Welcome to part 3 of our concrete countertop tutorial. In the previous two parts of the tutorial, we covered how to create a template for your counter and how to build the form into which you will pour your concrete. Now we’re moving on to mixing and pouring the concrete. This is the part where things really start coming together. So let’s start with ingredients.
The ingredients we’re using is a mix of items that can be purchased at your local home improvement store and some items you can find on the Countertop Solutions website. The ingredient instructions that I’m providing will cover 12 sq. ft. of 2″ thick counters or 16 sq. ft. of 1 ½” thick counters per batch. So adjust ingredients to your own needs.
Per batch you will need the following…
Ingredients from you local home improvement store:
– Two 80-lb bags of Maximizer Mix
– 24 lbs. of Portland Cement Type I or II in white (Choosing a white cement versus grey will give you a more accurate, vibrant color. Learn more about different cement types HERE.)
– Desired Concrete Color Pigments (You can purchase these locally, but we used Ashby pigments.)
(The above are Amazon links to simply show you what the products are. I recommend purchasing these items locally because the shipping cost will kill you!)
– Ashby Admin Mix (contains 8 lbs Ashby Polymer, 1 bottle of Ashby Water Reducer, 1 Ashby Super Pack, and fiber glass fibers)
For our 2″ countertop, we used nearly 3 batches of the above mix. For color, each batch had approximately one 16oz cup of the Ashby Harvest Gold color. Since natural stone has multiple color variations, we also added some Willow Green into the third batch for additional visual interest.
– Start your mixer. (I highly recommend not mixing by hand. If you don’t have a concrete mixer, which I don’t, you can rent one from most home improvement stores or tool rental stores for about $40 for a half day.)
Add ingredients to the mixer in the following order:
– 4 gallons of water
– Ashby Polymer, Reducer, and Super Pak
– 24 lbs Portland Cement
– 2 bags of Maximizer Concrete
I was going to throw these 80 lb bags into the mixer myself, but I didn’t want to show up the guys… I mean, you know how guys can get, right?
– Mix for a few minutes, then add the fiberglass fibers into the mix, a handful at a time.
– Add more water as needed, up to about a half gallon.
– Mix for about another two minutes. Note that the longer the concrete mixes, the more fluid it will become. You want to achieve a firm mix, but wet enough to slowly run through your open fingers.
In cooler temperatures you may require slightly less water. In warmer temperatures you may require slightly more.
Finally, its time to create that very detailed marbling throughout your counters. To do that, Ben created this amazing Marbleizer product that is incorporated with our ingredients. This is a close-up of our finished product with the marbleized finish…
Now, here’s the part where I wince in the corner of the room while you yell at me. The marbleizer product is only available to folks who attend the training. But you can still make amazing concrete countertops without the marbleizer. I will touch on that in a moment, but I do have to tell you that the class is awesome and totally worth attending. Plus, who wouldn’t enjoy a few day in Vegas?
Now, before we move on it’s time to take a quick break for a moment of cuteness with my little monster sitting in class oh so patiently…
Now, to make your countertops without the marbleizer, there’s only a few small changes to the mixing and pouring instructions: First, mix everything above except for the fibers. Remove one quarter of the mix from the mixer and pour it into your form for a 3/8″-1/2″ base. Then mix your fiber glass fibers in the mixer with the remaining three quarters of the mix, adding water as needed. Finally, pour that fiberglass mix over the previously poured base.
Now, back to our regularly scheduled program…
Next, transfer your mixed concrete into a wheel barrow.
Use a small hand-held bucket to scoop the concrete from your wheel barrow and pour it into the form.
What we’re doing here is pouring the concrete in such a way as to create channels for the dark veining that we will add shortly. If you’re not planning on doing any veining, then obviously you don’t have to be this specific with how your pour.
More channels for veins…
For the dark veins, we poured some of the mix into a bucket, added additional colored pigment in graphite and some more of the Harvest Gold.
Then used a spade handle drill with a mixer attachment to mix. You can also use one of these cool mixers.
Next, fill in your vein channels with the darker color. To get an interesting effect, Ben kind of slaps down the dark veining into the channels.
In natural stone, some veins can be lighter than the rest of the stone, rather than darker. So if you choose to do light-colored veining, then make sure to separate out your mix for the veining before adding any color to it.
Once you’ve filled in your veins, cover the remaining area with the rest of your concrete to fill the form.
When pouring concrete, it’s very easy for air pockets to form within the mix. You will need to get rid of the air pockets so they don’t show up as holes once the concrete dries.
To get rid of the air pockets, we use a concrete vibrator. There are two types: a table vibrator and a hand-held pencil vibrator. These can also be rented from your local home improvement store for about $40 for a half day.
We used a pencil vibrator, which is basically a big metal stick attached to a vibrating machine.
To use the pencil vibrator, slide the length of it into the poured concrete and slowly move it throughout. You’ll start seeing air bubbles slowly bubbling up to the surface.
Try not to touch the bottom of the form too much with vibrator so you don’t mess up your veining. Although, some movement of the veining can look very natural.
Continue vibrating the concrete until you no longer see air bubbles releasing at the surface.
Next, screed the surface.
Screeding is a term used for leveling the surface. To screed, use a 2″x4″ and run it slowly along the surface of your concrete with a back and forth sawing motion. This should push excess concrete to fill in any low spots and remove the high spots.
Finally, use a steel trowel to create a smooth, flat surface. An uneven surface may end up not sitting flush to your cabinets.
(Sorry for the blurry image. It’s a high action shot. Couldn’t be helped.)
Allow the concrete to set for 30-60 minutes before troweling. The concrete should be stiff enough to maintain it’s shape when troweling.
Now we wait. (This is the hardest part for me.)
Allow 48-72 hours time to cure. Concrete cures through a process called hydration. You can learn about all the technical details of hydration here.
If you’re as impatient as I am, you can speed up the curing process by applying heat and humidity. A slab heated to 120 degrees in 95% humidity will completely cure in 12 hours.
So while you’re waiting for your countertop to cure, have a cold drink and then head on over to the final part of this concrete countertop series: Grouting & Sealing Your Concrete Countertop.
But first, sign up for email alerts so you never miss a fun DIY…
[Special thanks to Countertop Solutions for inviting me to sit in on their class so I could bring you this fun tutorial!]
This post linked to some of these totally fabulous blogs and Remodelaholic.
That is incredibly cool. I had no idea you could get that finish from concrete! Thanks for sharing at Fridays Unfolded!
This is so beautiful. Thanks for sharing.
Maple Sugar at http://www.sisterswives.com
Thank you so much!
Concrete countertops really do amaze me. Thanks so much for sharing with SYC.
I do not see in the pictures that a support structure is used. Can you speak to why one is not needed with these molds? All research I have done says that a mesh or re-bar structure is a must.
Hi Scott, Good question. The kit for these countertops comes with several additives, including polymers and GFRC (glass fiber reinforced concrete). Together they add amazing strength and replaces the rebar. You can read more on GFRC on the concrete network HERE. Hope that helps and please let me know if you have more questions! :-)
Is there size limits for the GFRC concrete forms? Would it be problematic to use this approach but still reinforce the molds?
Thanks for your patience.
Hi Scott, Good question. I found this GFRC guide that makes the following recommendation: “GFRC can be cast in pieces up to 28’ in length. However, the longer the length, the more difficult it is to handle and ship the GFRC cast- ing. We recommend a maximum length of 12’ for most moldings. If longer lengths are required, pieces can be field joined.” Hope that helps.
Is there any reason why this couldn’t work with a standard countertop mix? Of course, I would use reinforcements and make other changes that standard concrete requires. I’m really more interested in whether I can achieve the stone look here with the standard concrete and pigments or even powdered veining products.
You can definitely get the veining done with standard products, but I’m not aware of any other marbling additive then the one I used with this project. My recommendation is to do a small test piece and see how it turns out. Hope that helps.