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Silicone Joint Sealers for Concrete Construction

Silicone joint sealants used in construction of new runway at Andrews Air Force Base.

Concrete Performance

Silicone joint sealants from Dow Corning Corp. were selected for use in the reconstruction of the primary runway at Andrews Air Force Base to provide a performance seal for the concrete joints. 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 replacing 11,300 feet of the 200-foot-wide concrete runway.

On the Fast Track

Because Joint Base Andrews only has two active runways, replacing the west runway needed to be done as quickly as possible to minimize the disruption of operations. The materials used for constructing 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, 888 Silicone Joint Sealant and 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.

Making a Quality Connection

The joints between the large airport runway slabs are specially designed to move within the silicone’s movement capabilities (+100/-50%) due to concrete thermal expansion cycles and as opposing slabs deflect during an aircraft takeoff or landing. These joint sealants meet the Federal Aviation Administration (FAA) P-605 silicone sealant requirements for use in airfield applications, and 890-SL 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 jobsite. 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 onsite 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.

Silicone joint sealants used in construction of new runway at Andrews Air Force Base.

How to properly remove silicone sealant

When properly made, silicone sealant joints that seal your doors, windows or bathtubs can last for many years. However, a silicone seal will inevitably reach the end of its useful life and will have to be replaced with a new seal.

For the sealant to be fully effective, however, you must properly remove the old silicone sealant joint before applying the new one.

Here’s how to do it.

1- Make an incision along the silicone seal

First, use a utility knife or razor blade and make an incision along the silicone joint, running the metal blade as close as possible to the wall. Perform this task while being careful not to cut the wall. Then repeat the process on the other side of the joint.

2- Remove a first layer of silicone sealant

Once you have cut the joint you want to remove along its entire length, you can grab one end and pull it. Some silicone sealant joints that have lost adhesion over time may be very easy to remove in their entirety, while others will be less cooperative. If you feel resistance, you can use a putty knife to help you remove the joint.

In most cases, after this step, the majority of the joint should be gone and only some residue should remain.

3- Remove sealant residue with a blade

Use a flexible plastic or metal blade to scrape off silicone that may have stuck to the surfaces. Place your blade at an angle and take your time to avoid scratching or damaging the surfaces. Normally, a few back and forth movements will be enough to remove the majority of the sealant residue.

4 – Finish the work by properly cleaning the surface

Once you have removed most of the silicone, wipe off the last traces of sealant with a cloth. You can make it easier by soaking it in an alcohol-based cleaning agent. The alcohol will act as a solvent, breaking down the remaining silicone, making it less sticky and easier to wipe off.

If you intend to make the new joint immediately after removing the old one, it is best to wait about 20 minutes for the solvent to evaporate completely before applying the new silicone sealant.

Have any questions? Ask the Adfast team for advice

In conclusion, the effectiveness and appearance of your new silicone seal will depend on how you remove the old seal. Follow these steps and you will have a good chance of making a new durable seal.

If you are wondering which sealing product to choose for your new seal, you can count on the products in Adfast’s Adseal product line. You can even contact our experts to be 100% sure you are making the right choice!

Find out how to easily and cleanly remove a damaged silicone seal from a joint that needs to be replaced with a new one.