Yes: "Crushed rock sand – An economical and ecological alternative to natural sand to optimize concrete mix" https://www.sciencedirect.com/science/article/pii

Yes: "Crushed rock sand – An economical and ecological alternative to natural sand to optimize concrete mix" https://www.sciencedirect.com/science/article/pii/S2213020916300921 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.