I believe the anticipated infrastructure work is underway at GRU and adding to the problems. Last week on UA 860 from GIG we were ready to leave 10 minutes prior to scheduled departure but the Captain announced there was no gate available at GRU so they would wait for a while at GIG. Left 15 minutes after scheduled departure. At GRU we waited another 20 minutes and then pulled up to Gate 12 where the jet bridge wasn't working, so down the stairs and on to buses, Then had to go through the security check. Reboarded to continue the flight at Gate 10. Had to wait some again as the Captain announced only one runway was in operation. Boarding out of Gate 4 is no fun, so I'm glad that didn't occur this past trip, but I expect it to happen more frequently