Concrete Mold Casting Instructions – 36″ plus 24″ x 8″ x 2-1/2″ Panel

Here’s the step-by-step guide to making a concrete casting for a raised garden bed using one of our 36 inch or 24 inch ABS plastic molds. The 24″ mold produces a concrete casting that weights approximately 33 lbs and the 36″ panel produces one that weights approximately 50 lbs.

Casting the Concrete Garden Box Panels

Watch the full length video for these ABS Vacuum Formed Molds:

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Prepare Your Materials – have your bag of concrete, water, shovel, wheelbarrow, gloves, mask, rubber mallet, small trowel, plastic sheets ready. Level a workbench or similar working surface in a protected warm environment.

high strength concrete, gloves, and a respirator in a wheelbarrow
high strength concrete, gloves, and a respirator in a wheelbarrow
check that the workbench is level
check that the workbench is level
spirit level on the workbench
spirit level on the workbench

Oil the Mold and Pipes – apply an even coat of oil to all inside surfaces of the mold. A small sponge or a clean cloth works well for this. Avoid using excess oil that forms any puddles. While holding the end with the small hole, apply some oil to each pipe.

bottle of food grade mineral oil and sponge
bottle of food grade mineral oil and sponge
applying mineral oil to the inside cavity of a concrete mold
applying mineral oil to the inside cavity of a concrete mold
applying mineral oil to a pipe
applying mineral oil to a pipe

Insert Pipes – slide the pipes into the holes leaving the pin hole end clear of the mold edge as shown.

sliding the pipe into the concrete form
sliding the pipe into the concrete form

Mix Concrete – empty most of the concrete bag into a wheelbarrow or large concrete mixing tray.

emptying bag of high strength concrete into a wheelbarrow
emptying bag of high strength concrete into a wheelbarrow

Slowly add cold water while blending the contents with a shovel.

adding cold water to concrete mix in a wheelbarrow
adding cold water to concrete mix in a wheelbarrow
mixing concrete in a wheelbarrow
mixing concrete in a wheelbarrow

I like the mix my concrete so that it still holds some shape in the wheelbarrow instead of so wet that it is fully liquified.

Alternatively, you could mix the concrete in a pail with a blending attachment on a high-torque mixing drill.

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adding concrete mix to a pail
adding concrete mix to a pail
adding cold water to a pail of concrete mix
adding cold water to a pail of concrete mix
mixing concrete in a pail with a blender attachment on a high-torque drill
mixing concrete in a pail with a blender attachment on a high-torque drill

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