Field Performance and Cost Effectiveness of Crack Sealing in Flexible and Composite Pavements

Surface cracking is one of the major surface distresses in asphalt concrete (AC) pavement, allowing water infiltration through the cracks, causing stripping in asphalt pavement layers, and weakening and deteriorating the base and/or subgrade. Its treatment, therefore, is one of the major activities in pavement preservation for many state DOTs. Among the various treatment methods currently available to preserve AC pavement with existing surface cracking are various forms of crack sealing. Crack sealing is not a common practice to Louisiana highways since the benefit of such treatment appears to be affected by the elevation of the ground water table. Studies completed in the 1960s for Louisiana showed that sealing roads in an area with a high ground water table accelerated AC stripping. The explanation was that crack sealing in such a situation prevented moisture from escaping upwards through the cracks of the AC pavements. The objective of this dissertation was twofold. First, this study quantified the benefits of using crack sealing with respect to its ability to provide immediate benefits and long-term benefits. Based on this evaluation, the research team developed regression models that predict crack sealing benefits; in terms of extension in pavement service life, based on the project conditions. Second, this dissertation evaluated the potential moisture damage in pavements treated with crack sealing. Based on this evaluation, the research team developed a regression model that determines whether crack sealing should be used to avoid moisture damage in a cracked pavement at a given site based on the ground water table depth and air relative-humidity. Furthermore, this project assessed the optimal application timing of crack sealing through evaluating its cost effectiveness using common economic measures. To facilitate implementation of the results, a user-friendly tool in the form of a spreadsheet was designed that could be used by state agencies during planning for crack sealing. This tool requires the user to input key project conditions such as the average daily traffic volume, thickness of the existing asphalt pavement, pre-treatment pavement condition, etc. For each input, typical ranges and recommended values are provided to guide the user in selecting the design values. Based on the provided input values, the tool would determine whether crack sealing is an effective maintenance treatment to be applied to an existing AC overlay based on the specific road conditions