Laboratory investigations of the effects of asphalt mortar and its viscoelasticity on the workability of asphalt mixtures

In order to understand the flow characteristics of asphalt mixture in the composition of materials, the influence of the viscoelastic properties of asphalt mortar on asphalt mixture workability was investigated. In this study, an asphalt mixture workability test device was developed and the corresponding evaluation index was proposed. Analysis of the basic and rheological properties of asphalt mortar for different filler-asphalt ratios and asphalt compositions, and evaluated the corresponding asphalt mixture workability. Finally, the distribution uniformities of asphalt mortar, aggregate and pore structure in compacted asphalt mixture were analyzed according to digital image processing techniques. The obtained experimental results showed that asphalt mixture workability was closely related to asphalt mortar viscoelastic properties. Also, rheological indices such as viscosity, complex shear modulus G*, phase angle δ and rutting factor G*/sinδ of asphalt mortar were to be highly correlated with workability index. As the viscosity of asphalt mortar was increased, workability index was also enhanced. In addition, lower asphalt mixture workability resulted in poorer uniformity of material distribution.