Much of the problem lies in the type of sand needed for construction, with desert sand “largely useless to us” as its grains are the wrong shape. “Eroded by wind rather than water, they are too smooth and rounded to lock together to form stable concrete,” explained the BBC. “The sand we need is the more angular stuff found in the beds, banks, and floodplains of rivers, as well as in lakes and on the seashore.”

Fascinating. I wonder if the rounded desert grains could be processed in such a way as to make them angular, say by crushing?