Effect of compaction method on bituminous mixtures voids distribution and magnitude

The effect of compaction method on the magnitude and distribution of Hot-Mix Asphalt (HMA) air voids (AV) and voids in mineral aggregate (VMA) were evaluated. Four different compaction methods were investigated: Marshall Compactor (35, 50, and 75 blow/side), Mechanical Kneading Compactor (2.7 and 3.4 Mpa compaction pressure), Super Pave Gyratory (1.25 degrees angle of gyration), modified Gyratory (1.25 degrees, and 6.0 degrees angle of gyration). The AV and VMA magnitude and distribution in HMA specimens prepared using laboratory compaction methods were compared to those obtained from field.The method of compaction found to have significant effect on magnitude and distribution of both air voids and voids in mineral aggregate. The laboratory compaction method that best simulate field compaction was found to be depended on aggregate gradation and mix parameter (AV magnitude, AV average size, VMA magnitude, and VMA average size) being evaluated. Regardless the used compaction method, the AV and VMA magnitude and distribution found to be less near the upper and lower surfaces of the specimen compared to that at the mid depth of the HMA specimen.