RANDOM CRACKING OF BRIDGE DECKS CAUSED BY PLASTIC SHRINKAGE

INVESTIGATION WAS MADE TO DETERMINE THE CAUSES OF SEVERE RANDOM CRACKING THAT AFFECTED TWO OF FOUR REINFORCED CONCRETE SPANS ON AN INTERSTATE SYSTEM BRIDGE. THE REMAINING TWO SLABS WERE UNAFFECTED. THE OVERALL CHARACTERISTICS OF THE CRACKING BASED ON VISUAL SURVEY WERE SIMILAR TO PLASTIC SHRINKAGE WHICH SUGGESTED THAT CRACKING HAD OCCURED EARLY IN THE LIFE OF THE DECK. TWO 4-IN. DIAMETER CORES WERE REMOVED FROM THE CRACKED ARED FOR PETROGRAPHIC EXAMINATION. EXAMINATION OF THESE CORES INDICATED THAT THE CRACKS TRAVELED AROUND RATHER THAN THROUGH AGGREGATE PARTICLES. CONSIDERING THIS AND THE FACT THAT THE STRENGTH OF THE CONCRETE WAS HIGH, IT WAS CONCLUDED THAT THE CRACKING OCCURED WHEN THE CONCRETE WAS RELATIVELY GREEN AND PERHAPS FRESH. RESULTS INDICATE THAT WHEN EARLY RANDOM CRACKING OCCURS, THE SEVERE DRYING CONDITIONS AS REFLECTED IN THE COMPUTED EVAPORATION RATE EXISTS. THE EXISTENCE OF SEVERE CONDITIONS DOES NOT ALWAYS RESULT IN THIS EARLY CRACKING. THIS WOULD SUGGEST THAT THE CRACKING CAN BE PREVENTED, OR AT LEAST BE REDUCED IN SEVERITY, BY CONSTRUCTION FACTORS THAT MODIFY THE INFLUENCE OF THE FOUR MAJOR VARIABLES OF AIR TEMPERATURE, CONCRETE TEMPERATURE, WIND VELOCITY, AND RELATIVE HUMIDITY.

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 57-61
  • Monograph Title: Observations of the performance of concrete in service
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00213697
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI
  • Created Date: Jul 21 1970 12:00AM