Investigation of Adhesion Properties between Asphalt and Calcined Bauxite Aggregate

This article presents a study evaluating the adhesion properties between asphalt and calcined bauxite. Limestone and granite were also compared with calcined bauxite. For this purpose, asphalt bond strength, surface free energy, and phase angle of asphalt and aggregate were tested. The chemical reaction and mechanical adhesion of asphalt-aggregate were also investigated using Fourier transform infrared spectroscopy (FTIR) and a surface roughness test. The results showed that the higher the alumina content of the calcined bauxite, the greater the adhesion. The adhesion properties of asphalt and aggregate were ranked as follows: limestone > calcined bauxite > granite. Based on the results of the gray correlation analysis, it can be concluded that the intermolecular interactions between asphalt and aggregate play a major role in adhesion. The interlocking caused by surface texture also affects adhesion to some extent. The larger work of adhesion and the more complex surface texture of calcined bauxite with higher alumina content are the main reasons for its higher adhesion. Calcined bauxite with low alumina content should be treated to enhance adhesion before it is used in asphalt mixtures for wearing courses.