Laboratory Rutting Test for Bituminous Mixture at Medium Temperature

Laboratory rutting tests for AC20 under the condition of different temperatures (30°C, 45°C and 60°C), wheel pressures and wheel running speeds were carried out with an improved wheel rutting tester whose wheel running speed can be adjusted. The test results show that (1) the rut index value of AC20 under the condition of 45°C, heavy loading and low speed can be inferior to that under the condition of 60°C, standard loading and standard speed; (2) it is difficult to induce rut for the AC20 at 30°C even under the condition of heavy loading and low speed. The analytic result indicates that not only the rutting due to variable high temperature but also the rutting due to medium temperature combined with heavy loading and low speed should be considered to study the rutting deformation of asphalt pavements in cold area. Therefore, it is suggested to improve the laboratory rutting test method for cold area by introducing the testing condition of heavy loading and low speed besides changing the testing temperature from 60°C to 45°C according to the traffic condition.