To make aerated concrete, add a foam-forming agent and stir in a significant amount of air. This serves to make the concrete significantly lighter, better insulating, and more resilient to fire. Making it can however be a bit of an issue, often requiring ingredients that aren’t purchased at the average DIY store. This is where [NightHawkInLight]’s method seems rather promising, requiring effectively only xanthan gum and dishwashing detergent.

For the small-scale demonstration, 15 grams of the thickening agent xanthan gum is mixed with enough alcohol to create a slurry. To this 60 mL of the detergent and 1 liter of water is added and mixed until the xanthan gum has absorbed all the moisture, which takes about 5-10 minutes. This mixture is then added to Portland cement with two parts cement to one part xanthan gum/detergent mixture and mixed for a while.

Of importance here is that this mixture will keep expanding in volume while mixing, so you have to have to keep an eye on the amount of air relative to concrete, as this will determine the strength and other properties of the final aerated concrete. If you continue past a certain point you will even create open-celled aerated concrete that’s completely porous, so you have to know what kind of concrete you want before you start mixing up a big batch.

The basic physics behind this approach seem fairly straightforward, with the air captured in soap bubbles by the detergent, reinforced by the xanthan gum to make them significantly more resilient. A normal concrete mixer seems to work fine, but a mixing rod or kitchen mixer seem to do a much better job at getting a predictable result.

After pouring the aerated cement mixture into a mold, it should be kept moist while it cures, as it is more fragile than typical concrete, but if done properly you can produce for example cinderblocks that are quite insulating, as well as something akin to AAC blocks, conceivably with even better performance.

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