We are involved in a dam repair project that includes the repair of erosion-damaged concrete in the distillery basin. Most of the damaged areas are near the splash zone. We are considering repairing the concrete with an epoxy mortar to resist abrasion. However, the concrete surfaces are always wet and we're concerned that an epoxy will not achieve adequate bond to the concrete. Can an epoxy be used for this application?
The ability of several cementitious and epoxy repair materials to bond to wet concrete surfaces was explored by the U.S. Army Corps of Engineers in technical report REMR-CS-25, "Spall Repair of Wet Concrete Surfaces," released in January 1990. Slant-shear bond testing was performed on 15 epoxies and seven cementitious products. To simulate wet surface conditions, the lower sections of the slant-shear specimens were stored in a moist room at 100% relative humidity until just before filling the upper half of the mold with repair material. The bond surface was examined just before filling the mold, and additional water was applied to the surface as necessary to obtain a glistening finish. The subsequent slant-shear bond tests resulted in seven products achieving bond strengths of 1800 psi or greater. Of these, four were epoxies. These results suggest that certain moisture-tolerant epoxies can bond successfully to wet concrete surfaces.