Testing the greywater resistance of popular bitumen modifiers

As part of a project for the Cape Town Metropolitan Municipality, methods of increasing the resistance of asphalt to grey water damage was investigated. In the first phase of this study, various asphalt mixtures and binder and additive combination were evaluated using a newly developed testing procedure. The objective of the study was to find suitable asphalt mixtures that will have reduced permeability and increased resistance to stripping and grey water damage. Previous studies have shown that moisture has an influence on the durability and performance of asphalt. In certain developing areas of the Cape Town Metro, the field performance of conventional asphalt mixtures and binders combinations has been found to be inadequate, allegedly due to the presence of grey water. It would appear as if grey water has a more significant influence on stripping resistance than “clean” or potable water. Nine different continuously graded asphalt mixtures where created using 50/70 base bitumen and four different modifiers and additives and combinations thereof. Each of these combinations was used to produce a number of asphalt specimens, which were conditioned to simulate moisture damage using the newly developed Moisture Inducing Simulator (MIST). The conditioning was applied at typical surface temperature, as well as typical induced pore pressures created by passing traffic, by pulsing hot water in a pressurised container. Three types of conditioning were used: No water exposure, clean water exposure and grey water exposure. Indirect Tensile Strength (ITS) tests were performed on each of the asphalt specimens as a measure of strength, after conditioning. This allowed for comparing the loss in ITS strength, due to conditioning, for each of the modifier combinations. These results provide valuable insight into the relationship between the different variables investigated as well as the increased resistance provided by selected binder & modifier combinations. This paper further provides the specific details of the test procedure development, recommendations on future studies as well as an in-depth look at the statistical repeatability and dependence of the results achieved.


  • English

Media Info

  • Pagination: 7p
  • 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: 01597110
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ATRI
  • Created Date: Apr 22 2016 11:14AM