The movement characteristics of aggregates in asphalt mixtures were investigated with wheel tracking tests under the following loading conditions: reciprocating motion, one-way motion, and one-way motion with braking. The outside wheel tracking tests used fine and gap graded (13F) asphalt mixtures.
The tests showed that the amount of rutting in one-way motion was larger than that in reciprocating motion. In the case of reciprocating motion, the surface heaved up at the right load end. In the case of one-way motion, the surface heaved up at the point 50 mm from both contact ends of the tire. Consolidation caused the rutting phenomenon during reciprocating motion, and flow caused the rutting phenomenon during one-way motion, based on the movement of aggregates as viewed from the right-angle direction to the loading. Therefore, the rutting phenomenon including the deformation in the transverse direction can be analyzed by wheel tracking tests based on one-way motion, or reciprocating motion, using the conventional wheel tracking test.
However, in the case of rutting during one-way motion with braking, the movement of aggregates in the wheel direction caused by tire friction was larger than movement in the depth direction. The inside of the asphalt mixture was dragged by tire friction in the wheel direction. Therefore, at locations where brake operation is frequently needed, the rutting phenomenon caused by flow and abrasion will be greater.