ASPHALTIC ROAD MATERIALS IN FATIGUE

RESULTS AND ANALYSES ARE PRESENTED OF RESEARCH CONDUCTED AT THE UNIVERSITY OF NOTTINGHAM ON ASPHALT PAVEMENT WEARING AND BASE COURSE MIXES AS USED IN PRACTICE. MIXED VARIABLES WHICH AFFECT STIFFNESS ALSO AFFECT THE FATIGUE LIFE. THESE VARIABLES ARE AGGREGATE TYPE AND GRADING INCLUDING FILLER, BITUMIN TYPE, PENETRATION AND CONTENT, DEGREE OF MIX COMPACTION AND RESULTING AIR VOIDS CONTENT. A MACHINE WAS DEVELOPED TO MEASURE THE DYNAMIC STIFFNESS OF SPECIMENS UNDER LOADING AND ENVIRONMENTAL CONDITIONS SIMILAR TO THOSE USED IN THE FATIGUE TEST. MATERIALS AND MIXES, AND TEST METHODS WERE INVESTIGATED AND EVALUATED. CONCLUSIONS ARE OBTAINED FROM THE STUDY OF THE FACTORS AFFECTING THE FATIGUE BEHAVIOR OF ASPHALTIC ROAD MATERIALS INDICATE THAT : (1) A LINEAR RELATIONSHIP EXISTS BETWEEN THE LOGARITHM OF THE AMPLITUDE OF THE APPLIED STRESS LEVEL, AND THE LOGARITHM OF THE NUMBER OF CYCLES TO FAILURE, (2) THE FATIGUE LIFE OF BASE COURSE MIXES TESTED UNDER CONTROLLED STRESS CONDITIONS IS HIGHLY TEMPERATURE DEPENDENT, (3) THE ADDITION OF SOME FILLER TO B.S. 594 BASE COURSE MIXES RESULTS IN LONGER FATIGUE LIVES, DUE TO A REDUCTION IN VOIDS AND AN INCREASE IN STIFFNESS, (4) THE ADDITION OF MORE BITUMIN TO B.S. 594 BASE COURSE MIXES RESULTS IN AN INCREASE IN FATIGUE LIFE, BUT AN OPTIMUM BITUMIN CONTENT EXISTS, (5) THE TYPE AND GRADING OF THE COURSE AGGREGATE, WITHIN THE LIMITS OF THE MIXES INVESTIGATED, DOES NOT GREATLY INFLUENCE THE FATIGUE LIFE, (6) VOIDS HAVE A DETRIMENTAL EFFECT UPON FATIGUE LIFE, AN INCREASE IN VOID CONTENT BEING ASSOCIATED WITH A DECREASE IN FATIGUE LIFE, (7) THE DISTRIBUTION OF A SET OF OBSERVED FATIGUE LIVES CAN BE ASSUMED TO FOLLOW THE LOG NORMAL DISTRIBUTION LAW, (8) AN INCREASE IN SPEED OF LOADING PRODUCES AN INCREASE IN THE OBSERVED FATIGUE LIFE, (9) THE FATIGUE LIFE OF B.S. 594 BASE COURSE TYPE MIXES IS PRIMARILY CONTROLLED BY THE MAGNITUDE OF THE TENSILE STRAIN, THE EFFECTS OF TEMPERATURE AND SPEED OF LOADING BEING ACCOUNTED FOR BY THEIR EFFECT ON THE STIFFNESS OF THE MIX, (10) THE TYPE OF BEHAVIOR DISPLAYED BY A MIX FOR THE PARTICULAR CONDITIONS BEING INVESTIGATED HAS A PROFOUND INFLUENCE UPON THE SLOPE OF THE RESULTING STRESS-LIFE OR STRAIN-LIFE FATIGUE LINES, AND (11) FATIGUE RESULTS SHOULD BE CONSIDERED IN TWO PARTS, ONE IN WHICH ONLY LINEAR MIX BEHAVIOR IS DISPLAYED AND THE OTHER IN WHICH NON-LINEAR BEHAVIOR IS DISPLAYED.

• Supplemental Notes:
  • Vol 38, pp 371-422, 41 FIG, 11 TAB, 19 REF
• Authors:
  • Pell, P S
  • Taylor, I F
• Conference:
  • Association of Asphalt Paving Technologists Proc
• Publication Date: 1969-2

Subject/Index Terms

• TRT Terms: Aggregate gradation; Aggregates; Air voids; Asphalt pavements; Bitumen; Bituminous aggregates; Bituminous mixtures; Compaction; Dynamic tests; Fatigue (Mechanics); Measuring instruments; Stiffness; Stresses; Temperature; Tension
• Uncontrolled Terms: Fatigue life; Tensile stress
• Old TRIS Terms: Air voids content
• Subject Areas: Geotechnology; Highways; Materials; Pavements;

Filing Info

• Accession Number: 00207105
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 27 1970 12:00AM