A loaded-wheel testing machine is used to evaluate the rutting characteristics of asphalt mixes. The 3- x 3- x 15-in. Asphalt beam samples used for the test can be prepared by kneading compaction or by static compression. The rutting tests are normally conducted at anelevated temperature between 95 deg f and 105 deg f. The repeated loading on the beam sample is generated by a pressurized rubber hose placed lengthwise on top of the beam sample and a loaded wheel riding back and forth at 44 cycles/min along the rubber hose. The pressure in the hose is maintained at 100 psi, and the magnitude of the wheel load is 100 lb. The rut depth developed on the beam sample along the wheel path under the rubber hose is measured at different numbers of repetitions and is used for evaluating the rutting potential ofthe asphalt mixes. This repeated-load mechanism has several advantages over the conventional wheel-tracking mechanism. Asphalt mixes ofthe georgia department of transportation standard type b mix, coarse b mix, base mix, and two other modified mixes using three different aggregate sources were tested by the proposed method to evaluate the effect of mix gradations and aggregate sources on rutting resistance. The results showed significantly different rutting resistance among the asphalt mixes tested. This paper appears in transportation research record no. 1269, Asphalt mix materials and mixtures 1990.
Abstract