Rutting of bituminous mixtures: wheel tracking tests campaign analysis

Rutting is one of the main failure modes in pavement structures subjected to mechanical loading. Wheel Tracking Testers (WTT) devices used to evaluate the rutting performance of bituminous mixtures were investigated by Working Group 3 (WG3) Mechanical Tests for Bituminous Materials, of the RILEM ATB Technical Committee 206. Three different bituminous layer systems (A, B and C) currently used in road construction were compared to evaluate the abilities of small and large WTT devices to quantify road materials rutting performance. The tested specimens were cut from large slabs extracted from the onsite pavement structures. Seven laboratories located in seven different countries, were involved in the testing program. Results show that the mean rate of rutting for small WTT devices is faster than for large WTT devices. Systems A and C show equivalent performance and can be considered good in terms of the European Standard's requirement. Results from system B indicate poor performance and it does not comply with the specifications of the standard. Nevertheless, a visual evaluation of the rutting showed a very good performance on the road for systems A and B and no apparent difference could be noted between these two systems.