Interstate 65 in Indiana required resurfacing due to cracking from heavy traffic loading. The roadway included asphalt concrete surface layers over a jointed concrete underlying pavement foundation layer. Standard mill and fill was considered, but INDOT wanted a solution that would yield a long-term solution. Analysis of the pavement conditions indicated that moisture was weakening the base and sub-grade.
To create a long-lasting moisture barrier, 190,000 square yards of PETROMAT® Enviro™ was installed on both the north and southbound lanes using 0.25 gallon per sq. yd. of asphalt cement tack coat.
Although some manufacturers tout strength and modulus as the most important properties for paving interlayer, research clearly points to stress absorption and moisture protection as the most important qualities of a paving fabric. The thickness of an interlayer will determine how well cracks and joints in the pavement are mitigated. The thicker the interlayer, the more crack inducing stresses are attenuated. When saturated with asphalt tack coat, PETROMAT Enviro is two to three times thicker than fiberglass-based interlayers – enabling resistance to reflective cracking comparable to an additional 1.5” of overlay thickness.
INDOT wanted to ensure the road could be recycled in the future. Another reason PETROMAT Enviro was selected is its ability to easily mill and recycle. When milled, Enviro is nearly indistinguishable in RAP, ranging in size from one inch in diameter or smaller. Plus, Testing shows that the performance of the asphalt pavement improves when adding reclaimed asphalt pavement, or RAP, containing milled Enviro.
INDOT was happy with the ease and speed of installation. Not only will PETROMAT significantly increase the lifetime of the road, but it will help prevent future maintenance issues. Over time, asphalt concrete containing RAP with fiber-glass is susceptible to stripping. Third-party testing of new asphalt concrete containing 30% ENVIRO RAP had no stripping after 20,000 cycles.
Editor's Note: Scranton Gillette Communications and the SGC Infrastructure Group are not liable for the accuracy, efficacy and validity of the claims made in this piece. The views expressed in this content do not reflect the position of the Roads & Bridges' Editorial Team.