I don't get the reasoning. Unweathered sharp sand has more surface area than stuff that has been tumbling in water for a long time, no? In my experience the rec

I don't get the reasoning. Unweathered sharp sand has more surface area than stuff that has been tumbling in water for a long time, no? In my experience the received wisdom is, that glacial esker sand, sieved, is good for concrete. Somewhat like the manufactured sand. But I might very well have misunderstood, or the old folks advice might not be right. Or it does not scale to industrial uses.