Analysis of Permeability of Kentucky Hot Mix Pavements

OBJECTIVES: The objectives of this study are: 1) to review the state of the art on the Superpave penneability issue, 2) to investigate the relationship between permeability and pavement performance, 3) to investigate different strategies to address the high permeability issue on pavements using Superpave mixtures, 4) to recommend appropriate solutions to the permeability issue based on the analysis of different strategies, 5) to recommend adjustments on current specifications to address the permeability issue. BACKGROUND: Currently, the biggest issue concerning asphalt pavements in Kentucky is permeability, which has also become an important issue in other states since the introduction of coarse graded Superpave mixtures. This is due to the fact that a high permeability can result in ingress of excessive amounts of water, which potentially can cause serious problems such as frost heave, stripping, asphalt emulsification, pumping, etc. Previous research has been conducted to develop a field permeability test for asphalt concrete and aggregate bases. According to the research results, some pavements in Kentucky experience an excessive level of permeability, especially at the construction joints. However, a solid strategy for addressing this issue is not available yet. The objective of this research is to fmd solutions to this problem. If permeability can be effectively reduced without affecting a pavement's other desired properties, or damage caused by high permeability can be controlled, a longer pavement service life can be expected. FY 2006 ACCOMPLISHMENTS: Various field tests were run on several asphalt pavements, designed with the permeability model, and the results were summarized. Permeability data collected from previous research was reanalyzed. The reporting process began, as new information was compared to existing data. FY 2007 PROPOSED WORK: Permeability from several additional sites will be collected and analysis will continue on recalibrating the permeability model. Comparisons of different options will be summarized, recommendations will be made, and a report will be finalized. PROJECTED COST THROUGH FY 2006: PROGRAMMED COST FY 2007: TOTAL ESTIMATED COST: $140,000 $ 65,000 $200,000