Density, Permeability, Infiltration, and Absorption Used to Assess Quality of Hot-Mix Asphalt Longitudinal Joints

Longitudinal joint quality is critical to the successful performance of hot-mix asphalt pavements. The implementation of longitudinal joint quality specifications is gaining momentum in many states, with density being the most common quality parameter. However, distress at the joint is caused by the ability of air and water to enter the pavement structure, an ability that may be more compatible with a measure of permeability. The objective of this study was to provide guidance for the implementation of joint quality specifications by compiling information that more completely describes the relationships of density, absorption, permeability, and infiltration. On two resurfacing projects, eight joint construction techniques were used, and the ability of each to improve joint quality was assessed. In addition, joint quality was evaluated with regard to proximity to the joint. In general, the joint heater, joint stabilizer, and notched wedge construction methods were the best performers in regard to density and permeability. Traditional rolling methods exhibited lesser quality, indicating that additional measures may be necessary to generate acceptable levels of joint quality. For the most appropriate measure of quality, permeability and infiltration adequately discriminated between varying levels of joint quality, as did nuclear density. Reasonable relationships were developed between density, permeability, infiltration, and absorption. Thus, density measurements can be used for assessing joint quality and simultaneously protecting against excessive levels of permeability.