Zombocom… the only limit is your imagination.

In all seriousness, rock crushing is energy intensive relative to just taking sand from the source.

Yes:

"Crushed rock sand – An economical and ecological alternative to natural sand to optimize concrete mix"

https://www.sciencedirect.com/science/article/pii/S221302091...

The main problem is that even though crushing rocks is affordable, illegal sand mining is even cheaper in regions where law enforcement is weak.

You'd also care about angular sand vs round sand grains.

it would be better to farm coral reefs and parrot fish