Silicone joint sealants from Dow Corning Corporation were selected for use in the reconstruction of the primary runway at Andrews Air Force Base. Also referred to as Joint Base Andrews, the base operates the only military runway within the National Capital Region and supports the presidential airlift mission (Air Force One), aeromedical evacuation flights and contingency response scenarios.

The west runway – one of just two at the base – was originally built in 1960 with an expected 25-year lifespan. Not surprisingly, by 2010 it was failing and needed to be completely replaced. The construction project, which began in late summer 2010, involved the replacement of 11,300 feet of the 200-foot-wide concrete runway and 25 feet of asphalt shoulder on each side.

Dow Corning® brand silicone joint sealants were selected as the material of choice to provide a performance seal for the concrete and asphalt joints.

On the Fast Track

Because Joint Base Andrews only has two active runways, the replacement of the west runway needed to be done as quickly as possible to minimize the disruption of operations. The materials used for the construction of the runway also had to be easy to work with under a variety of weather conditions.

As one-component, cold-applied materials with a constant consistency over a wide temperature range, Dow Corning 888 Silicone Joint Sealant and Dow Corning

890-SL Silicone Joint Sealant are ready to be used straight out of the container and can be applied by hand or with a pump – without the need to prime the concrete or asphalt.

Dow Corning 888 Silicone Joint Sealant also skins over rapidly, which helps speed up the construction process.

Making a Quality Connection

The joints between the large airport runway slabs are specially designed to move within the silicone’s superior movement capabilities (+100/-50%) due to concrete and asphalt thermal expansion cycles and as opposing slabs deflect during an aircraft takeoff or landing. In fact, Dow Corning 888 Silicone Joint Sealant and Dow Corning 890-SL Silicone Joint Sealant meet the Federal Aviation Administration (FAA) P-605 silicone sealant requirements for use in

airfield applications, and Dow Corning 890-SL Silicone Joint Sealant is designed for use in concrete-to-asphalt joints such as the shoulder joints of runways.

The silicone sealants must be stored properly and meet quality standards when they arrive on the job site. Kenseal Construction Products, the Dow Corning distributor for the project, knows the standards and helps run field quality checks along with the paving contractor.

“All of the material we received on-site was in prime condition for use. There was no wastage or spoilage, which can happen if the sealant is stored improperly or kept for too long,” says Rob Nielsen of Pavement Contracting Services, the company that completed the installation.

A Large Project With Big Expectations

The massive runway project required the use of nearly 300,000 linear feet of silicone sealant. Approximately 265,400 concrete-to-concrete contraction joints and more than 7,000 feet of concrete-to-concrete expansion joints were sealed with Dow Corning 888 Silicone Joint

Sealant, while about 25,000 feet of concrete-to-asphalt joints were sealed with Dow Corning 890-SL Silicone Joint Sealant, according to Nielsen.

“The project went very smoothly from the standpoint of the sealant supply,” says Nielsen. “The people at Kenseal worked very closely with us, and as a result, we always had the amount of sealant that we needed for each phase of the project. The quality and reliability of their service was an important factor in the success of the runway construction project.”

Ensuring Reliable Performance

Sealants keep water and salts out of the joints, which helps reduce erosion of the sub-base and corrosion of the metal tie bars embedded in the concrete slabs. And Dow Corning sealants are designed to provide a long-term seal that gives ongoing protection. The company’s silicone joint sealants have high movement capability, stretch easily without putting strain on the joint, and readily return to their original size after being stretched or compressed. They also are weather- and UV-resistant, and thus are a durable solution for runway construction projects.

Silicone Solution for the Future

Silicone sealants have been specified and used successfully in many airfield applications.

Dow Corning silicone pavement sealants meet the FAA Airport Construction Standard (P-605) for joint sealing of concrete runways and asphalt runway shoulders. Now, Dow Corning 888

Silicone Joint Sealant and Dow Corning 890-SL Silicone Joint Sealant are helping to ensure that Air Force One can take off and land safely at Andrews Air Force Base.

 For more information, visit dowcorning.com/construction.