[HN Gopher] Sargablock: Bricks from Seaweed
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Sargablock: Bricks from Seaweed
Author : thunderbong
Score : 131 points
Date : 2023-08-18 14:00 UTC (8 hours ago)
(HTM) web link (fortomorrow.org)
(TXT) w3m dump (fortomorrow.org)
| downrightmike wrote:
| [flagged]
| f6v wrote:
| In the 50s, my grandparents were making bricks from hay and mud.
| You'd be surprised, the houses are still standing. Very eco-
| friendly, should make a startup selling this.
| sedatk wrote:
| They can even call it something catchy, like "mudbrick(tm)".
| dopa42365 wrote:
| https://www.frontiersin.org/articles/10.3389/fmars.2021.7684...
|
| > 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
|
| That's far below concrete, isn't it?
| terminous wrote:
| - First-class brick has a compressive strength of 105 kg/cm2.
|
| - The compressive strength of a second-rate brick is 70 kg/cm2.
|
| - Common building bricks have a compressive strength of 35
| kg/cm2
|
| - The compressive strength of sun-dried brick is between 15 and
| 25 kg/cm2.
|
| Source: https://housing.com/news/compressive-strength-of-
| bricks-mean...
| abathur wrote:
| The primary link doesn't explain the other 60% of the
| formulation, but IIRC (from watching the video linked in my
| top-level comment) the other component is waste dirt from
| construction projects.
|
| I'd expect it to be less strong than concrete, so I guess more
| fair comparisons might be mud bricks, other mud-brick + X
| formulations, and traditional clay bricks?
|
| edit: but worth noting that the paper you linked does mention
| that someone _else_ is making "sargacreto" that is 40%
| sargassum and 60% concrete, though it says there aren't numbers
| to cite for its strength yet.
| frandroid wrote:
| Yeah I'm thinking, one 5-point earthquake and this falls apart?
| I mean it's better than mud bricks, but...
| toast0 wrote:
| You should be able to reinforce this while building, just
| like with other masonry.
|
| Additionaly, if the structures are fairly small, and the
| walls are properly tied together, that may be enough.
| hgomersall wrote:
| I'm not an expert, but I'd be surprised if concrete is at all
| earthquake resistant without rebar.
| dghughes wrote:
| Ancient Romans didn't use rebar in their concrete but they
| did use aggregate of different densities depending on what
| section of the building would be under stress. Plus if
| cracks form their concrete self heals due to the compounds
| used in it.
| mrguyorama wrote:
| How many earthquakes did ancient rome suffer?
| culi wrote:
| Concrete isn't known for being very earthquake resistant. If
| you're building for that wood is a much better choice
| ajmurmann wrote:
| Wouldn't the proper comparison be other bricks?
| karaterobot wrote:
| Yep, and well below titanium as well. So, if you've got a beach
| where a bunch of titanium washes up every year, my advice is to
| use that instead.
| benj111 wrote:
| whats the compressive strength of sand?
|
| could just use that.
| culi wrote:
| "Concrete" is a composite material that can vary wildly
| depending on composition and process. These tests on grade M10
| concrete for example concluded with 136, 131, and 147 kg/cm2
| for their 3 samples. For plain cement, generally grade M15 is
| used[1] which is about 153 kg/cm2
|
| [0] https://civilplanets.com/compressive-strength-of-concrete/
|
| [1] https://theconstructor.org/concrete/grades-concrete-
| strength...
| abathur wrote:
| I watched something on YT recently about this. I think it was
| https://youtu.be/2fXiboAGQvM (8m 12s, "How Bricks Made From
| Invasive Seaweed Clean Mexico's Beaches | World Wide Waste |
| Insider Business")
|
| It shows a bit of the process if you're curious.
|
| The guy seems to have a big heart, and (naively) appears to be
| turning a stinky problem into a win-win-win.
| tantalor wrote:
| naively?
| abathur wrote:
| I lack both the firsthand experience and research background
| to understand if there are ~obvious reasons (to people with
| domain knowledge) that this isn't actually a win-win-win.
| tantalor wrote:
| Oooooh I thought you were implying "the guy" was naive.
| Thanks for clearing that up.
| abathur wrote:
| Fair :)
| culi wrote:
| I also had the same impression. Only commenting to add
| another data point and point out it might be worth
| rewording if you're not outside the edit window :)
| abathur wrote:
| Long past, unfortunately.
| ricardo81 wrote:
| I guess this solution would also be carbon negative due to the
| locked carbon in the organic material.
| Cthulhu_ wrote:
| As long as the bricks aren't fired, but that looks like it's
| the case.
|
| That said, I'm sure the carbon will be released again if the
| bricks are broken and wetted. Best thing is to bury it
| somewhere dry I suppose.
| CapitalistCartr wrote:
| The link seems to be Slashdotted into oblivion.
|
| Here's an article in the Mexico News Daily explaining it:
|
| https://mexiconewsdaily.com/news/mr-sargassum-built-13-house...
| jibe wrote:
| When you make a brick from the Sargassum, does it release or hold
| onto the CO2?
| Cthulhu_ wrote:
| If it's dried, it should hold onto the CO2. Of course, if the
| brick is broken, weathered and wettened it'll probably release
| it again, plus if it's fired that process will emit more CO2
| than it sequesters.
|
| I don't think it's a carbon sink, but more like a way to make
| something useful (that isn't compost) out of something
| unwanted. Note that the people collecting it also get paid by
| the seaside hotels to do so.
| nine_k wrote:
| 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.
| samstave wrote:
| [flagged]
| dehrmann wrote:
| They're not kiln-fired, are they?
|
| It feels like they're just making adobe with seaweed instead of
| straw.
| nerdponx wrote:
| Sure, but why not?
| karaterobot wrote:
| The linked article says they are dried in the sun for four
| hours.
| zdragnar wrote:
| 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.
| Cthulhu_ wrote:
| That's how it was described as in a video about it too.
| jncfhnb wrote:
| > 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
| sverhagen wrote:
| 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?
| jncfhnb wrote:
| Will the house collapse is what I'm wondering
| tinco wrote:
| Why would they make bricks out of seaweed if they thought
| the house would collapse?
| natpalmer1776 wrote:
| 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.
| jncfhnb wrote:
| Because someone will buy it. Hence regulations.
|
| But that's the question. The question is has it been
| tested to be surely safe.
| hadlock wrote:
| 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.
| jccooper wrote:
| The seaweed is removed anyway; resorts and beach
| authorities remove it because it makes for an unpleasant
| beach.
| blacksmith_tb wrote:
| 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).
| abathur wrote:
| > 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)
| alimbada wrote:
| > _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.
| culi wrote:
| 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
| unwind wrote:
| _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.
| nine_k wrote:
| 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.
| 100k wrote:
| 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.
| 1024core wrote:
| > and 60% is "other organic material". I wonder what material
| is this.
|
| I'm guessing some binding agent like clay?
| twalling wrote:
| cached version -
| https://webcache.googleusercontent.com/search?q=cache:BvdFhn...
| nkg wrote:
| Sargassum is a disaster for the economy of caribbean countries
| because many rely on tourism (read white sand beaches), so it may
| be a good idea to take advantage of it, but how can we be sure
| that enough sargassum will wash up on the shore for the next 6
| months ? Wether we view sargassum as a disaster or sargassum as a
| raw material, the problem is that we can't control its flow.
| inkcapmushroom wrote:
| In that case it's probably smart he's doing this as a non-
| profit rather than a business. A business might go under if the
| sargassum stops, a non-profit can just wait or just go to other
| localities where they are getting sargassum and help them build
| homes there instead.
| mym1990 wrote:
| A non-profit is still...a business...its just a non-profit
| business. I don't think being non-profit exempts a business
| from staying alive without funding, wherever that comes from.
| I'm not saying your last point isn't valid though.
| Knee_Pain wrote:
| [dead]
| dvh wrote:
| Don't they mould?
| Modified3019 wrote:
| Yes, but only on prolonged contact with moisture.
|
| Same with wood.
| Tagbert wrote:
| Like any adobe-style brick, they need to be protected from
| moisture.
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