Underwater Repair of Concrete Elements with TRC Grouting System

The repair of underwater concrete structures is usually difficult work, requiring specialized materials and installation systems. This paper presents a carbon-textile-reinforced concrete (TRC) grouting system for underwater repair of concrete structures. One multi-purpose grout and two types of underwater grouts were considered in this study, and the bond performance between the substrate and grout was evaluated by a bi-surface shear test with cubic specimens. The bond strength of the repair material is greatly affected by the casting and curing conditions. When the multi-purpose grout is used, the average bond strength of the specimens cast and cured in dry conditions is only 22% of the specimens cast and cured in underwater conditions. On the other hand, the maximum difference in bond strength is, at most, 15.8% when non-dispersive, anti-washout grouts are used. Two types of installation methods were proposed and four full-scale RC slab specimens were repaired with the TRC grouting method, two for each installation method. Regardless of the installation method, the load levels that causes concrete cracking, steel yield, and the failure of specimens repaired with the TRC grouting system are at least 37.5%, 16.6%, and 21.7% greater than those of the unrepaired specimen, respectively. The test results further indicate that the influence of the grouting materials on the ultimate load-carrying capacity of the specimens repaired with the TRC grouting system is insignificant, and the maximum difference is, at most, 4%.