https://www.yaleclimateconnections.org/2020/07/climate-friendlier-alternative-to-traditional-clay-bricks/

"Kenoteq, a Scottish start-up, has developed an alternative called K-Briqs.

They’re made of 90% recycled construction and demolition waste, and they do not need firing, so manufacturing a K-Briq only produces one-tenth the carbon pollution of a traditional brick."

Bricks offer “some insulation” need numbers on it really

Posted By: WillInAberdeenhttps://patents.google.com/patent/GB2544656A/en" rel="nofollow" >https://patents.google.com/patent/GB2544656A/en

They don't claim patent for it being insulating. They claim it has much less embodied energy than bricks or blocks and requires less virgin material.

Thanks for the link. I found a page on the google patents site, but without the body of the patent? :(

It does say: "Air dried bricks also have a higher thermal mass due to their density. For example, the air dried bricks may have thermal conductivities of approximately 0.38-0.74 W/mk. In contrast, fired concrete brick thermal conductivities range from 1.2-1.8 W/mk." Which doesn't make much sense to me but does state numbers for conductivity.

The other question I have, due to my ignorance of chemistry, is whether the drying of the gypsum is irreversible. What happens if the 'construction unit' is inundated by flooding, for example?

Unfired clay bricks are similarly low in embodied energy.

Don't understand why people are talking about using bricks as insulation - nobody is claiming that's a good idea because it clearly isn't what bricks are for! Certainly the patent holders of these ones are not claiming that.

These ones are claimed to use a lot less energy to make than normal bricks and to avoid digging new materials, which both sound good to me, though surprised nobody else has done that.

DJH, the gypsum is plaster but is being used like cement. It has a crystal structure with two water molecules bound to each one of calcium sulphate. You heat it (a little) to drive much of the water out, changing the crystal structure. Then mix it with the aggregate and then add water. The dehydrated gypsum reabsorbs water and recrystallises, forming a binder round the aggregate. Then you dry out the remaining water, like drying plaster or concrete. Like concrete, the process cannot be reversed just by adding water. Portland cement does the same thing, but with dehydrated calcium silicate, which takes much more heat to produce.

Edit to add: would be interested how these bricks would be recycled once they eventually become waste - contain lots of gypsum so can't easily be landfill or recycled aggregate, but contains lots of other materials so difficult to recycle into fresh gypsum.

But the Prof is not selling the bricks as insulation, nor would we use them as such, which is what I said, and why your discussion of them as such is a red herring. The same description could be applied to aerated concrete blocks, but you won't find them in the insulation aisle either.

Once you have crushed and sieved plasterboard you mostly have gypsum, which you dehydrate by heating, as I described, to make plaster, and subsequently add water to stick aggregate together to make bricks.

The resulting bricks are mostly aggregate, containing all kinds of minerals. You might be able to reverse this by heating the bricks, but no promises what you would end up with, won't be pure gypsum.

Been taking a look and they seem very promising.

Interesting video: https://mashable.com/video/kenoteq-k-briq-sustainable-construction-samuel-chapman/

Patent: https://www.ipo.gov.uk/p-ipsum/Case/PublicationNumber/GB2544656

I've seen it mentioned that they have a BBA certificate, but it doesn't seem to have been published yet. In particular I'd like to see confirmation of durability.