Determination of Dynamic Moduli in Uniaxial Compression for North Carolina Hot Mix Asphalt Concrete

Abstract

This thesis presents results from an experimental study on the dynamic modulus testing of hot mix asphalts (HMAs) commonly used in North Carolina in uniaxial compression mode. Forty two mixtures with varying aggregate sources, aggregate gradations, asphalt sources, asphalt grades, and asphalt contents are included in this study. With the dynamic modulus database developed, several issues are investigated in this research. Effects of confining pressure on the dynamic modulus are evaluated by comparing results from uniaxial and triaxial compression tests. A modified dynamic modulus test protocol is developed by reducing the required testing time using more frequencies and fewer temperatures based on the time-temperature superposition principle. Hirsch and Witczak predictive models are evaluated. During this analysis a case study was conducted to determine how much pavement performance changes due to the predictive errors. Finally, effects of different mixture variables on dynamic modulus of asphalt concrete are evaluated.