Preliminary Analysis of Quality-Related Specification Approach for Cracking on Low Volume Hot Mix Asphalt Roads

Abstract

During the last twenty years, efforts have been made to implement performance-related specifications (PRS) for hot mix asphalt (HMA) construction in the United States. The National Cooperative Highway Research Program (NCHRP) Project 9-22: Beta Testing and Validation of Hot Mix Asphalt Performance-Related Specifications created software using models similar to those in the interim American Association of State Highway and Transportation Officials (AASHTO) Mechanistic-Empirical Pavement Design Guide (MEPDG). The program predicts an effective dynamic modulus (E*) parameter to determine information pertaining to major distress types. In this study fatigue cracking (bottom-up/alligator cracking) is analyzed. A predicted life difference (PLD) is then calculated between job mix formula (JMF) and as-built conditions, resulting in an assigned pay factor. In this study, a low volume HMA roadway in rural Rhode Island was analyzed using the volumetric-based models. A sensitivity analysis was conducted by varying asphalt contents, in-situ air void targets, and dust-to-asphalt ratios to evaluate their effects on fatigue cracking levels. The aim was to assess the suitability of the software as a tool for pay factor development in Rhode Island. Based on preliminary results, results are significantly sensitive to changes in JMF target in-situ air voids. Future considerations regarding pay factor development for low volume roadway projects include: added costs or savings as a result of implementation, the development of a more simplistic method of computing pay factors, and comparing results with pavement management system (PMS) information on other comparable flexible highway pavements in Rhode Island.