FATIGUE CRACK FORMATION AND PROPAGATION IN PAVEMENTS CONTAINING SOIL-CEMENT BASES

AN ATTEMPT IS MADE TO PREDICT THE FORMATION AND DEVELOPMENT OF FATIGUE CRACKS IN PAVEMENTS CONTAINING SOIL-CEMENT BASES, IT IS ASSUMED THAT TRANSVERSE SHRINKAGE CRACKS HAVE ALREADY FORMED. TO OBTAIN REALISTIC RESULTS, WE ANALYZED A TYPICAL PAVEMENT SECTION CONSISTING OF 3 IN. OF ASPHALT CONCRETE AND 8 IN. OF CEMENT-TREATED BASE RESTING ON A CLAYEY SUBGRADE. THE PROPERTIES OF THE CEMENT-TREATED BASE WERE DEVELOPED FORM AN EXTENSIVE LABORATORY INVESTIGATION, AND THE FATIGUE RESULTS OBTAINED ARE REPORTED IN SOME DETAIL. THESE RESULTS CONFIRM PREVIOUS FATIGUE STUDIES PERFORMED BY THE PORTLAND CEMENT ASSOCIATION. TO ESTIMATE THE STRESSES IN A PAVEMENT SYSTEM WITH TRANSVERSE SHRINKAGE CRACKS PRESENT AND THUS TO ESTIMATE THE POTENTIAL FOR FATIGUE CRACKING, WE USED A PRISMATIC-SPACE FINITE-ELEMENT PROCEDURE. THE RESULTS OF THE ANALYSIS SHOW THAT THE FIRST FATIGUE CRACK TO DEVELOP IS PERPENDICULAR TO THE SHRINKAGE CRACK AND IN THE POSITION OF THE WHEEL PATH. A CRACK OF THIS TYPE MAY PROPAGATE FAIRLY RAPIDLY BECAUSE OF STRESS CONCENTRATIONS AT THE TIP OF THE CRACK AND LEAD TO THE "CORNER LOADING" SITUATION BOUNDED BY THE SHRINKAGE AND PERPENDICULAR FATIGUE CRAKCS. THIS SITUATION CAN BE ANALYZED APPROXIMATELY BY USING THE WESTERGAARD FORMULA, I. E., TRANSFORMING THE ASPHALT CONCRETE LAYER TO AN EQUIVALENT THICKNESS OF CEMENT- TREATED BASE. THE STRESSES RESULTING FROM THIS ANALYSIS INDICATE THE POTENTIAL FOR ADDITIONAL LOAD-ASSOCIATED CRACKING LEADING TO THE POSSIBILITY FOR THE CORNER TO BREAK OFF. BECAUSE THIS SITUATION CAN REPEAT ITSELF WITH CONTINUED LOAD REPETITIONS, THE FAMILIAR DOUBLE- LADDER CRACK PATTERN IS ESTABLISHED. IT IS ALSO SHOWN THAT THE PRESENCE OF A LONGITUDINAL SHRINKAGE CRACK PARALLEL AND CLOSE TO THE FATIGUE CRACK MAY GIVE RISE TO SINGLE-LADDER CRACK PATTERN. THE CRACK PATTERN PREDIICTIONS ARE SUBSTANTIATED TO SOME DEGREE BY A FIELD INVESTIGATION. THE PROPAGATION OF LOAD-ASSOCIATED CRACKS WAS TRACED BY PERIODICALLY PHOTOGRAPHING AN UNDERSIGNED PAVEMENT CONTAINING A CEMENT-TREATED BASE OVER A PERIOD OF TIME DURING WHICH RAPID DETERIORATION DUE TO REPEATED LOADING OCCURRED.

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  • Supplemental Notes:
    • Sponsored by Committee on Theory of Pavement Design. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
  • Authors:
    • Pretorius, P C
    • Monismith, C L
  • Conference:
  • Publication Date: 1972

Media Info

  • Media Type: Digital/other
  • Features: Figures; References;
  • Pagination: pp 102-115
  • Monograph Title: Pavement technology
  • Serial:

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Filing Info

  • Accession Number: 00207498
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 15 1973 12:00AM