DURABILITY AND BEHAVIOR OF PRESTRESSED CONCRETE BEAMS REPORT II - POSTTENSIONED CONCRETE INVESTIGATION PROGRESS TO JULY 1966

INFORMATION IS DEVELOPED ON THE DURABILITY OF PRESTRESSED CONCRETE BEAMS. EXPOSURE TESTS WERE MADE OF END ANCHORAGES AND END-ANCHORAGE PROTECTION OF POSTTENSIONED BEAMS. TWENTY AIR-ENTRAINED, POSTTENSIONED CONCRETE BEAMS AND 280 AUXILIARY SPECIMENS WERE FABRICATED AND TESTED. FOUR POSTTENSIONING SYSTEMS WITH EITHER EXTERNAL OR FLUSH END ANCHORAGES AND 12 TYPES OF END-ANCHORAGE COMPONENTS, WERE USED. THE AUXILIARY STEEL REINFORCEMENT HAD A NOMINAL 3/4 IN. OF CONCRETE COVER. THE AUXILIARY SPECIMENS WERE TESTED IN THE LABORATORY TO DETERMINE THE STRENGTH AND PLASTIC PROPERTIES OF THE MIXTURES USED. THE 20 POSTTENSIONED 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. IN ALL OF THE BEAMS THAT SHOW EVIDENCE OF END-PROTECTION FAILURE, PORTLAND- CEMENT CONCRETE HAD BEEN USED TO ENCLOSE EXTERNAL ANCHORAGES. CONCLUSIONS AT THE TIME OF THE REPORT WERE THAT: (1) THE CONCRETE COVER OVER REINFORCING SHOULD BE GREATER THAN 3/4 IN. WHEN EXPOSURE TO SEA WATER IS INVOLVED, (2) 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, (3) THE FLUSH ANCHORAGES APPEAR TO HAVE BEEN MORE EFFECTIVELY PROTECTED THAN THE EXTERNAL ANCHORAGES, AND (4) EPOXY CONCRETE APPEARS TO BE SUPERIOR TO PORTLAND-CEMENT CONCRETE FOR END PROTECTION.

  • Supplemental Notes:
    • Tech Report NO 6-570, XII & 46 PP, 1FIG, 9TAB, 5PHOT, 5REF,
  • Corporate Authors:

    U.S. Army Waterways Experiment Station

    3909 Halls Ferry Road
    Vicksburg, MS  United States  39180-6199
  • Authors:
    • Roshore, E C
  • Publication Date: 1967-3

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Filing Info

  • Accession Number: 00214739
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 27 1994 12:00AM