|Concrete public furniture
The idea of using concrete for public furniture is a good one at that. Other materials heat up in the persistent sun rays, while concrete stays cool. Cleaning this type of product is easy - high pressure water gun, or rag and bucket of water.
As you can see this form is produced by a external form block which is most likely in two parts. A release agent is put on the form blocks surface, then the concrete is poured into the form. Also there would have to be some sort of binding agent. Some sort of fiber natural or synthetic that will give the chair structure and rigidity.
For the public in Buenos Aires....you guys are lucky to have these chairs!! They are quite comfortable as well!