Evaluation of Different VMA Estimation Methods for Asphalt Mixtures Containing RAP

Abstract

During asphalt mixture production, the bulk specific gravity (Gsb) of the mixture aggregate is not routinely measured to determine voids in the mineral aggregate (VMA), because this requires multiple tests and extended testing time. Instead, state agencies have used several alternatives to determine the VMA of plant-produced asphalt mixtures. This study determined the effect of these methods on the VMA determination during production. Materials, including virgin aggregates, reclaimed asphalt pavement (RAP), and plant-produced mixtures were sampled from 10 projects in Florida. Four methods were employed to determine Gsb of RAP aggregates, and six methods were used to calculate VMA of plant-produced mixtures. The study results indicated that Gsb of ignition-extracted RAP aggregate and the total aggregate blend can be used to calculate the VMA of the mixes during mix design and production if they have been adjusted to account for the effect of the ignition method on the aggregate material.