Development of a new revised version of the Witczak E* predictive models for hot mix asphalt mixtures

The main purpose of this dissertation is to present the development of a new set of predictive models for stiffness of asphalt cement binders and a new revised version of the Witczak dynamic modulus (E*) predictive model of hot mix asphalt (HMA) mixtures. Master databases of binder stiffness and HMA E* were compiled and revised. The binder stiffness database contained lab shear modulus (|Gb*|) and phase angle (deltab) data with ASTM (American Society for Testing Materials) viscosity (A i-VTSi) data. The database has 8,940 data points from 41 different binders. The majority of the HMA E* database has been developed from the test results obtained during the National Cooperative Highway Research Program (NCHRP) 9-19 Project (also conducted by Arizona State University). This database contained lab HMA E* data with aggregate gradation, mixture volumetric and binder Ai-VTSi data. The database has 7400 data points from 346 different mixtures. It is an extension of the Witczak E* predictive model database that has been periodically updated since 1969.; The binder stiffness master database was used to develop a new predictive model for binder stiffness. The first set of model equations in this model is a fully revised version of the widely known "ASTM Ai-VTS i Viscosity Model". The second and third sets of model equations in the model predict |Gb*| and associated deltab, respectively. The binder stiffness predictive model has been found to be rational, unbiased, accurate, and statistically sound.; The E* master database was used to develop a new revised version of the Witczak E* predictive model for HMA mixtures. This model was aimed at improving the limitations associated with the current version that has been used in the present draft of the new mechanistic-empirical pavement design guide (M-E PDG) developed under the NCHRP Project 1-37A. The new E* model has been found to be rational, unbiased, accurate, and statistically sound.; The new models developed under this Ph.D. research have similar mathematical structures as the ones used in the new M-E PDG. Therefore, it is hypothesized that the new models can be easily incorporated in a future revision of this pavement design guide.