Cairo Airport Roof Waterproofing
In 2020 and 2021 the roofs of the Ministry of Aviation building and the Seasonal building at Cairo International Airport were waterproofed with hot-sprayed pure polyurea. El Fath Contracting applied it. Krypton Chemical makes the resin.
Overview
Cairo International Airport, in Heliopolis, is the country’s main gate. The Ministry of Aviation building and the Seasonal building sit inside that operation. The Seasonal building takes the Hajj peaks, when the roof cannot be a reason to close a hall.
The work was the roofs. Hot-spray pure polyurea, in 2020 and 2021. El Fath Contracting ran the application. Krypton Chemical supplied the membrane.
| Place | Cairo International Airport, Heliopolis |
|---|---|
| Buildings | Ministry of Aviation building and the Seasonal building |
| Year | 2020 to 2021 |
| Work | Roof waterproofing |
| Membrane | Polyurea Rayston, hot-spray pure polyurea |
| Application | El Fath Contracting |
Challenge
An airport roof is a working lid over people who are not there for the waterproofing. You do not get a quiet month. The Seasonal building in particular fills and empties with the pilgrimage. A system that needs a week between coats asks the airport for time it does not have.
Heliopolis puts a hard sun on a wide concrete deck. The slab moves between noon and night. Water on a flat roof runs to the outlet and the parapet, and that is where a tired detail fails. A leak in a ministry building or a departure hall is not a stain you repaint. It is a ceiling over a public room.
The two buildings are different in use and the same in duty. Both need one film, stuck to prepared concrete, thick enough at the upstand, and fast enough that the bay is closed the day it is sprayed.
Solution
The membrane is Polyurea Rayston, Krypton Chemical’s hot-spray pure polyurea. Two components, heated and sprayed. Gel time is about 4 seconds at 25 degrees C, and the film is tack-free in about 30 seconds at spraying temperature. On a live airport that speed is the specification.
The typical build is 1.5 to 2.0 kg per square metre, about 1.5 to 2 mm. Elongation is about 324 percent, tensile strength about 16.2 MPa, tear strength 69 N/mm. Liquid water permeability is 0.002 kg per square metre per square-root hour. Those are the product’s own figures. They are why a sun-loaded roof can move without opening a path for water, and why the outlet gets the same film as the field.
The resin is aromatic, so the colour can shift in the sun. The mechanics do not. Where the roof must keep a set shade, an aliphatic topcoat does that. The waterproofing is the polyurea.
Application
The deck has to be a real substrate before the machine is heated. Pull-off at least 1.4 N/mm2. Moisture under 4 percent. Surface temperature between 10 and 40 degrees C, and the air not so wet that condensation sits on the concrete. Higher moisture does not stop the reaction. It makes the bond a gamble.
Preparation is mechanical. Open the pore, repair cracks first, take off sharp edges, and vacuum the dust. An airport roof collects grit. If damp is suspected from the slab, the datasheet calls for two coats of epoxy primer, the second blinded with quartz. Metal flashings are cleaned and primed with the polyurethane primer.
Both components are brought to about 25 to 30 degrees C, the amine side stirred and pigmented, then sprayed. Component A at 65 degrees C, component B at 75 degrees C, hose at 65 degrees C, pressure at least 140 bar. The pass is watched so 1.5 to 2 mm actually lands, including on the parapet and around each outlet. A thin corner on an airport roof is the leak.
Hardness starts within minutes. The datasheet tracks Shore A from five minutes through four days at 25 degrees C. The bay can be left. It should still be walked, and the outlets accepted, before the roof is called finished. El Fath’s crew did that application. Krypton’s job is the resin and the build the datasheet sets.
Results
Two roofs at Cairo Airport, the Ministry of Aviation building and the Seasonal building, carry a hot-spray pure polyurea membrane from the 2020 to 2021 works. The film is continuous across the field and up the details that take the water.
Crack bridging on the datasheet reaches class A5 at minus 10 degrees C and class B4.2 at 23 degrees C and at minus 20 degrees C. Cairo will not use the cold end. It will use the movement. Shore hardness of 87A and 35D leaves a film that can be walked for maintenance and still follow the deck.
Products
Polyurea Rayston
Hot-spray pure polyurea for both roofs. Typical 1.5 to 2 mm. Elongation about 324 percent. Gel about 4 seconds at 25 degrees C.
FAQ
Why hot spray on an airport roof?
A terminal roof cannot wait on a slow film. Polyurea Rayston gels in about 4 seconds at 25 degrees C, so a bay can be sprayed and the crew can move on while aircraft and passengers keep using the building.
How thick is the membrane?
The typical rate is 1.5 to 2.0 kg per square metre, about 1.5 to 2 mm. That is datasheet data, not a core cut from these roofs.
What does the concrete need first?
Pull-off of at least 1.4 N/mm2, moisture under 4 percent, and a surface between 10 and 40 degrees C. Open the pore, repair cracks, and vacuum the dust before the gun starts.
Can the roof move in the Heliopolis sun?
Elongation is about 324 percent, with crack bridging that stays elastic in the cold as well as at working temperature. A flat airport roof swings every afternoon. The film has to swing with it, including at the parapet and the outlet.
Will the colour stay?
Polyurea Rayston is aromatic. Sunlight can shift the shade. The strength does not follow the colour. An aliphatic topcoat holds the appearance where the roof stays open to the sky.
Photos
