Joints: chemistry or physics?  (126)

Joints: chemistry or physics?  (126)

Each time more, chemical products are relegating physical-based mechanisms to a second plane but, look at those amazing joints between concrete panels!! They are taken from old construction books.

Water tightness is entrusted to drainage: an open joint plus a draining cavity. The only sealing among panels seeks to solve air tightness.

This open joint between concrete panels in an old building in London proves to those young chemistry lovers that drained joints use to be the solution.
 

Nowadays the basis is chemistry, and the new question to be done is whether an on-site application or a prefabricated gasket.
Curtainwalls, unitized panels… they always use prefabricated gaskets, why not in concrete? Look at this panel seen in Amsterdam some years ago!!

We do not need to say that, in most of the cases, the strategy is combined: impermeable material sealing the joints in two different planes –outside and inside- and, in-between a cavity. If a lost drop of water gets in through a failure in the sealing, it will rapidly dry thanks to the ventilation ensured by those micro tubes that keep air circulating inside the in-between camera. But most important, those tubes help to equipressurize the air inside the cavity with the outside pressure, and so prevent the drop to get in!