This webinar presents the outcomes of Austroads Project APT1975, which conducted research to develop a new Austroads test method for evaluating the fatigue cracking performance of aged bitumen. The test method was developed for road agencies to select durable binders for constructing sprayed seal surfacings.

The development work included an extensive literature review of international fatigue cracking tests to identify suitable dynamic shear rheometer (DSR) tests. The most promising tests identified in the literature review were then conducted on a wide range of binders that were subjected to asphalt fatigue tests. This enabled selection of a reference binder test that showed the best correlation with asphalt fatigue life results.

The DSR time-sweep test was identified as a suitable reference binder test and was used to assess the fatigue cracking performance of bitumen samples after they were aged in a laboratory pressure ageing vessel (PAV) for up to 72 hours. The bitumen samples were then subjected to other DSR tests that could be performed in a shorter time than time-sweep tests, in order to identify a simple test that could be used instead of time-sweep tests which are time-consuming and complex.
The new Austroads test involves PAV ageing a 1 mm bitumen film for 72 hours and then measuring the complex modulus (G*) of the aged bitumen sample at 15°C using a test frequency of 10 Hz.