Development of Temperature-Effect Model for Predicting Rutting of Asphalt Mixtures Using Georgia Loaded Wheel Tester

Use of the Georgia loaded wheel tester (LWT) to evaluate rutting susceptibility of asphalt mixtures has gained acceptance by the asphalt paving industry. The test is typically conducted at 40°C for 8,000 cycles and the rut-depth value measured at the end of the test is compared with a maximum criteria of 5.0 mm or 7.5 mm to assess rutting susceptibility of the mixture. A temperature effect model (TEM) was developed using the LWT test data from seven asphalt mixtures. The TEM developed can be used to predict the rut-depth values of an asphalt mixture at different temperatures and number of loading cycles from the LWT performed on the asphalt mixture at one testing condition. The predicted rut-depth values from the TEM compared very closely with the measured values. For the five dense-graded hot-mix asphalt mixtures (HMA), only 7 out of 170 predicted rut-depth values deviated from the measured values by more than 0.8 mm. For the two stone-matrix asphalt mixtures (SMA), only 2 out of 64 predicted values deviated from the measured values by more than 0.8 mm. The TEM can be used to determine the equivalent rut-depth acceptance values at a lower number of rut-testing cycles, and thus can shorten the testing time for performing the LWT rutting susceptibility acceptance test. This can be useful for the field quality control of HMA. Using this predictive model, the LWT rutdepth acceptance criteria can be developed for asphalt mixtures at the temperatures more closely related to the actual pavement temperatures in the field.