Mixture design and performance characterization of asphalt mixtures prepared using paving-heavy crude oils for low-traffic volume roads

Abstract

Low-volume road development, a fundamental part of national economic infrastructure, requires further advances in identifying alternative materials for their construction. One of these alternative materials is paving-heavy crude oil (PHCO), defined as natural liquid asphalt. However, research on these materials is scarce, and no standards or specifications currently exist for preparing asphalt mixtures using PHCO (AM-PHCO). This paper assesses the feasibility of (i) designing AM-PHCO through the Modified Marshall Method for Cutback Asphalt-Aggregate Cold Mixture Design, with optimum filler content determined via energy parameters, and (ii) evaluating and differentiating moisture-damage and fracture resistances of AM-PHCO through conventional- and unconventional-testing. After characterizing the asphalt products, the mix design was performed for ten asphalt mixtures. Then, the performance of these mixtures was assessed through Marshall stability, indirect tensile strength, Fenix, and semicircular bending tests. The study included two neat and two nano-modified PHCOs and a couple of mineral fillers to produce AM-PHCO compared to control mixtures fabricated with a penetration asphalt binder. Results support the conclusions that (i) the mix design method used applies to AM-PHCO, providing new technical criteria to improve them through mix design standardization, (ii) mineral filler content optimization for AM-PHCO can use energy parameters computed from surface free energy, and (iii) testing employed in this study can differentiate AM-PHCO moisture damage resistance and fracture resistance. However, additional research can evaluate the suitability of adjusting conditioning protocols and current specifications for retained Marshall stability (75%) and retained tensile strength (80%) in characterizing AM-PHCO. Lastly, further research could explore PHCO aging effects on AM-PHCO performance and complementary performance parameters, including fatigue life, rutting resistance, and stiffness.