Evaluation of Various Hamburg Wheel- Tracking Devices and AASHTO T 324 Specification for Rutting Testing of Asphalt Mixtures

摘要

The Hamburg Wheel Tracking (HWT) device is a laboratory-controlled rut depthrntest that uses loaded wheel(s) to apply a moving load on asphalt mixture specimens tornsimulate traffic loading on asphalt pavements. Currently, different machines with variousrndegrees of compliance with the current AASHTO T 324-14 requirements are used by highwayrnagencies. The objective of this study was to assess the capabilities of commercially availablernand representative HWT equipment in the US and to evaluate different analysis and reportingrnmethods for rutting and stripping performance assessment from the HWT test. Afterrnperforming a comprehensive evaluation of HWT devices from different vendors, considerablerndiscrepancies among different equipment were identified. Furthermore, the available HWTrnmachines do not meet all the requirements set forth in AASHTO T 324 including those for thernwheel position waveform, the temperature range, and the reporting parameters. Evaluation ofrnthe analysis methods was conducted by applying six analysis procedures to the test data ofrntwo asphalt mixes with contrasting rutting resistance and moisture susceptibility. For thernpoor-performing mix, substantial differences were observed among the different methods,rnespecially in the reporting of the Stripping Inflection Point (SIP). For the good-performingrnmix, only two of the six methods successfully identified this mix as a non-stripping mix. It isrnrecommended that an approach similar to the one adopted by Iowa DOT be implemented inrnthe revised AASHTO T 324 specification.