the Best Aircrete Recipe – a Lightweight Portland Concrete Formula

My Best Aircrete Blend – 2nd Test

In the second blend I’ll use the same amount of cement and water, a bit less foam and almost a pound of perlite.

aircrete concrete lightweight recipe
Aircrete recipe that includes perlite

Add Perlite to Aircrete Mix

I want to see how this light volcanic sourced rock blends with aircrete and if it adds any strength or durability. Perlite is a hard, highly porous material made by super-heating volcanic glass.

perlite added to the wet aircrete mix
Perlite additive for 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 drill.

pouring the wet concrete aircrete mix into the form
Aircrete with perlite poured into plywood concrete form

This worked very well. The aircrete had a lumpy consistency but poured well into the forms. I jiggled the form to settle it, then added a bit more to top it up. I smoothed it with a trowel and left to thicken. I test the strength of these panels in a later video.

laying a reinforcing wire mesh before the aircrete hardens
Wire grid cut from galvanized fence

After a few minutes I laid in a double wire grid. I wanted to see if adding two layers of wire grid worked better than just one. To make this grid I simply folded a section of the galvanized fence in half and wrapped the ends into a flattened tube.
I pressed this in and smoothed with a trowel.

Liquid Concrete Dye

adding cement dye color to the mix
Red cement dye (pigment) poured into water

For the next test I’ll add about 1 fluid ounce of red liquid cement colour to the water. I’ll leave out the fibre on this one. I make a smooth cement slurry and add the foam. This air crete came out a light chocolate brown colour. I blend it well and pour it into a form. And I’ll lay in a double wire mesh and smooth with a trowel.

pouring the wet concrete aircrete mix into the form
Red dyed aircrete poured into wood form
laying a reinforcing wire mesh before the aircrete hardens
Double wire grid laid into wet aircrete in a form

The final test I’ll add black cement colour to the water. Leave out the fibre, but add perlite. I kept the density of the aircrete fairly consistent through these tests. Varying the fibre, perlite, and grid. And a bit of colour additives for fun.

adding cement dye color to the mix
Black liquid cement colour

I blend as before and pour into the form. When it starts to solidify I’ll add a single wire grid for reinforcement.

pouring the wet concrete aircrete mix into the form
So much fun pouring aircrete into the forms!

When the aircrete solidified that afternoon I covered the forms with plastic and left them for a couple of days.
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. Aircrete is fun to make. It’s involved for sure but not very labour intensive. Everything is blended in a pail with a drill. It’s light by default and has many uses.

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Strip the Aircrete Panels from Molds

Stripping aircrete panel from mold
Covered with plastic
Stripping aircrete panel from mold
Stripping the solid aircrete castings from the forms

All the panels came out of the forms without issue. They all felt sound and solid. There were no cracks or any signs of warpage. I lined them up on sawhorses to get a shot of them before curing.

These aircrete panels turned out well. No cracks and no warping
Four aircrete panels right after stripping from the molds

Curing Aircrete in Water Bath

These panels where submerged in water in an improvised tank that was a recycled bathtub. They soaked for two weeks then pulled out and allowed to slowly dry in my shop for another two weeks. This is the optimal curing method I have found.

submerging panels in bathtub to fully cure them for greatest strength
Cured in an improvised water tank – now thats recycling!

Then I weighed the panels and lined the first two I cast on the lawn and ran a line trimmer against them as a test of durability. I wanted to see how this denser aircrete held up to impact of the spinning line. And I wanted to see if the perlite helped.

Surface Durability Test

weed whacker durability test
DIY Aircrete Concrete durability test

These new panels did very well in the durability test. There was little damage to the surface. The perlite didn’t make much difference in this case, and didn’t increase the durability. Without a hard aggregate in the mix, this form of concrete is always going to be weaker. The trick is to find the right weight to strength balance for your application.

Weights and Final Thoughts

56 percent lighter than portland-based sand and gravel concrete
Aircrete garden panels were 56% lighter than gravel-based concrete

The panels were very close in weight and averaged 56% lighter than regular concrete. This denser aircrete has a very good finish and it faired much better than the previous ones in the durability line trimmer test. There’s some damage, but it looks minimal. And looks to be the same in the panel with perlite added. I think this is the best aircrete recipe I have used yet.

close up of the foamcrete garden panels
Some minor damage from the weedeater test

I don’t see any cracks or warping of any of these panels so I think the bigger ratio of portland to foam was the answer. It appears if you want strength and durability improvements you really need more cement. If that changes over time I’ll update my blog post.

close up of the foamcrete garden panels
Color additives worked

At this point I don’t see a huge advantage to adding perlite to aircrete. Or to doubling up the wire grid. But, it doesn’t seem to hurt either. So maybe the takeaway here is that it’s easy to add both if you wanted.
The liquid cement dyes worked well and it was easy to add. The next time I’ll even more to get deeper colours.

Introduction to the video
More talking

Darwin’s Foam Mate worked very well. It allowed me to quickly make foam just when I needed it. And just as much as I needed. So I can certainly recommend that.
Thanks for reading!

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