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|Title:||Ultrasonic velocity measurements in concrete, Lock and Dam No. 24, Mississippi River|
|Authors:||United States. Army. Corps of Engineers. St. Louis District.|
Thornton, Henry T.
|Keywords:||Alkali aggregate reactions|
Lock and Dam No. 24
|Publisher:||Structures Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; SL-80-2.|
Abstract: Ultrasonic velocity measurements were made through concrete piers No. 2 through 15, which constitute part of the dam structure. Velocity measurements were also made through selected concrete columns that support the service bridge. Areas characterized by low velocities are delineated. The velocity data indicate that a condition of cracking and deterioration exists in the concrete around and near the trunnion, head plates, and connections of the embedded anchorage beams in piers No. 2 through 15. In some piers the condition may extend down the top anchorage beam as far as 15 ft from the trunnion and down the lower beam as far as 6 ft from the trunnion. The columns that were tested have also been damaged by cracking. The cracking on the piers and columns has probably progressed over the years and was probably caused by dynamic and static stress concentrations due to gate vibration and structural movement, aided by freezing-and-thawing action, and possibly, alkali-aggregate reaction. It is recommended that steps be taken to eliminate inordinate vibration of the gates due to hydraulic action, that pooling of water on the structure be prevented, and that appropriate methods be employed for exploratory work to determine the type and extent of repairs needed to assure the desired long-range performance of the structure.
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