ASPHALT TEST: TEN DIFFERENT ROAD SAMPLES SHOW VARYING DURABILITY

THE CALIFORNIA DIVISION OF HIGHWAYS IN COMMON WITH OTHER AGENCIES HAS FOR A GOOD MANY YEARS BEEN INTERESTED IN THE QUALITY OF PAVING ASPHALTS. A TRIAL SPECIFICATION WAS DEVELOPED IN 1954 WHICH HAS BEEN REFERRED TO AT TIMES AS THE SPECIFICATIONS FOR PREMIUM ASPHALT. IN ORDER TO DETERMINE THE PERFORMANCE OF ASPHALTS COMPLYING WITH THE NEW REQUIREMENTS, IT WAS DECIDED TO PLACE A SERIES OF TEST SECTIONS COMMONLY KNOWN AS THE ZACA-WIGMORE TEST ROAD. ACTUAL CONSTRUCTION TOOK PLACE DURING 1954 AND 1955. TEN DIFFERENT ASPHALTS WERE USED. FAILURES HAVE DEVELOPED IN SOME OF THE SECTIONS WHILE OTHERS ARE STILL IN QUITE GOOD CONDITION. IT MUST BE EMPHASIZED THAT THESE MARKED DIFFERENCES IN PERFORMANCE EXIST EVEN WHERE ALL CONDITIONS OF CONSTRUCTION, AGGREGATES AND QUANTITY OF ASPHALTS WERE QUITE SIMILAR. IT WAS DECIDED TO PLACE THE TEST SECTIONS IN DUPLICATE AND MAKE THEM AS LONG AS POSSIBLE. A LONG TEST SECTION HAS A DEFINATE ADVANTAGE IN THAT IT PROVIDES AVERAGE CONDITIONS OF CONSTRUCTION AND ALSO PROVIDES A BETTER BASIS FOR FUTURE COMPARISON OF PERFORMANCE. WHENEVER POSSIBLE THE TEST SECTIONS WERE PLACED SO THAT ASPHALT FROM THE SAME REFINERY WOULD BE USED IN TWO LOCATIONS -- ONE ON THE NEW ALIGNMENT AND ONE SECTION OVER THE EXISTING PAVEMENT. THE VARIOUS ASPHALTS, PLACED IN THE TEST SECTIONS, ARE WEATHERING AT DIFFERENT RATES, BUT ALL SHOW A TENDENCY TOWARD A DEFINITE DECREASE IN THE RATE OF DEVELOPING HARDNESS OR BRITTLENESS BEGINNING AFTER APPROXIMATELY 16 TO 20 MONTHS OF SERVICE LIFE. HOWEVER, DUE TO THE TWO DIFFERENT CONSTRUCTION PERIODS, SOMEWHAT DIFFERENT STRUCTURAL SECTIONS, ACCOMPANIED BY OTHER UNAVOIDABLE VARIATIONS IT IS STRONGLY RECOMMENDED THAT THE ASPHALTS LAID IN PERIOD I BE DISTINGUISHED FROM THOSE LAID IN PERIOD II. IN OTHER WORDS, WE SHOULD CONSIDER THAT WE HAVE TWO SEPARATE TEST ROADS AND COMPARISONS BETWEEN TEST SECTIONS SHOULD ONLY BE MADE WITHIN EACH TEST ROAD. THE PERFORMANCE OF THE ZACA-WIGMORE TEST ROAD, TO DATE, CLEARLY SHOWS THAT ASPHALTS MANUFACTURED FROM DIFFERENT CRUDE SOURCES AND METHODS OF PRODUCTION CAN HAVE VARIOUS DEGREES OF DURABILITY UNDER EQUIVALENT CONDITIONS OF TRAFFIC AND CLIMATE. THE EARLY FAILURE OF ASPHALT E, WHICH JUST BARELY MET OUR 1954 STANDARD SPECIFICATIONS AND WOULD FALL FAR SHORT OF OUR PRESENT REQUIREMENTS, CONFIRMS OTHER EVIDENCE THAT THE PREVIOUS STANDARD SPECIFICATIONS PERMITTED THE USE OF ASPHALTS OF POOR DURABILITY WITH A COMPARATIVELY SHORT SERVICE LIFE.

  • Supplemental Notes:
    • Vol 40, Nos 5-6, PP 59-66
  • Authors:
    • Zube, E
  • Publication Date: 1961-5

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  • Accession Number: 00210962
  • Record Type: Publication
  • Source Agency: Highway Research Board Bibliography
  • Files: TRIS
  • Created Date: Jun 10 1994 12:00AM