Development of a Geomembrane System for Underwater Repair of Concrete Structures

Paper on file with ASDSO.

The U.S. Army Corps ofEngineers operates and maintains a wide variety of hydraulic structures, including mass-concrete gravity dams, rock-fill dams with concrete facings, and roller-compacted concrete dams. Concrete appurtenances associated with such dams include intake towers, outlet works, and stilling basins. Located at over 600 project sites throughout the United States, these structures are subjected to a wide spectrum of environmental conditions. Also, the advanced ages of these structures, more than 40 percent of which are over 50 years old, increase the potential for concrete deterioration.
Many of these structures exhibit concrete cracking, which allows water intrusion into or through the structure. Water leakage through hydraulic structures can also result from poor concrete consolidation during construction, improperly prepared lift or construction joints, and water-stop failures. When leakage rates through cracked or deteriorated concrete and defective joints become unacceptable, repairs are made. Conventional repair methods generally consist of localized sealing of cracks and defective joints by cementitious and chemical grouting, epoxy injection, or surface treatments. Even though localized sealing ofleaking cracks and defective joints with conventional methods has been successful in some applications, in many cases some type of overall repair is still required after a few years. Consequently, the potential for geomembranes in such repairs was evaluated as part of the Corps' Repair, Evaluation, Maintenance, and Rehabilitation (REMR) Research Program. (continued)