Adapting Specification Criteria for Simple Performance Tests to HMA Mix Design

Abstract

The objective of this project was to develop a software program for evaluating the potential performance of hot mix asphalt (HMA) mix designs in combination with their intended pavement structures. This Program for Integrated Analysis of HMA Mix And Structural Designs is coded as a Microsoft Excel spreadsheet (9-33A(Sep10).xlsm) and supporting files. The program incorporates the Mechanistic-Empirical Pavement Design Guide (MEPDG) spreadsheet solutions developed in NCHRP Projects 9-19 and 9-22. Predictions of permanent deformation (rutting) and fatigue cracking are made on the basis of the estimated HMA dynamic modulus, E*; thermal cracking predictions are based on estimates of the HMA creep compliance, D. The program will serve as a multi-purpose tool for HMA mix and structural design engineers. First, it provides an easy graphical check that a prospective job mix formula (JMF) falls within the acceptable limits of air voids and effective binder volume established by the project’s HMA specification. Second, using powerful, pre-solved solutions of the MEPDG, it provides rapid estimates of the performance of the JMF over the design life of the HMA pavement and whether the JMF will satisfy specific pavement distress criteria established by the agency. Third, it can test “what-if” scenarios by estimating how changes in the JMF, pavement structure, or both may affect performance. Finally, it can be used in forensic investigations of pavement distresses, by assessing the potential contributions of the HMA and pavement structure to distress development before any testing is conducted. This report presents (1) a description of the program’s inputs and outputs, (2) a brief review of the underlying performance prediction models, and (3) examples illustrating the use of the program to analyze specific mix-structure combinations. Technical familiarity with the MEPDG design principles, the E* Simple Performance Test (SPT) Specification Criteria Program, and the Quality-Related Specification Software (QRSS) will enhance the user’s understanding of the program.