DESIGNING LONG-LASTING RUT-RESISTANT ASPHALT CONCRETE USING MARSHALL MIX DESIGN METHOD

This paper summarizes the binder and wearing course mix design test results used during the sectional rehabilitation of the Tanzam highway in Tanzania. The mix design was carried out using the Marshall mix design procedures whereby the Marshall specimens were compacted to refusal using 500 Marshall blows. The optimum binder content was selected as the binder content, which gave 3% air voids at 500 blows - 0.4%. The rehabilitated pavement section has been heavily trafficked, with estimated traffic loading of 6 million equivalent standard axles traversing the pavement within three years with no noticeable rutting. Therefore, the Marshall mix design method can be used to design asphalt concrete for heavily loaded pavement if the binder content is correctly selected to limit the effect of post-construction densification.