Development of rutting specifications and possible replacement of tensile strength ratio by Hamburg wheel tracking device test

Abstract

Currently, the New Mexico Department of Transportation (NMDOT) does not have a specification for rutting that can be used for mix screening during the mix design stage. Though NMDOT uses Tensile Strength Ratio (TSR) to evaluate the moisture susceptibility of asphalt concrete mixes, TSR cannot be used to identify and differentiate the stripping and no stripping potential mixes. As such, this study attempts to develop a rutting specification using the Hamburg Wheel Tracking Device (HWTD) test and evaluate whether the HWTD test can replace the existing TSR test. A total of 33 asphalt mixes were collected from field pavement construction sites. Mixes were then compacted in the laboratory using a Superpave gyratory compactor and tested in an HWTD. Based on the test results, a maximum rut specification based on binder grade is established. Test data are also analyzed for parameters such as stripping slope and stripping inflection point, and their correlations with TSR value. A poor correlation is found between the HWTD parameters and TSR, which suggests the TSR test is not replaceable by the HWTD test.