Micro-Deval Testing of Aggregates in the Southeast

Abstract

Aggregate used in hot-mix asphalt (HMA) must be tough and durable, not only to withstand the effects of HMA production, transportation, and construction but also to resist the effects of traffic and the environment. Historically, the Los Angeles abrasion and impact test has determined the toughness of aggregates. The long-term durability characteristics of aggregates are generally determined using a soundness test: sodium or magnesium sulfate. During the National Cooperative Highway Research Program’s Project 4–19, the micro-Deval test, in conjunction with the magnesium sulfate soundness test, were recommended in lieu of the Los Angeles abrasion and impact test and other soundness tests. Therefore, a study was needed within the southeastern United States to evaluate the range in micro-Deval results that could be expected. This research characterized the toughness and durability of aggregates with respect to their micro-Deval test results. Seventy-two aggregate sources from eight different states were included in this research. These aggregates were rated as good, fair, or poor with respect to performance by the contributing state. On the basis of the results of this study, some large differences were found in micro-Deval test results within a given performance category. There was no relationship between Los Angeles abrasion and impact and micro-Deval test results.