Is it possible to just figure out the ratio of rocks and put them into a grinding machine to make custom sand?
"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.
In all seriousness, rock crushing is energy intensive relative to just taking sand from the source.
Let nature and physics do the rest.
You can probably engineer the sand somehow but it’s going to be costly.