My project: pouring concrete countertops Over existing tile
Inspired by several projects featured online such as this one, I decided this would be a great way to renovate the kitchen for less expense and labor. The existing tile countertops would be a nightmare to remove they have 1" thick 30 year old concrete as a bed, thick porcelain tile. I hated the bump dingy-white tile, the wide grout lines and the busy look of the grout as well as the impossibility of even just wiping crumbs off.
Keep in mind I am comfortable with the idea of these not turning out pro-quality, I did not expect them to. But I do want a smooth level surface for ease of cleaning, and I do need to fix some mistakes.
*So please don't laugh at my results, or tell me I should have done it all differently, it's too late now! Support and advice for my plan on fixing my mistakes would be appreciated. I don't think it is beyond help! The main reason of my post is just to document my progress, I do have a plan to fix the issues you see here.*
So, that said I couldn't just do it the easy way and use self leveling concrete like the people in the blog did. Everyone says that concrete will peel and crack, is not strong enough, etc. So I had to try and make my own improvements, and chose Rapid Set Cement-All all purpose building material/non-shrink grout.
I chose it because it can be used for applications from featheredge to 4" thick and has very high strength. The final thickness on most of the counter would be about 1/2" but some areas thicker and some thinner.
I did also purchase the "flow control" additive which helps the concrete flow into shapes and reduce the amount of water needed (plasticizers etc). I used it for one batch where I got the leak, I think it made the concrete flow TOO easily, though the mold. So I am wary of using that again for patching the edges, even though it adds yet more strength.
In retrospect it would have been much much easier to use one of those self leveling products, but I always have to make things hard on myself. I have never used concrete of any kind before, so it was a bit of a learning experience. For example I bought 50lb bags and it says to use 3-5 quarts of water per bag. It also sets in 10 minutes so I bought the retarder to give myself more time, but it was still less than 30 min. But no way could I mix and carry an entire bag in a bucket, I had to do half bag at a time, so measuring was inaccurate as I had to estimate half a bag of volume (why can't they translate 55lbs into volume for us?).
The first batch I did not mix well enough I was afraid of over mixing and ended up with some lumps. But overall that area did turn out one of the best! The next batch I used too much water tried the Flow Control additive as well as the retarder and had a tiny leak in the mold, there was a river of concrete running down the front I had to stop up with another board. Then I started getting better with the consistency of the mix, and was afraid to use the Flow Control again.
However in several spots I didn't get the concrete down into the edges well enough and will have to go back and patch those spots. The thicker mix worked better overall but I guess it didn't get down into the edges.
The biggest mistake I think I made was over-troweling in the area around the sink. I thought I was "getting better" at troweling and wanted to make it perfect so I kept at it too long, and the area around the sink is the worst part - all rough and with a fine powder on the surface from being over-worked after it had begun to set I guess. I kept misting with water to be able to work it. I will have to go back today and do a thin overlay on the top and try to level out the entire sink area.
I also was doing this alone and did not have enough hands and time to keep misting the concrete while it set so there are clay-like hairline fissures in some areas, but I think I can live with those once sanded and sealed they are tiny and will just add texture.
So I guess today I will be making a really stiff batch to patch the edges where the concrete didn't get down into the molds (too bad because the parts where it did ended up great) and try to level out the area around the sink.
Or maybe I should chip out some of the edges, put the molds back on and pack the concrete down into them - since the edges look so nice and clean with the molds I will never get that with a trowel.
I plan to keep using the same product because although it is difficult to work with, it does have a nice finish and very strong when done.... but I am certainly open to suggestions!
The embarrassing mid-way point photos:
before (painted walls down to where the new backsplash will go)
removal of the old sink and backsplash
pics of the "during" where I am today:
Old tiled-in sink removed, new sink installed in a plywood section with building paper over, pvc pipes for the faucet knockout, and foam plug for sink.
edge molds built
I didn't get any photos during the pour because I was SO busy and filthy!
Here is after the initial set I removed the top boards and left the lower on for support for now, also since some areas need patching it will keep the edge straight.
this was where I started the pouring, it's actually one of the better areas although least level.
this is the section where I used the Flow Control and had a major leak through the mold. Fortunately I planned to completely sand down and paint the cabinets next weekend that's why I didn't protect them. But this scared me off of using the Flow Control additive for the rest.
On the right the first area that did not get concrete in the edge - maybe the leak also made me wary of pressing too much into the molds, I don't know!
the dishwasher area turned out the best I think. I had unscrewed the dishwasher and pushed it back a couple inches to attach the molds across. We needed to run the DW so I removed all molds and pulled it back out to run last night.
My biggest mistake area - over troweled, sink plug was too big though I want to bullnose here so I guess I will do that by hand with the edging trowel and make a smaller plug that fits all the way inside. Totally neglected the front edge in my concern about the sink area. What a mess :(
and the last part I did - the surface was pretty good but edges again no good.
This post was edited by tinan on Mon, Feb 18, 13 at 12:42