Multiscale test research on interfacial adhesion property of cold mix asphalt

In order to establish proper evaluation methods and indicators for cold mix asphalt (CMA), various scales test methods were used to study the interfacial behavior between asphalt binder and aggregate. The surface free energy of asphalt binder was tested using sessile drop method, and the surface free energy of aggregate was measured using column wicking method. The adhesion work between asphalt and aggregate, moisture damage resistance indices were calculated using the basic surface free energy components. Macro mechanical adhesion property between asphalt binder and aggregate in two conditions (dry and damp) were obtained through the pull-off test. A freeze-thaw splitting test was conducted to verify the effectiveness of energy indices. The results show that diluents and additives used in cold mix asphalt can increase surface free energy of pure asphalt. Limestone has the largest surface free energy, and the largest adhesion work to asphalt in dry condition. Cohesion failure usually occurs in dry condition, while adhesion failure corresponds to damp condition. There are strong correlations between macro mechanical evaluation indicators and surface free energy calculated indices, which indicates that energy indices are a good method to quantize the moisture damage resistance of CMA. Limestone is generally better at resisting moisture damage than granite and basalt.