Evaluation of asphaltenes a potential alternative for cement in stabilized base courses using asphalt emulsion

Abstract

Stabilization of pavement base material using asphalt emulsion has been widely used to improve pavement performance. This technology produces a high-quality base course material with decreased energy consumption, carbon footprint, and raw material usage. Cement has been used as a common additive to improve these mixes strength and moisture resistance. However, some drawbacks are also associated with cement, such as negative environmental impacts, high costs, and low-temperature deficiencies. Asphaltenes is a by-product of oil-sand bitumen with little commercial value in current practice. To investigate the impact of asphaltenes on improving the rheological properties of asphalt binder, a series of binder characteristics tests using a dynamic shear rheometer, breaking time and microscopic evaluation is conducted on modified asphalt emulsion with asphaltenes. Asphaltenes is then added to asphalt emulsion-stabilized granular material, to be compared with mixtures prepared with cement. Two asphaltenes and cement-modified mixes are prepared and compared to unmodified mixtures. All mixes are tested for permanent deformation and moisture sensitivity using a Hamburg wheel tracker and flow number test, while the low-temperature properties are evaluated using indirect tensile strength tests. Dynamic modulus is also evaluated to analyze the viscoelastic behavior of the mixes. The results of this study reveal a considerable increase in the rutting resistance of asphalt mixes by adding 1% of both additives (by total weight of mix), and asphaltenes-modification shows less adverse impacts at intermediate and low temperatures than cement-modification.