Variability of Composition, Volumetric, and Mechanic Properties of Hot Mix Asphalt for Quality Assurance

Abstract

As hot mix asphalt (HMA) is the major paving material worldwide, how the quality of this material is assured is a critical issue. The current quality assurance (QA) practices include testing programs that yield inevitable variability as a result of, e.g., different operators, equipment, and methods. So far, very little research has focused on the variance and testing variability of HMA properties with respect to the material types and climatic conditions that are typical of Alaska. This study presents research to evaluate the variance in composition, volumetric, and mechanical properties between plant-produced and lab-designed mixtures of Alaska HMA, which was produced with various production/compaction scenarios and tested by different operating parties. The variability level of each tested property was quantified, compared with nationwide levels, and tested for influencing factors. This study further evaluated the method proposed in the National Cooperative Highway Research Program (NCHRP) 9-22 project, to predict the means and variability of mechanical properties with the measured composition and volumetric properties of Alaska HMA. According to the results, clear differences were observed between the plant-produced and lab-designed mixtures, and the magnitudes of the differences were higher for the volumetric and mechanical properties than for the composition properties. The variability of properties of Alaska HMA was within the nationwide range, with the lowest levels found on composition properties, followed by volumetric properties, and the highest on mechanical properties. The effects of the operating party and production/compaction scenario were also reported. The predicted results of the mechanical properties were found to deviate from the measured ones.