DURABILITY OF BITUMEN IN THEORY AND PRACTICE

AFTER A BRIEF REVIEW OF THE PHYSICAL HARDENING OF BITUMEN, WHICH IS CAUSED BY A CHANGE IN STRUCTURE OR BY LOSS OF VOLATILES, THE MORE IMPORTANT PHENOMENON OF CHEMICAL HARDENING, DUE TO OXIDATION, IS DEALT WITH EXTENSIVELY. THE RATE OF OXIDATION IS MUCH HIGHER IN THE PRESENCE THAN IN THE ABSENCE OF LIGHT AND THE REACTIONS ARE OF A DIFFERENT TYPE. OXIDATION IN THE LIGHT IS PROMOTED MAINLY BY THE ULTRAVIOLET PART OF THE SPECTRUM AND HARDENING IS RESTRICTED TO A DEPTH OF ABOUT 4 MICRONS. IN THE DARK, HARDENING MAY OCCUR DOWN TO DEPTHS OF 3 MM OR SOMEWHAT MORE, WHICH IS IN GOOD AGREEMENT WITH A THEORETICAL INTERPRETATION. THE CONSEQUENCES OF HARDENING IN THE DARK FOR ROAD CONSTRUCTION ARE DISCUSSED IN CONSIDERABLE DETAIL. IT IS SHOWN THAT, SINCE THE CRACKING OF ROAD CARPETS IS MOST LIKELY TO OCCUR UNDER THE IMPACT OF MOVING TRAFFIC AT LOW TEMPERATURES, THE TENDENCY TO THIS TYPE OF FAILURE SHOULD BE JUDGED FROM THE INCREASE IN STIFFNESS OF BITUMENS AT SHORT TIMES OF LOADING AND AT LOW TEMPERATURES, RATHER THAN FROM THE INCREASE IN VISCOSITY. DATA ON THE HARDENING OF A LARGE NUMBER OF BITUMENS ARE GIVEN. AN ACCELERATED TEST PROCEDURE FOR ASSESSING THE AGING CHARACTERISTICS OF BITUMENS HAS BEEN INVESTIGATED. THE ACCELERATION IS AFFECTED BY INCREASING THE OXYGEN PRESSURE. IT IS REPRODUCIBLE AND FAIRLY CONSTANT. RESULTS OF THIS TEST SHOW A SATISFACTORY CORRELATION WITH HARDENING DATA OBTAINED FROM ROAD TRIALS. A RECENTLY PUBLISHED TEST METHOD USING ACCELERATION BY INCREASE OF TEMPERATURE APPEARS TO BE PRACTICALLY EQUIVALENT TO OUR METHOD EXCEPT IN THE CASE OF AN EXPERIMENTAL BITUMEN WITH A LARGE CONTENT OF VOLATILES, WHERE THE HIGH-TEMPERATURE TEST GIVES TOO HIGH A VALUE.

  • Supplemental Notes:
    • Sec Vi, P 417
  • Corporate Authors:

    Fifth World Petroleum Congress Proc

    ,    
  • Authors:
    • Blokker, P C
    • Van, HOORN H
  • Publication Date: 1959

Subject/Index Terms

Filing Info

  • Accession Number: 00210954
  • Record Type: Publication
  • Source Agency: Highway Research Board Bibliography
  • Files: TRIS, ATRI
  • Created Date: Jun 10 1994 12:00AM