Premature rutting of heavy duty asphalt pavements has been increasingly experienced in recent
years primarily due to high pressure truck tires and increased wheel loads. Many asphalt
technologists believe that the use of large size stone (maximum size of more than one inch) in the
binder and base courses will minimize or eliminate the rutting of heavy duty pavements.
This research describes a development of new asphalt mix design procedure which is a better
indicator of road performance in Riyadh. The Marshall method has served well over the years but
as wheel loads and tire pressures increase, and as temperature is high, there was a need for an
update of mix design procedures.
This new method allowed the incorporation of aggregate size larger than 25mm, and the use of
vibratory compaction apparatus with 6.0 inch mould size diameter.
Results from the mix design study indicated that when compared to the conventional mix
characteristics, the introduction of larger stone to the asphalt mixture improves its properties
considerably.