The Effect of Voids in Mineral Aggregate (VMA) on Hot-Mix Asphalt Pavements

Abstract

This research project investigates the level of Voids in the Mineral Aggregate (VMA) in Minnesota paving projects. Researchers analyzed 10 paving projects from 1996 to determine if a VMA decrease occurred, the magnitude of the decrease, and the potential causes of the decrease. Potential causes include the generation of fines, high-production temperatures, and long storage or cure times. Three of the 10 projects had a VMA decrease of 1.9 or more. These three projects also had the highest plant temperatures and fairly long storage times, which makes increased asphalt absorption a likely cause of the VMA decrease. Five projects showed a moderate drop in VMA. Most had some increases in fines, and some had moderately high plant temperatures and storage times. The two projects with little or no changes in VMA had very little change in gradation, and moderate to low plant temperatures and storage times.