This is why scientists are mocked. You get some guys from materials science saying 'hey we can do this cool thing with beach sand and electricity' and they don't bother talking to the physical scientists about ocean erosion and why their idea does t make any sense.
They would tell you that beach erosion is inevitable. Either you let it happen, or you put a bunch of hard structures there instead. Then, the waves either undercut the hard structure, leading to more needed, or the wave reflection scours the beach and takes all of the sand out to sea or elsewhere along the coastline. Meankng no more sans next to you - just a concrete cliff.
Also sand is one of the most limited resources with actual cartels working on stealing it - and you want to use it as a primary building material? Instead of just a contributor like in concrete? What?