The objectives of this study were to evaluate the level of compaction at the construction joint in HMA pavements on new and existing projects; to determine the level of water infiltration and segregation at the joint and its effect on joint performance; to determine the most promising joint construction methods around the nation and worldwide by reviewing specifications, experiences, and construction practices for joint construction and the prevention of joint segregation; to develop specifications and construction methods to ensure the level of density necessary at the joint for proper performance; and to review special paving equipment (attachments) for improving densification for the unsupported edge.

Four methods of joint construction were evaluated in this study. These were the notched wedge (12:1), restrained edge, joint reheater, and Joint Maker. In addition, a number of joint adhesives were used. Some of the major conclusions and recommendations from the study include:

  • Contractors are consistently achieving levels of density at or near the construction joint that are within three percent of the lane density. It is recommended that specifications be written that would require contractors to achieve that level of density at or near the construction joint.
  • The reheater achieved the highest joint density of all the methods; however, only one short project was included in the study. The effects of reheating the mat could not be determined during construction, but will be evaluated during long-term monitoring. The restrained-edge method of joint construction achieved the second highest overall densities and statistically was significantly better than the conventional method of construction. The notched wedge only marginally improved densities overall, while the Joint Maker showed no improvement over conventional construction techniques. It is recommended that more projects be constructed using the restrained-edge method.
  • It appeared the notched-wedge method produced the lowest permeabilities at the joint.
  • Preliminary performance data indicate that all projects are currently performing well with projects having joint adhesives performing as well as, or better than, projects without joint adhesives. It is recommended that other projects be constructed using joint adhesives.

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The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Cabinet, nor the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. The inclusion of manufacturer names or trade names are for identification purposes only and are not to be considered as endorsements.