Quantifying the Mechanistic and Economic Impacts of Using Asphalt Rubber Mixtures

Abstract

As far as hot mix asphalt pavement goes, tension at the bottom layer of the HMA layer creates the most issues for pavement engineers. Adding rubber to asphalt mix has the ability to extend the life of a pavement and provide an end use to old tires that would otherwise end up in a landfill. It is already known that the initial construction cost of an asphalt rubber mix will be higher than that of a conventional mix, but the purpose of this paper is to see if the reduced layer thickness and improved fatigue life will offset the initial cost. After completing a mechanistic analysis using the FHWA software package named 3D Move, the pavement thickness required to last for 50,000,000 cycles (estimated endurance limit) is much less for the asphalt rubber mixes as opposed to the reference hot mix asphalt. The cost to construct one lane mile of the reference mix pavement designed for 70 mph traffic was $171,530.88 while the asphalt rubber mix at 70 mph came out to be $157,059.70. This is a $14,471.18 difference. Additionally, the cost to construct one lane mile of the reference mix pavement designed for 10 mph traffic was $231,932.76, while the asphalt rubber mix at 10 mph came out to be $200,162.55. This is a $31,770.21 price difference. Overall, analysis showed that AR modified asphalt mixtures exhibited significantly lower cost of pavement per 1000 cycles of fatigue life per mile compared to conventional HMA mixture.