U.S. Fish & Wildlife Service Low Hazard Dams - Association of State ...

damsafety.org

U.S. Fish & Wildlife Service Low Hazard Dams - Association of State ...

STANDING OPERATING PROCEDURES5.4 General Maintenance Items5.4.1 ConcreteRepair of deteriorated concrete should be discussed with the RDSO. The RDSO willmake all concrete repair decisions. Any vegetation observed growing from cracks in theconcrete should be removed.Over time, concrete surfaces will weather, leaving the concrete rough to the touch, or willhold moisture on the surface. When this occurs consider applying a protective coating tothe concrete to help prevent moisture from entering the structure. By applying aprotective coating to the concrete surface and sealing the cracks the chances of freeze /thaw damage will be greatly reduced, increasing the life expectancy of the structure. Priorto the application of a concrete sealer, the structure should be cleaned, existing cracksshould be sealed with a flexible sealant, and any spalling repaired. Any sealer chosen forthe concrete floodwall should be a water or solvent-based acrylic protective coating,which may be either clear or colored, and may be textured.Periodic maintenance should be performed on all concrete surfaces to repair deterioratedareas. Repair deteriorated concrete as soon as possible when noted; it is most easilyrepaired in its early stages. Deterioration can accelerate and, if left unattended, can resultin serious problems. Consult an experienced engineer to determine both the extent ofdeterioration and the proper method of repair. Seal joints and cracks in concretestructures to avoid damage beneath the concrete.More serious damage such as spalling should be repaired as soon as it is identified,especially if steel reinforcing has been exposed. All surfaces to be patched need to bestructurally sound, clean, and free of loose debris, oils, vegetation, paints, sealants, andother contaminants. Remove all deteriorated concrete to a minimum of ¼-inch in depth.Cut edges should be square with the concrete surfaces, and not feathered. Surfacesshould be sufficiently rough to ensure a good bond. Any existing reinforcing bars shouldbe thoroughly cleaned. If required, existing concrete should be removed to fully exposethe reinforcing bar. Sandblasting may be required to clean them thoroughly. All surfacesshould be fully saturated and freestanding excess water should be removed beforeapplying the repair material.Visible cracking, scaling, or spalling are signs of concrete movement and stresses withinthe concrete. Cracks in concrete walls that aren’t repaired are subject to freeze/thawdamage, which widens the gap and leads to additional spalling of the concrete. Whenexamining any concrete structures, spalling, scaling, or cracking should be very minimal.Figure 5-5 shows various degrees of cracking and spalling.5-8Revision No. 0October 2008

More magazines by this user
Similar magazines