220 stories in 90 days how long will it last.

[Mechatrommer]

I am still of the opinion that steel reinforcing probably should've been used here, and probably was supposed to be used, and may have prevented  the building from falling.

i dont think steel will stand a chance for so long underneath the hazardous area (water salt etc) once corroded it will worsen the concrete pile strength. but i'm not civil expert so not 100% sure. but cheaper will usually win, and backed by the "specialists". we have a situation like this few years back, and the code ammended to prohibit tall construction near the hill or slope. not anything to enforce steel in a pile. i can see steel'less piles are still in use, if i'm not mistaken from the look of em and heard rumours. also with newest technology, i can see alot of "cheap" buildings going up these days, esp for low cost apartment. i call them... cupboard buildings. scary if you ask me, but so far no incident yet, hopefully keep that way.

[HackedFridgeMagnet]

Yes I wouldn't like to live in one for too long either.
Apart from the rust,  the older ones may be safer.
I lived in one once that was 25 stories in Hong Kong, that was built on reclaimed swamp land.
I used to worry about it quite regularly.

[SeanB]

Steel reinforcing in concrete is good if they are more than 10cm beneath the surface, where the alkaline enviroment will keep them safe for centuries. Problem comes from salt penetrating the surface and changing this alkaline environment to either a neutral or a slightly acid environment, which then causes rust.

In the harbour they wanted to remove old WWII antisub barriers, and they took about 5 months longer than anticipated as the reinforcing, aside from being basically lots of old rail track, was still in near perfect condition. Lots of blasting and underwater cutting was needed to get it small enough to crane onto a barge for removal out to sea for reef building.

[G7PSK]

In the UK the minimum cover for steel reinforcement is 25mm. 

[SeanB]

Bridges and sea salt exposure need more than that for long life.