The factors affecting the compaction by traffic during the early life of asphalt concrete surfacings are discussed and an experimental study is described. Limited field data for gap-graded mixes are also presented. Temperature and tyre contact pressure, i.e. The local environment and traffic spectrum, were found to have a very strong influence. A low constructed density, 96 per cent of the predicted density, reduced the final density attained under traffic to 3 per cent below the expected density. The effects of binder content and viscosity were generally well predicted by 2 X 75 blow Marshall compaction. Layer thickness and maximum stone size were found to have an interrelated effect; thick surfacings, six times the maximum stone size in thickness, reached densities up to 2 per cent greater than thin surfacings, twice the maximum stone size in thickness, due to the effect of frictional restraint at the interfaces. Under high temperatures and tyre contact pressure, the effects of constructed density and layer thickness were greatly reduced. The study plus limited correlating measurements on roads in South Africa indicate that the 2 X 75-blow Marshall prediction underestimates the final density by 0,5 to 1,0 per cent for moderate coastal regions and by at least 1,0 per cent in warmer regions. (a). This paper was presented at the 2nd conference on asphalt pavements for Southern Africa, Durban, 29th July-2nd August, 1974. See also IRRD abstracts nos. 216602-216619. /TRRL/

  • Corporate Authors:

    Council for Scientific & Industrial Res S Africa

    P.O. Box 395
    Pretoria,   South Africa 
  • Authors:
    • Paterson, WDO
    • Williman, A
    • Pollard, J S
  • Publication Date: 0

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 11 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00131454
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: RR176 R&D Rept.
  • Files: ITRD, TRIS
  • Created Date: May 14 1976 12:00AM