In this paper, economic analysis on the effect of polyester fibers with high strength on the behavior of Hot Mix Asphalt (HMA) is performed. The results indicate that strength is increased by adding fiber to asphalt. Also, unit weight of asphalt mixture was used as a variable parameter in the analyses. The results show that in some certain percentages of fiber, in addition to the enhancement in mechanical properties of HMA mixture the economic benefit value becomes more than the cost and therefore adding polyester fibers with high stability is suggested for the mixture of modified asphalt concrete. Finally, it can be concluded that adding fibers in values of 0.2% to 0.5% has the best result on the asphalt mixture, which because of high resistance and economic aspects makes it more efficient to be used in the highways of warm regions containing traffic.

The cost of road construction or its repair is among the most concerns for the pavements engineers. Cracking and degradation is common mode of failure in asphalt pavements that occurs due to increasing traffic loads or even environmental conditions. For facing with these damages, some solutions are proposed including correction, quality improvement and increasing the asphalt resistance. In this research, by adding different percent amounts of black nano-carbon and polyester fibers as modifier in the asphalt mixtures and conducting several Marshall tests, it was observed that adding these two additives can improve generally the Marshall results. Polyester fiber causes preventing crack and damages of asphalt because of armed effect specification. According to the results, Marshall stability is increased up to 61%. Furthermore, an economic analysis was performed to investigate the cost of using such modified asphalt mixtures for constructing 1 km of a six line road and suitable percentages of additives were found from mechanical-economic analyses.