Engineered Paving Mat Solves Thin Overlay Challenge

Thin hot mix asphalt overlay calls for interlayer solution to retard reflective cracking of new surface course.

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Asphalt overlay work is Roseville, CA paving contractor JB Bostick's bread and butter, but it also presents its own set of challenges, particularly when placing a thin mat over an existing paving structure that has surface deformations like alligator cracking.

On a private development project two years ago, Bostick Asphalt Paving Contractors, which is based in Los Angeles, installed TruPave engineered paving mat from Owens Corning-Trumbull on the existing road surface before applying a new thin 1.5-inch wearing course. The Lake of the Pines residential development, near Sacramento, has a 32-mile road system and was in the process of initiating a pavement management plan to improve the aging asphalt that was beginning to deteriorate (potholes, longitudinal cracking, alligator cracking, etc.).

Bostick received a contract to repair and overlay approximately three miles of the road system. The 28-foot-wide road and cul-de-sac overlay project specified a thin 1.5-inch overlay, which caused concern over whether or not reflective cracking would occur within a short time after the new thin wearing course was placed.

CHEC Engineering Consultants, a nationwide consulting engineering firm specializing in pavement design, asphalt concrete materials analysis and construction inspection, was hired by the Lake of the Pines Homeowners Association to provide design and construction management for the project. CHEC recommended using the engineered interlayer to prevent reflective cracking to the new HMA surface course.

"We recommended the paving mat because of its design characteristics and it's the only interlay that's fully recyclable," says James Curtis, CHEC project manager. "It does cost approximately three times more than a polypropylene paving mat, but we think the performance benefits are worth it and our customers are satisfied with the longer-lasting pavements we're able to achieve."

Bostick was somewhat anxious about the proposed solution since it was their first experience in working with an interlayer. But it was a good project to learn how to work with an engineered paving mat because it was a small project. The paving crew was impressed how rigid and durable the mat was when paving in the tight cul-de-sac areas of the project. The engineered mat did not rip or wrinkle while the paving crew navigated the tight radius of the cul-de-sac areas with the track paver used on the project.

TruPave is an engineered pavement interlayer designed to create a moisture-resistant barrier, retard reflective cracking and stand up to high-temperature hot-mix designs, which means it will not shrink or melt during installation. And at the end of the pavement's life, the mat is millable and recyclable.

With two years of service following the placement of the engineered mat and the new overlay, the road has shown no signs of reflective cracking, joint separation or other surface deformations. Bostick also has another tool in their product and service offering to deliver a quality asphalt overlay.