There's a street in Cary, First Street, that suffers from very heavy traffic on a daily basis. The pavement on the street was seriously deteriorated with a PCI rating of less than 10.
The Future Project:
In order to prevent further cracking, a Mirafi® FG100 fiberglass grid and the paving fabric Mirafi® MPV 500 were applied to the seriously stressed areas. As Mirafi® MPV has a proven track record for successfully stopping reflective cracking and provide pavement longevity, it was used throughout the majority of the project.
Mirafi® FG is a new member of the line and is used effectively in cases that are extremely severe. Mirafi® FG offers an open grid pattern that interlocks with hot mixed asphalt that will give a maximum reinforcement through bonding with the new pavement layer.
Grids are manufactured with fiberglass yarns that are arranged in a crosswise and lengthwise pattern to increase relocation loading of the moving pavement. This bonding improves the structural integrity of the new layer. Then a polyester mat was placed on the grid to bond with the old pavement. This was followed by a liquid asphalt that would adhere to the grid which would allow for traffic for the hot mix overlay.
The high modulus flexible element, such as the fiberglass grid, will help to contain the crack before its expansion causes harm to the pavement overlay system.
The Mirafi® FG products are designed to offer high strength during very low strains of less than 5%. The property of this product is referred to as modulus which is very important for added reinforcement to a paved structure.
There were no problems in spreading a light tack coat in order to secure the Mirafi® FG100 to the binder course before applying the pavement overlay. The binder was spread at a rate of .07 gal/yd2 to bond the layers. Starting with a leveling course to fill the irregularly surfaces in the pavement and followed by the fabric installation and then one lift of IDOT hot mix to finish the project.
Mirafi® MPV 500 has been used in this city for many years and has shown to increase the life of the pavement's overlay. This was the first application of fiberglass used by the city as well. It is believed that Mirafi® FG100 will be an excellent alternative for removing and replacing pavement sections. Mirafi® FG can be applied very easily in pavement sections where Mirafi® MPV has been used. The finished project will be reviewed for overall performance on an annual basis.
Case Study: Palo Pinto, TX Asphalt Pavement Overlay:
The Future Project:
The 2 major highways that run in and out of Mineral Wells are Highways 281 and 337. Over the years, increased traffic from the growth of their population has increased stress on these highways. With average high temperatures of 97°F and lows of 32°F and precipitation fo 29.3-inches has created a harsh environment for their pavements. The TXDOT has a successful track record for utilizing pavement fabrics along with a tack coat as an inter-layer for overlays.
Approximately 12.6 miles of the two-lane Highway 281 and 11.3 miles of the two-lane Highway 337 delegated for this project. The design engineer chose Mirafi® MPV500 along with a tack coat for the project to create a waterproof membrane and help in the reduction of reflective cracking within the pavement's system. This process would prevent water infiltrating into the pavement system and the softening of the foundation.
Increasing resistance to the cracking, they chose to apply Mirafi® MPV500 which is designed for this purpose. Mirafi® MPV500 is a heat-set, non-woven polypropylene geotextile that offers a high asphalt absorption ability and is specifically designed for asphalt overlay applications.
The Highway Construction:
The condition of the two highways ran from slight pavement stress to severe pavement distress. The project consisted of the removal and replacement of the severely stressed pavement areas and a leveling process was applied to areas of irregular pavement surfaces.
Then, an asphalt tack coat PG 64-22 was applied at the rate of 0.20 gal/yd2 using a distributor truck. The temperature of the tack coat stayed above 325°F and the Mirafi® MPV500 was immediately applied using a bar rig that was attached to the front of the tractor. Using a push broom, the fabric was aligned and smoothed out. Then a 2-inch TXDOT Type D hot mix asphalt overlay was then put on the paving fabric.
The fabric and overlay were completed in a relatively short period of time. It is expected that the system will live up to their expectations as others have in Texas. The finished project will be reviewed for overall performance on an annual basis.
Case Study: Lanham, MD Pavement Overlay:
The Future Project:
The asphalt pavement in the parking lot of the National Asphalt Pavement Association (NAPA) was developing a great deal of alligator cracking and was delegated to be re-paved. After a thorough examination, it was deemed that the parking lot would need serious patching due to the unexpected pumping that was seen in some areas of the pavement's surface.
The Parking Lot Design:
After testing a few areas of the parking lot, everyone realized that a standard overlay would not do the trick. Proper repair would entail a full in-depth removal and replacement of the pavement in cross sections and over a much wider area than originally thought. Due to the costs and time, it would take to repair, they needed to reassess the situation. The final decision was made by the committee that included the contractors and the input from the President of NAPA. They decided to use Mirafi® MPV500 in order to reduce the infiltration of water into the pavement, offer stress relief between the current surfaces and patches, and apply a new overlay. Although this was not considered the perfect solution, it would increase the longevity of the new overlay.
After the completion of the patching and edge milling, American Paving Fabrics used PG64/22 at a rate of 0.25 gal/SY over the prepared surface and then applied Mirafi® MPV500. Finally, the overlay machines followed directly behind applying their HMA overlay.
The Parking Lot Performance:
The contractors involved in the rehabilitation project were given the NAPA Recognition Award in 2008. The completed project looked great and will be inspected on a regular basis to examine the service life and the inter-layer system's performance.
For additional information on geotextile fabric please see the official TenCate website