Crushed wood is stronger than steel | Hacker News Reader

Crushed wood is stronger than steel

nature.com

461 pointsokket172 comments

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 to produce an engineered product that has relatively little to do with the original wood. While this is very impressive the process does not sound cheap (it is time consuming and will produce quite a bit of toxic waste) and the way the article is worded leaves it ambiguous of the strength increase is relative to the original base material or if it is on an absolute scale using the same cross section.

The article states the result is 10 times stronger than the original after being compressed to 1/5th of the size, making it effectively thinner, lighter and stronger at the same time.

It appears that the increase in density is where the writer missed the fact that reducing the cross section but leaving the amount of material the same does not result in an increase in strength on an absolute scale, it merely means that if you then laminated five of the densified planks back to the original cross section the result would be 11 times stronger.

But then you'd lose much of the weight advantage.

So I suspect this is either a space or a strength gain, but not both to the extent the article indicates.

In the previous century there was a lot of research done on strengthening wood including gamma radiation and all kinds of other treatments, but none of those ever made it to very high levels of industrial adoption.

>making it effectively thinner, lighter and stronger at the same time.

The article never says it's lighter, and the paper is behind a paywall. Interesting process none the less.

It does say it is lighter, it says it removes certain compounds from the wood and then compresses the remainder without further additives. So it is lighter than the original wood but much more dense.

I mean I agree it's likely that the process makes the wood lighter. But no, the article doesn't explicitly say the end result is lighter. It explicitly says it's thinner and stronger.

I don't really know much about the process or whether the chemical treatment can potentially make the wood heavier/absorb some of the liquid, which would offset the weight of the material that's lost.

My point wasn't that there's no way the result is lighter. My point was that the article didn't mention the weight before and after, so it seemed presumptuous to me to claim it was definitely lighter.

I went to check the actual paper to confirm, hit a paywall, and so was unable to verify. I was hoping someone would comment with more details.

Do you mind sharing a picture of this done right? The end grain wood floor pics I found on Google look mostly hideous to me.

Not OP, but I found some interesting information here.

http://kaswell.com/about-us/history-of-woodblock/

Looks like it's good for outside flooring. Actually doesn't look that bad when used for that either, kind of like bricks.

(Actual gallery here http://kaswell.com/gallery/)

It also was a traditional flooring for workshops, because it tolerated heavy abuse.

More pics: https://www.google.de/search?q=stirnholzparkett&source=lnms&...

This used to be very common for machine shops to have wood floors, I found an article detailing it with some pictures. I worked in a couple shops that had wood floors, they were nothing to look at, it was an industrial setting after all. https://web.pa.msu.edu/services/machine-shop/shopfloor.htm

At Amazon in the new Day 1 building their main staircase to the lobby is built from wood ends and it is done very nicely. It looks great. There's probably pictures online of that.

edit, I found one picture from a geekwire article. Unfortunately you can't see the grain, the picture is from a far. https://cdn.geekwire.com/wp-content/uploads/2016/11/20161107...

>This used to be very common for machine shops to have wood floors

That is done because wood is soft and if you drop a tool or part on the floor it's far less likely to be damaged. Wood has been superseded by (usually vinyl IIRC) tile and/or rubber/plastic mats in a lot of places.

It's also done for the comfort of the people working there. Standing on concrete all day is more tiring than on a wooden floor.

Boulevard Brewery in KC has part of their event space floored with end grain. Overview pic: https://www.boulevard.com/wp-content/uploads/2017/03/BHB-7.j...

Closer up:https://media-cdn.tripadvisor.com/media/photo-s/0a/df/ba/b1/...

Here's a picture of the floor of the Square Root Restaurant in Brevard NC: https://www.tripadvisor.com/LocationPhotoDirectLink-g48979-d...

Each block is 6"x6" (15cm x 15cm) of pine. Apparently it lasts a long time, but took a long time to install.

I work at Red Wing Shoe Company, and our office has this type of flooring on the first floor: https://i.imgur.com/arWH5NR.jpg

That's gorgeous.

The labor cost to do it today would be substantial, I'm estimating it's around 4k-5k sqft of 2"x4" blocks!

The entrance to Trinity College Dublin is an 18th century gatehouse where the floor is made of hexagonal wooden blocks that have weathered quite well.

Sorry to go on a tangent, but your comment reminded me of a book I read about the Chinese culinary culture pre-revolution. Chinese chefs had, and may still have, wooden cutting boards that were conditioned somehow such that they were as hard as stone. (There was also an implication that they resisted bacteria unlike normal wood boards when not scoured properly.) These boards were passed down from generation to generation.

The bit about the cutting boards being as hard as stone, is that pure hyperbole or is it possible?

Doesn't having a cutting board as hard as stone defeat the purpose of having a cutting board?

Isn't the point of a cutting board to protect the counter top from the knife, mobility (move chopped food to another location) and being easy to clean? As opposed to a flat counter top which can get marred with marks, can't move, can be cleaned but not thrown in a sink.

They also protect the knife blade from damage: if you were to cut directly on stone, the knife hitting the stone would cause it to dull more quickly.

Also to provide a less damaging surface for the knife blade.

I'd say a much more important purpose of a cutting board is to protect the edge of your knife. If you hit the edge of your knife on something really hard, it'll chip, or fold--basically just ruin it. This might not be such a big deal for home cooks with super dull knives (after all, glass cutting boards still exist for some reason!) but for a professional I'd think a cutting board that destroys your knives would be worse than useless.

The purpose of a cutting board is to protect the things underneath it that are not as hard as stone.

Then you could just use a metal plate or glass, but we use the wood in order to protect the blade of the knife also. You'd have to re-sharp the chef knifes every few minutes if they were used on the surface harder than the blade.

You should, and it's called steeling.

There's a foil edge on very sharp knives that will wrinkle and fold after use on anything, even tomatoes, making the knife feel dull. It's not, and it doesn't require removing metal as with grinding or sharpening, but you can steel to realign that edge or strop to hone it depending on the blade and angle. Even if you don't work with blades often, you've probably seen this depicted in media.

It really doesn't matter what the cutting surface is to the knife if you have great technique. Since I don't always, I use thin, flexible plastic barriers. I would never recommend wood outside of having no other choices or using it as part of presentation, mainly because of cross contamination and difficulty in sanitizing if you cook sous vide or serve raw often.

Obviously I meant the stone sharpening, not using the knife steel. And as for the material, many sources say that plastic actually contains more bacteria and that end-grain wood is more gentle to a blade than plastic. On the other hand plastic is easier to clean when it's new, but it's also more prone to cuts than wood and they quickly get dirty (at least in my limited experience). IMHO every board needs to be scraped or sanded from time to time to remove the top layer completely, that's the only way to keep it clean.

My guess is that these wood boards would have much less friction than a stone equivalent, unless you had enough money to pay for a polished one.

You'd destroy your knives/cleavers with a stone cutting board. The wood needs to give a little bit so the blade doesn't chip and holds an edge long enough to be useful. Sounds like pop writing sensationalism, as with Damascus steel, which TV shows imply (or outright state if they have no shame) is better than any steel we currently know how to make.

Hard as stone is probably meant in a figurative sense, not a literal sense. End-grain wood is pretty hard, especially when compressed (for instance: by beating it with a hammer), but it is nowhere near as hard as stone. That said, there are some pretty soft stones :)

I've broken more than one high quality steel bit on various kinds of wood, but that's usually not a measure of how hard the wood is but how much friction there is between the drill and the wood and how much of the drill bit is inside the wood. If the wood were really hard you would not be able to enter the bit at all and it would never break but just sit there spinning on the surface.

Finally, the whole trick to a cutting board is that end grain wood will wear very little and the knife will be sharp much longer specifically because it is not as hard as stone.

Yes, many Chinese chefs and households still do use wooden chopping boards. I am not sure if the boards are as hard as stones, since there are many different kinds of stones. But thickness and the type of wooden do matter and will certainly make the wood very hard to crack (and to burn).

Here are some videos for the readers:

https://www.youtube.com/watch?v=oTNVDH6ZFLg

https://www.youtube.com/watch?v=isFTIHy7Duo

You will see pork bone chopping (beginning of the video), skin slicing (1:40), and meat grinding (5:30) in the second video.

Those are very typical boards in a restaurant's kitchen. The typical household chop board is a lot smaller and thinner, probably around 35" wide x 5" high. However, many families have moved away from wooden chopping board because plastic boards are easier to clean.

As far as resistance to bacteria, that will fall short with science. The passing down from generation to generation is a cultural effect. If you live with your in-laws, the board will of course be reused. Since wooden boards don't crack for years, yes, the board will be passed down. Butchers (Chinese and other cultures) use wooden boards because of the durability (Chinese chefs love chopping real fast with force). Real chefs prefer wooden chopping board (yeah, your famous Gordon Ramsay!)

Also, it is very common to see a butcher or a chef to stick the big kitchen knife on the side of the board tilted like the Leaning Tower of Pisa :-) The strength of a real butcher or a real chef can be so much more powerful than a MMA boxer.

EDIT: If you want a short English intro on this topic, https://www.youtube.com/watch?v=gDdoht0e1sg is solid.

Bamboo cutting boards are often advertised as having anti-microbial properties. No clue if there's any scientific backing to the claim, though.

My experience with bamboo is that it's far more vulnerable to mildew than similarly-utilised wood items.

none of those ever made it to very high levels of industrial adoption.

Non-exotic methods of strengthening wood, made it to high levels of production in spades: plywood, oriented strand board, microlam and glulam beams, and medium density fiber board (MDF) are direct examples. Wood I-joists and plate connected wood trusses are less direct. From a functional standpoint, standardization of lumber grades is a social technology that allows designing wood members with known engineering properties.

On the chemical front, pressure treated lumber increases wood's strength across a timeline. Fire treatment increases wood strength in a narrow set of circumstances.

Of these, plywood is clearly the most successful in terms of industrial adoption being used for aircraft, boats, and furniture among other things.

Yes, engineered wood is a mainstay of construction. But all of those processes were and are set up to be able to process a large volume in a relatively short time and leave very little to no waste, and what waste there is is sold off as fuel.

Plywood - especially the higher grades - is amazing stuff. I visited a plywood factory in Ontario and it really opened my eyes to how clever and precise the manufacturing of various kinds of engineered wood is.

It is, the WWII Mosquito Fighter-Bomber was made from high grade ply and it flew faster than contemporary aluminium fighters, was incredibly durable (except for some de-lamination problems in hot humid far-east environs) and was actually stunningly beautiful.

Also mostly plywood: the Spruce Goose https://en.wikipedia.org/wiki/Hughes_H-4_Hercules

which is simply massive: 320 ft wingspan, the largest of any flown aircraft.

Haha, that was the first aircraft I thought of too!

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

The earlier de Havilland Comet was also incredibly beautiful and made by innovative woodworking techniques: https://en.wikipedia.org/wiki/De_Havilland_DH.88_Comet?oldfo..., one of my favorite planes ever.

I too was surprised to find out just how much variety and quality of plywood there is. I always thought it was a relatively cheap, kind of crappy alternative to good lumber. But since I've started following hobby laser cutting, I've been finding out that good plywood really makes a difference if you want good results.

I've had really good experiences with birch based plywood of the better grades and for heavier applications a grade that is used in construction to make the forms for concrete casting.

Plywood: How it's made;

https://www.youtube.com/watch?v=xGnr8ATHHX8

Where in Ontario? This would be interesting to see for myself.

Thessalon iirc on Hwy 17.

There’s also stabilized wood. You basically fill all the space inside the wood with a hard resin. Small pieces are used for things like jewelry, knife scales, etc.

At what point do we have to stop considering processed wood as wood, but as a wood/resin or wood/adhesive composite?

Sometime after we stop considering processed food as food, but a food/sugar or food/preservative composite.

Stabilized wood definitely has a lot more in common with resin than with wood, in its mechanical properties.

Your comment reminded me of a technique that guitar makers have been using in recent years, which is to make wood more stable by roasting it in a kiln (which removes the moisture from the wood, and supposedly increases its stability).

If by "recent" you mean developed about 200 years ago, then yes.

From what I've seen, it's become more popular recently (last 10 years).

Its a technique older than guitars, not recent at all. Maybe you just took notice?

well at the very least the technique has been packaged/marketed as “torrefied wood”, and i think that’s what is being referenced here

Yep, plywood gets a bad rap: it's incredibly strong stuff. Aircraft plywood can be used to build entire aircraft, marine plywood can withstand harsh weather conditions for years, and birch or hardwood plywood can look very pretty.

Some plywood is amazing. Most is crap. Generally the stuff you buy at home depot for $25/sheet is crap.

And people tend to confuse plywood with OSB, MDO, MDF, etc.

And while marine plywood (BS-1088) is great stuff, and fir marine plywood is also pretty nice stuff, it's not magic. BS-1088 is will rot in a morning dew and fir checks horribly. You have to protect it carefully and keep it protected.

Plywood is the best combination of strength, weathering resistance, and workability of any material I've yet used. MDF is way cheaper, but it is so much weaker pound-for-pound[1].

1: One carpenter I talked to complained that MDF won't hold screws, and apparently this is a common complaint, but if you drill properly sized pilot holes and use sheetmetal screws it's pull-out strength is fine, particularly since you need thicker MDF than ply, so you can use a longer screw.

The primary advantage of MDF is dimensional stability. Dimensional stability is highly desirable for surfaces receiving veneers or high pressure ("plastic") laminate finishes. It's not really intended for structural applications, but for furniture and cabinetry it can be a reasonable option.

Another advantage MDF has is that it's heavy. Granted for most things you'd rather have light, but for stuff like speaker cabinets and sound deadening you want heavy.

Also, MDF makes a bad material for speaker cabinets. A good speaker cabinet not only is heavy, it have a really good characterized sound qualities that MDF, plastic or cheap plywood can't give. Because that are expensive!

Fire treated wood is called 'shou-sugi-ban' in Japanese and is occasionally used in commercial and residential applications. Fire treated wood has the benefit of being naturally fire-resistant, insect resistant, and water/rot resistant while also being a natural treatment (as opposed to a man-made chemical treatment.)

https://shousugiban.org/

https://www.treehugger.com/sustainable-product-design/materi...

HGTV's Fixer Upper had an episode where this treatment was used. They were fixing up an old boathouse and decided to use this method for the exterior.

There is still a street in Pittsburgh that is end-grain wood blocks. (In Shadyside, a short residential street.) They continue to treat it with tar. So I wonder if it was a similar idea.

Any chance you can find a google street view link for this?

I found this image, but it's from Philadelphia:

http://www.philly.com/philly/living/20151225_Changing_Skylin...

This might be what you're thinking of: http://www.pittsburghmagazine.com/Best-of-the-Burgh-Blogs/Th...

Here's a street view link: https://goo.gl/maps/smQp7BpkgHF2

It's a bit of a random little stub street, so I'd never noticed it during my 4 years of undergrad, but it's a neat lil artifact.

There's a tiny amount left in London:

https://www.ianvisits.co.uk/blog/2015/01/10/the-time-when-lo...

This seems to be a topic which animates a certain kind of urbanist nerd (of whom Ian Visits is the prince):

http://www.roadswerenotbuiltforcars.com/wood/

http://www.endgrain.org.uk/history/

That last page is from some Welsh applied research project on using more endgrain wood for surfaces; there's lots more interesting material on that site.

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.

There are no links or threads related to axial compression. I guess your original post ment that it is compressed during use rather than constrution.

It can be either way. The 'during construction' bit is done using compacting hammers and then afterwards it is sanded down again to expose the grain, the pounding can splinter the topmost layer. And after the sanding the floor is nice and smooth, the pounding leaves it somewhat uneven because the wood isn't equal density everywhere.

You can drop a hammer head down on that stuff and it won't even leave a dent.

The story does make a lot of references to previous work done, and even has a quote about how this method seems expensive and no better than existing methods.

It looks like the paper (https://www.nature.com/articles/nature25476) provides the detail you are looking for.

People may also find Pykrete interesting https://en.wikipedia.org/wiki/Pykrete

Its adding wood pulp to ice to make the ice much much tougher. It was invented by the epitome boffin Geoffrey Pyke, who proposed they build an aircraft carrier of it! https://en.wikipedia.org/wiki/Project_Habakkuk

They actually started the planning and final R&D! (That is before they realized that a slowly-melting ship isn't the most stable or sustainable solution to sea-travel and -defense.) https://en.wikipedia.org/wiki/Project_Habakkuk

There was a short piece on 99% Invisible about this recently: https://99percentinvisible.org/episode/mini-stories-volume-3... (worth a listen just for the part about the plaque they erected (?) where the ship now sits).

Did you mean to say "eponymic" instead of "epitome"?

I meant he was the epitome boffin.

But yeah, he was eponymic to Pykrete too :)

In that case, "epitomic" perhaps, as "epitome" is a noun?

Lovely link, by the way, I did find Pykrete very interesting!

> "I meant he was the epitome boffin."

Just FYI, it's common to use "of" or "of a" after "epitome", for example "he was the epitome of a boffin".

> epitome boffin

Speaking of which, he's first cousin to Magnus Pyke - the guy usually remembered in the US (if at all) as the Professor shouting "science!" in Thomas Dolby's "she blinded me with science;" both on the song and in the video. In the UK he was, like his cousin Geoffrey, much better known for being the quintessential boffin, though Magnus self consciously played up this stereotype in his long television career. Sort of like Bill Nye on the outside but Carl Sagan on the inside.

what does "boffin" mean in this context, is it like the US nerd, or (more recently) geek?

WWII era british slang for scientist/high level engineer.

Archetypal example would be someone like Sir Barnes Neville Wallis or someone more recognisable around these parts Tommy Flowers.

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

"Boffin is a British slang term for a scientist, engineer, or other person engaged in technical or scientific research and development. A "boffin" was generally viewed by the regular services as odd, quirky or peculiar, though quite bright and essential to helping in the war effort. The World War II conception of boffins as war-winning researchers lends the term a more positive connotation than related terms such as nerd, egghead, geek or spod."

To explain the modern use (which is very rare, outside of the tabloid news industry), a boffin is somewhat similar to geek, but it's used to describe knowledgeable people in academic / research fields, and occasionally in computing too. It's often said in a jokey way (I've never heard anyone describe themselves as a boffin), but it's not really an insult, there's a certain level of recognition that they know things that the person calling them a boffin does not.

So in the Dutch equivalent of Secret Santa, we have a tradition where the gifts are cheap, small and silly, but the giftwrapping should somehow be an elaborate prank. Does the US have something like that? Sounds like something people in college would do.

Anyway, I bring this up because friend of mine once decided to encase a small gift in the centre of a bucket full of pykrete.

The joke obviously would that the receiver would just have to wait for the thing to thaw because it was impossibly hard to break it. Then they discovered that somehow, the woodpulp in pykrete makes it extra insulating. On top of that, since it wasn't a flat slab but a roundish sphere (low surface area compared to volume), it didn't exactly absorb ambient heat quickly either. So that other friend apparently had to wait over a week before the thing was thawed enough break open.

I remember some time ago, watching an megafactories episode [1], about IKEA, and they described how they create durable, strong wooden frames, which they later using into making various furnitures. I am surprised there is no reference to that process, as I believe IKEA's has probably done 'a lot' of R&D on everything-wood (and probably disqualifies using $$$ criteria).

[1]: https://www.youtube.com/watch?v=vXI6Z3t6PDY

"Five layers of the material laminated together — just 3 millimetres thick in total — was able to halt a 46-gram steel projectile travelling at roughly 30 metres per second. [...] That’s much slower than the several hundred metres per second at which a bullet travels, says Hu, but it is comparable to the speed at which a car might be moving before a collision, making the material possibly suitable for use in vehicles."

That's not how this works. That's not how any of this works. Nature?

A ballistic impact seems like a poor model for a vehicular impact. You don't want a car to resist impacts the way armor stops bullets. A large, slow projectile isn't a small fast projectile, but should be comparable. This section seems meaningless.

"...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.

Maybe they're harder to harvest from the Earth -- costs more resources per unit to mine than logging?

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.

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.

Recently a graphene manufacturing process has been discovered that involved taking sheets of a high carbon wood (elm iirc) and shining a laser at it inside an argon atmosphere to make a surface layer of graphene.

When I first heard about it I thought of this use case and couldn't help but wonder if the technique might work with IPL or some other generalized light source with a longer illumination period. It would be cool to find out.

Reminds me of the surprising strength of armor made out of folded paper: http://mythbusters.wikia.com/wiki/Paper_Armor_Myth

Reminds me of Raymond Feist's Riftwar Cycle. The Tsurani's planet was devoid of metal so they had all wooden armor and weapons... uncomfortable silence

The Feist collaboration with Janny Wurts went into much more detail, and is in my opinion more readable than Feist's solo work.

Basically, as materials science goes, they skipped everything about metallurgy and went straight to ceramics, polymers, and composites. Seems like Feist took the concept from Teng-dynasty paper armor and just ran with it, including the pseudo-Asian flavor of the Tsurani.

And if you keep crushing it then it will become as hard as a diamond.

And if you keep going, you'll eventually create a black hole.

Mini black hole, evaporating fast unless you feed it faster!

Annnnd... Now I'm reading about black holes, no-hair theorems, how zero mass particles behave around black holes. Goodbye productivity! :)

https://youtu.be/_8bhtEgB8Mo

Black hole firewalls is a favorite conundrum of mine.

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 mass of ~ 311,000 tons, and would be... Impossibly small (2000 times smaller than a proton charge radius).

And that's why most of the time of the universe (from 10^40 years, long after the last stars have died, until 10^100 years) will be just black holes vaporizing, after which (10^100 to 10^2500) years it'll be just a few stray protons, photons, and electrons floating around (assuming they don't disintegrate either).

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

We haven't actually observed any Hawking radiation yet, mind you

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.

Really? On what do you base that statement?

They’re both made of carbon. Parent was being cheeky.

Indeed cheeky since wood is not pure carbon, as opposed to diamonds ...

Well if you really want to split hairs, diamonds can have impurities that can cause different colors (like the blue Hope Diamond)

If you keep going after that, it turns into Dragonforce

"Man of Crushed Wood" doesn't have the same ring though.

Interesting, but what about biodegradability? Will it not be eroded by microorganisms in the outdoors over time? It is still wood, after all.

It's still wood, and wood is only barely biodegradable. If you take decent care of it it'll last for centuries.

A fallen tree in damp conditions rots down in a year or so. Seems pretty biodegradable.

Your second sentence I have no problem with.

a fallen tree will also easily get overrun by bugs and animals and does not have a closed surface, making it prone to rot

Isn't that biodegrading? Surely almost anything can be cared for to prevent biodegrading.

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.

Rusting isn't biodegrading, it's chemical. Of course the lines aren't distinct, but they seem much clearer than you're suggesting.

In this case I don't think it really matters. No one says "my car is fine, it's just rusting not biodegrading". What matters is that the car is disappearing right before your eyes through natural processes that could have been prevented with normal maintenance.

Wood, when properly taken care of, lasts forever. Steel, when properly taken care of, lasts forever. Each of them will degrade without proper maintenance, and oddly enough they both have basically the same maintenance needs. Keep them dry, otherwise oil them occasionally.

Well, that can be seen as a feature as well. When it's no longer useful and left to its own devices, it will disappear all by itself rather than leaving a pile of toxic waste that someone else has to worry about.

If you mean ‘rot away’, then your statement is not true at all. Trees take a long time to rot away. If you meant ‘start to rot’, then yes, you’re right. https://www.google.com/search?q=how+long+does+it+take+a+tree...

Google says minimum 50 years.

> Will it not be eroded by microorganisms in the outdoors over time? It is still wood, after all.

Well-prepared and maintained wood lasts for centuries: Kirkjubøargarður, Hōryū-ji, Nanchan Temple, Greensted Church, various houses in Schwyz, … date back to before the 13th century (Hōryū-ji was finished early in the 7th century).

Over human historical scale — and assuming proper maintenance — the biggest issue is fire rather than decay (that's how most of Hōryū-ji's 7th-century materials were lost and had to be replaced).

It depends on the amount of water in the wood. If it is lower than 18% or so (we usually dry wood to this percentage when we use it as a building material) then neither insects or fungus will attack it and it won't rot.

Define "stronger"

The article is pretty confused about what they mean by stronger, on the one hand they use language that suggests tensile strength but they then go on to illustrate some non-quantitative measure by talking about penetration by pellets and deformation in collision like situations.

The paper is behind a pay wall, but their figures and extended data stuff is free to view here: https://www.nature.com/articles/nature25476#extended-data

They say that their ultimate tensile strength of their material is ~600 MPa. Steel ranges from 250-2500 MPa.

Typically it means UTS (Ultimate Tensile Strength), except in articles where "X is stronger than Y" when it means the weakest property of Y.

The title is completely false.

Metals are used for their material properties more than just strength but homogeneous strength and stiffness (in all directions) and tolerance to a wide range of environmental conditions (thermal and moisture cycling)

Not to mention ease of manufacturing.

The material described in the article will never make it out of the lab.

...products like this already exist, so maybe it will just lead to a refinement of an existing process: https://en.wikipedia.org/wiki/Hardboard

I broadly agree with you, but I think your being a little bit harsh. If the material is sufficiently robust to environmental conditions, then there is room for a strong, directionally biased material. It just won't broadly replace steel (or other alloys). It could find useful niche applications.

If its environmentally stable.

For example, carbon fiber has so many other nice properties that we'll put up with its directional strength and weave it.

Really, this isn't a bid to replace steel or al, but a bid to replace carbon fiber.

Engineered wood has been a thing for over 100 years. Wood has a lot of desirable properties that make it a good construction material (fire resistance for instance is much better than steel).

This article is definitely missing the wood for the trees to some extent, but it is an interesting development and even if the gain isn't going to be quite as large as indicated and there are some serious questions about whether it will scale or not that does not mean it isn't interesting research.

But I agree with you that this is not exactly around the corner for mass production, a whole pile of problems would need to be solved and after they are the product may well end up not being economically viable.

> (fire resistance for instance is much better than steel).

Specifically, steel melts/weakens in a fire, which can result in loss of structural integrity, while heavy timber will char and then very slowly burn.

http://www.mace.manchester.ac.uk/project/research/structures...

http://www.nzwood.co.nz/faqs/which-building-material-perform...

When the steel is inside concrete (in case of reinforced concrete), doesn't the concrete protect the steel? And since it's how most steel is used in construction, doesn't steel has an advantage here?

Concrete does provide some form of insulation as it has a fairly low rate of heat transfer. At the end of the day it'll still heat up though, and it's that heating up which weakens the steel, direct contact is not a requirement (there are specific methods like insulated concrete form which have higher fire resistance).

I have a technique I'd use to add heat resistance to steel.

Only necessary If we lived in a doomed world where engineers didn't exist and I was asked to make steel more heat resistant.

Cover steel beams in a relatively thick later of plaster of paris mixed with very find grain sand.

I built a charcoal forge out of that material (I used quartz sand I got from a pool supply store) and it's ludicrously heat resistant. It's lined with 4mm of aluminum (melting point 660°C) and the plastersand layer is about 25mm thick. I can melt steel bar above it without causing any visual changes in the aluminum body. I've used it about 20 times in the last year. Lots of spalling on the plaster layer but for most architectural applications I doubt you need to have a blower fueled inferno happen > 2 times a week during the summer.

I wager real engineers have more cost effective, data driven solutions. Just thought it was a neat fact.

They did a similar thing with spray on asbestos but this is obviously no longer an option.

If you use a clay like fire clay instead of plaster, it will be much more durable.

Hm, the fire clay I'm familiar with is extremely brittle once it has been through a heating cycle, do you have some specific kind in mind?

The stuff I know is more like glass.

The stuff I used wasn't that brittle. It is also designed to be used as a furnace lining, unlike plaster.

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

I think it would be so expensive to protect all the steel going into reinforced concrete that you could go directly with another material.

How can wood have better fire resistance than steel? I mean wood burns. /s

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...

It's pretty much the standard in steel construction for beams to be exposed. Fire safety is the reason elevator shafts and stair wells of steel buildings are constructed from cinder blocks.

Where I live, most (nearly all) are reinforced concrete. I don't think I've seen a an office building or flat with exposed beams. Of course, the usual construction methods can be different from place to place.

How is wood more fire resistant than steel? What are the metrics used for this?

Because it does not lose its strength as fast in a fire. Wood doesn't flow, it simply burns from the outside in and the inner parts not exposed to the fire are just as strong as they were before the fire.

By contrast: steel is an excellent conductor of heat and the interior of a beam is just as hot as the outside of the beam exposed to the fire.

See the comment above by phonon.

The key is that steel tensile strength goes down quickly as temperature rises. It softens dramatically long before it starts to melt. Wood does much better. My understanding is that wood weakens only by burning off on the surface. The unburnt core essentially seems to retain its mechanical properties for the most part.

The way a wooden structure behaves is very different from the way a steel (or steel reinforced concrete) one behaves, as the materials itself behave very differently.

Let's take as an example a "main" wood beam to support a normal floor (or roof).

It has been calculated to be sufficient with a cross section size of (say) 20x20 cm ( Width by Height, in some countries "square" wooden beams are normally used, in some other countries sizes with width half the size of height are commonly used), the dimensional calculation takes into account "exceptional" static loads, like snow (if a roof) or crowd (if a floor), and dynamic conditions (like earthquake) so they are over-dimensioned in normal use.

What happens in a fire is the same as if you were reducing the cross section by scraping some materials off the foot amd sides of the beam, let's say removing 5 mm at a time, so , after some time the cross section will be 19x19.5, and then 18x19, 17x18.5, 16x18, 15x17.5, 14x17 etc.

What gives a value of the resistance of a wooden (or however homogenous material) beam is its moment of inertia that is expressed in cm^4 and equates to WxH^3/12, so progressively you have:

20x20^3/12=13,333

19x19.5^3/12=11,740

...

If you graph it, you will see a progressive decline of resistance proportional to the reduction of the cross section.

Also you have to consider how carbonized wood (char) represents in itself a "defense" of the wood against fire, once the first layer of wood is carbonized by combustion, it becomes harder/slower to burn:

http://www.mace.manchester.ac.uk/project/research/structures...

Here a graph of charring rate is given:

http://www.mace.manchester.ac.uk/project/research/structures...

In practice, any wooden structure is fire resistant for 30-60 minutes, and the solution for increasing the fire resistance (if the wood cannot be protected by other means) is simply that of increasing the cross section.

"Modern" wood, like composite beams, plywood, etc., may behave differently given the presence of glues/resins, etc.

With steel the resistance is given by its tensile strength, that decreases very rapidly from around 300-400 C (easily reachable in a fire and roughly equivalent to the ignition temperature of wood):

https://www.steelconstruction.info/Fire_damage_assessment_of...

Portland is building a 5 story building with Cross Laminated Beams (all Wood, no steel structure). Its not this material, but is incredibly strong.

A 12 story wood building is also being planned in Portland (mentioned in article)

http://www.capitalpress.com/Oregon/20171005/nations-largest-...

NL has two wooden bridges that carry heavy traffic:

https://nl.wikipedia.org/wiki/Kr%C3%BAsrak

There is also some steel in there but the arch is entirely made out of wood.

>The title is completely false.

No idea why you claimed that. What is completely false is your claim, by the sound of it. Did the title claim anything about properties other than strength? No. I think you may have meant "The title is misleading (although literally true)" or something.

edit: Would downvoters care to explain why? Thanks.

Didn't Hydraulic Press Channel do something similar with crushing a paper sheet until it turned stonish? Well not that similar but it was an interesting phenomenon nonetheless.

Scientific American has more gee-whiz details: https://www.scientificamerican.com/article/stronger-than-ste...

(I'm totally unqualified to parse between the articles' potential uninformed optimism and fellow commenters' skepticisms)

If the wood ends up strongest with 45% of the lignin removed I'd try to engineer a species with a lower lignin content to begin with. So-called 'weeping' varieties (Weeping Willow etc.) get their specific hanging shape from a later onset of cell wall hardening due to delayed lignin deposition so those might be a good start.

I'm guessing this material has more compressive strength but less tensile strength than steel? If so, how could you replace steel with compressed wood as the title implies? They're totally different materials from a mechanical engineer's point of view.

I have read(@ Atomic Adventures by James Mahaffey) about "lockwood" made by irradiating wood. It's supposed to have been quite popular, used for floors, even bows. Have you encounter it?

Steel is the Worf of materials science.

Care to explain, please?

It's a reference to [The Worf Effect][1].

[1]: http://tvtropes.org/pmwiki/pmwiki.php/Main/TheWorfEffect

Exactly. Just to amuse myself, I spent a few minutes googling for materials that are "stronger than steel."

spider silk (a classic): https://www.npr.org/2017/01/14/509807212/spider-silk-is-stro...

bone: http://ipfactly.com/human-bone-is-stronger-than-steel/

a graphene sponge: https://www.materialstoday.com/mechanical-properties/news/sp...

carbon nanotubes: https://www.acs.org/content/acs/en/pressroom/presspacs/2010/...

silica nanofibers (because carbon is old news): https://prescouter.com/2013/02/new-material-is-lighter-than-...

fiber-reinforced hydrogel: https://www.global.hokudai.ac.jp/blog/new-tougher-than-metal...

One starts to wonder if steel was ever all that strong. But I'm sure the real lesson is there are a lot of ways to measure strength.

Yes, there are tons of things "stronger than steel" but lack the other advantages of steel.

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

*For some values of 'stronger'.

Fire? Termites?

But can jet fuel melt crushed wood?

Super interesting piece and as somebody who is interested in many things I appreciate such articles.

But seeing this on #1 feels a bit off on HN. Is there a slight possibility that the feed is sometimes curated (eg through different voting powers)?

Or there is simply quite a few people like you who find this interesting, as the YC posting guidelines put it:

"If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity."

"Super interesting" sounds like a good metric for top-voted entries, especially at 4AM (PST)

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