View Full Version : Need Cement finishing advice please!

10-30-2007, 12:57 AM
Hi guys! I'm hoping someone here can help me out. I've tried to find an expert to do this but they are so busy there's a two month waiting list.
I need to pour a floor inside the existing 1/3 of my shop. It's 9X30.
I plan on using the old floor as a guide for one side and lay 2X4 on the other side to guide a board to rough level it to the form.
Once that's done can I just use a bull float to get it smooth enough?
There's isn't a whole lot of room to get one of those motorized paddle deals in there.
The last floor I poured (the only one) turned out very smooth with the power machine. Waaaay too smooth. The floor was slippery to the point it was dangerous. I lucked out getting it that smooth as I sure didn't know what I was doing.
I don't care to ever have a floor that shiney again.
What would you all do?

A.K. Boomer
10-30-2007, 01:04 AM
Nice --- get into the archives and read on how i had the opposite problem, maybe we can swap recipes and equal out each others FUQE ups!

10-30-2007, 01:12 AM
Russ, last time I finished a slab I gave it some texture and traction by lightly dragging a stiff two foot broom across it.
Excellent traction...just don't trip and do a lip-stand!

10-30-2007, 01:23 AM
Willy...would I still need the machine or can I do this by hand? I'd have to cut a hole in the wall to get the machine in...unless the blades come off easy.

10-30-2007, 01:25 AM
AK...I remember something about you having troubles. BTW...if I used the search function....what the hell would we have to talk about? This place would suck if we all used the search button :D

10-30-2007, 01:39 AM
As usual, I did it by hand.:D
It's not that big a slab, you should have lots of time.

J. Randall
10-30-2007, 04:09 AM
Torker, if you are using big rock, you need to knock it down some with a jitterbug to get enough grout to the top to get an acceptable bullfloat finish. If you just use the float I would broom it and call it good. If you want it slick, then make you some knee boards and get out on it with a steel hand trowel when it sets up enough to ring under pressure from the trowel, you can get it pretty slick if you don't have to large an area.

10-30-2007, 09:03 AM
Remember, there isn't anything free. A "broom" finish, like a sidewalk, is fine as far as non-slippery goes, but it's harder to broom/clean/maintain. A real smooth finish is just the opposite, easy to clean, but slippery. It's up to you to decide which finish will be for you.

Since this is for a machinist' floor, I would think a strong broom finish would be hell to sweep up the chips. I would opt for a "light broom" finish.

Float the concrete with a bullfloat and let it sit. Get the aforementioned knee boards and a steel trowel and start trowling until the surface it getting fairly smooth. TIMING IS EVERYTHING! Then, use a fine hair push broom, wet it, then with just a little pressure, drag it across the trowels surface. You will soon see how much pressure will give you what you want. Keep cleaning the broom with water so it doesn't build up.

tony ennis
10-30-2007, 01:12 PM
I'd get the machine in there by hook or crook, esp if you don't have 5 pals helping.

10-30-2007, 01:58 PM
You can do it by hand with a trowel. Use a board to get the rough level and a trowel to smoth it out. Are you mixing it yourself or are you having it delivered?

I would finish it as slick as possible and seal it with a sealer. The final coat of sealer, mix in some sand. If you don't like it you can peel it off or add more sand and sealer if it is too slippery. The sealer will also stop oils and other products from seeping through the ciment.

I would also install an expansion joint, a sheet of black joe, between the 2 ciment floors OR anchor them together with rebar. You will have to drill into the old ciment, a foot or so, and anchor the rebar in the old floor with hydraulic ciment. Over time the 2 floors will move. Anchoring them together will help prevent them moving apart. An expansion joint will absorb the movements if they are not too great.

I can recommend some sealing products if you want.

Rob :)

P.S. Don't forget to slope the floor for water run off.

10-30-2007, 02:22 PM
ciment? or cement?. thats what it is in powdered form, after mixing with water, sand and gravel it becomes concrete. Not sure I put much faith in advice given by someone that can't even spell it or know what it is.

10-30-2007, 08:46 PM

I get them mixed because i am bilingual, English et Francais! It is ciment in one language and Cement in the other. I get them mixed up. Oops!

Rob :)

10-30-2007, 08:56 PM
Torker, I am not an expert on ciment and cant spell it too. You mentioned a 2x4 along one side. I would hope you make a shop floor much thicker than 4 inches and throw in plenty of rebar too. My shop floor is 4 inches thick and breaking up badly and sinking too! Iknow you have the Ohio and probably some other heavy pieces . Do it right the first time. JIM

10-30-2007, 09:49 PM
Russ if it were me I would power trowel it,but just enough so it's flat with no ridges.If it's a licttle slick,some epoxy floor paint swept over with sand while it's tacky and then second coated works good.It's popular in offshore power modules where there is lots of oil/water/grime present.

10-30-2007, 11:18 PM
Hey guys! Thanks for all the excellent advice on my seement project :D
Now you all have me leaning towards bashing a hole in the front wall and lugging a machine in there.
Yup...I'm buying the strongest seement they mix, putting in lots of rebar, in floor heating and the slab will be more than 4" thick. I'm shooting for 6" deep but may make one end 8" deep for the heavier stuff.

10-30-2007, 11:36 PM
Where is my room again?:D

10-30-2007, 11:41 PM
LOL! Ya Darin...I can see it now...You movin in....we'd have to buy a semi to haul all the new treasures into the yard :D

10-30-2007, 11:53 PM
Semi?Just one?Canada Rail not have a line nearby?:D

10-31-2007, 05:26 AM

I am installing radiant heat in a garage right now. We ran 1/2" ipex in the floor. Your runs should not be longer then 200 to 250 ft long. If they are too long they cool the water too much and cause condensation in the boiler when it returns. We also installed blue foam in under the cement to stop the heat from escaping through the ground.

ARe you running water or Glycol? How are you planning on heating the water/Glycol?

10-31-2007, 09:07 AM
Rob...I'm buying one of those outdoor wood fired water heaters. I'm going to have three fair sized buildings to heat and out here in the bush that's looking the best.

Bill Pace
10-31-2007, 09:45 AM
I'll join in with my finish experience .... I broomed my floor and have regretted it ever since,-- as already mentioned, its a bitch to clean. On a later pour I had the guys power smooth it and added a paint/finish with some type of anti skid/slip and its SO nice to sweep/clean up.

A.K. Boomer
10-31-2007, 10:41 AM

I get them mixed because i am bilingual, English et Francais! It is ciment in one language and Cement in the other. I get them mixed up. Oops!

Rob :)

Well --- that kinda cleared things up a little --- its a good thing he didnt call you a hillbilly:) I just love it when someone tears into someone about thier spelling --- only to find out that the slip up was actually due to them being a more advanced species, its poetic justice i say...

Back to the cement, I thank all the replys I had awhile back and did achieve my best batch to date, I made it so thick I had to hoe it out of the mixer, but it had more "butter" to work with and I almost got the entire peice sealed off, not perfect, but pretty good.

10-31-2007, 01:07 PM
I read one post that talked about the 4" floor being a problem. mine is only 4" and holding up fine with quite a bit of machinery on it. It was standard 4kpsi mix. It had "fibermesh" (fiberglass) added and I also used re-mesh (wire mesh) in addition...which may be overkill. None of that, however, is a substitute for a stable base. Concrete is very hard to crush if its well supported. If your base is moving around, you will have issues. I used plastic under my slab and the concrete contractor did point out that it may (slightly) increase the likelyhood of cracking because its slick and guarantees that it will not adhere with the base.

The base should be maybe well-compacted CA6 or something...and the ideal is pea gravel on top of that, but mine did not have the latter.

As for finish, you can power trowel until its really burnished as you mentioned in the past. That has the side effect of producing a more fragile "skin" on top. I would just quit earlier when troweling, but would not go with a broom finish for anything inside. It works well for sidewalks etc. but wiping up oil spills etc would shred a rag...not to mention your knees if you need to kneel while working.

If you can get help, I think you will find that the power trowel will go in through a passage door---sideways. How do you plan to get the concrete in there if the power trowel is a problem?:o


10-31-2007, 04:47 PM

For my shop floor (26 x 26 x 5 1/2" thick), I had the floor power trowelled smooth. For a finish, I used 2 coats of a roll-on 2 part epoxy paint. The paint store had traction material (clean silica sand +/- 20 mesh) available in a quart carton I sprinkled on between coats 1 & 2. Prior to painting, I did an acid etch and rinsed off well before allowing to dry. It's been 8 years now and no issues yet. I did lay OSB in sheets over the floor to protect it while moving my machines around though. My floor sweeps up easy and is positively non-stick.

My $0.02 cdn - now $0.021 US


10-31-2007, 10:10 PM

My dad and i looked into the exterior wood burner stove. They look good. I have heard alot of positive stuff about it. Apparently they can really smoke and are not as "efficient" as the salesman say. Surprise surprise. They are an open system meaning the lines are not pressured.

3 buildings to heat. Using a fan over a coil or radiant heat to heat your buildings? 3 different circulating pumps?

Rob :)