Effect of flat and elongated coarse aggregate on field compaction of hot-mix asphalt

It has long been believed that coarse aggregates that have a flat and elongated (F&E) shape are detrimental to the properties of hot-mix asphalt Several attempts have been made to establish a relationship between these aggregate particles and performance. It is believed that decreased performance may result from either aggregate breakage or less than optimum particle orientation. The question of mixture performance is set aside, and the focus is on the construction effects in asphalt mixtures with high percentages of F&E aggregate. Research shows that for a given gradation and aggregate type, increasing the percentage of F&E,will increase the amount of aggregate breakdown. One focus is to determine if the same relationship between percentage of F&E particles and breakdown that has been documented in laboratory settings can be observed in the field. The other focus is on a comparison of the aggregate breakdown caused by the gyratory compactor with the aggregate breakdown in the field.