Use of mechanistic-empirical method of pavement design for performance sensitivity analysis to asphalt pavement fatigue

Abstract

There are several factors (geometric, mechanical and loading) that can influence the design of the flexible pavement and its performance regarding the appearance of fatigue cracks. Therefore, the mechanisticempirical  methods for design are widely accepted and used in the field of paving engineering. However, for  mechanistic analysis there is a range of fatigue models that can provide different pavement design. This study aimed to analyze the performance sensitivity to asphalt layer fatigue according to data derived from a mechanistic-empirical design of the pavement and considering different fatigue models. The following variables were considered in the fatigue models: the mechanical properties of the structural materials, the thicknesses of the structural layers and the load applied to the structure. The asphalt design mixtures contemplated in the research were defined according to the Marshall mixing design method, framed in two granulometric ranges applicable to asphalt concrete with polymeric binder. The mechanistic-empirical protocol involved the pre-design of pavement structures using the empirical method of the National Department of Transport Infrastructure  (DNIT) and its mechanistic analysis using the computer program Elsym5, which considers that horizontal layers are formed by elastic-linear and isotropic materials. The results showed that fatigue performance and surface course layer design varied according to fatigue models applied in different scenarios. However, the sensitivity of performance to surface course fatigue determined by these models, given the variations of the factors studied, was approximately the same. Thus, it was concluded that the fatigue of surface course was more sensitive to the variation of the thickness of the surface course layer than to the variation of the applied load value, followed by the soil resilience module of the subgrade.

Keywords: SBS-modified asphalt mixtures, mechanistic-empirical analysis, fatigue models.