Development of a Database for Surface Energy of Aggregates and Asphalt Binders

Texas Department of Transportation (TxDOT) project 0-4524 evaluated the influence of surface energy of aggregates and binders on the resistance of asphalt mixtures to moisture damage. The results from this research lead to the development of a three-tier approach to assess the moisture damage resistance of asphalt mixtures. This approach is based on testing and evaluating the physical and/or mechanical properties of the constituent materials, the fine aggregate mixture, and full asphalt mixture. In the first tier, an energy-based parameter termed the energy ratio (ER) is calculated using the surface energy measurements. This parameter is used as a screening tool to select binders and aggregates that have good resistance to moisture damage. The second and third tiers rely on measuring the mechanical properties of the fine aggregate mixture and full asphalt mixture, respectively. This report documents the results of an implementation project of the testing methods and analysis approaches of the 0-4524 project. This implementation project included (a) providing training on the developed experimental and analysis methods, (b) conducting measurements of the surface energy of binders, additives, and aggregates, and (c) developing a database of surface energy measurements. This database will be useful as a diagnostic tool for finding the cause of poor moisture damage resistance in mixes and to suggest remedies through modification with anti-strip agents, lime, polymers, other additives, or through a change of materials in extreme cases.