Longitudinal Joint Data Collection Efforts in Virginia between 2005 and 2009

Premature deterioration of asphalt concrete at longitudinal joints has been a problem for many transportation agencies for years. The primary cause of this deterioration is the lack of in-place density. To address this issue, the Virginia Department of Transportation (VDOT) and the Virginia Asphalt Association (VAA) formed an alliance to seek a solution to the problem. Instead of developing a new specification for longitudinal joint density and potentially increasing construction costs, the alliance developed a communication and training plan focused on proper joint compaction. This plan included a joint construction memorandum and a field training program. During the implementation year (2005), data collection revealed improved density values at the joints. In subsequent years (2006 and 2007) the joint densities began to decline. Therefore VDOT and VAA emphasized adherence to proper joint construction during the 2009 paving season. Results collected through July 2009 indicated a significant improvement in joint densities. A substantial improvement was noted in the SM-12.5 surface mixes. Average differences of less than 2% between mat and joint densities for the 12.5-mm mixes were obtained. Statistical results from analysis of variance and F-tests also confirmed this trend.