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concrete flatwork

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Let it be known already i'm a carpenter by trade, but over the years i have done a little concrete work. That being said its been a while since i actually got down to hand finishing with a steel trowel. I have been trying to pour concrete in a pole barn that i built for myself i've been pouring in sections because i'm working by myself. Now all this being said, I have never really been around fly ash before. What a pain in the tail that is to try and finish. I get the surface mag. floated and wait a bit and start with my steel and it keeps picking up these little bits of coal dust or it shatters across the surface. It is probably adding 2 or 3 times more effort to get a nice steeled surface. Now to my question. Do any of you "pros" out there have any ideas regarding what i am doing wrong or am i just behind the times and need to go rent a power trowel. Go easy i'm an old retired carpenter that knows he don't know it all.

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You are ordering it with fly ash.

That is what you are doing wrong.
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I've never seen anyone pour concrete by themselves. If I ever do, I will probably stop and help them.

What size pours are you doing?

I've had a lot of luck pouring 12' wide pours, then troweling down the sides and reaching out with the trowel as far as I can. Then I get on two pads and go right down the middle. These are typically only 24' long, but I have done them 72' long.

If you don't have a trowel on a stick, get one of these. Then you can do the hand troweling much faster.
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Fly Ash does not bond with water the same as portland cement does. This is all at a molecular level. Therefore, when fly ash is present on the surface of the concrete it loses it's water faster than portland. This leads to more "sticking" of your trowel. I would say you are being a little aggressive with your hand troweling. You need to keep your trowel flatter and allow the concrete more time to set to the point where it will sustain a steeper trowel angle. Just because you are troweling by hand doesn't mean it is a once and done finish.

For a pole barn I would recommend a fresno. Bull float once, rough in your edges, bull float again, fresno, work your edges with the mag and flat trowel, trowel the body of the slab with a low pitch, trowel your edges to finish and then final finish your slab body.

Or just rent a power trowel. We have had good luck with fresno only for ag applications. just keep hitting it until its good.
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