Resource
Surveys of concrete armored coastal structures
Bulletin on file with ASDSO.
Concrete armor units (CAUs) are used to protect coastal structures from erosion when stone is not economically available. These structures include breakwaters, jetties, groins, and revetments. CAU s come in a variety of shapes (Figure 1) and can be placed quasi-randomly or uniformly and range in mass from 1 to 50 tons. CAU shapes commonly used in the past by the Corps of Engineers include the dolos, tribar, and tetrapod.
CAU shapes generally can be grouped according to how the shape resists movement. Blocky shapes resist movement primarily through self weight and surface friction, whereas slender shapes have additional movement resistance through the interlocking of slender appendages. Historically, slender armor units, such as the dolos, tribar, and tetrapod, have had a high degree of breakage because impact loads, induced by unit movement, produce high stresses in relatively weak slender central sections. Reinforcing bars and fiber reinforcement have been used in many Corps CAUs but have provided little apparent performance improvement. Under the REMR work unit "Breakwater Concrete Armor Units for Repair," the Coastal Engineering Research Center (CERC), Waterways Experiment Station, has been tasked with improving the hydraulic stability and structural capacity of existing armor shapes and ultimately with the development of optimal armor unit shapes that are more stable and stronger than existing units.
