Ali Mansourkhaki - Associate Professor, Dept. of Civil Engineering, Iran University of Science & Technology
Ehsan Yaghoubi - M. Sc. Student of Road &Transportation Engineering, Iran University of Science & Technology

The link between aggregate gradation and asphalt mixture performance has been recognized since asphalt mixtures were first used. Almost all of HMA properties are affected by aggregate gradation of the mix. In this study, type 4 and 5 mid-limit gradations of Iran Highway Asphalt Paving Code were chosen and adjusted by Bailey method. An excel spread sheet was developed so that time was saved in calculations. Optimum bitumen content for each mix was determined, using Marshall method. Experiments of Marshall Stability and dynamic creep revealed that mixtures using Bailey method gradations were improved, both in Marshall and creep properties.

HMA, Gradation, Bailey Method, Marshall Stability, Dynamic Creep