DURABILITY AND BEHAVIOR OF PRESTRESSED CONCRETE BEAMS. REPORT 2. POSTTENSIONED CONCRETE INVESTIGATION PROGRESS TO JULY 1966.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
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The investigation was concerned with exposure testing of end anchorages and end-anchorage protection on posttensioned beams. The study consisted essentially of the fabrication and testing of 20 air-entrained posttensioned concrete beams and 280 auxiliary specimens. The auxiliary specimens were tested in the laboratory to determine the strength and plastic properties of the mixtures used. The 20 beams were installed at the Treat Island, Maine, exposure station in June 1961, where they are being subjected to freezing and thawing in sea water. After 5 winters of exposure, three of the 40 end-anchorage protections have become detached, one has become loose, and 15 have developed a crack at the bond line with the beam. It is concluded that a concrete cover over reinforcing steel should be greater than 34 in. when exposure to sea water is involved b differences among the four methods of end preparation of beams that received portland-cement concrete protection over external anchorages do not seem to be significant in the performance of the anchorage protection c flush anchorages appear to have been more effectively protected than the external anchorages and d epoxy concrete appears to be superior to portland-cement concrete for end protection.
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