Incorporating functional performance in mixture design of porous pavement

Abstract

Skid resistance and tire/road noise are critical functional elements of a modern pavement system and can affect roadway safety and environmental comfort. Although porous surface layer serves mainly as a functional course in most applications, the considerations on skid resistance and acoustic absorption in porous mixture design is inadequate in the existing specifications. Most current mixture design procedures assume that functional performances are adequate if volumetric and composition requirements are satisfied. However, the gap between design indices and in-situ performance should be bridged through thorough understanding of the mechanisms and relationships between them. This paper proposes an analytical framework to integrate skid resistance and tire/road noise performances into porous mixture design, based on numerical prediction models previously developed and validated by the authors. The framework takes account of the long-term effect, seasonal variation and temperature influence on skid number and sound pressure level. A functional performance index (FPI) is computed as the final output of the framework, denoting the quality of a porous mixture design with respect to its functional performance. A case study is then discussed to demonstrate the feasibility and capability of the proposed framework. With adequate knowledge on mixture properties and appropriate estimation on empirical parameters, this framework can help improve the quality of porous mixture design and enhance performance of the finished pavement.