SPECIAL STUDY OF BLUE RAPIDS BRIDGE DECK

THE LOCATION AND PROGRESS OF THE SPALL AND HOLLOW PLANE TYPE OF DAMAGE OCCURRING IN A SCALE FREE AIR ENTRAINED CONCRETE DECK OF A PONY TRUSS BRIDGE NEAR BLUE RAPIDS, KANSAS WAS STUDIED BY 'TAPPING AND MAPPING'. MAPS WERE MADE TWICE EACH YEAR BETWEEN AUGUST 1931 AND MAY 1964 TO SHOW THE PROGRESS OF THE DAMAGE. THESE STUDIES REVEALED THAT THE DAMAGE INCREASED FAR MORE DURING THE WINTER THAN DURING THE SUMMER. FREEZE-THAW OF WATER ENTERING A PRE-EXISTING PLANE WAS CONSIDERED TO BE THE MAJOR CAUSE OF THE INCREASE IN DAMAGE. FREEZE-THAW SUSCEPTIBLE AND ALKALI- REACTIVE CHERT COARSE AGGREGATES CAUSED POPOUTS AND CONTRIBUTED TO THE FORMATION AND EXTENSION OF HOLLOW AREAS AND SURFACE SPALLS. VIBRATIONS DUE TO LIVE LOADS ALSO CONTRIBUTED TO THE FORMATION AND EXTENSION OF THE FRACTURE PLANES. PACHOMETERS WERE USED TO MAKE BAR DEPTH MAPS OF MORE THAN ONE-FOURTH OF THE DECK SURFACE IN AREAS OF HEAVY DAMAGE AND IN AREAS OF VERY LITTLE DAMAGE. THESE MAPS REVEALED THAT DAMAGE WAS RELATED TO SHALLOW STEEL. SURFACE SPALLS WERE PRIMARILY ASSOCIATED WITH STEEL LESS THAN 1 INCH DEEP AND HOLLOW AREAS WERE ASSOCIATED WITH STEEL UP TO 1-1/2 INCHES DEEP. STEEL 2 INCHES OR MORE DEEP WAS NOT ASSOCIATED WITH SPALLS OR HOLLOW AREAS. THERE WAS A SHARP DECREASE IN THE AMOUNT OF DAMAGE WHEN THE AVERAGE STEEL DEPTH EXCEEDED 1-1/2 INCHES. DAMAGE BEGAN PRIMARILY AT THE SHALLOWEST STEEL AND PROGRESSED TO DEEPER STEEL. SAW CUTS WERE MADE THROUGH THE CONCRETE SURFACE TO THE CLEAVAGE PLANE AND A SLAB OF THE CONCRETE SURFACE WASH PULLED OUT TO REVEAL THE CONDITIONS IN THE PLANE. CORES WERE USED TO SUPPLEMENT INFORMATION OBTAINED FROM THE PULLOUTS. THE SURFACE OF THE CONCRETE HAD A HARD, CARBONATED CRUST BELOW WHICH THERE WAS A WEAKENED ZONE DUE TO WATER GAIN FROM BLEEDWATER TRAPPED BELOW THE CRUST WHILE THE CONCRETE WAS HARDENING. WHEN THE STEEL WAS SHALLOW IT TOO WAS IN THE WATER GAIN ZONE RESULTING IN A DOUBLY WEAK ZONE NEAR THE SURFACE OF THE CONCRETE. VERTICAL SUBSIDENCE CRACKS OVER THE STEEL ALLOWED WATER AND DEICING SALT TO PENETRATE TO THE STEEL. CORROSION OF THE STEEL AND FREEZE- THAW DISTRESS OF THE CONCRETE FOLLOWED INITIATING THE FRACTURE PLANES AND SURFACE SQUALLS. PH MEASUREMENTS REVEALED SPOTS ON THE REINFORCING STEEL OF THIS AND OTHER BRIDGES IN KANSAS THAT WERE QUITE ACID WITH PH OF E OR LESS EVEN THOUGH THE PH OF THE CONCRETE IN GENERAL WAS 12 TO 14. THE LOW PH AREAS WERE USUALLY ASSOCIATED WITH CORROSION PITS IN THE STEEL. /BPR/

  • Supplemental Notes:
    • Hpr, 64-3
  • Corporate Authors:

    Kansas State Highway Commission

    State Office Building
    Topeka, KS  USA  66612

    Bureau of Public Roads /US

    400 7th Street, SW
    Washington, DC  USA  20590
  • Authors:
    • Crumpton, C F
    • Pattengill, M G
  • Publication Date: 1969-4

Subject/Index Terms

Filing Info

  • Accession Number: 00206373
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS
  • Created Date: Oct 28 1994 12:00AM