[justagrunt]

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.
Thanks


"The time is near at hand which must determine whether Americans are to be free men or slaves." – George Washington

 

[NYCB]

You are ordering it with fly ash.

That is what you are doing wrong.

 

[cleveman]

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.

 

[PPRI]

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.