Review of the AG/PT-233 fatigue test protocol and its link to structural pavement design

A reliable and robust fatigue characterisation method is a key component of performance based asphalt mix design. This paper reviews the procedures in Austroads AG/PT-233 four point bending test method for fatigue, based on a comparison to international test methods. Experiments are performed to compare material behaviour in the four point bending test under haversine and sinusoidal displacement controlled loading. The findings indicate that haversine displacement control testing using the AG/PT-233 protocol in effect results in a sinusoidal strain response of half the intended amplitude. This is an important consideration when comparing the results of AG/PT-233 testing to the asphalt fatigue equations in the Austroads Guide to Pavement Technology, which were developed based on sinusoidal testing. The paper further demonstrates the use of the four point bending beam equipment in the construction of complex modulus master curves.