Pouring concrete countertops doesn't have to be difficult. I'll cover the step by step process from mixing the concrete to placing and screeding the concrete mix in the mold.
For more information on forming, different concrete mixes, reinforcement, and finishing techniques, click on the links at the bottom of the page.
The tools you will need for pouring are: mixing bucket, 1/2 inch drill, mixing paddle, hand float, hand vibrator, mask, rubber gloves, and a 2x4 screed.
You will also need pre-mixed bags of concrete countertop mix, water, and a measuring cup.
When the forms are prepared and you are ready to go, the first thing to do is add the correct amount of water to the mixing bucket. Add the exact amount of water it says on the pre-mixed bag. This will ensure a mix that isn't too soupy or wet.
Always put the water in the mixing bucket first, then slowly add the dry mix to the mixing bucket while you are mixing with the drill. This method will make sure you don't get any lumps in the countertop mix. Mix one bag at a time for consistency throughout the entire process.
After about 3 minutes you should have a well mixed concrete mix about the texture of clay. Use your hands, with rubber gloves, and press the mix into the mold. This is a 2 person job, you want to work fairly quickly but carefully.
You are going to spread a layer of mix over the entire bottom of the mold, filling the mold about half way. Press the mix into corners, seams, around knockouts and sinks, using your fingers to remove any voids and air bubbles.
Using a hand-held vibrator, you can vibrate around the outside edges and bottom of the forms to help remove any air bubbles.
After you have filled the forms half way, lay in the concrete countertop reinforcement. Keep the reinforcement about 1.5 inches away from the edges.
Continue to fill the forms up to the top of your forms. Vibrate the edges one more time, keep the vibrator moving and don't hold it in one spot for an extended period of time.
Screed the concrete mix level with the top of the forms, removing any excess mix as you go over the edges of the forms. Hand float the surface to a smooth even texture.
Clean any excess concrete mix off the tops of the forms, sink knockouts, and any other inserts you have in the countertop.
Pouring concrete countertops upside down means this is the bottom of your countertop. It will sit on the cabinets better, if you take the time to clean around the inserts and make sure the bottom is level.
After you're done, cover the countertop with a sheet of plastic to cure it. Leave the plastic on the countertop for about 4 days. The longer it cures the stronger it will be.
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