DEVELOPMENT OF A PROTOTYPE PERFORMANCE-RELATED SPECIFICATION FOR HOT-MIX ASPHALT PAVEMENT CONSTRUCTION

By providing a rational basis for adjusting a contractor's payment based on the as-constructed pavement quality characteristics, performance-related specifications (PRS) for hot-mix asphalt (HMA) help ensure that newly constructed pavements and overlays survive their intended design lives. Over the past decade significant advances have been made in PRS technology for HMA pavement construction. This paper provides an overview of the methodology embodied in the PRS for HMA pavement construction developed during the WesTrack project. Due to its rigorous analytical nature, it has been coded into a Windows-based program named HMA Spec. In the methodology, the difference in life cycle costs of the as-designed (target) and as-constructed pavements forms the basis for pay adjustment to a contractor's bid price. The methodology utilizes models developed during the WesTrack study to predict pavement performance in terms of permanent deformation and fatigue cracking accumulation. The models incorporate, as independent variables, certain key materials and construction (M&C) factors, i.e., HMA layer thickness, HMA mixture air void content, asphalt binder content, and fines content that are known to influence pavement performance and are under the direct control of the contractor. The PRS also addresses stochastic variability of the M&C factors through a Monte Carlo simulation process to mimic real-world variability in these factors. The paper also provides the results of preliminary analyses of pay factor sensitivity to variation in the key M&C factors utilizing one of the performance models. The results indicate pay factor sensitivity to M&C factor variability and expected trends in pay adjustment.