Effects of Chemical and Microstructural Constituents on the Healing Characteristics of Asphalt Binders

Self-healing of asphalt binders and mixtures during rest periods of cyclic loads is a topic that has been studied more carefully recently. To better understand the effects of the chemical characteristics on the healing behavior, this paper characterizes the chemical composition of binders based on the following tests: chemical fractionation (SARA), gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), and chemical elemental analysis. In addition, the microstructural composition of the binders is also evaluated based on testing results obtained in an atomic force microscope (AFM). In such tests, the area fractions of the three main binder microstructural components, i.e., catanaphase, periphase, and paraphase, are determined. The chemical and microstructural compositional results are then compared to linear amplitude sweep (LAS) test results obtained with and without rest periods for the eight asphalt binders investigated. These comparisons indicate that the overall self-healing characteristics of the binders are related to their microscopic characteristics and this understanding may be useful for the selection and even for the fabrication of materials that are more resistant to fatigue.