Investigation of Superpave fine aggregate angularity criterion for asphalt concrete

Fine aggregate angularity (FAA) requirement is one of,the aggregate consensus properties recommended by SHRP. Many state highway departments include FAA as part of their Superpave(R) mixture design specifications. Recent concerns about pavement performance and aggregate shape have caused these agencies to reinvestigate whether standard FAA testing provides information indicative of performance. This paper presents the results from standard FAA tests and digital imaging to investigate the validity of FAA requirements. Testing was performed on four asphalt mixtures representing a range of FAA values. Dynamic modulus testing was performed at three temperatures and five frequencies, and master curves were obtained using nonlinear regression. Asphalt pavement analyzer data obtained at one temperature were analyzed with respect to the rutting curve and rate of rutting. The experimental results for aggregates and mixtures were analyzed together by using statistical methods to develop correlation coefficients and linear trends. It was found that dynamic modulus and rut resistance values were strongly related to aggregate blend FAA. Some additional parameters from digital imaging also predicted modulus and rut resistance very well and should be included in future research.