Hacker News Reader

Comment by nine_k | Hacker News Reader

In short: sargassum seaweed is washed onto shores anyway, why not use it to make bricks? They form the bricks using a standard block-making machine, dry them at the sun, build small houses out of these, and plan to donate these houses to local families in need.

They say that they use 40% of seaweed in the bricks, and 60% is "other organic material". I wonder what material is this.

I also wonder how well the sargassum bricks withstand weather.

View on HN

> 60% is "other organic material". I wonder what material is this.

IIRC from the YT video in my top-level comment, it's dirt.

> I also wonder how well the sargassum bricks withstand weather.

dopa42365's comment (https://news.ycombinator.com/item?id=37176903) links a paper with the following claim:

> Studies carried out by the Secretariat of Ecology and Environment of Quintana Roo state, Mexico, found that the resistance of the bricks is 75–120 kgf/cm2, while its durability can be up to 120 years, regardless of the region or climate type where they are used (Desrochers et al., 2020). Currently there is no other sustainable material as resistant, or with such a long useful life. Sargabricks are therefore seen as a viable and safe material for the creation of ecofriendly buildings.

(edit: But the OP link also contains this 120y assertion. I haven't checked the paper's citations, so I'm not sure if everyone's depending on the cited study's analysis, or if that study is laundering claims by the people making the bricks)

> I also wonder how well the sargassum bricks withstand weather.

In the video they mention the first house built using these bricks was in 2018. It's still standing and looks like it's in good condition. They also mention the homes they build with these bricks are strong enough to withstand hurricanes.

Worth noting that these characteristics generally hold for most cob bricks as well. It doesn't seem like it's particularly special because of the seaweed except that it's a way to use an abundant resource. Significant imo because of the minimal treatment necessary and lack of ecological harm in construction.

Wanna renovate? Wanna expand your building? Wanna take it apart and rebuild it entirely? It's basically just dirt so it's flexible to future growth and needs with minimal costs. The West tends to build buildings as if they're permanent but of course even skyscrapers need to come down eventually. All that glass, plastic, and even stuff like asbestos previously, is eventually gonna be taken apart. Usually mostly dumped to a landfill

Round homes without sharp corners fare better than rectangular homes in hurricanes probably because the wind shearing force is lower. Deltec Homes sells round, radial homes: https://www.google.com/search?q=deltec+youtube+hurricane

Hempcrete on structural forms like LEGOs another type of CEB Compressed Earth Block: https://en.wikipedia.org/wiki/Compressed_earth_block

Radial blocks make turning corners with various radii easier; so that the wind doesn't grab the ~K'Nex cube of the structure and shear it under the roof and around the stairs.

They're not kiln-fired, are they?

It feels like they're just making adobe with seaweed instead of straw.

Sure, but why not?

The linked article says they are dried in the sun for four hours.

Yeah, that's distinctly different from kiln firing. Various clays take on significantly different physical characteristics depending on heat treatment.

It is possible to build a solar powered kiln, but "dried in the sun" is a different process than what clay goes through- which makes sense, since organic matter and dirt wouldn't benefit from a kiln anyway.

That's how it was described as in a video about it too.

> sargassum seaweed is washed onto shores anyway, why not use it to make bricks?

I mean the obvious question is whether that is a safe construction practice

What kind of safety are you thinking of?

What I'm wondering is: are there other impacts from removing the seaweed from the shores; does it change the ecosystem around the shore in undesirable ways?

Also: is the supply really up for the demand?

Will the house collapse is what I’m wondering

Why would they make bricks out of seaweed if they thought the house would collapse?

Why would someone build an MVP for a product that has no clear or viable path to monetization? Because someone wants the product to exist enough that they're willing to give you money to make it happen.

Because someone will buy it. Hence regulations.

But that’s the question. The question is has it been tested to be surely safe.

The Bible describes Egyptians making bricks from mud and straw. In europe and the US it's referred to as "cobb" which if you plug that word in to youtube is a deep rabbit hole of building sturdy and sustainable homes for cheap, even today. You need thicker walls (about triple) than what you might see in a lightweight modern home made by 2x4s and drywall, but the lower cost of materials (and much lower cost of labor) offsets this. The incredible thermal mass of the walls also helps to regulate internal temperature during the daytime. But to answer your question, typically no they do not collapse unless the roof goes without any maintenance, which is unlikely in a tropical region.

Well they do say the seaweed is invasive, so removing it seems like it would actually be plus for the beach ecosystem (unless it's replacing some native seaweed that no longer washes up, I suppose).

The seaweed is removed anyway; resorts and beach authorities remove it because it makes for an unpleasant beach.

I wonder what material is this.

Maybe old fishing nets and random plastic trash, considering its all recovered from beaches? Heh. Nah, perhaps hay/grass? Not sure what acts as a binding agent, either.

Incorporating old, strong plastic filaments would be a terrific reuse idea.

I don't think the get enough disused fishing nets for that, and these nets would need a lot of cutting.

I helped with a study of the compression strength of concrete blocks when I was in high school. It was a long time ago, but IIRC, the blocks augmented with monofilament (it was fishing line) performed well.

Create it into a slurry and extrude it though an oven and use material for all commercial and civic projects... make curbs or asphalt alternatives from this.

> and 60% is "other organic material". I wonder what material is this.

I'm guessing some binding agent like clay?

Clay is inorganic, it's a mineral

Reply on news.ycombinator.com