Impact of Asphaltenes on Permanent Deformation of Stabilized Base Course Using Asphalt Emulsion

The pavement base course has a significant impact on pavement long-term performance. One of the methods to improve pavement strength is stabilization of the base course with asphalt emulsion for an adequate response to traffic loading and weather condition. Regardless of the advantages of this method, asphalt emulsion stabilized materials usually suffer from low resistance to permanent deformation, and to overcome this problem, additives are added to the mixtures. Asphaltenes derived from Alberta oil-sands, which is a by-product of bitumen deasphalting process, could be used as an additive, and it is expected to enhance the mechanical properties of mixtures considering it to be a polar fraction of asphalt binder. This study investigates the application of asphaltenes-modified asphalt emulsion for stabilization of granular base aggregates. The effect of asphaltenes powder on the permanent deformation properties of the modified mixtures was studied through three different tests including Marshall stability and flow test, Hamburg Wheel-Tracking (HWT) and flow number tests. The test matrix included the samples with two asphaltenes contents (1 and 2% per total mix) for the same optimum emulsion content. The optimum emulsion content was found to be 3.7% according to the test matrix, while for asphaltenes, the optimum content was found to be 1%. According to the performance tests result, The Marshall stability test indicates that there is an increase of about 47.9% and 96.9% in stability values for 1% and 2% asphaltenes-modified mixtures, respectively. In addition, Marshall quotient and HWT test results indicate that modified mixtures are more resistant to rutting as compared to the unmodified mixtures. Rutting resistance index (RRI) increases about 140% for both asphaltenes contents. Flow number test results showed about an 81% decrease in deformation of modified samples in comparison to unmodified samples. Thus, the overall results show the resistance of asphaltenes-modified mixtures to permanent deformation was significantly greater than unmodified mixes.