Influence of Horizontal Traction on Top-Down Cracking in Asphalt Pavements

Abstract

Traditionally, in pavement analysis and design, stress-strain analysis is carried out by assuming wheel loads as uniform vertical traction acting on a circular area. However the contact forces at the tire-pavement interface are not purely vertical. Considerable amount of horizontal traction is developed when a tire moves on the surface of the pavement. It is expected that the state of stress and strain in a pavement in such a case might be completely different. In this study, three dimensional finite element stress-strain analysis of a multi-layered pavement system subjected to both vertical and horizontal tractions was carried out. A linear viscoelastic model was used to characterize asphalt layers and a Drucker-Prager model with a linear hardening rule was used to characterize the elastic-plastic response of the granular material of the base layer. It was observed that due to the application of horizontal traction considerable horizontal tensile strains are produced at the surface of the asphalt layer. These horizontal strains at the surface are tensile to the rear of the loaded area and compressive to the front of the loaded area. Also, the maximum horizontal tensile strain occurs at the surface and not at the bottom of the asphalt layer. In order to investigate the influence of the increased horizontal tensile strains at the surface on top-down cracking, the strains obtained from the finite element analysis were used in typical top-down crack prediction models and the number of repetitions to failure was determined. It was found that the addition of horizontal traction significantly reduces the allowable number of repetitions.KeywordsTensile StrainAsphalt MixtureAsphalt PavementCalifornia Bearing RatioLoaded AreaThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.