An accelerated pavement test was conducted at CAPTIF (Canterbury Accelerated Pavement Testing Indoor Facility), Christchurch, New Zealand, between 1999 and 2001, for the purpose of validating the use of the repeat load tri-axial (RLT) apparatus.
Both resilient and permanent deformation characteristics of unbound granular materials obtained using this test were compared to the measured results from the pavement test that was run previously.
The aim was to ascertain if the few RLT tests that are conducted on unbound granular materials do provide viable results that can be used to predict performance for roads constructed with these materials.
The pavement test was subjected to 1 million wheel passes where primarily surface rutting was measured at regular intervals. Strains and stresses were measured within the pavement under a range of tyre loads.
RLT tests for resilient modulus and permanent strain were conducted on all three granular materials, and permanent deformation modelling was also carried out.
Materials evaluation based on deformation resistance depends on choosing RLT test stress conditions that correspond to the worst conditions in the pavement.
Further research is required to determine with more accuracy the stress conditions that exist spatially within the pavement, but it is expected that the layered elastic computational methods currently available to pavement engineers will never be able to fully model these real conditions.
Keywords: accelerated pavement testing, pavements, repeat load tri-axial, apparatus, roads, traffic, unbound granular materials