James Trepanier, Illinois Department of Transportation
John Senger, Illinois Department of Transportation
Todd Thomas, Asphalt Materials, Inc.
Marvin Exline, Asphalt Materials, Inc.
After performing for 12 years, the IDOT test pavements were evaluated and found to have longitudinal joints that exhibited significantly better performance than the control joint sections and were in similar or better condition than the rest of the pavement.
With their inherently lower density, longitudinal joints fail by cracking, raveling and potholing because of the intrusion of air and water. Due to these issues, the Illinois Department of Transportation (IDOT) developed a concept to seal the longitudinal joint region from the bottom up. Multiple test sections were constructed in 2001 through 2003 to determine how a newly developed material, called longitudinal joint sealant (LJS), would improve joint performance. It is now also called a void-reducing asphalt membrane (VRAM) by some other states. LJS/VRAM is a high-polymer-modified asphalt binder and is placed at the intended location of a longitudinal joint prior to paving.
As mix is paved over it, the LJS becomes fluid and migrates up into the high level of interconnected voids in the joint region of the mix. After compaction, the LJS/VRAM makes it impermeable to moisture while sealing the longitudinal joint itself. The IDOT test pavements were evaluated after twelve years and found to have longitudinal joints that exhibited significantly better performance than the control joint sections and were in similar or better condition than the rest of the pavement. Laboratory testing of cores near the joint area showed decreased permeability and increased crack resistance with LJS as compared to similar cores without LJS. The life extension of the joint area is approximately three to five years, and the benefit is calculated to be three to five times the initial cost.