Make Lightweight Concrete Garden Boxes – Vermiculite Aircrete PART 3

Vermiculite Lightweight Concrete

So for this blend, I picked up a bag of number three vermiculite. It’s a mineral that’s expanded by heating in a furnace. It looks a bit like mica.

Fine Vermiculite #3 size
Fine Vermiculite

The ingredients are: portland cement, sand, vermiculite and glass fiber. I wetted the vermiculite slightly first before adding it to the sand in the wheelbarrow to make it easier to blend.

Ingredients for Vermiculite Lightweight Concrete Mix
Ingredients for Vermiculite Lightweight Concrete Mix

For this first test it’s one part portland cement, two parts vermiculite, and one part sand, and as always, a pinch of glass fiber. This mixed easily in the wheelbarrow.

Vermiculite – 1st test

Vermiculite Lightweight Concrete recipe
Vermiculite Lightweight Concrete recipe

Once it’s well blended, I add the Portland cement. It felt quite dry and it took a bit more water than I expected.

And like before I filled the forms half away, settled it a bit with the reciprocating saw, add the mesh, and then top it up and repeated on the other form. And smooth the bubbles that formed with a trowel, and repeated that for the other form.

Laying in wire reinforcing grid for vermiculite blend
Laying in wire reinforcing grid for vermiculite blend

And these are the vermiculite 36 inch panels coming out of the forms. Removing the sides and ends and then just gently prying the panel free with a paint scraper.

Removing Vermiculite Concrete casting from forms
Removing Vermiculite Concrete casting from forms

This blend mixed very well and was noticeably lighter, even in the wheelbarrow. And this made it easy to fill the forms.

It settled well with vibration and had a nice texture while troweling and edging. It came out of the forms easily and has a nice smooth finish. It felt noticeably lighter than regular concrete and I think it would be quite durable.

Troweling and edging 48" vermiculite concrete panels after pouring
Troweling and edging 48″ vermiculite concrete panels after pouring

It weighed, on average, 38% lighter than regular concrete!

My vermiculite lightweight concrete panels weighed, on average, 38% lighter than regular concrete mix
My vermiculite lightweight concrete panels weighed, on average, 38% lighter than regular concrete mix

Now let’s look at the aircrete.

Aircrete

The aircrete uses fewer ingredients: Portland cement, shampoo to create a foam, and some glass fiber for extra strength.

Aircrete Ingredients - Portland Cement and Shampoo
Portland Cement and Shampoo

So I begin by diluting the shampoo in water. 15 fluid ounces of shampoo to 2.5 gallons of water.

Diluting the foaming agent (shampoo) in water
Diluting the foaming agent (shampoo) in water

This will be the dilution that I’ll use to create the foam. I stir this with a paint mixer attachment for my drill on a low setting — just to dissolve the shampoo in the water.

I use Suave Daily Clarifying Shampoo as my foaming agent.

Aircrete – 2nd test

Aircrete formulation

I’ll use a digital scale to weigh my gradients. I use 9.4 pounds of portland cement, 5 pounds of water, 1.5 pounds of the shampoo dilution and a pinch of fiber.

Using a digital scale to weigh ingredients
Using a digital scale to weigh ingredients

I’m weighing the cement and to that I’ll add a little handful of the fiber. I then weigh the water.

Weighing foaming agent dilution into pail
Weighing foaming agent dilution into pail

And then I also weigh the shampoo dilution and it’s 3 pounds to make my foam. It’s easier to make twice the foam needed. I find it just mixes better.

I experimented with a some different shape mixers to make my foam.

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