A review of the development of the non-recoverable compliance, Jnr, for use in South Africa

Higher traffic volumes and traffic loads have led to an increase in premature pavement failures as empirical binder testing has increasingly failed to predict pavement performance. Moreover, empirical tests cannot effectively characterize polymer-modified binders which are being increasingly used in South Africa. This has resulted in a move to establish bituminous binder specifications based on fundamental engineering properties capable of accurately predicting the performance of asphalt mixes. Asphalt pavements are most susceptible to rutting at high in-service temperatures, where the in situ binder plays an important role in resisting deformation from repeated loading, along with the complementary resistance provided by the aggregate structure. The non-recoverable compliance, Jnr, as determined by the dynamic shear rheometer has been found to be an improved indicator of asphalt deformation. Jnr is measured using the multi-stress creep recovery (MSCR) method and considerable work has been done in the last three years in South Africa in preparation for adopting a modification of the Jnr as part of a performance graded specification. The paper reviews the advantages the MSCR method has over other methods confined to measurements within the linear viscoelastic (LVE) region of the binder. Constraints undermining the current MSCR test method are demonstrated. Two temperature zones for South Africa are presented and the Jnr-stress characterisations for typical binders were determined for these zones. A correlation plot of shear strain (permanent deformation indicator) for four asphalt mixes versus Jnr demonstrated the effectiveness of the non-recoverable compliance parameter. The paper concludes by statistically examining the precision and bias of the test method as currently practiced in South Africa and presents a recommendation for the parameters to be implemented for the South African version of the test method.

Language

  • English

Media Info

  • Pagination: 13p
  • Monograph Title: 11th Conference on Asphalt Pavements for Southern Africa: CAPSA15, 16-19 August 2015, Sun City, South Africa

Subject/Index Terms

Filing Info

  • Accession Number: 01597064
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ATRI
  • Created Date: Apr 22 2016 11:11AM