THE BEHAVIOR OF ASPHALT PAVEMENTS UNDER VARIABLE REPEATED LOADS

THE MOST MODERN METHOD OF ASPHALT PAVEMENT CONSTRUCTION CONSISTS IN MAKING THE CARPET, BINDER, AND BASE COURSE WITH ASPHALT MIXTURE, SO THAT THESE THREE LAYERS WORK ALTOGETHER AS A UNIQUE PLATE RESTING ON THE SUBBASE, WHICH LATTER IS USUALLY MADE OF COMPACTED GRANULAR MATERIAL. IT IS ACKNOWLEDGED THAT THESE BITUMINOUS PAVEMENTS, EVEN IF CORRECTLY BUILT ON A WELL COMPACTED SUBGRADE, START TO CRACK IN A PECULIAR MANNER (CHICKEN WIRE) AFTER HAVING BEEN SUBMITTED FOR SOME TIME TO HEAVY TRAFFIC. RECENTLY THIS CRACKING HAS BEEN ATTRIBUTED TO FATIGUE FAILURE AND TAKEN INTO CONSIDERATION IN THE DESIGN OF THE PAVEMENTS BY INCREASING EMPIRICALLY THE THICKNESS IN RELATION TO THE AMOUNT OF TRAFFIC, THE TRUE NATURE OF FATIGUE FAILURE PHENOMENON NOT YET BEING KNOWN. IN ORDER TO FIND OUT ABOUT THIS KIND OF FAILURE, THE AUTHOR PERFORMED SOME TESTS ON SAMPLES MADE OF BITUMINOUS CONCRETE. EACH SAMPLE, IN THE FORM OF A SMALL PRISMATIC BEAM, HAS UNDERGONE REPEATED BENDING MOMENTS OF OPPOSITE SENSE. IT HAS BEEN OBSERVED THAT THE INCREASE OR CURVATURE DUE TO EACH CYCLE WAS DECREASING WITH THE REPETITION OF APPLICATIONS OF THE BENDING MOMENTS HAVING THE SAME VERSE, AND INSTEAD THERE WAS A SHARP GROWTH OF INCREASE OF CURVATURE WHEN THE VERSE OF THE BENDING MOMENT WAS CHANGED. FROM THESE RESULTS THE AUTHOR ASSUMES THAT EACH APPLICATION OF THE BENDING MOMENT LEAVES RESIDUAL STRESSES, WHICH AFFECT THE BEHAVIOR OF THE MATERIAL UNDER OTHER CHARGES. THEREFORE IT IS THE AUTHORS OPINION THAT THE PRESENT THEORY OF THE ELASTO-VISCOUS BODIES IS NOT APPLICABLE TO THE DESIGN OF THE FLEXIBLE PAVEMENTS, SINCE SUCH THEORY IGNORES THE RESIDUAL STRESSES. ACTUALLY THE FATIGUE FAILURE OCCURS WHEN THE TOTAL AMOUNT OF INTERNAL STRESSES, PARTLY DUE TO THE CONTINUALLY INCREASING RESIDUAL STRESSES, AND PARTLY CAUSED BY THE EXTERNAL CHARGE, PRODUCES THE CRACK OF THE MATERIAL. A DEEP STUDY OF THE RESIDUAL STRESSES IN THE BITUMINOUS MIXTURES IS, THEREFORE, TO BE CONSIDERED A PRELIMINARY AS WELL AS NECESSARY STEP TOWARD THE REALISTIC APPROACH TO THE DESIGN OF FLEXIBLE PAVEMENTS. (AUTHOR)

• Supplemental Notes:
  • Preprint VoL, PP 124-131, 2 FIG, 2 REF
• Authors:
  • Ferrari, P
• Conference:
  • Intl Conf Struct Design Asphalt Pvmts
• Publication Date: 1967-1

Subject/Index Terms

• TRT Terms: Accelerated tests; Asphalt pavements; Bituminous pavements; Failure; Flexible pavements; Pavement cracking; Pavement design; Repeated loads; Residual stress
• Subject Areas: Highways; Pavements;

Filing Info

• Accession Number: 00206644
• Record Type: Publication
• Files: TRIS
• Created Date: Aug 1 1994 12:00AM