Joint Sealant Performance on Asphalt Mixture Longitudinal Joints

Abstract

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 treatments such as fog seals or void reducing asphalt membranes (VRAM). Qualitative evidence in Indiana appears to indicate that longitudinal joint lives have been improved using joint treatments, but the specific materials and application rates used to treat longitudinal joints in Indiana has not been quantitatively investigated. This research aims to 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 to provide guidelines for future joint 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 of the asphalt specimens was reduced by the presence of a fog seal treatment, the benefits were irrespective of the fog seal material. The results also indicate that the fog seal should be reapplied at five to seven year intervals. The testing of the field samples indicated that both the SS-1h fog seal and VRAM treatments were effective in reducing the permeability of the asphalt mixtures. The VRAM samples had statistically higher permeability coefficients than the SS-1h fog seal samples, which may be attributed to potential construction or material issues. 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. Additional research is recommended to verify and support these results and recommendations and to further compare and understand the performance of SS-1h and VRAM treatments over time.