Adhesion characteristics of montmorillonite modified asphalt unveiled by surface free energy and AFM

The contact angle and micromorphology of asphalt were collected by sessile drop method and atomic force microscopy (AFM), respectively. Then, the effect of inorganic montmorillonite (MMT) and organic montmorillonite (OMMT) as asphalt modifier to adhesion ability between asphalt and aggregate was explored and analyzed based on the surface free energy (SFE) theory and AFM. The results demonstrated a rise of SFE, dispersive and polar components of asphalt, as well as an improvement in the adhesive ability with the incorporation of MMT or OMMT. The SFE of 70#/MMT and 70#/OMMT modified asphalt increased by 6.93% and 8.03% respectively. The SFE of SBS/MMT and SBS/OMMT modified asphalt increased by 10.65% and 11.38%, respectively. Meanwhile, the microstructures of asphalt could be changed by MMT and OMMT modifiers. The root means square roughness (Rq) of 70#/MMT and 70#/OMMT modified asphalt increased by 14.34% and 31.32%, respectively. The Rq of SBS/MMT and SBS/OMMT modified asphalt is increased by 30.00% and 53.64%, respectively, which indicated the improvement of the adhesion ability.