The properties of coarse and fine aggregates used in HMA concrete mixtures are very important to the performance of the pavement system in which these mixtures are used. Because many of the currently used tests were developed to characterize aggregates empirically without, necessarily, any relationship to the performance of the HMA in the pavement system, their use has contributed to improper aggregate selection that has led to less than desired pavement performance. Under NCHRP Project 4-19, "Aggregate Tests Related to Asphalt Concrete Performance in Pavements," Auburn University was assigned the task of recommending a set of aggregate tests that relate to the performance of HMA concrete used in pavement construction. To accomplish this objective, the researchers reviewed relevant domestic and foreign literature; identified aggregate properties that influence the performance of HMA concrete in pavements; identified and evaluated, in a laboratory investigation, the aggregate tests currently used in the United States and other countries as well as potential new aggregate tests to measure HMA performance-related properties; and recommended a set of performance-based aggregate tests. The report documents the work performed under Project 4-19 and discusses the linkage between aggregate tests and the performance of asphalt concrete pavements. The recommended set of aggregate tests can be used to evaluate and select aggregates for use in HMA concrete mixtures. The report includes descriptions of those recommended test methods that are not currently being used in the United States. These test methods will be particularly useful to highway agencies and are recommended for consideration and adoption by AASHTO as standard test methods.
Abstract