Relationship analysis between surface free energy and chemical composition of asphalt binder

• Saturates, aromatics, and wax have negative influences on the surface free energy.
• Resins and resins/asphaltenes have positive impacts on the surface free energy.
• The effect of the asphaltenes on the surface free energy is negative.
• Four models are obtained via multiple regression analysis.

The statistical methods of a single regression and multiple regression analysis were applied to correlate the relationships between chemical composition and surface free energy of asphalt binders. The experimental samples were twenty-three asphalt binders used in a Strategic Highway Research Program (SHRP). The results of single regression showed that the concentrations of saturates, aromatics, wax or asphaltenes played the roles of lowering the value of the surface free energy of the asphalt binder. On the contrary, the resins, ratio of resins/asphaltenes, and the colloid index played the roles of increasing the value of the surface free energy. The correlations of elemental content of C%, N%, and S% with the surface free energy of the asphalt fitted fairly well into the quadratic curves. The multiple regression analysis implied that the four proposed regression models yield satisfactory results. More asphalt binders are strongly suggested to validate the findings of this study.