October 1, 2005

Reagan National Airport (originally National Airport) in Washington, D.C., was completed in 1941 with an art deco design and architecture. Cracks began to appear in the terminal walls with the passage of time and it became necessary to fix the problems.

It was originally thought that simply filling the cracks would do the job. However, it was soon discovered that a lot of the concrete was no longer sound. The weight of the original pour in 1941 forced the reinforcing steel too close to the exterior surface. As a result, the rebar became severely rusted, which eventually led to major spalling over a significant percentage of the building’s outer walls. Some of the repair areas were up to 3-feet across and 9-inches deep.

Jahn M90 concrete repair mortar was selected for the job. The product offers compatibility with concrete substrates and a healthy pH factor that blocks corrosion and carbonation. It freely releases the moisture and minerals that inevitably accumulate inside repairs, and needs only one application no matter how deep the damaged area.

The Jahn M90 was custom formulated by Cathedral Stone Products Inc., Hanover, Md., to attain a close match of the texture, color, and physical properties of the original Reagan Airport concrete. Cathedral Stone trained masons recreated the form lines embedded into the concrete by the wooden forms used for the original pour. Any minor appearance variations between the repair areas and the original concrete were virtually eliminated when a final coating of potassium silicate was applied.

The first step in restoring the exterior of Reagan Airport involved excavating all unsound concrete to a depth at least 2-inches below the rebar. Sandblasting removed the rust from the rebar and any other loose material. Workmen with mirrors checked the back of the rebar to make sure all rust was completely removed. At this point, the excavation sites were thoroughly checked by Cathedral Stone Products professionals.

If everything was satisfactory, the rebar was painted with a special epoxy coating and the custom-formulated concrete repair mortar was installed. After the mortar cured, the entire job was again inspected. Even slightly unsatisfactory work was pulled out and redone.

After all repairs on the building were completed and signed off by Cathedral Stone, a 10-year warranty against failure was turned over to airport authorities. Unsound concrete was removed, sandblasting removed rust from rebar (which were then painted with a special epoxy coating), and custom-formulated concrete repair mortar was added to complete the job.