system. A clear epoxy bond coat was applied to a small area of prepared concrete surface. Epoxy mortar was applied to the bond coat while the bond coat was in a fluid to tacky condition. Curing and post curing of the epoxy mortar by use of propane infrared heaters and heat lamps were required. Painting of the cured mortar with an epoxy phenolic paint was specified.