Sealing Curved Expansion Joints–Possible, Practical, Routine
JFK INTERNATIONAL AIRPORT, New York, NY—the curve in the departures roadway at the new Jet Blue terminal is both elegant, functional and ergonomically steers traffic to optimize flow. The roadway is structurally separated from the terminal building by an expansion joint. The joint is therefore curved.
Curved expansion joints can induce complex movements in the joint materials chosen to seal them. These movements can be managed, however, by a combination of the flexibility of high-quality materials and through the conservative sizing of the joint openings in relation to the expected movements. This being done, the capability of a manufacturer to fabricate and configure the joint system to follow the curve without compromising watertightness becomes the next challenge, followed in turn by the installation of the systems by a qualified contractor.
EMSEAL routinely handles curved expansion joints. Outside radii in joints in the vertical plane are handled through the flexibility of the material in the case of EMSEAL’s Seismic Colorseal family of unique hybrid silicone and precompressed foam sealants. In tight curves, notching of the back of these materials is used to relieve the bending stresses and facilitate the curve.
Inside radii in the horizontal plane are handled by EMSEAL’s deck expansion joint systems, like Thermaflex, through the flexibility of the thermoplastic-rubber extrusions. In in tight radii conditions the thermo-plastic rubber extrusions can be segmented and factory-welded to follow curves while ensuring continuity of seal. The curves of joints in ice-floor perimeters and other horizontal deck joints around curved or elliptical columns have routinely been handled by EMSEAL’s hybrid foam materials like the DSM System.
In the case of Jet Blue, the deck design required the use of EMSEAL’s Migutan FP system for split-slab construction. This is because the roadways at airports are also roofs. The roofs are over the arrivals area. There is nothing worse after a long flight and all its hassles than to have to wait for your cab beneath the icy drips of leaks from above.
Airport departure roadways are usually designed as split-slabs with a buried waterproofing membrane on the structural deck and a topping slab as the wear course. Expansion joints used to isolate the roadways from the terminal building must be watertight. In order to be watertight, the joint must tie into the deck waterproofing membrane.
Migutan FP from EMSEAL was specifically designed to achieve this incorporation. The principle of static integration of the Migutan FP side flashing sheets into the deck waterproofing membrane is in total contrast to buried flashing sheets, loops, and “band-aid” systems that suffer from tensile stresses during extension movement and flex-fatigue at the joint edge. The integration into a sandwich of the deck waterproofing membrane material of the Migutan FP side flashing sheets ensures watertightness while joint movement is accommodated by the elastomeric insert at the wear course surface.
Following the curve in the deck is no problem either. Working with EMSEAL’s technical staff, the contractor provided field measurements and condition surveys from which EMSEAL produced detailed shop drawings showing the configuration of the materials to handle the radius. The materials were manufactured and marked according to the shop drawings making installation straightforward and efficient.
In tighter radii, it is easy to envision EMSEAL’s precompressed foam sealants following the curve. However, even when watertight integration into a split-slab or plaza deck is required, Migutan FP can also fit the bill. A case in point are the concourse joints in the new DC Nationals baseball park. These joints run tangent to elliptical columns.
Templates made by the contractor for each column became the basis of shop drawings by EMSEAL. From the shop drawings and using the templates as a quality control check, unique curved joints were produced for each of the columns.
The curves were fabricated in all the metal Migutan FP components including mounting flanges, retainer legs, stainless steel capping strips, and coverplates, but also in all of the rubber components that ensure watertightness and continuity of seal. The rubber components include the side flashing sheets that integrate into a watertight sandwich with the deck waterproofing membrane, and in the central sealing insert that bridges the expansion joint opening.
The bottom line is that through careful joint-gap sizing, material selection, field measurement, fabrication and installation, watertight, curved expansion joints are both possible and practical, and for EMSEAL, routine.
Contact EMSEAL for assistance with your curved expansion joints–we’ll bend over backward, frontward, and sideways for you: 1-508-836-0280 or firstname.lastname@example.org.