[HN Gopher] Concrete goes carbon-negative
___________________________________________________________________
Concrete goes carbon-negative
Author : mfiguiere
Score : 102 points
Date : 2023-05-08 15:59 UTC (7 hours ago)
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(TXT) w3m dump (spectrum.ieee.org)
| betimsl wrote:
| BOOM! -- with ONLY one move, world is getting better and better
| everyday!
|
| I know this sounds idealist, but, They should make this patent
| free to all.
| hosh wrote:
| It would be interesting to see if:
|
| - this concrete formulation is self-healing like Roman concrete
|
| - Whether that absorption property is dependent on other factors
| like heat (our cities create a heat island effect)
|
| - Whether adding in things like rebar give rise to any unexpected
| interactions
| photochemsyn wrote:
| The best options appear to be replacing the heat source that
| drives the calcination step for making cement from limestone with
| either an electric plasma arc furnace or green hydrogen, both
| sourced from solar/wind inputs:
|
| https://arstechnica.com/science/2022/11/the-road-to-low-carb...
| broguinn wrote:
| > Biochar is made today by heating waste materials like wood
| chips, rice husks, or *water-treatment sludge* at high
| temperature in a low-oxygen environment.
|
| Holy shit.
| throw0101b wrote:
| _Vox_ recently had a good video on the topic:
|
| * https://www.vox.com/videos/2023/4/20/23691222/cement-carbon-...
|
| * https://www.youtube.com/watch?v=asLWBGtAhZk
| hinkley wrote:
| I don't see if they way where they source the biochar. I think
| ultracap people switched to bamboo biochar for superior
| structure. There's probably a different trade off for structural
| materials. Say poplar or Osage orange.
| hannob wrote:
| It seems that there is now an increasing number of startups and
| researchers trying some form of completely unusual cement
| production to lower the carbon footprint. This is in principal a
| good thing, but...
|
| I can't help to think that such overhyped reporting isn't
| helpful. Concrete will not be caron-negative any time soon. This
| is very early research. It's good that it's being done, but it
| should also be clear that this is very far away from an
| industrial process that can be used for real.
| stronglikedan wrote:
| If Veritasium is to be believed, we use more cement than any
| other substance apart from water, so imagine the impact that
| lowering the carbon footprint of concrete, even just a little,
| would have.
|
| https://www.youtube.com/watch?v=rWVAzS5duAs
| porkbeer wrote:
| He is not.
| akira2501 wrote:
| > such overhyped reporting
|
| What part of the reporting did you feel was hyped?
|
| What I took from it is: Some researchers and companies are
| working on similar projects to reduce carbon footprint of
| concrete. Some have some interesting results but with some
| rather extreme compromises. It ends with industry not being
| interested yet, but work continues anyways.
|
| Isn't the exactly the level of reporting you would expect from
| an insider publication like IEEE?
| hannob wrote:
| The headline implied something that isn't true.
| dheera wrote:
| What if the lifetime of the building is considered? Don't
| concrete buildings presumably last much longer in the face of
| fires, tsunamis, and other disasters? Whereas entire towns of
| wooden houses get ravaged by fires every year in California?
|
| Speaking of which, is there any possibility of making a brick
| that is 80%+ carbon (for the purpose of sequestration) and non-
| flammable? Like some sort of low-cost carbon fiber brick?
| clnq wrote:
| > A startup called CarbiCrete is also developing carbon-negative
| concrete. Instead of cement, the company uses waste slag from
| steel-making in its concrete mix, and uses carbon dioxide
| captured from industrial plants to cure the concrete. One
| downside is that the concrete has to be pre-formed and cannot be
| poured and set on site.
|
| What a big obstacle to adoption -- too many building techniques
| rely on on-site pouring, I hope they can engineer some solution.
| yetihehe wrote:
| I've used a lot of prefab concrete blocks for my house. For
| foundations - big concrete bricks, for ceilings - big
| prefabricated long strips with rebar. Of course, not all, but
| it's most of concrete used in my house. You could also make
| small pavement bricks from that, it doesn't need to be poured
| in place and uses noticeable amounts of concrete, it's used a
| lot in Europe.
| Sharlin wrote:
| Most multi-storey buildings are made from prefab elements at
| least where I'm from. Making those carbon-neutral would be a
| big deal, even if the concrete couldn't be used for bridges and
| whatnot.
| AgentOrange1234 wrote:
| I love the privacy policy. We will do whatever we want, we don't
| respect DNT, you cannot opt out. No thanks IEEE.
| mbfg wrote:
| For those wanting to know more about concrete and cement,
| Veratasium has a newish video:
|
| https://www.youtube.com/watch?v=rWVAzS5duAs
| cptskippy wrote:
| Maybe it's my misunderstanding but isn't concrete usually
| prepared local to the construction from ingredients like cement
| that are shipped in from remote locations?
|
| > To get around that problem, the duo first treated the biochar
| with waste water that was produced during concrete production.
|
| Is the waste water from biochar-cement based concrete suitable
| for use in creating subsequent batches of biochar-cement?
|
| How feasible is it to capture this waste water from producing the
| concrete and ship it back to the cement factory for producing
| cement?
| tastyfreeze wrote:
| biochar != charcoal
|
| Charcoal is black carbon produced by incomplete combustion of
| ligneous material. Biochar is charcoal that has been filled with
| nutrients, bacteria and fungi.
| jdmichal wrote:
| https://en.wikipedia.org/wiki/Biochar
|
| > Biochar is the lightweight black residue, made of carbon and
| ashes, remaining after the pyrolysis of biomass. Biochar is
| defined by the International Biochar Initiative as "the solid
| material obtained from the thermochemical conversion of biomass
| in an oxygen-limited environment".
|
| You may be thinking of biochar specifically as a soil
| amendment, where it is sometimes loaded with probiotics and
| such:
|
| https://en.wikipedia.org/wiki/Biochar#Soil_amendment
|
| > She pointed out that when pre-charged with these beneficial
| organisms, biochar promotes good soil and plant health.
| ThorsBane wrote:
| This is really amazing news. This in addition to rapid global
| adoption of renewables at the present rate are remarkable and
| encouraging breakthroughs.
| dylan604 wrote:
| Hate to burst your bubble of excitement, but just today (or
| over the weekend) Texas is in the news for the wrong reasons
| (yet again, and no guns involved in this particular news).
| Legislation is being pushed to encourage natural gas and
| slowing down wind/solar. New regulations to place annual
| permits on wind farms because of the blight on the scenery type
| excuses. The people are gas lighting the public (pun intended)
| to the point that they blame renewable energy for the failures
| of the gas plants during the '21 freeze and the public is
| accepting it. So in Texas, discounts for fossil fuels, extra
| fees for renewables.
| palata wrote:
| This, plus the fact that nothing remotely competes with
| fossil fuels. The simple fact is that after fossil fuels, we
| will have less energy, and there is no silver bullet: we need
| to start doing less with less energy, and stop hoping for a
| technological breakthrough that will save us.
|
| Bad news is that we still have enough fossil fuels to finish
| screwing up the climate.
| gregwebs wrote:
| > Finally, he adds, biochar is made from "biomass that otherwise
| will be landfilled where it releases carbon dioxide, or methane,
| which is a stronger greenhouse gas than carbon dioxide."
|
| I thought biochar is a carbon stable form that is in demand as a
| soil amendment?
| Sharlin wrote:
| Biochar is simply charcoal with some specifics as to how it's
| made, and charcoal is just pyrolysed biomass.
| dumpHero2 wrote:
| Here's a VOX video about this problem, pretty cool! :
| https://www.youtube.com/watch?v=asLWBGtAhZk
| mchannon wrote:
| Making cement releases carbon dioxide in the conversion of flimsy
| calcium carbonate to sturdy calcium oxide by roasting it.
|
| Reversing the process by injecting carbon dioxide in curing
| cement is turning sturdy calcium oxide into flimsy calcium
| carbonate. Every pound of CO2 you sequester this way necessitates
| multiple pounds of CO2 released elsewhere to get that oxide to
| your construction site (production + transportation).
|
| The economics and carbon footprint are similar to corn ethanol-
| attractive and green if you pay no attention to the total
| balance.
|
| A corn belt politician I'd expect this from. IEEE should know
| better.
| cultureswitch wrote:
| Why do you write like Yoda?
| macawfish wrote:
| Why does it have to be either or? Aren't there plenty of use
| cases for the concrete with less compressive strength? Stuff
| like floors and walls of smaller buildings could be perfectly
| fine with the 25 MPa, couldn't they? Patios? Foundations of
| smaller buildings?
|
| If there's a good amount of stuff that doesn't need the higher
| compressive strengths, I'd think there could be some decent
| potential to offset with this stuff. Applications that really
| need higher strength wouldn't need to use this carbonized
| stuff.
| hinkley wrote:
| I don't think it's an accident that a lot of the carbon sink
| concrete companies are doing precast products.
|
| Factory conditions allow for tighter tolerances, which means
| you can dial in the product. Concrete poured outside has a
| range, and the worst case scenario is tightly controlled, but
| at the cost of potentially overspecced concrete. Or at least
| more expensive workers.
| lostlogin wrote:
| For some of those scenarios, couldn't concrete be abandoned
| altogether?
|
| Wooden building work pretty well, though forestry has plenty
| of its own problems (see New Zealand and it's series of slash
| disasters).
| readthenotes1 wrote:
| China, by far the largest user here, builds very tall
| vacant buildings with concrete. Wood can only take you so
| high
| hinkley wrote:
| With manufactured beams it can take you higher than you
| think, but building codes need to be adjusted.
| blackflame7000 wrote:
| [dead]
| tristor wrote:
| There's need, and there's expect. Unless you expect every
| homeowner or other property owner to do expensive and
| destructive testing prior to a reconfiguration, remodel, or
| bringing in heavy semi-stationary loads onto their property,
| it's somewhat critical that concrete behave like concrete
| regardless of its initial use case.
|
| A simple example is in my previous home when I had a section
| of the master bedroom closet partially walled around a Class
| C TL-30 rated firesafe, and the room partially reconstructed
| with ballistic armor in the walls and a vault door, to turn
| it into a safe room for valuables + home protection. The safe
| had a weight of nearly 9000 pounds in a footprint of 64 by 30
| inches on the floor. I was only able to do this because the
| house was a slab on grade construction and we knew the
| footing depth and slab thickness of the concrete would handle
| the weight.
|
| If this had been some sort of "eco concrete" it would have
| cracked and eventually failed under that weight, and we would
| not have known this because the slab thickness would have
| been the same.
|
| P.S.: Since everyone always asks because it's hard to find
| actual safes (most "safes" are garbage RSCs), it was custom
| built by a local safe-maker and expect to pay $$$$$. The safe
| I had installed was $35k, and that didn't include the room
| tearout/rebuild or the vault door, just the freestanding safe
| that went into the room.
| flavius29663 wrote:
| stupid question: why keep such valuable items at home in
| the first place? if they are replaceable, you can just
| insure them. If they are not, they are better stored
| somewhere else, no?
|
| By having such high valuables at home, aren't you putting
| your family at risk?
|
| Also, why talk about these things on the internet? Isn't
| that painting a target on your back too?
|
| I understand the safe room, just not the safe.
| tristor wrote:
| > why keep such valuable items at home in the first
| place? if they are replaceable, you can just insure them.
| If they are not, they are better stored somewhere else,
| no?
|
| You would think, unfortunately banks have done a great
| sleight of hand in the US limiting their liability
| related to safe deposit boxes /and/ safe deposit boxes
| available to rent are nearly impossible to find. Nearly
| every bank branch in any major metro will have a waiting
| list that is years out to get a box.
|
| What's so valuable? Well, basically the same stuff most
| people keep in a random desk/dresser drawer, but ought to
| have in a safe: Paperwork mostly, guns, jewelry. It's not
| like I'm storing anything worth tons and tons of money,
| but the insurance break on getting everything fully
| covered when you have that sort of safe is significant,
| and it's one-time up front expense to ensure you can
| properly store things like paperwork, guns, and jewelry
| which is easily worth tens of thousands of dollars
| anyway.
|
| The only difference between me and every other random joe
| that buys a gun safe at bass pro/cabela's, is that I know
| what an /actual/ safe is, and I went about acquiring one
| rather than the cheap RSC you can bypass with a pry bar
| and a hammer or a sawzall.
|
| > By having such high valuables at home, aren't you
| putting your family at risk?
|
| Many people have things at home equally valuable, they
| just don't bother actually doing anything to protect
| them. I don't think doing the work to protect them adds
| any additional risk.
|
| > Also, why talk about these things on the internet?
| Isn't that painting a target on your back too?
|
| Sure, I suppose so. That's true of so many things. I
| think it's important to be transparent with information
| though and then mitigate or hedge any risks that come
| with it. For instance, in my case, I'm nearly always
| home, I'm always armed, and my valuables are well
| protected. If someone were to find out and decide they
| wanted to rob me, the most likely outcome is they'd be
| leaving in a body bag, so they're unlikely to think that
| is a wise idea.
| flavius29663 wrote:
| Speaking of bank safe boxes, when the IMF and the EU
| forced Greece into capital controls, meaning people could
| only get $400 a week out of their own accounts, plus
| money for rent...the safe boxes were also controlled. So
| you were no longer allowed to be alone with your safe
| box, an employee had to be present to make sure you're
| not getting money out of there.
|
| https://www.reuters.com/article/eurozone-greece-
| cash/greeks-...
| balderdash wrote:
| NYT article describing your exact point on the perils of
| bank safe deposit boxes
|
| https://web.archive.org/web/20230108123245/https://www.ny
| tim...
|
| Edit: HN discussion
| https://news.ycombinator.com/item?id=20545276
| tristor wrote:
| To expand on this, generally if you have an itemized
| insurance rider for personal property on your homeowner's
| insurance or renter's insurance, everything is covered,
| but anything stored offsite such as a storage unit or
| safe deposit box is only insured to a small percentage
| (10% or less usually) of the total general unscheduled
| property coverage and cannot be covered with a
| scheduled/itemized rider. This combined with the shady
| way banks treat safe deposit boxes means that ironically
| in the case of /anything/ short of a flood or fire, you
| are better off having a safe at home vs a safe deposit
| box, even for insurables like guns/jewelry/collectibles.
|
| A safe deposit box /might/ be marginally better for
| backup drives and paperwork simply because it's offsite,
| but a 3-2-1 (one is none, 2 is one) policy/process is
| better. This really sucks for paperwork because the
| government is stupid and usually only the actual original
| matters (e.g. signed marriage license or birth
| certificate) and certified copies aren't sufficient.
|
| I HIGHLY recommend anyone who wants to be an actual
| responsible adult to buy a /real/ safe for their home and
| stick the things that will utterly destroy their life if
| they're lost/stolen/destroyed into that safe, and keep a
| spare key/combo to it with whoever is the executor of
| their will/estate. Nearly every person in America over
| the age of 30 has tens of thousands of dollars in
| valuables worth protecting, they just may not think of it
| as that. It's something like the deed to your house & the
| associated title and mortgage paperwork, your car titles,
| insurance policy information for valuables, your marriage
| license, your passport & birth certificate or other
| identifying documents, etc. This stuff is absolutely
| worth protecting, and the dinky "document safe" for $30
| at Walmart isn't going to do jack shit.
|
| EDIT: Edit to add that a real safe doesn't have to be
| $35k. I bought a huge safe when I did it. If you want a
| small fire-rated Class B TL-30 safe that weighs in the
| neighborhood of 500-800 pounds, can hold most things
| other than rifles/shotguns/long-guns, you can find
| something decent for less than $5k without much trouble,
| which is around what it costs for a "nicer" "gun safe" at
| bass pro anyway.
| nicenewtemp84 wrote:
| When you include car titles, something people lose
| constantly and costs $15 to replace at the DMV... It
| makes me wonder about all the other things you listed
| being easy to replace also and you're just trying to
| explain why you got a safe for paperwork.
|
| My mother guards her social security card and passport
| like they are the keys to life. She was absolutely
| shocked that I let a scooter rental shop in Vietnam hold
| my passport as collateral.
|
| People lose or get robbed of everything important all the
| time. There's a process for everything. I rather not
| worry and just live my life and deal with things as they
| come, not worrying so much.
| tristor wrote:
| > People lose or get robbed of everything important all
| the time. There's a process for everything. I rather not
| worry and just live my life and deal with things as they
| come, not worrying so much.
|
| You have a much rosier picture of things than I have. I
| have had to learn the hard way about some of these
| things, it sounds like you've been lucky so get to be
| happy-go-lucky. I hope you continue to have good luck in
| your life. Car titles are only easy to replace while you
| retain possession of the vehicle and are the recorded
| owner in the DMV database.
|
| If someone steals the car + title (which happened to me
| once when I foolishly did what many people do and left
| the title in the glove box), they can easily re-register
| the vehicle to themselves and you have basically no
| recourse unless you can conclusively prove they forged
| your signature or fraudulently registered the vehicle.
| Once the successfully record the title change you are
| pretty screwed, as the saying goes "possession is 9/10s
| of the law", and it's sadly pretty true. You'd think
| reporting a car stolen to the police would block someone
| re-registering it, but that wasn't the case then. It was
| over 15 years ago, maybe things are better now as much
| vehicles are electronically titled, but I'd still
| recommend not losing it.
|
| Maybe my viewpoint is simply a matter of age. Things are
| much more electronic now and paperwork is less important
| because there are electronic records. On the flip side,
| if the electronic records are wrong, sometimes paperwork
| is the only thing you have to prove that.
| slt2021 wrote:
| If you call police and report your car stolen the next
| day it is stolen - police report will be your argument
| and you not only will get your car back, also whoever re-
| registered vehicle will go to jail (also a state Notary
| who verified forged signature will go to jail as well)
|
| most stolen cars go to spare parts or export to Global
| South as junk/scrap and you can't do that without DMV re-
| registration.
|
| if you truly have modern car (like BMW 2017 or newer),
| then you can just disable and lock it remotely from an
| app, and geolocate it.
| nicenewtemp84 wrote:
| Almost no states I have bought and sold cars in requires
| a notary to do any regular title transfer.
| slt2021 wrote:
| pls give me a state name, from my experience all state
| will require either in-person presence of an owner
| (verified by ID) or a notary who verified the signature
| of title holder for transfer
| nicenewtemp84 wrote:
| California for starters with all 35 million residents.
| Nevada. Arizona. Oregon. Washington.
| vel0city wrote:
| Add Texas and New York to the list of states which don't
| require a notary for a private party vehicle transfer.
| Between NY, CA, and TX that's like 57M licensed drivers,
| so quite a few cars.
| tristor wrote:
| Same in every state I've lived (7 at this point), all it
| requires is that the title is signed by the owner (or the
| signature looks like it was signed by the owner). The DMV
| /might/ care to look at the signature when they accepted
| it vs when they transferred it, or they might now. No
| notary or witness required.
| nicenewtemp84 wrote:
| In California I've heard that DMV can not, or will not,
| question a signature. I bought and sold cars to pay my
| way through college, during prime craiglist years, and
| had to 'recreate' countless signatures when forms were
| missing or required or even when I was lied to by
| sellers. Sounds reasonable I assume, unless we think
| there's a database of signatures somewhere in a
| government office DMV has access to, how in the world
| would they even be able to question a signature?
| nicenewtemp84 wrote:
| Part of being happy go lucky involves not being totally
| oblivious. There's a big difference between worrying
| enough to put your car title inside a $5k safe, and
| worrying so little you keep it inside the car itself.
| lostapathy wrote:
| That type of room i not just a safe, but also a "panic
| room." Which could be anything from living in a terrible
| area and worried about civil unrest, to someone wanting a
| 100% confidence their tornado shelter would protect them
| no matter what.
| tristor wrote:
| In our case the panic room was definitely more weather
| related than burglary concerns. During the course of
| living in that location (I am in a different state now,
| but was there for 12 years in that house) we had 5 major
| weather incidents that were declared disasters by the
| state, and once nationally. We never had a single home
| invader, trespasser, burglar, or otherwise. The safe was
| more about fire risk than theft risk, but if you're going
| to do it you might as well go all the way. It was TL-30
| rated but also rated for 4 hours at 2500F. Same thing
| with the safe room, if you're going to build it, might as
| well protect against everything.
| trilbyglens wrote:
| Texas resident confirmed.
| tristor wrote:
| Not any more, but yep, I was a Texas resident when that
| work was done and that is where that house is located.
| ryukafalz wrote:
| > A simple example is in my previous home when I had a
| section of the master bedroom closet partially walled
| around a Class C TL-30 rated safe, and the room partially
| reconstructed with ballistic armor in the walls and a vault
| door, to turn it into a safe room for valuables + home
| protection.
|
| But... why? This does not seem like a typical use case.
| rcoveson wrote:
| Why can't people just do exclusively normal things in
| their home, like eat corn flakes and consume popular
| media?
| vkou wrote:
| You're free to churn butter by hand using a toothpick in
| the comfort and privacy of your own home, but I wouldn't
| take complaints about toothpick integrity from someone
| doing that seriously.
|
| There are much better arguments against shitty,
| compromised concrete than 'I need to park a semi-truck in
| my bedroom closet.'
| rcoveson wrote:
| There are much better arguments than "I want to blow up a
| bomb in my house" as well. Oh, and there are better
| arguments than "I want to dig the house out of the ground
| and drop it from a great height".
|
| One example of a reasonable argument is: "I want to put a
| very heavy safe on the floor, which works fine when it's
| normal concrete".
| marcosdumay wrote:
| Well, it is not really atypical to have one of the
| thousands of possible atypical use cases in any home.
| mrexroad wrote:
| I get your point that it's convenient to be able to blindly
| trust a slab, but in older houses you often have slabs that
| are too cracked, have settling underneath, or are otherwise
| unsure or suspect enough to blindly assume the "concrete
| will behave like concrete." In those cases it's pretty
| straight forward to just cut/demo out section of the slab,
| dig a new footing or prep for new slab in that area, and
| then reinforce as spec'd for the intended load. E.g. car
| lift in older garage. Even w/ new(er) construction I
| wouldn't be trusting it to handle any sort of outlier use
| case without testing, or at least having the original
| blueprints w/ specs for the slab.
| robocat wrote:
| Off-topic, but could you tell me how much you think of your
| spending you recovered? Presumably lower home policy is a
| few hundred a year, and possibly you got a slightly higher
| price when you sold? I am ignoring your other soft
| benefits, and just curious about the financials.
| cwkoss wrote:
| Non-eco concrete is also not fungible, there are many
| different kinds each with different mechanical properties.
| prpl wrote:
| I'd be a little cautious dropping in several tons of mass
| over a few inches of concrete unless I knew it was
| reinforced (depending on age of house), in good shape, and
| soil conditions - even for slab on grade. Pour conditions
| are highly variable too - how do you know the contractor
| wasn't drunk that day.
|
| I suppose the point is that it doesn't matter what concrete
| was used as long as you knew how it was actually built and
| current conditions of the foundation (and below the
| foundation for that matter).
| eecc wrote:
| ok, then color-code the pour. Just toss a tint into the
| mixer and all you need to to in case of later modifications
| is drill a pilot hole and look at the color of the dust.
| jollyllama wrote:
| TIL "RSC". TY.
| tristor wrote:
| > The only difference between me and every other random
| joe that buys a gun safe at bass pro/cabela's, is that I
| know what an /actual/ safe is, and I went about acquiring
| one rather than the cheap RSC you can bypass with a pry
| bar and a hammer or a sawzall.
|
| While I'm on that topic, there's a few things everyone
| should know about safes.
|
| An RSC, or Residential Security Container, has a very
| minimum standard, and the "gun safes" even though they
| are heavy and bulky at bass pro are usually RSCs. They
| are legally required to be marked, and if they are marked
| RSC, they are no more secure against burglary than your
| typical sheet-steel locking cabinet at the hardware
| store. Sometimes they're actually worse. The big thick
| door and the big thick walls on those "gun safes"? Well,
| generally it's two thin sheets of steel with drywall
| sandwiched between them. Why drywall? Well, it helps with
| fire protection and is the primary way in which the safe
| gets fire rated.
|
| So let's talk about that drywall for a second. When you
| have a fire rated safe that uses drywall and it doesn't
| hermetically seal it, that drywall can actually cause
| corrosion of firearms or other metal objects and
| degradation of papers stored within the safe. Modern
| drywall is exceptionally corrosive, but usually this
| isn't a problem in homes because it's painted over on the
| inside to seal it and it off-gases to the outside where
| homes aren't perfectly sealed. In a safe though, you have
| a seam-welded outer shell, drywall, then carpet glued
| over it (which is also corrosive as well), or in better
| safes a seam-welded outer shell, drywall, then a tack
| welded inner shell with no carpeting.
|
| Why does drywall cause corrosion and degradation of
| paper? Two compounds in drywall are responsible:
| Formaldehyde and Sulfur. Carpet also contains huge
| amounts of Formaldehyde typically, as does the carpet
| adhesive. Formaldehyde off-gasses and is itself deeply
| corrosive. Sulfur compounds in the drywall combine with
| moisture in the air to produce a chemical reaction when
| encountering naturally occurring pyrite in the powdered
| rock base of the drywall to produce iron hydroxide and
| sulfuric acid when coming into contact with exposed iron
| and high carbon steel (e.g. what guns are made of). The
| iron hydroxide off-gasses and the sulfuric acid is left
| behind and causes corrosion and pitting.
|
| Don't be a big dummy, buy a real safe, not the crap they
| sell for thousands of dollars at big box stores with less
| than $100 in materials costs. If you are okay with the
| security level of an RSC you can get by with a plain
| locking steel cabinet.
| rch wrote:
| I don't immediately see any claims that this material is fit
| for all purposes regular concrete would be.
|
| The first application that comes to mind for me is an
| alternative to styrofoam-fill insulating concrete forms.
| Biochar sounds like an improvement vs even waste diverted
| styrofoam.
| Y_Y wrote:
| I'm surprised a publication aimed at professional engineers
| thinks it could get away with a sleight of hand like that.
| mchannon wrote:
| I doubt it's intentional. It's just the modern day equivalent
| of a perpetual motion machine or a "machine that makes water
| out of air" (dehumidifier).
|
| This particular subject matter area falls in a blind spot
| where electrical, chemical, and environmental engineering
| meet, and nobody gets rich pulling the rug out like I just
| did.
|
| I write about this in my book Fat Gas. Plenty of modern-day
| snake oil salesmen out there.
| anon4242 wrote:
| > a "machine that makes water out of air"
|
| Isn't that just your typical air-con unit?
| mchannon wrote:
| Exactly.
|
| But you will find dozens of examples in a google search
| of people who somehow think they've solved the world's
| water woes by collecting condensate off a disassembled
| A/C or dehumidifier, and ignorant uncritical news
| reporters buying it hook line and sinker. Collected
| funding, even had a whole embarrassing incident at Cal
| involving the freshman engineering class a few years ago.
|
| There is definitely a need for clean water out of air,
| but it's got some subtle limitations: you don't need it
| when it's already raining, and the further you get from
| that condition, the less well dehumidifiers work in terms
| of gallons produced per kwh consumed. Below 50% RH,
| you're getting bupkis for condensate. Most of that energy
| is spent cooling off air but not quite cold enough to get
| it to leave its moisture behind.
|
| Here's an easy thought experiment next time you run
| across one of these "inventions". If a cubic foot of air
| at 40% humidity contains .24 mL (sorry for mixed units)
| of water, give them the benefit of the doubt and say
| their setup is 100% efficient for pulling every last
| molecule of water out of air. and it runs on a 28cfm
| computer case fan. How many gallons per hour would that
| be? 0.1. The reason these suck is not that they don't
| work in dry conditions (though they don't), but that they
| don't move enough air to be useful.
| ZeroGravitas wrote:
| They covered a few products and techniques. Which one
| specifically are you talking about?
|
| The CarbiCrete one for example uses CO2 to cure the concrete,
| but doesn't use cement.
|
| https://www.sciencedirect.com/science/article/abs/pii/S09596...
|
| > steel slag has shown the potential to replace cement as an
| alternative binder if carbonation activation is performed.
| mchannon wrote:
| Since Elsevier is hiding the meat in that journal article, I
| can only go off what I read, but it looks identically flawed.
|
| * Compressive strength of normal concrete: 25-50MPa
|
| * Compressive strength of their slag concrete with 2h CO2
| added: 12MPa
|
| * Compressive strength of their slag concrete with 24h CO2
| added: 24.3MPa
|
| My takeaway:
|
| Using slag instead of cement = good idea.
|
| Using slag OR cement plus CO2 = bad idea.
| Faaak wrote:
| BTW: You can access most scientific articles through sci-
| hub: https://sci-
| hub.ru/https://www.sciencedirect.com/science/art...
| digging wrote:
| I'm following as a layperson, can you explain how to reach
| your takeaway from the bullets presented? It seems like #3
| is almost identical to low-end normal concrete, so "good
| idea". Not sure what "24h" vs "2h" refers to though.
| krick wrote:
| Weird to assume IEEE or any other large enough organization
| that has people being paid money to write posts on the internet
| (i.e. PR dept) is somehow different from "corn belt
| politicians" and won't be pushing the same agenda. The main
| point of doublethink is that people that are not good at it,
| are not allowed to speak publicly anyway, so it's kinda besides
| the point if some random engineer has problems evaluating how
| come that worse concrete is better concrete.
| manojlds wrote:
| Could you give some links on claim on ethanol mixing not being
| a great alternative?
| mchannon wrote:
| First one's on me, the rest you can pay for, or google:
|
| https://e360.yale.edu/features/the_case_against_ethanol_bad_.
| ..
| Mystery-Machine wrote:
| Transportation can be carbon neutral. So you can remove that
| from equation. At least there are many ways people are trying
| to reduce transportation carbon emissions to as close to zero
| as possible.
| palata wrote:
| Nothing that uses energy can reasonably be carbon neutral in
| a world that depends mostly on fossil fuels.
|
| Transportation uses energy, therefore transportation is not
| carbon neutral.
| BHSPitMonkey wrote:
| The comment didn't say "transportation is carbon neutral",
| they said it can be. You point out that the world depends
| "mostly" on fossil fuels, which correctly implies that
| there are instances in the world where this isn't the case.
|
| e.g. Transportation using EVs that get all of their
| charging from a solar installation.
| moffkalast wrote:
| It can be. But is it? Will it be any time soon? Isn't the
| Tesla Semi the only EV truck on the market and isn't being
| produced in any major quantities yet? It'll probably be
| decades before any of those reach your average concrete
| production site where they're still using trucks from the
| 90s.
| vel0city wrote:
| There are many truck manufacturers shipping trucks today.
| The Teslas that Frito Lay received weren't their first EV
| trucks, they had been operating EV trucks before they
| received the Teslas.
|
| https://www.teslarati.com/daimler-freightliner-ecascadia-
| pen...
|
| https://afdc.energy.gov/case/404
| throwawaylinux wrote:
| Even if you buy carbon neutral electricity, increasing
| the demand for it will end up increasing carbon positive
| electricity production (in the large scheme of things).
|
| And we'll ignore carbon to manufacture the truck and
| create and maintain the roads, warehouses, and other
| transport infrastructure.
| zardo wrote:
| > Isn't the Tesla Semi the only EV truck on the market.
|
| At this point, I don't think anyone that makes a heavy duty
| truck _doesn 't_ sell an EV version.
|
| Volvo started selling an EV concrete mixer this year.
| henearkr wrote:
| In this new process, it's not the cement (by its classical
| definition) that is cured by the CO2 in the air, it's the
| calcium-enriched biochar. Thus the cement part is still sturdy,
| and the biochar part avoids making it flimsy because this
| calcium treatment enhances its binding with the cement.
|
| It looks like the main problem with previous experiments with
| biochar added in cement was that the biochar did not bind well,
| making a crumbling result, but this article is about solving
| precisely that.
| mchannon wrote:
| The article claims "[t]his calcium carbonate strengthens the
| biochar" but this runs counter to my understanding and I'd
| like to see some numbers, particularly versus alkalized
| biochar that is never exposed to CO2.
|
| How important is binding in compression (which is what
| concrete is used for)? Not very.
|
| Carbonate doesn't strengthen, it weakens. And if forming
| carbonate in biochar strengthens versus standard biochar, I
| would imagine forming oxide in biochar would strengthen even
| more.
| henearkr wrote:
| No, the full quote is "This calcium carbonate strengthens
| the biochar and helps it bind better with cement, giving
| strong concrete."
|
| The binding part is very important. It holds grains between
| them. For example that's the difference between a hard
| granite and a crumbly, sandy granite rock (that's called
| "decomposed granite"). It's day and night.
|
| And I also believe them that the treated biochar is
| stronger than the untreated one. Maybe if the same process
| was used to treat the cement itself it would be a disaster,
| but here that's not the case.
|
| What do you mean "forming oxide in biochar"?? The oxide of
| biochar is CO2. Are you trying to make fun of me heh...
| xchip wrote:
| Spot on, and add you say, IEEE should know better
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