Make your own Lightweight Concrete Garden Boxes! This is PART 3.5, showing options to make your garden boxes from Perlite-based concrete. You can build these forms and precast your own 48″, 36″, or 24″ reinforced lightweight concrete panels that link together to make long lasting and durable concrete garden boxes.
Here is the weight of 3 cured panels made from regular concrete: . 48″ – 69lbs, 36″ – 50lbs, 24″ – 33lbs.
Background for the Cast Lightweight Concrete Garden Box Project – PART 3.5
Hi it’s Kent from MAN about TOOLS and this is a follow up video to Part 3 of my series of making garden box panels from lightweight concrete. These reinforced concrete panels link together to make long lasting rot proof garden boxes.
In part three I experimented with some concrete mixes looking for a good alternative to gravel-based concrete that was light and durable. In that part I looked at three blends. As that was more than enough to cover in one video. The vermiculite blend was my favourite but, I also wanted to try perlite as an aggregate.
So that’s the focus of this video. And to also add some colour to the concrete.
Perlite is a hard, highly porous material made by super-heating volcanic glass. Some viewers thought that perlite would be superior to vermiculite as perlite does not absorb as much water.
I’ll show the mixing, pouring, and unmolding, then look at the weight and durability results as compared to regular gravel-based concrete.
I’ll be using the forms I built in part 2 of the series.
Lightweight Concrete Ingredients
This lightweight concrete blend is made from portland cement, perlite, and sand.
To some of the batches I’ll add a small amount of glass fibre for extra reinforcement.
You add about one pound of this fiber per cubic yard of concrete. So when I calculated how much I needed per batch it came down to a third of an ounce per 48 inch panel.
Lightweight Concrete Mix with Perlite- 1st Test
Here’s the proportions I used for the first attempt at perlite concrete: one part portland cement, two parts perlite, and one part sand. These proportions are by volume.
I didn’t realize how dusty the perlite would be so I was glad I was working outside. A mask would have been better. And I did wear one later on.
I add the perlite and sand to my wheelbarrow first. And add a little water to wet the mix.
Once it’s well blended, I add the Portland cement. And continue to add water a little at a time.
When I saw that the mix ratio was looking good and the wet perlite concrete blended smoothly, I added half as much more of the ingredients, in the same proportions, to increase the batch size so I’d have enough to fill my 48 inch form.
Filling the Form
I add a few shovel fulls to the form and push the perlite mix around the pipes with a small trowel.
I used a reciprocating saw, without the blade, to vibrate the form and settle the concrete mix. Then I laid in a section of reinforcing wire mesh.