Effects Variability Number of Load Repetitions on the Optimum Thickness of Asphalt Layer with Respect to Fatigue and Rutting Behaviour on the Sand Bed Soil Area

Abstract

This study investigates the effect of the variability of a number of load repetitions on the asphalt layer thickness, and also the elastic modulus of pavement materials on the behaviour of flexible pavement structural on the sand bed soil with respect to fatigue failure and rutting failure using the mechanistic design approach. The framework is evaluated for a six-layered flexible pavement system. The major focus of this study is the influence of variability associated with the thickness and resilient moduli of an asphalt layer on fatigue and rutting failures is discussed. The methodology is based on the damage analysis concept which is performed for both fatigue cracking and rutting for flexible pavement by using KENLAYER program for analysis strains in the upper and lower of each layer. Data collection is dependent on the AASHTO 1993 and Asphalt Institute sources used to construct the statistical distributions of layer thicknesses and elastic moduli. The results of pavement analysis showed that the thickness of the foundation, elasticity modulus of the foundation, and sand bed are the key elements that control the equilibrium between fatigue and rutting lives respectively. The study also concluded that increasing the thickness of the surface layer significantly lied to increase the pavement life, while increasing the elasticity modulus of the surface mildly increases the pavement life. The investigated pavement components are; thickness and elasticity modulus for pavement layers. Sensitivity analyses were conducted to identify key input parameters that have the most effect on the optimum thickness of the asphalt layer.

Keywords

• layer thickness,
• pavement stiffness,
• rutting deformation,
• fatigue distress