Polished concrete tables.

[Mike D]

Re: Polished concrete tables.

Hey Guys,

Not to high jack the thread but I am about to try and pour a pour in place counter myself and would love a little (or a lot) help. With out repeating myself my thread http://www.fornobravo.com/forum/8/ro...tml#post113960 I just posted a similar question. (post 192)

-I don't think I will spend the money on a wet grinder, mostly because I don't want to expose too much aggregate.
-What is a normal thickness for a pour in place counter. (I was thinking 2 1/2?)

I would love any advice (Nic?- not to call you out or anything)

Mike

[Neil2]

Re: Polished concrete tables.

"What is a normal thickness for a pour in place counter. . (I was thinking 2 1/2?)"

1 1/2 inches is fine. This is the thickness of all the counter tops I have done (10 or so). Remember that finishing is very messy process. You may want to consider doing this in a different location then move them into place. You can do this with several helpers or rent/borrow an engine hoist.

[Mike D]

Re: Polished concrete tables.

Neil-

Thanks for the reply, the counter will go all around the oven, look at the picture it makes more sense to pour in place. I thought that if there is rebar in the counter, 2 1/2" is nessesary. I am planning on doing another one as a side counter and moving it later.

Mike

[ggoose]

Re: Polished concrete tables.

Mike,

Here is a youtube link for concrete countertops that is pretty good:

YouTube - ‪Building Concrete Countertops with Buddy Rhodes‬‏

Like Neil2, they also build their countertops 1.5" thick, and recommend something called "ladder wire", rather than rebar. They, as well as Sacrete (and others), produce a 5000psi mix specifically for countertops.

gene

[Tscarborough]

Re: Polished concrete tables.

I did mine a full 2", but 1-1/2 is fine with 5000 PSI mix. Ladder wire is used to lay CMU walls, and comes in 2", 4", 6", and 10" widths. I did the perimeter, wrapped the sink hole, and laid some across the inside corner. As a rule, even 3/8" rebar is overkill for a counter top.

[Nic The Landscaper]

Re: Polished concrete tables.

These guys pretty much covered it. The thinnest I will go with a bag mix is 1 1/2" typically I like the look of 2" to 2 1/2". With a higher PSI sand mix I've gone as thin as 3/4"

For this application ladder wire, welded wire mesh, or 3/8" bar would all be more than sufficient.

As for finishing, I would highly recommend wet finishing, the dust generated from dry finishing it terrible for you and I've honestly never seen a dry honed surface that I cared for. If you want a lower aggregate exposure start with a 100 or 200 grit pad.

[Mike D]

Re: Polished concrete tables.

Thanks guys, I was definitely going do a wet polish, but with a RO sander with diamond wet pads. Maybe some day I will invest in a better polisher.

-I know of the buddy roads style, but I was going for more of Futong cheng. The side counter top will span over a speed rack (food prep area), so I wanted to put rebar in it to give it some strength.

Would 2" be too thin for rebar?

Mike

[Mike D]

Re: Polished concrete tables.

Here is a picture of the area for the side counter. I want them to match in thickness, so I want to use rebar just in case someone sits on top of the counter or something.

Mike

[ggoose]

Re: Polished concrete tables.

I think it depends on the thickness of your rebar. If you use 3/8ths inch rebar ,that yields a 3/4" thick overlap wherever the pieces cross; 1/2" overlap for 1/4 inch rebar, etc. Remember, the rebar must go in the bottom third or so of the counter for maximim strength, but if the counter is to thin for the rebar, you might get ghosting or even cracking wherever the rebar is. I guess If I were using rebar I would go for the thinnest rebar and at least a 2" counter thickness, though I say this not from experience in pouring countertops, but from researching the topic.

[Neil2]

Re: Polished concrete tables.

You can get 3/8 into a 1.5 inch counter top but it is tricky. It is getting harder to find, but if you can locate some 1/4 inch rebar this will be easier to place.

I like to use rebar but failing that 4x4 WWF (welded wire fabric) should do the job.

Also, I strongly recommend that you produce a couple of practice pieces (stepping stone, benches, etc ) before you do your main counter tops. Having a bit of experience will pay off.

[Mike D]

Re: Polished concrete tables.

-ggoose- I wasn't going to overlap the rebar, but tie it to the wire mesh (6x6") mesh.
-Neil2- I could do a couple of practice runs but if I have to rent a mixer it makes things more complicated. I assume the pour in place will be very similar to the 2 slabs I did already.
-I think the overall size of the oven wants a thick counter to balance the weight of it. I think I will do 2 1/2" (it's the thickness of a brick), anything thinner just looks kinda wimpy next to the oven.

Mike

[splatgirl]

Re: Polished concrete tables.

Thickness is mostly an aesthetic thing. My interior tops are 2". At my WFO, I have a 4" thick poured in place top because I felt that thickness suited the overall look of the structure better.
You honestly don't really need a power tool if you are just doing a project or two. I did just about all of the finishing on my interior slabs with hand pads only.

For poured in place tops, the amount of time you'll spend on polishing is directly related to your skill with a trowel, aka flatwork. If you are familiar with concrete finishing, you know that you can get a surface that is pretty close to glass perfect with time and patience while the material is wet...think concrete floors in a big box store. That finish is achieved with repeated floating and "burning" with a (power) trowel. This is fairly easy to do by hand in smaller scale, but it's all about timing and experience...and elbow grease.
If you haven't done flatwork like this before, observing a professional floor pour and the finishing process will teach you a ton. Even watching something like a patio or stoop pour would be helpful.

[Mike D]

Re: Polished concrete tables.

Thanks Splatgirl-

I was wondering if it was realistic to use only hand wet polishers. I got better as I poured the slabs, from the foundation to the top hearth slabs. I would in no way say I was good at it. That is partly why I was going to pour the prep area counter upside down in a mold, to get a nice flat top.

Mike

[Mike D]

Re: Polished concrete tables.

I still don't know about the coloring. Does anyone have a gauge for using Iron oxide for a dark gray counter with sacreat 5000 (gray base)? Do you do it by weight or teaspoon? If I rent a mixer and put 2 bags of concrete with counter flow, roughly how much Iron oxide does one use?

Mike

[splatgirl]

Re: Polished concrete tables.

Ohhhh. If you are going to mold vs. cast in place, you would for sure be good with just hand pads. There will be very little work to do on on a molded top if you don't want lots of aggregate showing. The more work end of that deal is that you'll probably have voids that will need to be filled with slurry. Not a big deal, just an extra step vs. poured in place.
Don't rent a mixer for a 2 bag project--that is crazy. A wheelbarrow and a mason's hoe will do you just fine for mixing by hand--I've mixed several hundred bags this way. I've also had decent luck with one of those rolling mixer can thingies--I can't think of the name of it offhand, but it's like a lidded 5 gallon pail with mixing paddles formed into the plastic, and you put the water and mix in, screw on the lid and roll it around on the ground to mix. It works good for small stuff.
Odjob I think it's called.