Understanding the Molecular Surface Charges of Asphalt or Clay Particles and Application in the Transportation and Oil Sands Industries

Asphalt binder is a mixture of many different types of molecules. At the molecular level, one can visualize the asphalt binder as a colloidal system with asphaltene molecules dispersed in oil with naphthene and polar aromatics. The functional groups of the asphaltene molecules are essential in keeping them dispersed as colloids. These polar functional groups include alcohol, amine, carboxylic, and phenolic groups. The polarity of asphalt molecules are very important in allowing them to adhere to the inorganic aggregates, which also bear charges at the surface. The application of this understanding to the aging of paving asphalt, asphalt modification, the Superpave direct tension test, aggregate specific gravity determination, ash as modifiers in asphalt, low-volume road chemical stabilization, and the oil sands industry are discussed.