Pour a Concrete Countertop for an Outdoor Bench

CSA Mortar Mix for Countertop Pour

I’ll be using the same mortar mix that Michael Builds uses for his countertops.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Ingredients to make concrete countertop

I’ve used this mortar mix for my thin concrete garden boxes and the legs on my garden bench. The results are very good, it mixes and pours easily and settles well with very little troweling.

Ingredients for Countertop Pour

So to pour this potting bench countertop I’ll be using 3 bags of RapidSet brand CSA Mortar Mix, using a mixing attachment for my drill and I’ll be adding a plasticizer to make it pour like water. Along with a small amount of citric acid to extend the working time. And, I’ll add a small amount of glass fiber to increase the crack resistance.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Ingredients to make concrete countertop

Preparing the Concrete Form for Casting

It’s very important to level the form along it’s length and width and support it on a sturdy workbench or sawhorses.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Level form over sawhorses

Next I  need to spray it with some type of oil to keep the concrete from sticking.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Spray form with WD-40 Penetrating oil

I’ve been using vegetable cooking spray in the past but I’ll be using some WD-40 penetrating oil on this pour. This is what Michael has been using so I wanted to see if there’s any difference.

Concrete Countertop Formula I used

Here’s the proportions for the mix: A 55 pound bag of CSA Mortar Mix (25kg), 5 quarts of water (4.7L), a bag of plasticizer 2.1oz (60g), and about 2 ounces of citric acid powder (50g). 

Mix the First Concrete Batch

I measure and add the water to a 5 gallon pail.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Add measured water to bucket

Then add the citric acid and plasticizer and dissolve it.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Adding dry mix to pail

Then I add about a third of a bag of the dry mortar mix at a time.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Mixing concrete in a pail

Blending it smooth with the mixing attachment on a drill. To the last bit of dry mix I then add a small amount of glass fibre. I am following the manufacturers recommendation for the amount of fibre here. 

Hand Stir to Break up Clumps

Once I have it blended I give the bucket a good stir by hand to check for any clumps stuck to the side or bottom of the pail.

Cast your own Concrete Countertop for a Potting Bench with a Galvanized Corrugated Metal Roof
Scraping pail by hand

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