Analysis of the Air Voids within Superpave Gyratory Compacted Hot Mix Asphalt Specimens

Analysis of the Air Voids within Superpave Gyratory Compacted Hot Mix Asphalt Specimens Andrew Manuel Aguilar The influence of mix design properties on the mechanical properties of Superpave hot mix asphalt samples has been researched by the state of West Virginia with the Asphalt Mixture Performance Tester (AMPT) since its acquisition in 2013. The dynamic modulus, flow number, and number of cycles to failure through uniaxial fatigue testing are all affected by the mix properties of the sample being tested. It has been a concern if samples prepared with the Superpave gyratory compactor (SGC) for testing with the AMPT have a uniform distribution of air voids within the sample.;Through review of literature the uniformity of air voids within a sample has been found to be a function of the mix properties of the samples, the equipment used to compact the sample, and the geometry of the sample. The compaction equipment and sample dimensions have been found to consistently have a significant effect on the uniformity of air voids within a sample. The effect of mix properties on the uniformity of air voids within a sample has been found to vary by mix design. The goal of this experiment was to determine if there is a significant difference in the air voids measured in the middle of Hot Mix Asphalt (HMA) samples in comparison to the air voids in the ends of the sample.;This thesis has found that the SGC prepared samples for AMPT dynamic modulus testing has produced samples with significantly greater air voids in the middle than the air voids at the ends of the specimen with a significance level of 0.05. It was found that the measured air void difference in the middle and ends of the samples prepared with the SGC is not affected by the method of measuring the air voids or the sample\u27s mix properties. From the results of this thesis it is recommended that samples are prepared by SGCs from manufacturers other than the Pine AFGC125X used in this research to verify that compacted samples with a non-uniform air void distribution is not unique to the SGC used in this study. It is also recommended that a heterogeneity index threshold be explored in order to distinguish samples that have an acceptable air void distribution for performance testing with the AMPT