Designing sustainable, long-lasting asphalt pavement without accumulation of fatigue cracking is an important goal of transportation agencies. If the tensile strain at the bottom of asphalt layer is kept below a certain value (endurance limit), fatigue damage either does not occur or can be healed during the time period between load applications. The objective of this study is to introduce a simple approach that can be used to determine the minimum asphalt layer thickness that would avoid fatigue cracking accumulation. In this approach, the endurance limit model previously developed by a National Cooperative Highway Research Program (NCHRP) study was used with certain simplified assumptions. A wide range of subgrade stiffness, hot-mix asphalt (HMA) stiffness, and traffic volume variations, covering typical roadway conditions was used. The study concluded that the minimum HMA layer thickness required to avoid accumulation of fatigue cracking ranges between 140 mm (5.5 in.) and 240 mm (9.5 in.) under the stated conditions and assumptions. Increasing traffic volume decreases the rest period between load applications and increases the minimum asphalt layer thickness required to avoid accumulation of fatigue cracking. Increasing asphalt concrete stiffness decreases the endurance limit and decreases the minimum asphalt layer thickness required to avoid accumulation of fatigue cracking. Subgrade stiffness does not have much effect on the minimum required surface layer. The results of this study should not be used directly to design specific pavement sections. Rather, the approach introduced here is intended to be used as a guide for a more detailed design procedure by the user incorporating actual traffic loads and volume distributions, specific environmental conditions, and more realistic material properties. Designing pavement to avoid accumulation of fatigue cracking should produce good long-term performance and should have significant design and economic implications.
|Original language||English (US)|
|Journal||Journal of Transportation Engineering Part B: Pavements|
|State||Published - Jun 1 2017|
ASJC Scopus subject areas
- Civil and Structural Engineering