Make Lightweight Concrete Garden Boxes – Vermiculite Aircrete PART 3

Manual Foam Generator

Foam spilling out of pail using a first-try mixer mod
Foam spilling out of pail using a first-try mixer mod
Paddle mixer
Paddle mixer with screen sewn on

With wire, I sewed some window screen onto this paddle thin-set or grout mixer. When I tried to make foam, it spun the entire mixture a little too much. So this one was a little too aggressive.

"Egg-beater" type attachments with screen sewed on
“Egg-beater” type attachments with screen sewed on

The next time I sewed the screen to a smaller, egg beater type mixer. I tried adding a little bit of stainless steel scrubbing pad to the center of it. I don’t think that really made a difference either way.

Various mixing attachments
Various mixing attachments

So this one worked better because it didn’t spin the entire mixture and didn’t cause it to overflow from the pail so I got a lot better result this way. I’m using a 5 gallon pail with 3 lbs of shampoo dilution. So when the pail is full I get a foam density of 3 lbs per 5 gallon volume.

Making foam without a foam generator
Making foam without a foam generator
Dense foam after a few minutes of high-speed mixing
Dense foam after a few minutes of high-speed mixing

Portland Cement Slurry

Now with a paint mixer, I’ll add my Portland cement and fiber to the water, a bit at a time. I want to create a smooth portland cement slurry. So I add a bit, spin it, add a bit, spun it until its smooth.

Slowly adding portland cement and glass fiber to water in the pail
Slowly adding portland cement and glass fiber to water in the pail

I also stirred the mix by hand to make sure that there was no dry cement stuck to the edge, or clumps in the bottom of the pail. And this worked pretty well. Now the slurry is ready for the foam.

Well blended smooth cement slurry
Well blended smooth cement slurry

I add half the pail of foam to the cement slurry.

Adding foam to cement slurry
Adding foam to cement slurry

I’ll use my mixer to blend it all evenly. I hand stirred with an improvised stir stick to make sure that everything was blending right to the bottom of the pail, and I got a nice even aircrete mixture. And this looked really good.

Foam and cement well blended
Foam and cement well blended

I was really happy with how this turned out.

Then I added the aircrete to the form — giving it a bit of a jiggle to help settle it into the corners.

Pour Aircrete into Forms

Pouring aircrete into garden box forms
Pouring aircrete into garden box forms

And then I added a bit more to top it up.

Pouring aircrete into garden box forms
Pouring aircrete into garden box molds

Try to get as close as I could to being full, without over filling too much. A little bit over is okay cause the mix is going to settle and some of the bubbles are going to collapse.

Adding galvanized wire grid after aircrete thickens
Adding galvanized wire grid after aircrete thickens

Then I can smooth it with a trowel. And then lay in the pipe wrap wires, and once it sets up a bit I gently lay in a galvanized wire reinforcing grid, so it settles in right in the center. And I made a couple more batches and filled a few more forms. I was happy with how this was blending and how the grid was sitting in well.

The aircrew had enough density that I felt comfortable that the wire mesh was not going to sink all the way to the bottom of the form. I need to push it into place so I was happy with the aircrete density.

Aircrete setting up and holding its shape
Aircrete setting up and holding its shape

It was a hot day so I think that also helped the aircrete to set up faster — and I think that’s quite desirable because then there’s not as much time for the foam bubbles to pop. When the aircrete set up I covered the forms with plastic and left them for a couple of days.

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