J-Band is a void-reducing asphalt membrane (VRAM) product. In a recent MnDOT-funded project, researchers evaluated the use of J-Band in an asphalt pavement on State Highway 22 in Blue Earth County. Tests showed higher bond strength, lower permeability and air void levels, and improved crack resistance.
VRAM products—mixes of asphalt binder, polymer, and modifiers—hold new asphalt in place and migrate upward into the asphalt layer, filling air voids and keeping the asphalt from spreading and losing density. Little research has been conducted on VRAM performance, so MnDOT and other agencies rely mostly on anecdotal evidence and manufacturer claims in judging VRAM products and applications.
The researchers found that VRAM seems to improve asphalt strength and reduce water incursion, and it can be expected to improve asphalt mat performance. J-Band was found to reduce air voids from 8.5% to 5%.
In laboratory testing, VRAM performed better than control sections in terms of bond energy, fracture energy, work of fracture, and surface energy. The high fracture resistance indicates a likely improvement in cracking resistance at the joints. Reduced air voids and permeability in the tested samples also suggest lower water intrusion and better long-term pavement performance.
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