Development of a New Revised Version of the Witczak E* Predictive Model for Hot Mix Asphalt Mixtures (With Discussion)

The main purpose of this paper is to present the development of a new revised version of the widely known Witczak E* Predictive Model. The model development was aimed at overcoming the limitations of current models available to the pavement community, which are used for predicting the dynamic modulus (E*) of hot mix asphalt mixtures (HMA). A comprehensive study was completed at Arizona State University to conduct numerous E* testing and finalize a huge E* database, containing 7400 data points from 346 HMA mixtures. This database was used to develop the new E* predictive model. The model is capable of accurately estimating changes in E* of HMA mixture as a function of changes in mixture volumetrics, material properties, temperature and loading frequency (or time) for the entire E* database used. The model has been found to be rational, unbiased, accurate, and statistically sound. The new mechanistic-empirical pavement design guide entitled “Guide for Mechanistic- Empirical Design of New and Rehabilitated Pavement Structures” developed under National Cooperative Highway Research Program (NCHRP) Project 1-37A uses the current version of Witczak E* Predictive Model in its input levels 2 and 3. It is hypothesized that due to its similar sigmoidal structure as used in the guide, the newly developed E* model can be easily incorporated in a future revision of this pavement design guide.