In their marketing materials, the U.S. Army Corps of Engineers Middle East District often refers to their ability to accomplish projects in “some of the toughest construction environments in the world.” This saying was recently put to the test at an undisclosed location in the Middle East as they made repairs to one of the installation’s runways.
“Airfield pavement is something that’s particularly challenging,” said Dean Ash, a mechanical engineer and the project engineer for the work. “Runways obviously need to be designed to withstand huge amounts of stress. Combine that with a pretty harsh environment and there’s little room for error.”
According to Ash, the project had to overcome numerous challenges in order to deliver a product that would meet the Air Force’s operational needs. Those challenges included, extremely high temperatures, sand storms and a language barrier among the workers.
“At one point, I believe there were up to six different languages being spoken by workers on this project. Our District has extensive experience in the Middle East so it’s something we’re used to dealing with but when you’re working with something that’s highly technical, it doesn’t leave any room for error so we really had to make sure everyone was one the same page,” he said. “There was really a team effort all around, from the Air Force, the contractor all the way down to the construction crews.”
Ash said that sandstorms also posed a challenge since sand particles in the concrete mix could compromise it, but with day time temperatures often over 120 degrees, heat was by far the biggest challenge.
According to Ash, temperature and relative humidity can have a huge impact on concrete curing. Temperature and moisture content in the mix, and of the surface of the concrete once poured, have to be maintained at certain levels to prevent plastic shrinkage cracking, creating debris hazards on the runway.
Crews often worked at night to try to mitigate the heat but also came up with other innovative solutions.
“The contractor rented a chiller to introduce three degrees Celsius water into the batch plant during batching. The contractor also used ice to cool down the temperature of the aggregate that went into the mix. These steps were able to get us a usable mix but it was challenging,” said Ash.
Getting the right concrete mix was critical to the project and the team had to prove they were going to be able to do that before they could begin work on the runway. This meant placing 200 meters of concrete ensuring quality prior to beginning work on the runway.
“Getting the mix right was important,” said Ash. “But it was also about the craftsmanship of the contractors. They had to demonstrate their ability to produce the concrete out of the batch plant at the correct rate to keep up with the slip form paver; the paver operators had to prove they can operate the equipment properly, and the finishers had to demonstrate proper technique to meet specifications without over finishing. Everything really needed to come together and the test lane was the “practice run” that ensures all aspects of the contract, the materials and the workmanship, can come together to produce an acceptable product.”
We worked closely with the Air Force on this and needed to make sure we’d be able to get this done before shutting down the runway. That meant making sure we had the right materials locally and ensuring we had the concrete mixes right.
To do this, the District relied on support from the Transportation Systems Center of Expertise (TSC) out of the Omaha District which has engineers with a background in airfield pavement. Because of the unique challenges associated with the environment, the TSC was able to take some lessons learned from the project.
When the project was finished, the contractor had placed over 4000 square meters of concrete over eight lanes. Completion of the work will significantly increase the operational capability of the airfield, which serves as the primary tactical airlift hub for re-supply missions throughout the Persian Gulf Region.