Evaluation of Long-Term Performance of Stone Matrix Asphalt in Washington State

AbstractStone mastic asphalt (SMA) has been used for decades to extend the life of asphalt pavements, especially in terms of rutting resistance. However, its performance and cost-effectiveness have been debated. This study evaluates the long-term performance of an SMA pavement and its control hot-mix asphalt (HMA) pavement in eastern Washington State. The field performance of the SMA pavement and HMA control pavement was evaluated based on the data in a pavement management system and site visits. Field cores were extracted from both the SMA and HMA pavements and subjected to indirect tension (IDT) dynamic modulus tests, creep compliance tests, studded tire wear resistance tests, and intermediate and low temperature IDT fracture tests in the laboratory. SMA and HMA asphalt binders also were extracted, recovered, and subjected to performance grading, multiple stress and creep recovery tests, and monotonic tests. This study found that in the field, the SMA pavement outperformed the HMA pavement in terms of rutting and cracking resistance. Results of the laboratory tests of the field cores verified that the SMA material performed better than the control HMA material in terms of top-down, bottom-up, and thermal cracking resistance. Results of the recovered binder tests showed that the SMA mixture exhibited less aging than the HMA control mixture and that the recovered SMA binder provided better rutting, fatigue, and thermal cracking resistance than the HMA binder. Therefore, SMA pavements, when designed and constructed properly, are a viable solution for prolonging the life of asphalt pavement.