Development of Oxidation Kinetics Models for Rheological and Damage Properties Based on “In-Service†Asphalt Binders

Abstract

Oxidative aging can lead to the susceptibility of asphalt pavement to cracking. Most studies on oxidative aging of asphalt binders are related to the prediction of the aging properties of asphalt binders based on oxidation kinetics. Development of kinetics models often involves short-term and long-term aging in the laboratory of original binder at different temperatures and for different times, and experiments of original and aged binder. However, for many rehabilitation projects or forensic studies, the original materials of pavements that were constructed years ago are not readily available to develop kinetic models. The development of a kinetic model based on asphalt binder in an in-service pavement is greatly needed to predict the properties of asphalt binder subjected to further aging for the purpose of overlay design, or to backcalculate the original properties of binder before aging for the purpose of forensic studies. This study develops a methodology to develop Arrhenius kinetics aging models using asphalt binders that already have been aged, instead of using original binders. Five asphalt binders (one neat and four modified) were included in this study and were subjected to three stage aging. The carbonyl areas of the aged binders were determined using Fourier transform infrared spectroscopy, and the rheological properties and damage properties were determined using a dynamic shear rheometer (DSR). First, the relationships among the model parameters of the oxidation kinetics models for the crossover modulus, DSR function, shear strength, and critical strain energy density of the asphalt binders were developed based on aging of original materials. Based on the relationships between model parameters and experiment results of asphalt binders that have been aged separately, Arrhenius kinetics aging models were developed. The effectiveness of these models which are developed based on aged binder were verified. The developed kinetic models for crossover modulus, DSR function, shear strength, and critical strain energy density of the asphalt binders can be used to predict the properties of asphalt binders subjected to further aging in the field for the design of overlays in the Mechanistic-Empirical Pavement Design Guide or Pavement ME, or to determine the properties of original asphalt binders before aging for the purposes of forensic studies, based on the cumulative aging effects of in-service pavement temperatures.