Condition Survey of Locks and Dam 3, Monongahela River

摘要

A condition survey was performed at Locks and Dam No. 3 on the Monongahela River in Pennsylvania to evaluate the concrete condition at the locks and dam, and to make a projection of the concrete condition of selected project features to approximately year 2010. Data from the original construction of the locks, and major rehabilitation of the locks and dam between 1978 and 1980 were evaluated. A visual field investigation was conducted to determine the present concrete condition in the locks. Freezing and thawing of the older nonair-entrained concrete is the major deteriorating mechanism in the structure. A maximum vertical rate of deterioration for exposed original concrete was calculated to be 1.06 in. per year: a horizontal rate of deterioration of 0.90 in. per year was determined with a new concrete overlay serving as low-permeability cover. Where original concrete is exposed on vertical faces, the worst case damage of an additional 32 in. is estimated by the year 2010. Sections of the walls refaced with high quality air-entrained concrete should be serviceable until the year 2010, while local high stress areas may require repairs as deficiencies are formed. (FR)