The effect of filler content on dynamic creep results

A major finding of the ALF asphalt deformation core trial held in Queensland was that the dynamic creep test failed to rank the deformation resistance of mixes with different aggregate gradations in the same order as ALF testing. An important difference between the two mixes was the amount of added filler. A study was designed to determine the effect of different proportions of added filler on the dynamic creep and the wheel tracking results for mixes Cl and C2. Wheel tracking was used as a surrogate for ALF testing since a full scale pavement experiment to study the effect of filler on rutting was not practical. Gyropac cylinders for modulus and creep testing, and roller compacted slabs for wheel track testing, were manufactured with a range of added filler contents. Analysis of the Gyropac cylinder results indicated that there was a single linear relationship, which applied to both Cl and C2, between resilient modulus and total filler content of the mixes. The creep results also indicated that a single linear relationship applied to both mixes. No such single relationship was found between creep slope and air void content. The results suggest that, for the mixes studied, filler content was the dominant variable controlling creep slope. Examination of the wheel tracking data indicated that there was no single linear relationship between tracking rate and filler content. A hypothesis was put forward to explain the findings. It was suggested that creep slope is dependant mainly on the consistency of the binder/filler mastic and that addition of filler increases the consistency of the mastic. Resistance to permanent deformation in the creep test thus depends mainly on binder consistency because the test specimens are unconfined. In the pavement situation, however, permanent deformation requires the overcoming of "frictional" effects associated with the aggregate particles and rearrangement of the aggregate structure, in addition to binder effects.

Language

  • English

Media Info

  • Pagination: 4.1-13
  • Serial:
    • Issue Number: 12

Subject/Index Terms

Filing Info

  • Accession Number: 01435608
  • Record Type: Publication
  • Source Agency: ARRB
  • ISBN: 086910683X
  • Files: ATRI
  • Created Date: Aug 24 2012 7:07PM