Precast Concrete Countertops

FOUR: POUR THE CONCRETE

The key to successful precasting is good consolidation of the concrete and is best achieved with the use of table or form vibrators. We use vibrators manufactured by Vibco, who specializes in vibration and compaction equipment for a wide range of industrial applications.   If you are planning to produce any quantities of concrete countertops, a quality set of table vibrators is an unavoidable necessity.

Step 1 – Fill the Form

  • Begin filling the form by placing a layer of concrete into the bottom of the mold. At this point, focus on covering the entire mold base, not filling the mold.
  • Once the mold base is covered in concrete, turn the table vibrators on high. This will liquify the concrete so it can flow into the mold details.
  • With the vibrators running on high, continue to fill the countertop mold. The concrete should be leveling itself under this much vibration, so don’t add too much concrete… you’ll just have to remove it later.
  • Once the mold is completely filled with concrete, turn the vibrator speed to low and let them run for another 5 minutes. This low vibration will help drive trapped air from the concrete.

Step 2 – Level the Back Surface

  • If you’ve over-filled the mold, take a 2″x4″ or a straight edge and screed the back surface flat while the table vibrators are still running.
  • With a trowel or float, smooth the back side of the countertop to ensure there are no large stones or lumps that will prevent the countertop from sitting flat on the cabinet bases.
  • Clear away any concrete that is covering the tops of your form walls or screws. This will make things easier when it comes time to de-mold the countertop.
  • Cover the countertop with a sheet of plastic to trap as much moisture as possible. We don’t want the countertop to dry out while it’s curing.
  • If you’ve used the CHENG Pro-Formula Concrete Countertop Mix, allow the countertop to cure for 4 or 5 days.
Previous: Mix the Concrete

Keep your costs low with Sakrete 5000 Plus concrete from your local home improvement center and CHENG Pro-Formula Concrete Countertop Mix.

Next: Demold the Countertop

After 5 days in the mold it’s time to remove the countertop but since the concrete is still young extra care must be taken to avoid problems.

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