Considerable interest has been generated in recent years in using big stone gradations to reduce rutting and shoving in asphaltic concrete. This report documents mix design procedures and a laboratory testing program to determine the stability and rutting potential of a big-stone gradation. A series of creep tests was performed on a big-stone gradation and the results were compared to creep tests performed on a Class I base mixture. The big-stone mix average approximately 50 percent rutting potential as compared to the Class I base. One creep specimen of the big-stone mixture was compacted using polymer-modified AC-20 grade asphalt cement. This specimen performed with less strain than the big-stone specimens compacted with an unmodified AC-20 asphalt cement (at loading times greater than 4000 seconds. One specimen was compacted using an AC-40 asphalt cement. This specimen failed at a short loading time (approximately 1000 seconds), indicating a brittle mixture.

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The contents of this report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Kentucky Transportation Cabinet, the Federal Highway Administration, nor of the University of Kentucky. This report does not constitute a standard, specification, or regulation.