Apron at Centralia Shows Minimal Wear After Three Decades of Use

The 30-year-old apron at Centralia/James T. Field Memorial Airport (YCE) in Huron Park, ON, has only recently started to show a few cracks, thanks to a fiberglass material installed between its asphalt layers in 1993. A series of site visits to YCE by the product manufacturer confirmed that the areas reinforced with fiberglass have held up better than others paved at the same time without it.

New United Goderich Inc., a privately held corporation, has owned and operated the airport since 1997. These days, YCE is primarily a hub for heavy maintenance and aircraft modifications, with two large paint bays; workshops for interior refurbishment, composite/structures repair and custom cabinetry; an avionics diagnostic department and an engineering department. One of its two hangars is large enough to accommodate a Boeing 737 or Airbus A320. With a workforce of more than 100 skilled employees, YCE provides a one-stop option with a variety of interior and exterior services for aircraft owners.

Two runways—5,012 and 4,400 feet long—suit the various Gulfstreams, Learjets, Falcons and other heavy corporate and private aircraft that fly in and out for maintenance and refurbishment. The reinforced apron is located in front of the airfield’s control tower, which was decommissioned in 1967.

Looking Back

During World War II, the airport served as a training base for pilots of the Royal Canadian Air Force and other Commonwealth troops. In 1947, it was renamed RCAF Station Centralia. After its military use ended in 1967, the facility reemerged as Huron Air Park with several manufacturing companies as tenants. The airport later became known as Centralia/James T. Field Memorial Airport.

Ontario Development Corp. acquired the airport in the late 1960s and updated the airfield in 1992. Due to harsh weather conditions in southern Ontario, paved surfaces were experiencing severe cracking, and the apron had become highly oxidized and brittle. Its surface layer showed various types of cracks, posing a potential threat to aircraft safety from loose debris being sucked into jet engines.

Initially, Ontario Development considered adding a thicker overlay to the apron without any reinforcement, but that approach was deemed expensive and only a temporary solution because thermal stresses would cause the cracks to resurface over time. As an alternative, engineers recommended the GlasGrid^® Pavement Reinforcement System as a more cost-effective and durable option. GlasGrid^® 8501 was specified to create a strong interlayer reinforcement to resist the spread of reflective cracking.

The installation contract was awarded to Cox Construction, and work began with the initial placement of hot mix asphalt over the apron section in late fall 1992. Bay Mills Limited, which has since been acquired by Saint-Gobain ADFORS, delivered two truckloads of GlasGrid^® from its manufacturing facility in Midland, ON, and installation was slated to be finished within a month. However, harsh winter weather delayed completion of the initial asphalt course. In the meantime, the GlasGrid^® material was stored in a hangar for the winter. Paving and installation of the reinforcement mat resumed in June 1993, without any tack coat required over the asphalt surface installed six months prior. The final portion of the project took only three days.

Saint-Gobain, the company that currently produces GlasGrid^®, was originally founded in 1655 as a mirror glass manufacturer in Paris and produced glass for the lavish Hall of Mirrors at Versailles. In the 350+ years Saint-Gobain has been in business, it has expanded to 70 countries and added a wide variety of glass products, including GlasGrid^®.

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Subsequent Site Visits

In February 2007, Pryde, Schropp, McComb Inc. conducted on-site inspections at YCE and confirmed that the GlasGrid^® System had effectively reinforced the apron pavement. “After enduring Canadian weather for 13 years, the cracking is minimal, and we are satisfied with the performance of the GlasGrid^® product in this application,” said Brad Pryde, the design engineer responsible for the project at the time.

Subsequent visits in 2018 and late 2022 also yielded positive reports. During the most recent inspection, the apron had begun to show some cracking. “Considering the original condition, it’s quite impressive that the apron has lasted for 30 years,” commented Dean Pettitt, a local engineer familiar with GlasGrid^® and the severe conditions at YCE. 

Why Fiberglass?

Greg Lyons, technical service manager at Saint-Gobain ADFORS, explains that more than 50 years ago, there weren’t many options to help asphalt resist tensile loads. Early products used to resist cracking in asphalt pavements contained polypropylene, which has a melting point similar to that of asphalt and also has been found to complicate the recyclability of asphalt pavement at end of life. Steel wire mesh is more resistant to mechanical damage, but it is cost prohibitive and also likely to oxidize and rust. Glass fiber coated with an appropriate formulation that resists oxidation facilitates a strong bond to the asphalt and has been found to be the most economical choice for proving long-term performance, says Lyons.

Lyons explains that glass fibers have an “elongation at break” of approximately 2.5%. This value indicates the minimal deformation required to achieve full tensile strength, and is expressed as a percentage of its initial dimension. The melting point of glass is also much higher than that of plastics or metals. “Glass may start to soften around 840°C (1,545°F) but its melting point is much higher,” he details. “Fiberglass products remain thermally unaffected by the high hot-mix asphalt paving temperatures of about 150 to 160°C (302 to 320°F).

Greg Dadson, facility and airport manager at YCE since November 2020, has personally observed the strength of the fiberglass Saint-Gobain uses in its pavement reinforcement interlayer material. “I’ve had to cut down through it in some places to do things underground, and it’s hard as hell to get through,” Dadson remarks.

GlasGrid^® is made of fiberglass strands formed into a grid and coated with elastomeric polymer formulation, and then coated with a pressure-sensitive adhesive. In the application at YCE, crews applied 1.5 inches (40 mm) of asphalt over the entire apron area. Once rolled and adequately compacted, the GlasGrid^® was placed on the full width and length of the apron. Next, the surface was rolled with a pneumatic roller, and finally, a layer of at least 2 inches (50 mm) of wearing course asphalt was paved on top of the fiberglass grid. The deeper the fiberglass grid is placed beneath the top asphalt, the better it will perform, notes Lyons.

Current Condition

The areas paved at YCE without GlasGrid^® back in 1992 will need to be replaced soon. “They paved the far end of Runway 16 at the same time, and it didn’t last,” Dadson reports. “There are cracks in the asphalt that I can walk in with my boots—they’re that wide.”

In contrast, he expects the apron pavement that was reinforced with the fiberglass mat to last another 10 to 20 years before it needs to be addressed. “The apron is hands down the best asphalt in the whole airport,” Dadson remarks. “I wish they had just done the whole airport with it.”

Whenever the time comes for YCE to update its apron, the existing asphalt and GlasGrid^® will not necessarily need to be milled down and rebuilt. “Theoretically, if you’re going to pave on top of the GlasGrid^® reinforced section, it can stay in place and still perform—there’s no need to take it out,” remarks Jeffrey Rasche, industry manager for interlayers and pavement maintenance with GlasGrid^® product master distributor Tensar Corp. “After addressing any localized deficiencies, a new layer of asphalt could be placed over the existing surface and the benefits of the initial installation of GlasGrid^® will continue. If raising the final grade is a concern, then a proportion of the existing wearing course depth could be removed via milling, and a new wearing course can be placed over the entire apron. Often, there is not a need for another installation of GlasGrid^®, but if the wearing course must be removed—and was initially installed thin—another application of GlasGrid^® may be required.” 

Getting It Right

Lyons says that long-term success for a fiberglass pavement reinforcement system hinges on three important factors: favorable subsurface conditions, selecting the right product and proper installation. Regarding site conditions, he advises against using the product in areas with a weak subgrade or “punchy pavement” because the pavement will continue to shift, reducing the effectiveness of the reinforcement.

Dadson adds that determining where to use such a project is key, and you can’t assume it can be applied over rolling spots. “You have to fix the thing that’s heaving out of the asphalt,” he says. “You can’t just put it over top and think it’s done.”

Choosing the proper product is also key. It is essential to identify a pavement reinforcement interlayer material that aligns with the intended application and has the appropriate coating and properties for an airfield’s particular conditions. 

Finally, the installation process is crucial. Even with the finest materials and appropriate tools for the job, there is still a risk of mishandling the project.

At YCE, the subgrade was sufficiently strong. In addition, the installation contractor set up its own asphalt plant on the airport property, which meant crews worked with hot asphalt produced close to the application site instead of having to transport the “perishable material” over long distances. “Cox Construction did a great job of paving, and they did quality work,” Lyons notes. “We had everything going for ourselves on this project.”