Case Study 5: Identifying Weakened Panels in a 7.5-mile Concrete Seawall at Marina Del Rey, Los Angeles, California.
Problems arose when several 20-ft wide panels in the retaining seawall collapsed into the water. The problem was found to be corrosion of the reinforcing steel due to a faulty construction joint below the water line. Corrosion of the steel caused disintegration and weakening of the surrounding concrete. Not all panels were affected. Impact-echo was used to identify areas in which corrosion of rebars and weakening of concrete had occurred, and in those areas the panels were repaired and new anchors were installed to hold them firmly in place. Compared to the alternative of replacing the entire wall, the use of impact-echo saved an estimated $100 million in the repair and rehabilitation of the seawall.