On the densification of cold recycled asphalt mixtures

The mechanical behavior of cold recycled asphalt mixtures (CRAMs) is directly connected to their volumetric properties. Therefore, the objective of the present research was to investigate the effect of different composition factors on the densification of CRAMs. To this aim, a new empirical modeling approach for characterizing and comparing the densification of CRAMs using the gyratory compactor was proposed. The methodology was then applied to CRAMs produced using four gradations, two asphalt emulsions, two cements, various water contents, and several superplasticizer dosages. The densification curves were analyzed using three parameters representing the self-densification, the compactability, and the compaction energy. These parameters were linked using a mathematical model, which was represented using three interrelated pairwise relationships. The results showed that the grading distribution of the CRAMs was the main parameter controlling their densification behavior, whereas the water content and other composition factors played a minor role.