Cooling Tower Expansion Joint Sealant

I'm not sure if it was polysulfide or not, but the last aluminum business entrance door I had put in was caulked with Butyl, I think. Quite expensive, and once the tube is opened you'd best use it all, or it will just cure in the tube. Like 5200 marine sealant (best stuff since sliced bread).

Butyl is one of those sealants that you have to have experience installing, you can't mess with it like some caulks you can tool and touch up with a wet finger. The installer laid down a beautiful bead in one pass and then left it alone.

A high grade Polysulfide sealant should last much much longer than 5 years. It is possible that whatever type was installed was a cheapo version or was "cut" for flowability. Also, in is extremely important that the substrate surface to which it will be attached must be thoroughly dry and free of dirt and debris. You don't say whether the sealant joint is exposed to the elements. Most polysulfide sealants are used within (buried) within a structural or other element, thereby protected from weathering.

I agree that butyl sealant will be much better for use in a concrete structure if it is exposed to the weather.

This is in a concrete basin to a wooden cooling tower. It is open on the sides to allow air to flow in with large fans mounted on top to pull heat and air through the cascading water.

The water is about 5ft deep and the joints are exposed for about 3ft on the outside from the ground. Picture a 6.5ft deep pond set 3.5ft in the ground with 5ft of water inside. The joints run from side to side and are only exposed to the sun on the outer edges. When the tower is running the whole area is damp with dripping water from mist that escapes the open side louvers.

We don't believe the previous sealant was cut for flow and are confident that the contractor prepared the surface properly.

Drew K

What about that black rubber tar stuff I see them spreading on the highways? It looks like it is spread hot by a guy with a coffee can on a stick. I saw some workers using it in the U.S. midwest to fill in cracks in the blacktop, some were quite large.

Drew K

So then, are you referring to the joints in the concrete basin, or joints between sheets of plywood decking on the return deck above? Thermal cycling of the cooling tower between hot and cold weather, or forward air flow to reverse air flow may result in sufficient thermal expansion/contraction to gradually loosen nearly anything, and if the wood is being attacked by alkaline halogen oxidizing biocide, I can't think of any sealant that can penetrate new wood deep enough not to let go when wood fibers give up and come loose from the surface of the wood.