Make Lightweight Concrete Garden Boxes – PART 3.7 – CSA Air Crete

Okay, here’s how I made the panels.

Ingredients to make CSA Air crete

The CSA aircrete is made from only a few ingredients: CSA cement, shampoo to create a foam, a little glass fiber for extra strength, and a plasticizer to liquefy the mix. I’ll also add some liquid colour too.

CSA aircrete foam dilution formula

I’ve covered the shampoo dilution steps in other videos so I’ll just do a quick summary here.

Slowly dissolving the shampoo in water with a mixing attachment on a drill

It’s 15 fluid ounces of shampoo to two and a half gallons of water. I stir this with a paint mixer, on a low setting, to dissolve the shampoo in the water. Then I store the dilution in jugs for later use. This Suave Daily Clarifying Shampoo works really well for aircrete.

Suave Daily Clarifying Shampoo to make aircrete foam

To make the foam I’ll be using the large Foam Mate that Darwin from The Honeydo Carpenter sent me. I pour the shampoo dilution in the tank, connect my air hose, and it makes awesome foam.

Filling the Foam Mate tank with shampoo dilution

Link to Darwin’s channel and his Foam Mate .

Making aircrete foam with the Foam Mate and an air compressor

I don’t have pure CSA cement so I’ll use a product called Cement All. It has CSA cement mixed with fine sand.

Rapid Set Cement All bag for CSA Aircrete

I use a digital scale to weigh my ingredients. I use 15 pounds of Cement All, 3 pounds of water, 3/4 of a pound of foam, 1 teaspoon of plasticizer, and a pinch of fiber.

Formula to make CSA Aircrete

I start by adding a teaspoon of the plasticizer to the water.

Pour dry Cement All into water

Then slowly add the Cement All to the water while spinning the slurry with a paint mixing attachment on a drill.

Adding small amount of glass fiber to CSA cement slurry

I don’t want any clumps or dry cement on the bottom or sides of the pail. I use a dowel to hand stir the mix to prevent this.

I’ll add the glass fibre and mix that in.

Adding some foam to CSA cement slurry

Now the slurry is ready for foam. I connect my air hose to the Foam Mate and once it’s flowing well and becomes thick I add some to the slurry pail. I have a mark on my stir stick that approximates the amount of CSA aircrete I need to fill one 36″ form. For a five gallon pail, I need it filled to the 8″ mark as a minimum.

Blending foam to CSA cement all slurry

I think on this first batch I added a little too much foam. But I decided to go ahead with it anyways knowing that the density of this first panel would be lighter.

Pour wet CSA air crete into plywood form

I pour the CSA aircrete into the form, giving it a jiggle to settle the mix into the corners.

Laying in wire grid to reinforce aircrete

Once it begins to thicken, I lay in a galvanized wire reinforcing grid. Pressing it down so it settles right in the center. Then I smooth the surface with a small trowel.

Adding plasticizer to water

As before I start by dissolving the plasticizer in the water.

Pouring cement colour into water

For this batch I’ll also add some liquid cement dye. About one fluid ounce.

Red dye used to color concrete

In this second batch I’ll use the same amount of water and Cement All as I did in the first.

Blending foam to make CSA aircrete

As before, I slowly add the cement to the water. Then add the glass fibre. Hand stirring to free up any clumps from the sides or bottom of the pail. Then add the foam and blend it again with the mixer.

Stir mix with dowel, and check depth of wet aircrete

I think I got the foam right on this blend. Just enough to bring the mix up to the 8″ mark on my stir stick.

Pouring red dyed aircrete into wood forms

After the mix began to thicken I laid in a double wire grid. I make this grid from a section of galvanized fence. Folding it over to form a thin wire cage.

Adding double wire grid to reinforce CSA air crete

In the third mix I upped the cement ratio. It’s now 20 lbs of Cement All, 4 lbs of water, about the same amount of foam, 2 teaspoons of plasticizer, and a bit of fibre.

Increase the density in last CSA Aircrete formula

And I’ll add charcoal liquid colour to the water this time.

Black liquid cement dye used this time

Once well blended I add the foam and mix that in well.

And last test aircrete into the plywood form

And then pour it into the form. Shaking it to settle the CSA aircrete. After it begins to thicken I added the wire grid. I pressed this in and smooth with a trowel.

Grid layed in and gently pushed into center of casting

When the CSA aircrete began to warm, and the surface dried with a white haze, I sprinkled water over it. I repeated this for an hour. Keeping the surface wet as it cured. I covered them with plastic and left them overnight.

CSA concrete warming and drying

One hour water curing CSA Aircrete

The next morning I stripped the forms from the castings. I remove all the screws from the form, gently wiggle the sides to free them, then remove the panel from the base and stand it on one side. And then remove the ends.

Removing screws to disassemble the forms

The sand in the Cement All was noticeable in these panels compared to Portland-based aircrete. And I had hoped that it would make the panels more durable and impact resistant.

Little wiggling helps to remove the form ends

All the panels came out of the forms well. They all felt sound and solid. Other than some surface blemishes around the panel inset, there were no significant cracks or any signs of warping.

Good looking casting!

As in my last two videos, these panels where also submerged in water in an improvised tank. They soaked for two weeks then were pulled out and left to slowly dry in my shop for another two weeks.

Air crete curing by water submersion

I then weighed the panels and lined them up on the lawn and ran a line trimmer along them all. As a test for surface durability. The first two panels didn’t do so well. The line trimmer cut grooves in the surface.

Line trimmer (weed eater) durability test

The third panel, with a higher percentage of Cement All did better. It only had minor damage.

Denser CSA aircrete panel did better than first two

The first two panels were very close in weight and averaged 64% lighter than regular gravel and sand based portland concrete.

Yup…they are light

The third panel was 52% lighter than regular concrete. I used more Cement All in this one cause I just had a hunch that this type of aircrete needed to be denser.

The denser (and more durable) third panel is also still very light

The panels look good and the bubbles appear to be uniform. I didn’t see any cracks forming or any warping as they fully cured and dried. So the density of the cement seems to be adequate so the panel can resist the internal stresses that build up during curing and drying.

I had hoped that the stronger CSA cement would make these panels more durable but they didn’t do so well against the line trimmer. The denser third one did better than the first two.

Closer image of dense third panel with line trimmer damage

So I hope that was helpful. And I think it showed that aircrete can be made from CSA based cement.

I can’t say just yet that it’s any better than a portland based version. There’s a possibility that the sand is actually detrimental and weakens the tiny bubbles. I’d have to get my hands on some pure CSA cement to see if that was the case.

And that`s it for now

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