Lightweight Concrete Garden Boxes – Pt 3.5 Perlite, Portland & CSA Cement

Stripping the Panels from the Forms

The next day I removed the form sides, and ends, and these castings came out fairly easily. I first stripped the 48″ panels. Removing the screws and gently wiggling the sides, then rocking the ends. Then tipping the panel up and prying off the base with the help of a paint scraper.

stripping the forms
Stripping 48″ panel

Both 48″ forms looked identical and time would tell if the addition of the glass fibre would make any difference.

Finished cast Lightweight Perlite Concrete garden panel
Looks awesome!

Next, I stripped the 36″ red coloured panel. It too looked good and I didn’t see any issues. Right out of the form it kinda looks like red clay brick.

stripping the forms
Stripping 36″ form

And finally ,I stripped the black dyed CSA concrete panel. It felt harder and that’s to be expected as it cures quicker than portland.

Finished cast Lightweight Perlite Concrete garden panel
Deep red colour
stripping the forms
36″ black dyed CSA perlite panel being stripped from form after solidifying
Finished cast Lightweight Perlite CSA Concrete garden panel
Ta DAA!!!

Submerging the Concrete Panels to cure

To help all the panels cure to their maximum strength, I completely submerged them in water in an old bathtub. After a few weeks I removed them to dry slowly in my shop before weighing.

panels curing for several weeks submerged in water bath
Curing concrete in a water tank (bathtub)

Durability Test

Then I could test them for durability. As in Part 3 of this series I lined up panels on the lawn and ran an edge trimmer against them.

Durability surface testing concrete
Durability test with Line Trimmer

The line trimmer didn’t damage the perlite concrete at all.

Durability surface testing concrete
Weed Whacker durability test against concrete edging

Like the vermiculite, the perlite-based concrete mixed easily and was noticeably lighter. And this made it easy to fill the forms.

looking at concrete surface damage from durability test
No damage!

It settled well with vibration and has a smooth texture while troweling and edging. It came out of the forms easily and has a nice smooth finish.

(Disclaimer: As an Amazon Associate I earn from qualifying purchases. Thank you for helping to support my content this way. )

Test Results

Summarizing tests and results
Summarizing tests and results

It passed the weed eater test so I think, all in all, perlite concrete in these proportions makes a good lightweight alternative for these garden panels.
The panels weighed, on average, 34 percent lighter than regular concrete. And this was a bit lighter than the similar vermiculite panels from part three.

talking about the test
Good surface finish

Significant Weight Reduction

The CSA perlite panel was 45 percent lighter. Since CSA concrete is stronger than Portland I was able to use more perlite in the mix.

34 percent lighter than standard concrete
Perlite Concrete garden panels are 34% lighter

The drawback is the CSA cement is more expensive and sometimes harder to find. And, the portland ones appear to be strong enough, and light enough.
The colours worked well and blended evenly. I think I could have used less of the red as it came out deeper than I expected. The black looks pretty good though and I’d use that again. And maybe even more.
I’m happy with perlite and it makes a light, strong, and durable panel for these garden boxes. I wouldn’t hesitate putting them in my garden if weight was an issue for me.
In the next episode I’m going back to look at aircrete. I’ve worked on some new blends and got really good results. So that’s coming right up.
And, while you are here, please hit the Support Link to help us make more projects and videos like this. We really appreciate anything you can do to help us out!

Related Posts

  1. YouTube Thumbnail CSA Aircrete Lightweight Concrete Garden Boxes - MAN about TOOLS
  2. thin CSA Concrete Garden Box Plans - MAN about TOOLS
  3. YouTube Thumbnail asking How Strong is Lightweight Concrete? - MAN about TOOLS
  4. YouTube Thumbnail Lightweight Concrete V1 - MAN about TOOLS
  5. Make Concrete Garden Beds
  6. Make Concrete Raised Garden Beds part 2 of the series
  7. YouTube Thumbnail SS Concrete Panel V1 PART 1 - Assembled box on grass
Shopping Cart
Scroll to Top