You can find more articles like the one above with a simple Google search.
I don’t doubt that this is a real issue, I seem to see similar articles popping up every few months. But, it seems to me there is abundant sand. Clearly the industry does not think so and they are a better one to listen to but…how is this true?
Looks abundant to me. What am I missing?
The very quick version is that desert sand is the wrong kind for concrete. Concrete needs grains that are sharp edged to hold together properly, but desert sand has been smoothed by the wind. On the other hand, sand worn from water action tends to have the right properties, but it’s in much more limited supply.
Quick example from here:
Beach sand on the left, dune sand on the right. You can see the grains on the right are much more rounded. As a component of concrete, they have much less “grab” on the cement binder, so the resulting product isn’t as strong. The grains on the left are irregular and will interlock more.
What Strangelove said.
That, and … not a lot of new building sites in easy reach of the Sahara, are there? Industries like construction and glassmaking tend to get sand from fairly close to themselves.
This is what I would have guessed. That it was not economically viable to ship Sahara sand to where it’s needed.
I never would have guessed that this is the reason why Sahara sand is no good for concrete:
It seems odd and counterintuitive. I would have thought that sand worn by water would be smooth and rounded, and sand worn by wind would be more sharp-edged. Learning fascinating little facts like this is part of why I love the SDMB.
Note that the chemical composition of the two different sands is often very different - desert sand tends to be more silica-rich, and with high iron content. Beach sand tends to be more calcium carbonate, and contain a high fraction of of things like shell and coral fragments.
Although the best sand for concrete is neither of these, both have drawbacks - desert sand too round, beach sand too salty.
River sand. That’s what is preferred. Also, pit sand. Or else, rocks (granite, sandstone, limestone) crushed down to sand size.
“How is there a sand shortage in the world?”
Pretty much the same way there’s a shortage of anything: We thought the sand was infinite, and it wasn’t.
See also: Trees, oil, cod, bison, passenger pigeons…
I blame the shortage, and changing dietary habits, of parrotfish:
Even beach sand has a use by. Long term processing rounds it down. River sand is the usual go to for construction. It tends to be less tumbled, and retains its angular edges.
As a counterpoint, there is a sand mine near where I live that mines an ancient beach that boasts sand of almost perfect spherical grains of a consistent size. This turns out to be ideal for use as a propant for fracking at moderate depths.
Yeah, this is why I try to put crushed rock on my driveway. Sharp angular edges interlock. Pea gravel is basically a bunch of ball bearings.
I concur.
And that is expensive.
So concrete is bad. The cement is a major greenhouse gas contributor and the specific sort of sand requirements are destroying rivers.
I’ve read some on various less environmentally harmful alternatives to standard concrete, from alternatives to the sand and to the cement and to alternatives for the complete product of concrete for some applications (engineered wood, aka mass timber, for example) but not sure from what I’ve read how close to broad roll out any of these are. Anyone know more?
I’m sure they’d figure something out if the sand was actually useful. The great irony is that places like Dubai have to import their sand from as far afield as Australia.
Sand, sand, everywhere, nor any grain to keep.
Here in tourist central Florida we import a lot of beach sand. Mother Nature keeps washing it away. So impolite.
We send barges and dredges out to pick it up from offshore in the Bahama banks and bring it here. Doubtless at some level of abstraction that’s a sustainable circulation. But overall, we’re digging up the seafloor in the Bahamas and dumping it in front of Florida hotels.
I read that the stuff gets more expensive all the time. And that AGW will increase storm severity and natural sand removal. While sea level rise suggests we need to keep building beaches either taller or further inland. In many cases much further inland.
Mass timber is rolling out, but concrete is the world standard for a reason–strong, consistent and easily fabricated. And it is twice the CO2 impact of the entire aviation industry (IIRC). Steel and concrete construction is the industry standard for high loads and I’m not sure that’s going anywhere soon. Probably trying to find alternate fuels (a la Iceland with Aluminum) would be the best bet.
Same thing with railroad ballast. Crushed rock is used rather than smooth stones so the angular edges will lock the ties in place.
Not sure about just “have to”, there’s probably also an element of “can afford to” and “better theirs than ours” to it. They seem quite culturally attached to their dunes, in the Gulf.
Not really. Bahamian banks oolitic sand is deposited in situ, not brought in. It’s basically unsustainable.
I suspect it is far from becoming standard for moderate height construction but the economics of quality sand shortages and CO2 impacts may have us seeing more engineered timber over the next decades …
Brother used to run a rock crusher. I used to run a chipper for logs that where way to big do with a chipper towed behind a truck. It’s very, very scary stuff. This was decades ago. OSHA would have a heart attack today.
I was adding a decorative gravel border to my driveway and one of the options I was leaning towards was essentially pea sized pieces of beach glass. It looked really nice and would have worked really well, but I’m glad someone had the sense to point out that anytime someone walks across it, it’s going to get scattered across the driveway or kicked into the grass. I hadn’t even considered that.