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Crushed wood is stronger than steel

nature.com

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Re: Crushed wood is stronger than steel

#121

Post by jfrankamp »

fouric wrote: post #112

"...eco-friendly alternative to using plastics and metals..." Would someone be able to explain to me why metal isn't "eco-friendly"? I understand that some plastics degrade into small, unfriendly particles over time (and others can't be recycled), but I always thought that metals were fairly easy to recycle with a very high recovery rate.

Mining ore, processing metal is difficult and energy intensive and produces waste tailings. Steel doesn't grow on trees while wood does. It is unclear from my reading whether or not the process in the article produces a lot of waste, or if the chem bath they use can be recycled in-situ, but the reduced ecological cost of material acquisition alone makes this idea worth pursuing.

Re: Crushed wood is stronger than steel

#122

Post by djrogers »

baud147258 wrote: post #102
jacquesm wrote: post #28

Earlier quoted context omitted.

Correction: the outside of wood burns. But a wooden beam is going to slowly degrade over time during a fire, a steel beam will be fine right up to the point where it reaches a critical temperature and then it will collapse instantly. Wood degrades more gracefully giving occupants of a structure a few crucial minutes more to leave if the building is on fire.

If the wood is load-bearing, once it has reached a sufficient degradation level, it'll collapse just as well as any steel beam. And since steel is usually embedded in concrete, it'll be protected for some time, increasing the time before it reaches a critical temperature and collapse. Still I thank you for your answer, it explained what I did not understand in your comment.

I think your assumption that steel is usually embedded in concrete is incorrect. It can be, but it's also often not. Have you never seen steel beam construction with exposed beams? It's not at all uncommon...

Re: Crushed wood is stronger than steel

#124

Post by philipkglass »

anvandare wrote: post #51
jahnu wrote: post #17

Earlier quoted context omitted.

Are there any interesting trivia figures for that? Like how long would it take to evaporate a black hole with an event horizon the size of a basketball, golf ball, grain of sand, whatever?

You can play around with it here: http://xaonon.dyndns.org/hawking/ * basketball (radius ~ 12cm): 1.4e54 years * golf ball (radius ~ 2cm): 6.5e51 years * grain of sand (radius ~ 1mm): 8.1e47 years So all of them "so ludicrously long that these are just numbers". To put it in human terms: * a black hole with a mass of 70 kilograms will evaporate in 0.028 nanoseconds * a black hole that will evaporate in 80 years has a…

How small can a black hole be before it would evaporate faster than it can consume ordinary matter? If I set the radius in the calculator you linked to approximately equal the proton radius at 8.4e-16 meters, I get a luminosity of just about 1 gigawatt and a lifetime of 500 gigayears. If such a black hole were drifting through e.g. a giant cube of water, specific gravity 1.0, would more mass be added to the black hole per second than it loses via evaporation? How far beyond the event horizon is such a black hole's gravity strong enough that ordinary matter doesn't have the compressive mechanical strength to resist the gravitational forces exerted by the black hole? My questions may be faulty or incoherent because I don't have enough background.

Re: Crushed wood is stronger than steel

#126

Post by thatcat »

jacquesm wrote: post #6

The most expensive wooden floors have the end grain exposed facing upwards and this is then compressed down, much like the top of a good quality butchers block. Those floors are just about indestructible. The heavier such floors are used the stronger they get! The wood in the article is compressed crosswise to the grain (so they get thinner rather than shorter), using the original planks as the raw organic material t…

After a bit of searching, the only descriptions of cutting board compression techniques I've been able to find are compressed perpendicular to your description.

Do you have a good source for more info on axially compressed end grain flooring or cutting board construction techniques?

Re: Crushed wood is stronger than steel

#127

Post by jacquesm »

thatcat wrote: post #126
jacquesm wrote: post #6

The most expensive wooden floors have the end grain exposed facing upwards and this is then compressed down, much like the top of a good quality butchers block. Those floors are just about indestructible. The heavier such floors are used the stronger they get! The wood in the article is compressed crosswise to the grain (so they get thinner rather than shorter), using the original planks as the raw organic material t…

After a bit of searching, the only descriptions of cutting board compression techniques I've been able to find are compressed perpendicular to your description. Do you have a good source for more info on axially compressed end grain flooring or cutting board construction techniques?

https://www.google.nl/search?q=butchers+block&client=firefox...

Plenty of floor links already in this thread.

Re: Crushed wood is stronger than steel

#128

Post by vanderZwan »

fouric wrote: post #112

"...eco-friendly alternative to using plastics and metals..." Would someone be able to explain to me why metal isn't "eco-friendly"? I understand that some plastics degrade into small, unfriendly particles over time (and others can't be recycled), but I always thought that metals were fairly easy to recycle with a very high recovery rate.

Could be a matter of embodied energy. Growing trees, when done right, comes with a free CO2 sink (not enough to off-set the CO2 produced in harvesting and processing, but it still helps). Metals can be very energy-intensive to refine, even from recycled metals.

Re: Crushed wood is stronger than steel

#129

Post by freehunter »

tremendulo wrote: post #125

Why doesn't wood that paves streets biodegrade?

Short answer: creosote.

It's basically tar made from coal, they soak the wood in it and the tar makes the wood far more durable and waterproof. It's the same reason railroad ties can last basically forever.

https://en.wikipedia.org/wiki/Creosote

Re: Crushed wood is stronger than steel

#130

Post by freehunter »

pbhjpbhj wrote: post #67
mr_overalls wrote: post #60

Earlier quoted context omitted.

Yeah, "decent care" means "kept away from moisture, fire, and bugs." Such care can be difficult in the long term, but yields results like the beautiful 700 year-old woodwork in this English cathedral. (And of course the comments mention the Buddhist temple Hōryū-ji.) http://blog.longnow.org/02009/01/12/how-long-can-wood-last/

I agree completely. The only part I disagree with its the claim wood is "barely biodegradable". Almost anything can be preserved.

If we're disregarding proper maintenance, almost anything can be biodegradable too. Steel will easily rust into dust in an alarmingly short period of time, but we have 100-story buildings made of un-rusted steel lasting for a century and maybe centuries more. Compared to cars from 5 years ago rusted into oblivion even while they're still being driven.
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