Masonry Structures

composing the area that is exposed to wave action. In repair of the damage, consideration must be given to the cause of damage, such as an unusually severe storm, need for strengthening of structure, and too steep side slopes. Unless it is evident after study by design engineers that changes in design are required, the structural damage should be repaired with the same materials used in the original to restore the structure to its original strength, elevation, and cross section. Depressions washed out of the bottom in the vicinity of structures should be replaced with sand or GRANULAR materials up to the original level before replacing stone. You can do this either by dumping from the undamaged part of the structure or by placing the materials from a barge from a floating derrick. Masonry Structures Structures, made of cut stone and cast concrete, made into shapes and fitted up tightly together, or laid up with mortar or similar material, are considered masonry structures. Units may be bonded together by overlapping, by metal clamps, dowels, or bed plugs, or by shapes of the blocks (fig. 7-29). All metal fastenings should be zinc-coated and well bedded in mortar. Sections of masonry that have washed out or have been damaged should be completely rebuilt, bonding the units to each other or using metal fastenings as necessary. Masonry walls that have cracked because of unequal settlement can be rebuilt, adding reinforcing bars, as shown in figure 7-30. Repair of cracked walls should be delayed until settlement is complete if possible. Where sections of walls have been displaced by sliding, an investigation should be made to determine the cause before it is rebuilt. If water builds up back of the walls, the weep holes should be cleaned and new ones installed to relieve the pressure. Walls that fail because they are inadequate should be redesigned before they are rebuilt. It is advisable to provide clamps for reinforcement where the displacement of a wall is minor. If it is not necessary to rebuild the wall, it can be reinforced by drilling holes down through the wall at the rear of displacement and a short distance beyond, inserting steel rods in the holes and filling the holes with cement mortar (fig. 7-31). Earth Structures The use of earth for waterfront structures is confined largely to dikes and levees. It is also used for the interior of such structures as causeways, moles, and breakwaters; as backfill for quay walls and similar Figure 7-29.—Anchoring masonry blocks. Figure 7-30.—Repair to cracked masonry walls. 7-30