HAMBURG WHEEL TRACKING DEVICE RESULTS ON PLANT AND FIELD CORES PRODUCED MIXTURES

This project was conducted to determine the correlation of field performance to Hamburg Wheel Tracking Device (HWTD) testing results. HWTD measures the combined effects of rutting and moisture damage by rolling a steel wheel across the surface of an asphalt concrete specimen that is immersed in hot water. The test results from this laboratory equipment have been promising in regard to evaluating the moisture susceptibility of hot mix asphalt mixtures. While there is some information on the relationship between the laboratory results from this test and the field performance, it is quite limited. This 5-year research project will be an important step in validating the test and ensuring that the test results could be reliably used to predict performance. Three designs (Superpave, CMHB-C, and Type C) and three aggregate sources (siliceous gravel, sandstone, and quartzite) were used for this study. The test sections including nine different mixture designs were constructed on IH 20 in Harrison County to observe the performance of the overlays under real traffic conditions. Field performance will be observed through visual pavement condition surveys and non-destructive tests for four years. In the second year of this project, the samples from plant mixes and cores from the test sections were taken for each mixture type. The samples were tested using a HWTD by TxDOT's Flexible Pavements Branch of the Materials and Pavements Section of the Construction Division.