Perma Flex®, a federally registered trademark, is a unique overlay system designed to utilize existing asphalt as a base for a new surface course. It was developed in the early 1970’s to combat reflective cracking, a common flaw found in traditional overlays. Reflective cracking refers to the tendency of existing cracks to migrate into the new asphalt surface. Without a barrier of protection, a 1″ to 2″ surface course will develop crack patterns identical to the existing pavement. The end result is an expensive means of duplication current surface conditions. For this reason most reputable contractors will not overlay a heavily cracked surface until these failures are addressed. Perma Flex® is the only asphalt mix design developed exclusively for overlaying cracked surfaces.
The mix design of Perma Flex® includes carefully sized aggregate and a combination of liquid asphalt bonding agents blended specifically for each job. The sized aggregate wedges into existing cracks. PermaFlex® has been formulated not to contain aggregate sizes that promote reflective cracking. The liquid asphalt agents allow for a continuously bonded flexible crack-retarding barrier ready for a smooth watertight asphalt surface.
The Perma Flex® Process
Assessment: A qualified contractor licensed to install Perma Flex® must determine if the existing surface is a Perma Flex® candidate. The parking lot should be visually inspected and trouble spots identified. Any drains, metal grates or manholes should be elevated to accommodate the additional inches.
Repair Work: Deteriorated asphalt that is unsuitable for overlay must be removed and replaced with hot mix asphalt. These areas are patched prior to an overlay. If stabilization of the sub base is required, additional stone will be needed under the replacement asphalt. The amount of stone required if any, is unknown until the excavation of old deteriorated asphalt is complete.
Leveling Course: With some applications it is necessary to place additional asphalt in low areas to improve the profile of the finished surface. The end result is a smooth level-riding surface that promotes water drainage.
Perma Flex® Overlay: The entire surface will be sprayed with a tack coat. The tack coat is usually supplied with a truck-mounted distributor. PermaFlex® is trucked on-site and dumped into a paving machine to be spread. The asphalt paver will be set at the required inch thickness for application. Once in place, the new mat of Perma Flex® will be rolled for compaction. The compacted surface will be sprayed with tack and the final asphalt topping will be spread and rolled for compaction.