
Sand and gravel mining “greatly exceeds natural renewal rates” - sergeant3
http://www.newyorker.com/magazine/2017/05/29/the-world-is-running-out-of-sand
======
philipkglass
Nature is not crushing rock into gravel and sand as quickly as humans are
using it. But it is straightforward for humans to crush bulk rock. The New
Yorker article actually mentions crushing quarried material toward the middle
of the piece. Here is a study from 2008 about replacing sand with crushed
stone in concrete (from India, where natural sand shortages are acute),
"Experimental Study of Artificial Sand Concrete":

[http://ieeexplore.ieee.org/document/4580058/](http://ieeexplore.ieee.org/document/4580058/)

EDIT: probably shouldn't link directly to sci-hub copy.

The short version: crushed stone is a fine substitute for natural sand in
concrete. It actually improves strength modestly compared to concrete made
with natural sand. ("Concrete with stone crusher dust was reported to show
17%, 7%, 20% higher compressive, tensile, flexural strengths respectively than
those of conventional concrete.")

Of course it takes energy to quarry and crush bulk rock. But the energy input
is manageable. The Bond Work Index for granite is 10-15 kWh/ton; for
quartz/quartzite it's also up to 15 kWh/ton. That means energy cost up to
$1.50/ton at 10 cents/kWh for an electrically driven crusher.

[https://www.911metallurgist.com/blog/table-of-bond-work-
inde...](https://www.911metallurgist.com/blog/table-of-bond-work-index-by-
minerals)

For comparison, current concrete sand seems to run about $45/ton:

[http://www.earthmaterials.com/1_concrete.htm](http://www.earthmaterials.com/1_concrete.htm)

~~~
greglindahl
You can also crush used concrete to replace aggregate:

[https://en.wikipedia.org/wiki/Concrete_recycling](https://en.wikipedia.org/wiki/Concrete_recycling)

That doesn't help in countries like India which are growing rapidly, but it
can make a big difference in most parts of the US.

~~~
monknomo
I've driven by two large concrete and asphalt recyclers in two different
states within the last week. Definitely a big thing!

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perilunar
So why can’t we convert the useless ‘round’, ‘smooth’ desert sand into useful
angular sand?

E.g. use concentrated sunlight to fuse sand grains together [1], then crush to
the desired grain size.

It’s got to be a better solution than shipping sand halfway around the world.

[1]
[http://www.markuskayser.com/work/solarsinter/](http://www.markuskayser.com/work/solarsinter/)

~~~
janekm
Making bigger rocks from smooth sand to crush into pointy sand would only make
sense once we've run out of bigger rocks.

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telesilla
A building under construction near me has a large sign around it advertising a
local alcohol company: it provides sand via recycled bottles (for the
concrete, I assume). I'm curious how efficient this is in relation to finding
new mining exploits nearby, or if this is just marketing.

~~~
honopu
Could just be marketing or for Aesthetics. Glass and concrete don't always mix
that well. My hobby is concrete countertops with glass fibers, and these are
specifically alkali resistant. Concrete and glass don't mix well without
additives, which may or may not matter for eco friendliness. You will find
some fly ash in some concrete mixes, which is a byproduct of power plants more
common.

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bdamm
Obviously it'll become more expensive until we no longer need the resource,
find an alternative, or recycle. Next.

~~~
0xdada
Concrete is a very good material so I don't see "no longer needing it"
happening any time soon. Finding an alternative and recycling both sound like
hard to tackle and expensive, I wouldn't say this scarcity can be so easily
dismissed.

~~~
hueving
Crushing rocks to make sand is a fine alternative. It's just a matter of
additional cost, which will become viable as shortages drive up the cost of
natural sand.

------
RichardHeart
[http://www.nytimes.com/1995/07/29/us/alabama-to-make-
prisone...](http://www.nytimes.com/1995/07/29/us/alabama-to-make-prisoners-
break-rocks.html) (I support prisoners having good job training, choices and
wages.)

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hawski
I wonder: if Mr Musk's will ever succeed with The Boring Company, would it
significantly help with the shortage? By succeed I mean doing tunnels right
and left.

~~~
jalayir
Not really. You can't use just any soil for construction, it has to be a
sandy/grainy variety.

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aurizon
granite or other rock can be crushed and sieved to the right mixture. There is
lots of granite and sandstone etc

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omginternets
[disregard this: I jumped the gun]

~~~
obstinate
That's not what this article is about.

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graycat
Similarly the sun won't last forever and is not renewable.

So what?

Latest is that the expansion rate of the universe is slowing. So, one might
predict a big crunch and the end of everything. So what?

Looks like someone wants to get eyeballs for ad revenue. No thanks, not with
that _story_.

 _Stories_ of the form the sky is falling no longer get my eyeballs. People
who write such stories need to find other, more useful work to do.

~~~
TFortunato
Did you even read the story... it's not a "sky is falling" story. (A Miami is
falling story, maybe :-P)

It's really more of an interesting look at a resource that few in our part of
the tech world even think about, and some of the challenges they face, if you
can look past the headline.

~~~
graycat
No it's not: Wake up. You've been taken in. It's just "the sky is falling", or
"Oh we've got trouble, right here in River City. Trouble starts with a T and
that rhymes with a G and that stands for gravel." It's just a scare headline
and story to get eyeballs for ad revenue.

The good news about such nonsense grabbing people by the heart, the gut, below
the belt, always below the shoulders, never between the ears, is that it
really is the most scary story they can find. So, all other stories they can
find are less scary than their story which is not scary at all which means
that all is well. Good.

Maybe if there is some serious problem, then they will write about that, too.

