Correlating Permanent Deformation Characteristics of Hot Mix Asphalt with Aggregate Geometric Irregularities

Regression analyses were performed to study the correlation between the permanent deformation characteristics of hot mix asphalt (HMA) mixtures and their aggregate geometric irregularities. Permanent deformation of HMA mixtures was characterized by permanent strain, creep modulus, and slope of the creep curve from unconfined repeated load deformation tests. The fine aggregate angularity (FAA) test was used to characterize fine aggregates while coarse aggregates were characterized with either the particle index (PI) test, the modified National Aggregate Association flow test (modified NAA), or image analysis. Regression analyses indicate strong correlation between the permanent deformation characteristics of HMA mixtures and the aggregate geometric irregularities. Use of imaging indices for characterizing coarse aggregates gives better coefficients of determination than do other coarse aggregate characteristics such as PI and modified NAA. The imaging indices have major potential in evaluating aggregate geometric irregularities for engineering analysis.