How To Make Professional Polished Concrete Countertops

You can use the following procedure to make countertops for many other applications.

We start similarly to the way our grill island (link to Build The Ultimate Outdoor Kitchen Grill Island article) began. Not with digging, but with a form.

Measure your island and be sure of the dimensions before you start. Because of the irregular shape of the field stones on the sides we added a 2 inch overhang on all sides. This time instead of using 2 x 4’s for forms we are going to use melamine. 

If this is the route you choose then you can skip down to the next section. 

The other option follows the same procedure with one added step before it gets sealed. The countertop gets polished.

If you plan on polishing your project, it allows you to place objects and designs into your top! Now is the time to unleash your creative side! After all you are building a concrete countertop from scratch, why not put your unique “stamp” on it.

Our project needs two forms. One for the main countertop for food and grill prep, and one for the elevated bar area.

For the bar area we placed broken glass and a “K” made from pieces of granite representing my last name. This is just an example of what's possible. Be creative, you can place just about anything in your countertop.

That Personal Touch

To create the “K” I took one of the rocks and sliced it into 1⁄2 inch thick pieces on my wet saw. Then I cut the slices into strips to form the letter.  

I drew a circle on my form, and used white glue and covered the circle. Returning to my childhood here, I was thinking it would work the same way glitter worked on projects from preschool.

I placed my pieces of cut stone and pressed them into the center to form the letter. Then I took the broken red glass and sprinkled it all around within the circle. Allow the whole thing to dry overnight.

Not sure if regular white glue is the best thing to use to hold it all in place, but it worked OK for me.  On my next project I will try using rubber cement or something a little more durable than white school glue.

Mix It Up

It’s time to get our hands dirty again. My choice in concrete was a high early strength concrete. 

There are several types of concrete countertop mix (link to Amazon for price and availability) on the market. The one we chose was fortified with fiberglass to help reduce cracking. To determine how much concrete you will need, refer to the manufacturer guidelines.

Mix the concrete thoroughly into a peanut butter like consistency. Shovel, or bucket it into your form. I started in the corners first, and made sure to pack it tightly. Rubber gloves are a must for this. The concrete will chemically burn your skin.

If you are going to put a design on your top, be sure not to disturb it too much when you place the concrete on top of it. It works OK if you pack it straight down, but try not to move it side to side.

Fill the form completely, then use a straight 2 x 4, or other straight edge to pull toward you in a sawing motion and level off the top (really the bottom). The same way it was done when building the foundation.

Time For a Shakedown

To remove any voids and air pockets the whole thing needs to be vibrated. This allows any air trapped in the concrete to rise to the surface. 

Your countertop is upside down, so any air trapped at the bottom will leave a void in the top. I’ve watched people use a rubber mallet to accomplish this, but it seemed like a lot of work, especially on a large countertop. 

My solution was to use my reciprocating saw (link to Amazon) without a blade on it. I held it directly under the form, and on the sides, and vibrated it like crazy. 

It’s amazing how much air gets trapped in the concrete during the mixing and pouring process. Do this until minimal air bubbles rise to the surface… yes, it takes a while.

Don’t Rush The Cure

When curing concrete, don’t let it cure too quickly. I kept my countertop covered with plastic for a week, spraying it with a hose daily to keep it moist. This helps to slow down the curing process. This will reduce the chance of cracking. 

I poured my concrete into the form that I had resting right on the grill island. It took approximately 4 and ½, 80 lb bags for a total weighing 360 lbs. That’s 163.3 kilograms for my friends outside the United States. This thing is too heavy for one man to move!

DIY Concrete Polishing

Hand held concrete polishers all work about the same. Look for one that has variable speed so you can adjust it to fit the finish you are trying to achieve. 

I found this concrete polisher (link to our review of this polisher). It comes with the polishing disks you will need.

Some polishing disk sets, come with more grits than others. The discs are numbered. The lower the number, the more coarse and more aggressive the grit is. 

These disk sets are fairly cheap. If you already have a polisher and not a diamond disc set (link to Amazon) you will need one before you begin.

This is what the upper bar countertop looked like right out of the form. It looks bad before you get at it with the polisher. 

Mix up a dry mix of 1 part Portland cement, and 1-part fine grout (I used fine grout because I had some left over from another project). This will make a slurry.

The color of your grout will affect the color of your slurry. I used black grout so it would blend in and be subtle. Instead of using water, use latex bonder (link to Amazon). The bonder helps the slurry stay put in the tiny spaces.

It will look more and more beautiful with every grit. When you’re finished you won’t believe that it was only ordinary concrete. 

I Can See The Finish

Allow the top to dry completely before adding sealer to it. There are countess options for this as well. I just chose a high gloss sealer to bring out the colors in the concrete.

If you are going to acid stain your top, now is the time to do it. I don’t have experience with acid stain, but I have seen the amazing results you can achieve with it.

If you plan on experimenting, I suggest this acid stain sample kit (amazon link). After all that hard work, it’s a good idea to “try it before you buy it”.

As you can see below, sealing the concrete really brings out its natural color.

I used these LED light strips (link to Amazon) that operate on a remote control. They are awesome, use very little electricity and the color can be changed to fit the mood.

These lights are encased in silicone and are flexible. I attached them to the underside lip of the counter using clear silicone. Use tape every foot or so to hold the lights in place until the silicone sets up.

After a couple hours remove the tape and go over the whole thing with more clear silicone. This will not only hold everything in place, but it will seal the lights and completely keep them out of the weather.

Conclusion

In our next post we will be adding the final touch to this project, adding a lamp post to our bar.

Now you know how to build the ultimate outdoor kitchen grill island complete with polished concrete countertops. Time to fire up the grill (link to our grill review article) and let your grill master skills come in to full play! 

You may start to make some new friends. The tempting aroma of delicious grilled food will be sure to draw in the neighbors.

All the hard work finally payed off, creating an amazing outdoor space that will last for years with little to no maintenance. Take some time and enjoy this before moving on to the next project (link to other outdoor projects)!

~Jeff