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Comment by periheli0n | Hacker News Reader

This would never be possible in the UK.

Rainwater and sea spray would corrode any exposed rebar away within a few years.

In fact, I wonder whether it is such a good idea to build on rebar that has been exposed to the environment for an extended period of time.

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when people actually care about protecting the starter bars (exposed rebar to star the next floor), you can cast a very weak concrete (1-2 MPa crushing strength) around them. When construction continues, you just chip out the weak concrete, clean the bars with a wire brush and carry on.

But if there is never good intention to actually "finish" the construction, then it wouldn't matter much.

True, but still, moisture can creep in where rebar exits the concrete, and lead to rebar corrosion inside the structure. Less of a problem in Egypt than in the UK or similar climates.

sea spray? Britain isn't a narrow coastal strip.

You can wrap it in plastic and this is a non issue

My experience living on a Florida key gives me the intuition that that is false, unless by wrap you mean seal

I was unaware of how incredibly destructive the combination of daily, continuous, direct sunlight, humidity, and salt water was until my parents moved to Florida. It's really incredible. A few years and literally every material is mottled and crispy.

The entire state of Florida should be a nature preserve, maybe it already is.

Plastic doesn't hold up well to sunlight.

Luckily this isn’t an issue in the UK.

Spray it with truck bed liner, job done.

One could always paint the exposed rebar to protect it.

The point of sealant is that it won’t come off easily. But rebar with painted-on sealant is most likely less able to properly attach to concrete. Therefore, it might be difficult to use properly sealed rebar for further construction?

Grind it off or use some kind of paint remover.

Worst case I guess you could use paint stripper on it before use?

But I expect rebar-sealer exists for exactly this use...

Rebar sealant would only help if the entire rebar is sealed, not just the exposed bit, since moisture will creep in where the rebar exits the concrete. And even then, moisture inside the concrete wall may well cause other problems in the long term.

Or just use non metallic rebar (basalt)

Not a good idea. Paint on the rebar will severely weaken the concrete adhesion in just a few years.

Construction codes in a number of countries prohibit that.

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