I'm redoing my kitchen right now and am thinking about doing concrete counters. Any of you folks have experience with them? Any help would be appreciated. Pictures would be awesome.
Thanks,
Dave

I bookmarked This several years ago and it was much better before photobucket whacked the pics but you may be able to get something out of it.

From what research I did when I was thinking about doing this is use glass fibers and use a plasticizer so you can use less water which strengthens the concrete. They make molds you can buy if you want to incorporate a sink into your countertop, but they are expensive.

I think the hardest part is thinking and working in the negative.

There is a YouTuber I follow called DIY Pete. He has done several concrete countertop projects.

I did not cast counter tops for a kitchen, I made a tub surround for a master bath soaking tub. It is about 4'X7' with a void to accept the drop in acrylic tub. It turned out awesome, much better than expected and I'm picky. I don't have time to host pictures at the moment but I will update with pics, materials used and steps taken to get to the final result.

I have always thought concrete was a cool material for surfaces. When it was time to do the master bath I took the opportunity to cast my own tub surround.

Step one.... research and read up, which appears you have been doing.

I used a 4'X8' sheet of melamine for the base of of the mold. Since the bottom of the mold will ultimately be the top of your counter top, using this substrate offers the smoothest surface to make the polishing go faster (not to mention it releases easily).

The form needs to be built on a level surface. This needs to be able to support the weight of you project. I used two steel saw horses with three 2"X3"X3/16" square tubes to support the weight. The steel tubes also allowed me to level them prior to setting the sheet of melamine down.

I ripped a few 1.5" pieces from the 4'X8' sheet to form the sides and used some scrap to create the void for the tub and curtain rod wrapped in tape to create the faucet knock-outs. It is important that the sides and anything within them are of the same height for level screeding of the the concrete once poured. The strips are fastened with drywall screws in drilled and countersunk holes. When you screed, you don't want screw heads in your way. COVER THESE HOLES WITH TAPE so concrete doesn't fill the holes making removal of the screws difficult.

Caulk all seams sparingly. If you leave big globs or a fat bead it will leave that impression in the counter top (see photos). I used black silicone since it shows up on the white mold.

I bent up and tack welded (they don't have to be welded, ties are fine but i'm OCD) the reinforcement you see. It is placed in the mold right in the middle of its depth. Use wire to suspend it at the right height. Wire tied to the re-bar, then screwed to a few countersunk screws.

VIBRATION - I had an old garbage disposal from the kitchen remodel. I took it apart and welded a counterweight to one side of the macerator. When it is plugged in, the imbalance causes it to shake like crazy. I happened to have a variac sitting around and used that to control voltage and slow it down a bit. I made a mount for it and mounted it underneath the center of the form (the four bolts you see on the form).

I realize these may be a bit out-there but it worked and I think it helped get the result I ended up with. Find a way to vibrate the mold after the pour.

Wipe out the mold so that its clean. I forgot if I added Johnson's Paste Wax to the mold to make release easier but I don't think I did.

I used the Cheng Concrete ad-mix in the color platinum. Then borrowed a cement mixer from a friend. It took 3 batches to fill the form. I divided the ad-mix before hand so I could meter it out accurately in each batch.

I poured the concrete from the mixer to 5 gal buckets and transferred it that way. I vibrated between pours (3 minutes or so) and let it go for about 5 minutes after the last addition.

Screed of the excess, I had none as I barely had enough to fill the mold (miscalculation). I just troweld the concrete to make it as level as I could.

Cover and let cure for 48 hours.

Break mold away and cut wires holding re-bar.

Have three friends come help move top to back yard and rotate exposing smooth surface.

There were a few small pinholes (1/16"). That were filled with reserved concrete dust/fines. The minute ones I just left.

I used a variable speed 4/1/2" angle grinder and bought the diamond discs in various grits to polish the top and radius the edges. I rigged up a tube to the garden hose to keep the pads cool and cuttings clear. Polishing took about 1.5 hours.

I then waxed the surface with my rotary buffer and Johnson's Paste Wax available at Home Depot.

It has held up great and looks like a mirror.

This message has been edited. Last edited by: shiftyvtec,

I've never got around to yet but have been planning for a long time.
I bought this book a few years ago that is very informative.

Fu-Tung Cheng ~ Concrete Countertops

Definitely going to try at some point.

^^^That guy also has some videos on Youtube.

Buddy Rhodes offers classes and DIY tips on them, too.

I'm a big fan.

Thanks for the tips so far. I've become familiar with all the names mentioned. It's come a long way since I looked into it years ago. I'm going to do the fiberglass reinforced. I'm going to use some of DIY Pete's links for some of the tools. Here goes another round of tool purchases.

I would never do concrete, way too porous, absorbs everything.....etc.....Nor would I do countertops with tiles either for the same reasons but they're even worse because pots and pans catch on them and tip over too easy.

Bump

I was considering doing a concrete bar top but never did. One good tip I got from a friend of a friend who does them for a living as far as vibration was to buy a cheap handheld orbital sander, like one of the detail ones and put it into a 1 gallon freezer bag and move it around right in the mix.