Rutting mechanisms and advanced laboratory testing of asphalt mixtures resistance against permanent deformation

Permanent deformation in asphalt layers which manifestation on pavement surface is named rutting represents one of the most significant distresses of asphalt pavements. Depending on the level, it can be a huge inconvenience for traffic safety, driving comfort, and overall pavement life-cycle. Rutting may be classified into three basic types: one-dimensional or vertical compaction, lateral flow or plastic movement, and mechanical deformation. As an addition to Superpave? mixture volumetric design three, so called, simple performance tests (SPT) were recommended. Each of these tests in conduced in uniaxial or triaxial compression of cylindrical specimens. They cover the determination of dynamic modulus, repeated load permanent deformation test (flow number), and static load permanent deformation test (flow time). These tests provide relatively good insight in on-site mixture performance. An application of these tests provides a potential link between mixture design and structural analysis that was an underlying goal of substantial amount of earlier flexible pavement researches.