Cost-benefit analysis of the construction of different flexible pavement structures considering the axle load and type of binder

Resumo

The status of Brazilian highways reflects a deficient pavement performance when they are subjected to loadings imposed by heavy traffic. Current legislation, as enacted by Contran (National Traffic Council), has increased the axle weight limit for cargo vehicles by up to 10%. Therefore, the aim of this study was to determine a cost-benefit ratio by using different types of structures, asphalt binders and load intensities. Typical pavements were determined and then analyzed by the software AEMC (SisPav) to obtain the horizontal tensile strain (εt) values at the bottom of the asphalt concrete layer and, later, the N_FATIGUE value. It was found that the increase in weight, within values covered by legislation, might result in a reduction of approximately 50% in the N_FATIGUE value for the pavement structures analyzed. As for economic impact, the same weight increase caused a mean increase of 120% in the cost of repeated loading on pavement structures (R$ N_FATIGUE^-1). It was also observed that structures with more robust asphalt concrete layers can provide the best R$ N_FATIGUE^-1 ratios. The best results for granular materials were found with thinner layers, associated with a thicker coating. The benefits of modified binders were shown by the analyses of the best structural options: both the polymer-modified binder and the rubber asphalt binder offer significant structural and economic improvements to the structure.