Man turning mud into eco-friendly concrete

[Brad]

https://www.bbc.com/news/av/stories-61597537

Sorry it's a short video.

[rcjordan]

I saw that. Hate videos. Waiting for an article.

[Brad]

I saw that. Hate videos. Waiting for an article.

Highlights:

Very low carbon footprint.
It can be produced in same cement plant as regular concrete with no alterations or new equipment.
It is excellent insulation.
The dirt comes from construction sites.

DOwnside:

Only 1/6th as strong as regular concrete so cannot be used for large buildings.  They showed it being used in Europe for a 2 story apt building of modest size.

[rcjordan]

Thanks.  Price?  Long-term durability?

[Brad]

>Price?

Unknown. They implied the price would come down drastically if they could hit mass production.

The insulation qualities come from solid, poured in place walls.  They didn't say it but I'm assuming a coating of stucco in wet climates for protection and just because poured concrete is mighty ugly.  You might be able to use this in a 3D printed home instead of regular concrete.

  Brand name is Cleancrete.  I found this.
https://oxara.ch/technology/

[rcjordan]

>You might be able to use this in a 3D printed home instead of regular concrete.

Yeah, we've had 3 or 4 clay-based 3d printed homes posted here over the years.  I'm thinking these are only suitable for dry-ish locales. They'd dissolve here in Humidland.  (Near 100% RH most of the last 5 days.)

[Brad]

>dry-ish

Yeah I'd like to see some data on this stuff in rainy/humid climates.  I mean you have dirt, water and chemicals to make this stuff, does the minerals in the chemicals start to leach out over the years as the Cleancrete is subjected to weathering?  Also how porous is it to vapor?

[rcjordan]

Fix could be as simple as spray-on epoxy coatings.

[littleman]

In the video there was a blip about the secret ingredient being mineral salts.  I wonder how much better this is than regular adobe?

[ergophobe]

The contractor who built our house grew up building adobe. That's what his father did. He said adobe only works if you have a lot of cheap labor. In his case, he switched to straw bale construction because it was the closest he could get to adobe and still be able to build with a professional crew (as opposed to an owner-builder situation where the owner has either lots of time or lots of friends/kids)

Another friend went into rammed earth for similar reasons.

Both like the feel of adobe, but it's hard for it to compete with techniques that lend themselves to more "industrial" production.

I also wonder how adobe does in places that require engineering. Since it's a site-built material, that might be part of the issue too (though the same would apply to rammed earth and site-built "concrete")

[Brad]

Decades ago I read about bricks made onsite, using onsite dirt, with a machine that formed that dirt into bricks under massive pressure.  It seemed like a solution who's time had come.  Then the subject disappeared and I never saw it again.

I can now see why it didn't take off: labor.  You still need trained brick layers for this type of brick construction and laborers to move the bricks around plus mix mortar etc.   

This is exactly why most home builders have switched from concrete block foundations to poured concrete in my area.  Poured concrete costs more materially but uses less labor and is faster than setting blocks ending in a net savings.

That's what caught my eye with this Cleancrete stuff, it has the advantages of poured concrete and makes sense for regions where wood construction is not cheaper than concrete.

[ergophobe]

So... we just helped a neighbor form up her footings. We have steep lots and fairly high live loads (snow) so engineers want to make them very strong. It seems like it's cheaper to put 5000 pounds of rebar into the footings than to do more careful calculations. So that's how they roll.

One option she explored was block foundation. They thing is, it requires several concrete pours, because to meet modern engineering, the holes in the block have to be stuffed with poured concrete and rebar, and since you can't have gaps, you need to get a pour every few feet of block. So not only do you need skilled bricklayers, you need to schedule concrete trucks and a pump over and over. It sounded like it had become super complex to do block walls in our area. The old houses, of course, are just block and mortar, but you cannot get a house like that approved today.

[BoL]

Not a new concept, but reminded of it as there's a local supplier: https://www.mojeek.com/search?q=hempcrete

It's considered carbon negative due to the embodied carbon of the plant.

Looks like it has similar strength issues.

[DrCool]

>Decades ago I read about bricks made onsite, using onsite dirt

When I was in Zambia a few years back we were helping build some buildings for a hospital and all the bricks were made on-site. Just some guys mixing everything by hand, filling the brick molds, and then dumping them out of the mold to dry. The contractor that was with our group kept talking about how something like that would never fly in the states, the bricks weren't strong enough, OSHA would never let this fly, etc. A couple times I just wanted to slap him and tell him there is no real city within a couple hundred miles, no way to transport any bricks even if they could buy them, and these guys have been building like this for decades and their buildings are still standing.