Make your concrete countertop mix
right and it will pave the way to a phenomenal addition to your kitchen. Do it wrong and you (and your guests) will wish that you had installed a traditional laminated countertop. Here's how to create an effective countertop mix from scratch.
Note: Concrete countertops are advanced DIY projects that require considerable experience and skill with concrete.
Pouring a concrete countertop is a big project.
I'm not trying to deter you from making one and it isn't like splitting the atom to mix and pour concrete well, but... getting the counter top mixture, the techniques, and the finishing just right requires genuine concrete skill and experience.
That's why it's a good idea to make sample pours first so that you can get an idea what you're working with and how small variations in the concrete mix can make a difference.
Many people start with a premixed countertop mix. They are specially formulated to be flowable and high strength with plasticizer that makes it flow well even at a low water / cement ratio.
A low water / cement ratio is important for a good result that resists cracking. The Quikrete mix has high enough flow that the need for mechanical vibration is minimized, and it's made for minimal shrinkage.
Alternatively, you could start with regular bagged concrete mix that is rated for a hardness of 5,000 psi or greater.
"Scratch" Concrete Countertop Mix
Here is a concrete countertop mix you can make "from scratch" that's enough to make a small test block and that can be scaled up by weight.
You can use a kitchen or postal scale to weigh out the sample measurements.
I recommended that you use white sand and white cement if its not a cost problem to maximize your coloring results.
Tools and Materials You'll Need:
- Wood or melamine, plus screws to build the mold
- Bagged countertop mix (or "scratch" recipe)
- Dyes or pigments if you're coloring your countertop
- Hand wet polisher with water feed (rent this)
- Diamond polishing discs of various grit
- Tupperware to make concrete samples
- Electric concrete mixer
- Concrete vibrating tool (rent this)
- Ear protection
- Eye protection
- Dust masks
Product / Weight in Grams
Portland Cement 210g
Nycon G nylon fiber 1g
Fritz-Pak FR1 Water Reducer 5g
If instead you're using Quickrete Countertop Mix or Sackrete 5000, or some other pre-mixed countertop mix, start with about 875 grams of dry mix and about 85 grams of water to make a sample.
Whether you're using a bag concrete mix or my "scratch" concrete countertop recipe, use the smallest amount of water necessary to craft a mix that you can work with.
For concrete coloring, try weighing out a small amount (a teaspoonful, for example) of the pigment and adding it to your sample.
Of course, you can only estimate how it's going to look once it's cured, but again, you have to start somewhere.
Write down how many grams of colorant you use in every batch so you'll have a basis for guessing how much more or less you need in subsequent samples and so you'll also know about how much you'll need for the final product once you get the color you want.
If you want a darker concrete countertop - all the way to a dark charcoal gray - start with Quickrete Countertop Mix, which is darker than the scratch recipe above, and add charcoal coloring.
Start with one bottle per bag of concrete countertop mix when mixing the final countertop.
Of course you can still experiment with the colorant in your sample slabs.
After you've poured your sample, allowed it to set and removed it, ask yourself what's right and what's wrong about it.
Color will likely be the thing that determines what you should try next.
When you have a sample that pleases you, keep it and let it cure under conditions as close to the curing conditions of the final countertop as possible.
In fact, you should keep all of your samples so you can try out your concrete polishing and sealing techniques on them.
Once you have your sample smoothed to the finish you want, you can seal it with concrete countertop sealer according to the directions.
Alternatively, you can seal it with beeswax (which may not be the best at standing up to what the average kitchen countertop endures) or even pure tung oil (like what is used on wood).
It just depends on the final look you want. Now that you know what you need to do to make your concrete countertop mix, read this helpful article on How to Make Concrete Countertops.
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