Construction procedures that will provide an improved centerline joint in asphalt concrete pavements.

Construction procedures that will provide an improved centerline joint in asphalt concrete pavements.

Deterioration of longitudinal joints is widely recognized as one of the major factors contributing to failure of asphalt pavements. Finding ways to improve the durability of longitudinal joints will lead to improved service lives and lower life cycle costs. Research and field trials have been directed towards improving joint performance since at least the 1960s. Most of that work was addressed improving the density at and around the joint. This report summarizes an extensive review of the pertinent literature, a review of state specifications and inspection of several trial projects in Indiana related to longitudinal joint construction and performance. Recommendations are given for new and continuing efforts to encourage or require the construction of durable longitudinal joints.

Due to the nature of construction, it is common for longitudinal joints in asphalt pavements to have lower densities and higher permeabilities than the main portions of the pavement lanes. To address this concern, many states employ joint sealant techniques such as fog seals or void reducing asphalt membranes (VRAM). Qualitative evidence in Indiana appears to indicate that longitudinal joint lives have been improved by the use of joint sealers and adhesives, but the specific materials and application rates used to treat longitudinal joints has not been quantitatively investigated. This research aims to specifically investigate the fog seal materials and application rates specified for use on longitudinal joints in Indiana and to compare the performance of fog seal and VRAM treatments in order to provide guidelines for future joint sealant treatments. These objectives were accomplished by employing laboratory testing of both laboratory prepared specimens and field samples.The research performed on the laboratory specimens found the application of fog seals can improve the performance of the longitudinal joints with respect to permeability. While the permeability was affected by the presence of a fog seal treatment, the benefits were irrespective of the specific fog seal material. The results also indicate that the fog seal should be reapplied at 5-7 year intervals.The data from the field samples indicated that the VRAM samples had on average higher air void contents than did the SS-1h fog seal samples. Additionally, the VRAM samples had permeability coefficients that were statistically higher than the SS-1h fog seal samples. These differences may be attributable to the lack of VRAM migration up into the asphalt surface mixture. While the SS-1h fog seal treatment appears to have better performance than the VRAM, the effectiveness of the treatments over time is not known.

Construction of durable longitudinal joints is a critical element in the longevity of Hot Mix Asphalt (HMA) pavements. Achieving uniform density both longitudinally and transversely on the pavement will assist in meeting the goal of high-performance HMA pavements. A variety of techniques have been successfully used to construct good longitudinal joints. The objective of this document is to identify proper techniques for the various procedures, not to recommend a single technique.