Levels of Variability in Volumetric and Mechanical Properties of Asphalt Mixtures

Abstract

The objective of this study was to quantify the levels and sources of variability in the measurements of volumetric and mechanical properties of dense-graded asphalt mixtures on the basis of existing test data from state agencies and contractors. To achieve this objective, data were collected from state DOTs and research agencies, and a statistical analysis was conducted on a per-state basis to provide an overall quantification of the levels of variability for the different volumetric and mechanical properties. A meta-analysis based on the collected data was conducted to identify sources of variability for volumetric and mechanical properties. According to the results of the analysis, levels of variability for a wide range of volumetric and mechanical properties were quantified. Levels of variability were comparable for various state DOTs located in different climatic regions. It was determined that results obtained by the state and contractor were statistically equivalent for the majority of the volumetric properties. Nominal maximum aggregate size (NMAS) of asphalt mixtures appeared to influence the magnitude of the variability observed for the various volumetric and mechanical properties. The results presented in this paper were part of the National Cooperative Highway Research Program (NCHRP) Project 9-48 entitled