TESTING REPEATABILITY OF THE HAMBURG WHEEL-TRACKING DEVICE AND REPLICATING WHEEL-TRACKING DEVICES AMONG DIFFERENT LABORATORIES

The purpose of the study reported in this paper was to assess the repeatability of the Hamburg and other similar devices among seven agencies. Four of the agencies (TxDOT, FHWA, Colorado DOT and Koch Materials) used a Hamburg device manufactured by Helmut Wind. The specifications for the others were alike except for that used by Superfos Construction, Inc. which uses a solid, rubber tire with a higher load to induce damage rather than a steel wheel. To other agencies were the University of Arkansas and the Utah DOT. All participants compacted test specimens with a kneading linear compactor. A limestone and gravel aggregate were used for the two HMA mixes. The limestone was 100 percent crushed and the gravel was 85 percent crushed material. One percent hydrated lime and 10 percent mineral filler were added to the gravel mix.. The TxDOT modified the test specimen configuration so that the wheel tracking was accomplished on a test specimen comprised of two specimens compacted in the Superpave Gyratory Compactor.