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Lava driveway

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'Round these parts, a lot of old (and old-style) buildings are faced with flint. The fields are just full of the stuff, and you have to use it for something.

Flint melts at around 1000-1200°C, which can be easily achieved with a hydrogen flame. It should, therefore, be possible to cover a driveway with a thick layer of flint, and then melt it lavaesquely. Upon cooling, you would be left with a supremely hard-wearing driveway.

MaxwellBuchanan, Jan 30 2019

I know just how he feels. https://supposedlyf...com/2015/03/zao.jpg
[MaxwellBuchanan, Feb 05 2019]

A short film of Max in his lab https://www.youtube...watch?v=FnblmZdTbYs
[Loris, Feb 06 2019]

Lava morphologies https://en.wikipedi...ava#Lava_morphology
You'd probably want a rolling, ropey lava rather than a sharp, prickly lava [notexactly, Feb 07 2019]

Lava driveway Lava_20wells
Another method [8th of 7, Feb 07 2019]

[link]






       Couldn't lava flows in places, which have volcanos, be diverted into large Thermos style flasks that get shipped to anywhere in the world where lava is in short supply?
xenzag, Jan 30 2019
  

       Hard wearing? Flint? You can buy tungsten carbide plates for a few hundred.
bs0u0155, Jan 30 2019
  

       Synthetic diamond driveway
pocmloc, Jan 31 2019
  

       when the sun hits it at a certain angle, that's going to look interesting.
bs0u0155, Jan 31 2019
  

       According to das wikipedia, flint is basically minute crystals of quartz.
I'm /not entirely/ convinced that melting and resetting it would get you back a material similar to what you started with.
Loris, Jan 31 2019
  

       No, it probably wouldn't, but you'd get some sort of glassy material.   

       Incidentally, given that flint contains a modest amount of water, I'm wondering if a microwave might do the job. I shall report any interesting results.
MaxwellBuchanan, Jan 31 2019
  

       Incidentally, I've seen a video on youtube where someone tried to make an obsidian sword by melting it down and casting.
One of the problems they had was that the obsidian foamed up as it was melting.
Flint and obsidian are created by very different processes, and they're probably only somewhat similar in composition, so that may or may not be an issue. (edit : huh, quartz is SiO4, obsidian is mainly SiO2.)
  

       You'd also want it to be /quite/ a thick layer, or it would shatter when something heavy like a car moved over it.
Would it spoil the artistic vision too much to melt it ex situ in a furnace, then cast into position? It would be easier to get a consistently well- melted, even temperature mix.
And probably less collateral scorching.
Loris, Feb 01 2019
  

       I'm told (by the expert sitting here next to me) that flint (as above //basically minute crystals of quartz// - or cryptocrystalline) melts at 1710°C - the 1200°C melting point cited above would require an added flux. After melting, it would re-set into 'fused quartz' - a kind of amorphous silica glass. If you cooled the driveway very, very slowly, it would set as crystalline quartz. Opal is basically just silica with bonded water, so under the right conditions you could have an opal driveway.
hippo, Feb 01 2019
  

       //1710°C// Hmm. That's higher than even pure silica. I think the lower temperature is correct, perhaps because of impurities that lower the melting point.
MaxwellBuchanan, Feb 01 2019
  

       //melt it ex situ// that would be the sensible option, alas.   

       Incidentally, I am just now microwaving a lump of flint in the lab microwave. Currently at 115°C after 60s.   

       (1 minute 15s later): 155°C
(another 1 minute 15s later): 183°C
I am beginning to wonder whether internal moisture will cause this thing to explode violently. But hey - another minute can't hurt.
MaxwellBuchanan, Feb 01 2019
  

       OK, another minute gets it to 205°C.
And another minute gets it to 222°C, and it is making little crepitatious sounds.
  

       I think this is where a wise person would stop. I have picked pieces of microwave out of my face before, and it is less enjoyable than it sounds.   

       The temperature rise seems to be very very roughly linear with time, which suggests we are getting somewhere. I'm sure I remember reading/seeing that glass can be melted in a microwave, but only if you start it off by softening with a flame - presumably because softened glass absorbs microwaves but cold glass doesn't. So, I'm not sure what would happen with my flint. Maybe its internal trapped water would absorb enough to energy the middle to melting point, whereupon the melted silicates would absorb more energy. So then you'd have an ever-hotter molten rock centre trapped in a splintery, glass-like rock. Which sounds quite like a bomb.   

       I'll have to try this again when I've got a surplus microwave and a long extension lead.
MaxwellBuchanan, Feb 01 2019
  

       Why don't you grind it into powder and microwave that?
That should mitigate any inclination it has to brew up.
  

       (Disclaimer: don't actually know; no responsibility accepted; try at your own risk.)
Loris, Feb 01 2019
  

       ////melt it ex situ// that would be the sensible option, alas.//   

       It does have a bright side.
First consider the relatively humble concrete mixer lorry.
Now imagine the flint liquefying lorry. Bask in it's glory!
Loris, Feb 01 2019
  

       Oh yes - that is an excellent point. The entire drum would be glowing a bright yellow, flakes of slag would be dropping off it, and there would be an intense heat haze rising therefrom.
MaxwellBuchanan, Feb 01 2019
  

       I think it would need full kiln insulation or it wouldn't be able to carry enough fuel to melt the whole batch. But perhaps cars which drove too close behind it might find the paint on the bonnet would start to smoke and peel off.
Loris, Feb 01 2019
  

       If you want a fused silica surface, what you're probably looking for is Trinitite.   

       The good thing is that it can be produced extremely quickly, using locally available materials.
8th of 7, Feb 01 2019
  

       Yes, but I've heard it can cause unevenness in the surrounding area.
MaxwellBuchanan, Feb 01 2019
  

       Surely a Laver driveway would be easiest?   

       8th does have a point, creating Trinitite does have its bright side.
not_morrison_rm, Feb 01 2019
  

       // cause unevenness in the surrounding area //   

       On the contrary; guaranteed to produce a nice level surface for several kilometres radius from Driveway Zero.
8th of 7, Feb 01 2019
  

       //several kilometres radius// Well, that would take care of the front lawn and part of the north-east asparagus bed. However, the Head Gardener (who, it turns out, is a fraud - he's actually a plant and tree gardener) has expressed concerns over the sequoias in the north-west greenhouses.
MaxwellBuchanan, Feb 01 2019
  

       According to a somewhat dog-eared but relentlessly optimistic leaflet we've found called "Protect And Survive", a coat of white emulsion paint over regular glass windows will fully protect against megaton-range thermonuclear devices detonating right outside.   

       So that's all right.   

       Everything else will be instantly vapourized, but the glazing will be fine. Oh, how we laughed. Are there any more in the series ? We expected to find other familiar characters like Roger Mellie, Buster Gonad and The Fat Slags, but they're not in it. Shame.
8th of 7, Feb 01 2019
  

       // //1710°C// Hmm. That's higher than even pure silica. I think the lower temperature is correct, perhaps because of impurities that lower the melting point.// - well, the Wikipedia page for Silicon Dioxide says 1713°C so I think I (or rather, the materials scientist I asked) was right
hippo, Feb 03 2019
  

       // the materials scientist I asked //   

       You ASKED someone ? Someone who knew what they were talking about ? Shame on you ... that's cheating. You're supposed to make dogmatic pronouncements based on half-remembered and mostly irrelevant facts.   

       Asking an expert is not allowed (unless that expert is you (allegedly)).
8th of 7, Feb 03 2019
  

       // One of the problems they had was that the obsidian foamed up as it was melting. //   

       I wonder if glass foam would be more durable than a solid block since it wouldn't crack as easily.
discontinuuity, Feb 04 2019
  

       //Wikipedia page for Silicon Dioxide says 1713°C// Yes, but that's presumably pure SiO2. Flint has impurities, which will probably lower its melting point (just as they do in glass making; soda glass melts at a much lower temperature than pure silica).
MaxwellBuchanan, Feb 04 2019
  

       // I wonder if glass foam would be more durable than a solid block since it wouldn't crack as easily. //   

       I expect it would be softer, but maybe also stronger in some ways. Softer because each little bit of glass would have less surrounding glass to support it.
notexactly, Feb 04 2019
  

       Ceramic foams have been the subject of intense research for decades. They offer the prospect of stiff, durable, insulative and cheap (because there's a lot of air in them) construction materials. So far, the major problem -amongst many -is maintaining the homogeneity of the material while it sets (for cement-based mixes) or dries and is fired (for clay-based blends).   

       Glass foam, being a silicate but solidifying from a melt rather than drying or setting, is also being researched but unsurprisingly suffers the same problems.   

       Cadburys, the makers of "Aero" chocolate, have a patented process for forming homogeneous bubbled chocolate from a viscous melt, but attempts to analyse the products have always failed because the investigators eat the test samples.
8th of 7, Feb 04 2019
  

       // I wonder if glass foam would be more durable than a solid block since it wouldn't crack as easily.//   

       It might well be - a non-isotropic version is glass fiber, produced by extrusion - which can be processed into composite materials with that property.
Loris, Feb 05 2019
  

       Hmm, a Cadbury's chocolate drive way, with sufficient cooling it might work, and really piss small children.
not_morrison_rm, Feb 05 2019
  

       A fluffy pastry for you and your molten rock driveway [+].   

       Pressing dinosaur shapes into the unsolidified muck might add an air of prehistoricosity. Would there be any way to add the lingering stench of sulfur?
whatrock, Feb 05 2019
  

       A little further experimentation reveals that:   

       (a) When heated sufficiently, flint spalls off shards of flint
(b) The velocity of the shards is jolly high
(c) The temperature of the shards is also jolly high
(d) Said shards remain very hot for at least 60cm of their journey and
(e) Reflexively bringing your hand up to a cheek with shard of hot flint stuck in it is not helpful.
MaxwellBuchanan, Feb 05 2019
  

       //So far, the major problem -amongst many -is maintaining the homogeneity of the material while it sets .//   

       The problem is the air. Totally different density, a homogeneous mix would be simple to achieve with the ceramic voids supported by something like aluminum. If that's a touch pricey, then using additional ceramic would yield excellent homogeneity. I've informed marketing of my invention, bs0-biceramic with molecularly stabilized co-matrices will be available in 6 standard blends. Custom orders will be expensive.
bs0u0155, Feb 05 2019
  

       //Reflexively bringing your hand up to a cheek with shard of hot flint stuck in it is not helpful//   

       But on the plus side, a whole day of drinking has ended worse.
bigsleep, Feb 05 2019
  

       Round these parts, the day ain't over yet.
MaxwellBuchanan, Feb 05 2019
  

       "It's all fun and games until someone loses an eye ... "
8th of 7, Feb 05 2019
  

       It can be fun and games even after that, depending on who's eye it was.
MaxwellBuchanan, Feb 05 2019
  

       Am I right in thinking this experiment involved a Bunson burner? Was the microwave just too slow?   

       Why don't you try the pre-grinding thing?   

       And maybe wear safety glasses /and/ a face-shield next time.
Loris, Feb 05 2019
  

       It did indeed. I know a Bunsen fame won't get hot enough (though it'll melt soda glass), but wanted to find out what would happen. I did.   

       Pre-grinding - perhaps. Or I might just try some flint gravel, which might be a bit like popcorn.   

       //maybe wear safety glasses// That would be very, very dangerous. Protective gear is there in case of a serious accident. Without it, you can only have fairly minor injuries. This philosophy has seen me through 57 years of reckless fate-tempting. But I appreciate the thought.
MaxwellBuchanan, Feb 05 2019
  

       //Bunsen fame// - yes, he *has* acheived quite a degree of fame
hippo, Feb 05 2019
  

       "The light that burns twice as bright", shirley ?
8th of 7, Feb 05 2019
  

       No, it's fine - just needed a 110V transformer.
MaxwellBuchanan, Feb 05 2019
  

       // Protective gear is there in case of a serious accident. Without it, you can only have fairly minor injuries. //   

       <Downloads 2019 TT Superbike race entry form/>   

       <Starts to fill in form with [MB]'s details/>   

       <Bout of hysterical laughter, ending in wheezing and hiccups/>   

       <Resumes form-filling while still giggling and smirking/>
8th of 7, Feb 05 2019
  

       I hope it is ground flat before use. Some lava is textured like razor-edged pumice with fiberglass bits sticking out.   

       I hoped this would be an idea to reserve a parking space by heating it to 1200C
sninctown, Feb 06 2019
  

       //I'm sure I remember reading/seeing that glass can be melted in a microwave//   

       It can, fairly easily (as long as it's not Pyrex or anything like that of course, which might just take longer?), I've done it myself with a coffee jar I was using to nuke some soil for a sealed terrarium.
Skewed, Feb 06 2019
  

       //Bunsen fame//   

       Oh dear. I think I've just made a connection which will never be forgotten. Link.
Loris, Feb 06 2019
  

       Anyone can tell that's not real, [Loris]. [MB]'s specs have square frames.   

       Also, <link> to Prior Art.
8th of 7, Feb 07 2019
  

       You of all people, [8th] should know that I wear a monocle. Especially after the llama incident. I'm just glad we got it back.
MaxwellBuchanan, Feb 07 2019
  
      
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