Effects of Measured Tire Contact Stresses on Near-Surface Rutting

Abstract

Instability rutting occurs within the top 50 mm (2 in.) of the asphalt concrete layer. This type of failure is attributed to the asphalt mixture properties and poses a considerable safety problem in terms of hydroplaning. A literature review has shown that several researchers have presented observations that attempt to explain near-surface rutting, but a clear and complete identification of the failure mechanism does not exist. Measured tire-pavement interface stresses were studied to determine the effects of tire structure, load, and inflation pressure on the tire-contact stress distribution. It was shown for the two tire types investigated, bias-ply and radial tires, that their loading patterns were different. Bias-ply and radial tires were modeled as input loads from actual tire-pavement stress data. The input loads were then analyzed with an elastic layer analysis program (BISAR) to predict the pavement’s response under the different loadings. The analytical evaluations performed illustrate the differences in stress distributions under the modeled tires within the top 63 mm (2.5 in.) of the pavement. The loading characteristics of radial truck tires appear to induce surface tension, which results in the loss of confinement. The combination of surface tension and high shear stresses that were predicted in the analysis might be a possible explanation of the mechanics of this mode of failure.