Air-entraining admixture in concrete

[Johan Gunverth]

I'm preparing some outdoor stair casting that will be done in the spring and need to protect the concrete from frost damage. Sika has a product called Aer that comes in three variants: SikaAer-S, SikaAer-5, and SikaAer15b. Which of these is suitable for casting an outdoor concrete stair using a regular cement mixer?

Alternatively, are there other products that we consumers can buy?

...and, no! I don't want to call the concrete truck.

 

[LLLVäxjö]

Probably doesn't matter. Seems to be just different ingredients but the same function.

Good luck getting the right air content without measuring equipment

 

[Johan Gunverth]

...Good luck with achieving the right air content without measuring equipment

Aha! So it's that sensitive. I'll have to think a bit more then.

 

[LLLVäxjö]

Aha! So it is that sensitive. Need to think about it a bit more then.

It's sensitive, but certainly not impossible. I just thought of something, we who work with concrete use air content meters, but for the happy home mixer, it might be precise enough if you weigh the concrete before and after the addition.

Like: you mix to the right consistency, fill a jar, weigh the jar, then add the additive into the mixer, mix moderately, fill the jar again, which hopefully weighs about 5% less.

In any case, that gives you something to go by. However, one problem is that the air content increases with longer mixing time, which complicates it a bit.

Does anyone have experience with mixing concrete with air at home?

 

[Johan Gunverth]

The concrete thus swells noticeably. Does the air formation stop when the concrete "stops," i.e., is not mixed anymore?

The problem with a concrete truck is that it's such a small amount and therefore feels unnecessarily expensive. It's not being foolishly frugal that drives it.
Otherwise, I have both Ballast and Maxit quite nearby. Maybe I should go there and get pre-mixed instead...

 

[LLLVäxjö]

The concrete noticeably swells. Does the air formation stop when the concrete "stops," i.e. is not mixed anymore?

The problem with a concrete truck is that it's such a tiny amount, and therefore it feels unnecessarily expensive. It's not a matter of being penny-wise and pound-foolish.
I have both Ballast and Maxit quite nearby. Maybe I should go there and pick up pre-mixed instead....

I don't think it can increase after mixing.

How necessary is it to have air in a staircase then? I myself don't have much knowledge about it.... Maybe it can be compensated to some extent with a higher quality type instead?

 

[Johan Gunverth]

...
How necessary is it to have air in a stair then? I don't really have much knowledge about it myself.... Maybe it can be somewhat compensated with a higher quality instead?

That's what I'm asking myself too. I got some opinions that it should be done, but at the same time, I see stairs that grandpa made in the 50s that are still intact and nice. He only used regular home-mixed concrete. A bit "richer" though, as he says. That should mean a somewhat larger proportion of cement.