Located in the world’s automotive capital, the Detroit Metropolitan Airport (DTW) serves more than 30 million passengers annually. As one of the busiest airports in the region, the facility generates more than $10 billion annually. Recently, the Wayne County Airport Authority decided to renovate the westernmost runway (4L/22R) was needed. Rough pavement can harm aircraft suspension systems, especially during landings. Most suspension components are only designed to absorb the impact of landings and are unable to handle uneven pavements over a long time.
The $84 million renovation project was awarded to Ajax Paving Industries Inc. In a decade, Ajax has been involved in more than 60 airport and highway projects. This was the largest portland cement concrete (PCC) runway project in the U.S. in 2016.
Ajax overcame several challenges for the renovation project. In less than six months, 260,000 cubic yards was to be poured while complying with stringent Federal Aviation Administration (FAA) and Unified Facilities Guide Specifications (UFGS) paving specifications. The FAA’s P-501 concrete specification required Ajax to meet 0.1-inch line smoothness tolerance and 0.05-inch grade tolerance from theoretical zero.
The reconstructed runway is 10,000 feet long and 150 feet wide. Typically, it is used for aircraft arrivals and can accommodate low-visibility operations. The project also involved rebuilding taxiways, which safely connect aircraft from runways to the passenger terminals. In total, the project encompassed 6.5 miles of airfield pavement. The runway’s original cross section consisted of 17 inches of PCC, a bituminous base of 9 inches, and an aggregate base of 18 inches. For the renovation, the old PCC was completely removed and replaced, along with 3 inches from the bituminous base. The new concrete runway was placed at a width of 18.75 feet, and a thickness of 18.5 feet.
The transverse contraction joints and longitudinal construction joints are reinforced with 1.5- by 20-inch epoxy coated dowels. The dowels on the transverse contraction joints were supported by dowel-basket assemblies secured to the subgrade with the dowels on 18-inch centers. Mesh reinforcement was used only in tapers and odd width taxiway pours.
Guntert & Zimmerman's (G&Z) S850SL paver was fed up to 4,000 cubic yards of concrete daily using a fleet of both dump trucks and agitors. Each dual drum plant produced as much as 500 cubic yards of concrete per hour. At both plants, the mix was formulated to meet FAA’s P-501 spec design parameters. The paver’s spreader plow allowed the concrete to be quickly distributed, even at the lower end of the concrete slump limit.
Crews also used G&Z’s TC1500 texture cure machine. Both the G&Z S850SL paver and TC1500 are four-track and equipped with 90-degree steering and counter-rotation capability.
“The quality of product coming out of the G&Z S850SL paver was excellent,” says Pete Mann, Ajax’s project manager. “The trailing finishing pan with adjustable fixed edger assemblies provided not only an excellent surface finish, but also sharp and crisp non-slumping edges.”