Abstract:
Asphalt binders play an essential role in the performance and properties of asphalt mixtures.
The increase in heavy loads, greater traffic volume, and high tire pressure, combined with a
substantial variation in daily and seasonal temperatures, are the main responsible for the failure of
asphalt pavements. To avoid or mitigate these failures, the present research proposes the use of
thermoplastic polymers, the High-Density Polyethylene (HDPE) and Linear Low-Density
Polyethylene (LLDPE) and nanoclay Dellite 43B for modification of asphalt in order to improve
its rheological and thermal properties. The nanocomposites were prepared using the solution
intercalation method in a high shear mixer for a mixing time of 1.5 h, at 180 °C and 5000 rpm.
Several test methods were carried out on the binders, including penetration, softening point,
ductility at 25 °C, viscosity at 165 °C, short-term aging in a rotational thin-film oven test (RTFOT),
thermogravimetric analysis (TGA), and decomposition kinetics by the Coats-Redfern method. In
addition, the penetration, softening point and viscosity at 165 °C results, were used for the
determination of the optimal formulation using orthogonal Taguchi design with 2 factors and 2
test levels. The addition of Dellite 43B improved the rheological and thermal properties of neat
asphalt and HDPE/LLDPE-modified asphalt. The results of the physical characterization showed
decrease in penetration and ductility, increase in softening point, thermal susceptibility and
viscosity. On the other hand, the durability characterization of asphalt binders showed that the
addition of nanoclay prevents the diffusion of oxygen molecules and heat through neat asphalt and
polymer modified asphalt matrix, therefore the triple binders showed lower weight variation, lower
viscosity aging index and higher ductility retention after RTFO tests. The thermal analysis showed
that nanocomposites have greater stability at higher temperatures by exhibiting higher amounts of
residue and improved initial and final decomposition temperatures. In this study, the optimized
formulation has 3 wt.% of LLDPE and nanoclay by weight of asphalt. All nanocomposites binders
are a suitable solution for paving roads in countries experiencing high temperatures combined with
long periods of heavy rain.
