Performance Characteristics of In-Plant-Mixed Stone Mastic Asphalt SMA Using Different Rejuvenators

摘要

Various rejuvenators already enable an increased amount of reclaimed asphalt pavement (RAP) within the mix design of hot mix asphalt (HMA). The aged RAP binder presents higher values of softening point compared to the virgin binder. Therefore, the use of rejuvenators has the potential to improve the characteristic of the final mixture. However, it is still not entirely understood how the asphalt mixtures containing rejuvenators may behave in terms of aging and to what extent the rejuvenating action remains effective and stable. The goal of this study is to evaluate four different stone mastic asphalt (SMA) mixtures prepared with different rejuvenators with respect to their aging behavior on the basis of performance characteristics and to qualify the effects on the mechanistic pavement design procedure. The SMA mixtures were mixed in the plant where three different rejuvenators were used. Each mixture was compacted in the laboratory using a German sector compactor and each slab cored into cylindrical samples. To study the aging effects of the rejuvenators, the specimens were conditioned on the basis of AASHTO protocol R30 - Standard Practice for Mixture Conditioning of Hot Mix Asphalt. Three aging levels were imposed on the mixtures and the resulting performance properties in terms stiffness and fatigue were addressed by Cylindrical Indirect Tension (CIDT). Subsequently, the performance properties were used as input in the mechanistic pavement design procedure currently used in Germany. Additional analysis of the rejuvenated extracted binder was performed with the Binder-Fast-Characterization-Test (BTSV) recently adopted in Germany. Overall, a substantially different trend was observed across the three rejuvenators as confirmed by the mechanistic pavement analysis. The latter appears to be capable of providing an evaluation of the impact of rejuvenators on the changes in performance properties due to pavement aging.