Evaluation of Coarse Aggregate Quality with respect to Current Specifications for Pavement Mixtures

Abstract

In many states, coarse aggregate specifications for pavement mixtures are outdated and do not reflect the current level of knowledge concerning desirable aggregate properties for pavement applications. Because the performance of pavements is highly dependent on the quality of aggregate used within them, the quality of the aggregate must be evaluated based on the consistency of desirable aggregate properties. The primary objective of this research was to evaluate the compliance and consistency of coarse aggregate properties with respect to current specification requirements. To evaluate compliance and consistency, testing data from local sources in the state of Minnesota were compared to regional and national records on aggregate quality and specification requirements. Percent within limit calculations were conducted to evaluate the compliance of aggregate properties with respect to the current quality requirements of abrasion resistance, soundness, and percent spalling material. The results of the study demonstrated that aggregates complied very well with current specifications. However, when evaluating the variability of test results, inconsistency between different sources was noticeable even though quality requirements were easily met by tolerance criteria. This study emphasizes the inconsistency of aggregate properties among sources subjected to the same (or similar) specification requirements.