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"The 5bn tonnes of cement produced each year thus account for some 8% of the world’s anthropogenic CO2, and generate abnormally high emissions per dollar of rev
by woleium 4y ago
"The 5bn tonnes of cement produced each year thus account for some 8% of the world’s anthropogenic CO2, and generate abnormally high emissions per dollar of revenue earned compared even with other polluting industries (see chart). Yet if less than 0.1% by weight of graphene is added to the mixture, concrete ends up 30% stronger. And stronger concrete means less of it is needed, with a consequent reduction in CO2. "
- samus 4y agoHoping for the best, but hopefully this doesn't turn out to be such a hassle like asbestos :)
- sgt101 4y agoThe question is does it shed nanographite or other nano-carbon particles and if so, at what level. Of course, open fires and photocopiers produce these particles as well so there is some level of background exposure that appears to be somewhat "safe". I expect the "no such thing as safe" crowd will be out if they sniff the opportunity for a witch hunt or 10 [1] [1] https://particleandfibretoxicology.biomedcentral.com/articles/10.1186/s12989-019-0299-z https://particleandfibretoxicology.biomedcentral.com/article...
- Aldipower 4y agoComparing my concrete wall to a photocopier seems a little bit strange.
- thfuran 4y agoWhy?
- Aldipower 4y agoBecause if I do not use my photocopier it does not emit anything, it just emit things during usage. In contrast I do not "use" my wall. It maybe emits things when it is newly made, but otherwise it does not emit things.
- PolygonSheep 4y agoThe same arguments was true for asbestos as well. Asbestos building materials are totally harmless if left undisturbed. But eventually that wall will have to be be repainted/sanded/drilled into/knocked down.
- zikzak 4y agoI did some IT work at a business that also was a training company for a long time and during renovations I had a desk between a server closet (like small room packed with servers hosting web sites) with no door on it and a massive "bizhub" style copier that was running constantly making training binders for the training business (yes, this was a while ago). My hearing was just shot at the end of each day and I was inhaling so much gunk from the printer that it was like living in a major city with a smog problem (as in stuff was coating the inside of my nose, my skin, etc). It took me a while to realize what was going on and I moved a few doors down to some older office space we had in the back of another business in the same strip of office spaces (this place had an ant infestation and no AC but at least I could breath again). It was a real eye opener in terms of noise/crud.
- scotty79 4y agoAre nanocarbon particles harmful? After all it's just carbon. Oragnisms should have a ton of mechanisms for dealing with it safely.
- orangepurple 4y agoEven non-reactive particles like asbestos can cause a persistent inflammatory response eventually leading to cancer, chronic fatigue, malaise, etc. The ones that get the most attention these days are PM-2.5: tiny particles or droplets in the air that are two and one half microns or less in width, penetrate alveoli, and go straight into your blood stream. More info: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4740125/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4740125/ In about a decade or two brake dust pollution will be more recognized as a severe public health problem. It's not on the hype cycle yet. https://pubmed.ncbi.nlm.nih.gov/32593898/ https://pubmed.ncbi.nlm.nih.gov/32593898/
- xxpor 4y agoNot just brake dust (which is probably solvable), but also rubber from tires.
- scotty79 4y agoBut pure carbon is somewhat reactive, so maybe it could be cleaned by the body. Is it not?
- orangepurple 4y agoNot sure, but there is definite collateral damage because it is biologically active. From Fig 2. of https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7789336/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7789336/ Mechanism of DNA methylation and histone modification alterations induced by nanomaterials and nanoparticles: Exposure to NMs and NPs alters the functioning of chromatin-modifying proteins, e.g., DNA methylation and demethylation machinery, and histone-modifying enzymes, causing changes in the pattern of DNA methylation and histone modifications. One of the most common effects of NMs and NPs is the induction of cellular stress, e.g., oxidative and endoplasmic reticulum stress, and metabolic disturbances, e.g., one-carbon metabolism and the citric acid cycle. These events are causing DNA damage and repair response and metabolic alterations affecting the functioning of chromatin-modifying enzymes. Any or all of these events may result in hypomethylation of DNA and altered histone modification patterns. Additionally, exposure to NMs and NPs causes activation of the inflammatory response that, in turn, may cause DNA hypermethylation and histone modification changes
- gonzo41 4y agoI worry about structural safety ratios and the inevitable knock off products that end up failing after completion
- eurasiantiger 4y agoYou mean like what commonly happens in developed countries with standardised construction materials? /s
- GekkePrutser 4y agoOr that it will cause another issue like aluminosis in the future. https://www.kaitekarquitectura.com/en/aluminosis/ https://www.kaitekarquitectura.com/en/aluminosis/ Also caused by an additive (alumina) that made concrete stronger, but turned out later that it started to rot like crazy when it gets wet
- anakaine 4y agoIt's would be golden if we could remove a great deal of the CO2 produced regardless of whether graphene was present in the mix. Or, hear me out, devise a concrete that reacted with atmospheric co2 to produce something more benign. That way it changes from an emitter to being a passive remover.
- nebopolis 4y agoPoured concrete actually is a passive remover! The issue is the process of baking carbonate rocks at high temperatures to form the cement. This not only takes a lot of energy, but it inherently drives off CO2 from the rock. Over the decades as concrete slowly gets stronger and stronger it absorbs back a small but substantial fraction of the CO2 it emitted. The way to make this better is to be able to have mixes with lower fractions of cement for a similar level of strength - hence using graphene in this case.
- thinkingkong 4y agoA passive remover but still a net emitter?
- Veen 4y agoYes, the concrete manufacturing process emits more CO2 than aging concrete absorbs.
- hkt 4y agoMaybe the solution is dense, high rise concrete buildings surrounded by woodland. The size of the woodland being determined by the net emissions from the concrete.
- neodymiumphish 4y agoThe emissions occur during production. Concrete itself doesn't emit CO2, it's the cement being made from limestone that generates emissions.
- IshKebab 4y agoI'm guessing it's stronger in tension, which is not super useful for concrete which is only used in compression.
- lebski88 4y agoI'm not an expert but is that true? Road bridges are commonly concrete. In this application they use tensioned steel inside the concrete to help with the tension and other forces.
- IshKebab 4y agoYeah exactly. The steel resists the tensile forces and the concrete resists the compressive forces. Concrete is very weak in tension. That's why it's basically never used without steel reinforcement. I think increasing the tensile strength is mainly useful to prevent cracking which looks bad and can allow water to get to the steel.
- barbegal 4y ago30% stronger doesn't mean 30% less usage though so it would be interesting to see how much less concrete can actually be used in typical applications.
- samatman 4y ago30% stronger might mean considerably more savings than 30% by weight, especially if the graphene concrete has better properties under tension (where concrete is abysmal). Stronger materials can have a larger volume to surface area ratio safely, picture an X shaped pillar rather than a full cylinder.
- advisedwang 4y agoIt depends a lot on situation. 30% stronger could mean even better than 30% less usage, when most of the weight of a structure is other concrete.
- baxtr 4y agoInterestingly this is also trending right now: https://news.ycombinator.com/item?id=31440518 https://news.ycombinator.com/item?id=31440518
- t_mann 4y agoStronger concrete sounds much more interesting than just that less concrete means less CO2. Should open up some design possibilities for architects.
- jl6 4y agoOr we build skyscrapers 30% higher.
- BLanen 4y agoEconomists have never heard of Yevon's paradox. Surprising. Increased efficiency will lead to more use, not less.
- etrautmann 4y agoI read this as less concrete used for any one application. It's also not clear to me that this would reduce net costs, as producing bulk graphene is likely not as cheap as any other conceivable additive. From an environmental perspective, if required volume is reduced but cost is the same, then worldwide consumption could be reduced.
- robbedpeter 4y agoIt's cheaper than many other additives. Graphene flakes are all that is needed for concrete reinforcement, and it's trivial to produce, even at scale. Carbon chunks are thrown into industrial blenders with water and detergent, resulting in graphene flakes sheared and then separated in suspension. The flakes are separated, washed, and dried. Large graphene sheets are hard. Tiny flakes are trivial, gradeschool kitchen science.
- Carioca 4y agoFor it to come into effect, the cost of the concrete should be a major part of its usage. This may or may not be true in this case, since there's land costs and a lot of regulations
- sp332 4y agoIt's "Jevons", and it is pronounced with a "j" sound.
- yboris 4y agohttps://en.wikipedia.org/wiki/Jevons_paradox https://en.wikipedia.org/wiki/Jevons_paradox