Performance analyses of conventional hot mix asphalt with waste additives

The continuous increase in traffic volume demands performance enhancement of pavements. Common techniques for this performance improvement utilize modifications in the conventional hot mixture asphalt (HMA) through additives. Utilization of urban waste materials as additives for HMA provides opportunity for effective utilization and disposal of these unwanted materials. In this research, two waste materials, low-density polyethylene (LDPE) and crumb rubber (CR), are tested as additives to HMA for performance enhancement, optimization, and cost effectiveness. Performance evaluations are made through comparing stiffness modulus. Stiffness moduli of conventional and waste-material-modified HMA mixtures are evaluated through creep testing. Further, the effect of asphalt binder content, additive content, and mixing methodologies (1 and 2) were also investigated in this research. The experimental results showed a 22.4% increase in stiffness modulus with increases in asphalt binder content. Modified HMAs showed better (5–15%) results than conventional HMAs. Between the two modified mixtures, LDPE modified mixtures displayed better strength (about 1.5 times higher) than CR modified mixtures. Mixing methodology-1 resulted in 9.35% lower stiffness modulus values than the methodology-2. The results also showed that the excessive use of asphalt binder as well as waste material additive reduced the stiffness modulus up-to 21.9% and 15% respectively. Further, it was observed that the addition of waste material additives to conventional HMA mixtures increased the viscosity of mixtures which resulted in an increase of load-bearing capacity in terms of stiffness modulus.