Advanced Characterization of Asphalt Concrete Mixtures Reinforced with Synthetic Fibers

Abstract

This study evaluates the behavior of fiber-reinforced asphalt mixtures using advanced material characterization and performance prediction models. The polymeric nature of the proprietary blend of polyolefin and aramid fibers used warrants examining the contribution of the fibers not only to the physical network of the mixture but also to the extent of modification of the asphalt binder upon mixing. The effect of adding these synthetic fibers on the performance of asphalt concrete mixtures is assessed in the state of compression to investigate the resistance to rutting by (1) using a viscoelastoplastic continuum damage (VEPCD) model to provide an accurate and realistic assessment, and (2) by conducting a mechanistic-empirical (ME) analysis using Pavement ME software because it is the state of practice in pavement design and analysis. Upon addition of fibers, the developed VEPCD models indicate an overall improvement in the performance in terms of predicted strain in response to a given stress profile. Fibers are found to impose a faster recovery of viscoelastic strains during rest periods and lower strains during loading when added to a warm mix asphalt (WMA) mix containing unmodified binder. Fibers are also found to reduce the viscoplastic strains of both hot mix asphalt (HMA) and WMA mixtures at 5°C and of HMA mixture at 35°C. The performance improvement due to fibers is enhanced when using fibers of shorter length, using fibers in mixtures with wax-based additives, or in mixtures with coarser gradations.