[katieHaylor (OP)]

Nan says:


Apparently there's a global shortage of sand for construction and land reclamation. This gives rise to illegal sand mining and destruction of the environment and wildlife, and organized crime. Though abundant, desert (and sea) sands are said to be of no practical use for being too fine-grained.

Is there any research on making use of desert sand? Do we see any hope that one day it will make economic sense to use desert sands for something?

What do you think?

[evan_au]

hope that one day it will make economic sense to use desert sands for something?

At one time, today's desert sands were very productive:
- Today's Saharah desert at one time was a very productive environment including rivers. Radar can see the old valleys under the sand.
- Today's Australian desert at one time was a very productive forested environment supporting a variety of megafauna
- Various reasons have been suggested for these dramatic changes, including the end of ice ages, and the arrival of humans upsetting the ecology

One imagines that if these effects were reversed, the desert might again become productive.
While the previous megafauna are now irretrievably lost in  Australia, existing megafauna in Africa could conceivably extend their range (providing we don't kill them all for their horns and tusks).

For now, the most productive use of deserts seems to be for solar power.

[alancalverd]

Sea sand can be awkward for construction as it requires significant washing in fresh water (an even scarcer resource than sand) to remove soluble impurities and is generally too smooth to make strong mortar or concrete: river sand is generally cleaner and sharper, and is usually quarried close to a source of fresh water (river beds don't move very far) and pebbles. Some desert sand might be useful but it also contains soluble-ish impurities which is why some plants can grow in sandy deserts.

[chris]

Sea sand can be awkward for construction as it requires significant washing in fresh water (an even scarcer resource than sand) to remove soluble impurities and is generally too smooth to make strong mortar or concrete

Is that because marine sand is likely to have been subject to more attrition owing to tidal movements, Alan?

[alancalverd]

Yes. Some small grains are great for egg timers and kids' sandpits because they are nearly spherical and don't clump or abrade skin, but sandcastles and motorways turn to mush when it rains.

[evan_au]

Sand derived from ocean sediments contains salt. This can corrode the reinforcing bars and premature failure.

[alancalverd]

Hence the need for extensive washing....

My mining engineer son described one such structure as "a sheet of voids held together by brown stains". And then the roof fell in.

[chris]

I'd not thought about the salt side of the equation at all. Thanks for raising that.