Crushed or ground glass is already used in concrete: http://www.concrete.org.uk/fingertips-nuggets.asp?cmd=display&id=783 http://www.concrete.org.uk/fingertips

Crushed or ground glass is already used in concrete: http://www.concrete.org.uk/fingertips-nuggets.asp?cmd=display&id=783 http://www.concrete.org.uk/fingertips-nuggets.asp?cmd=displa... Interestingly, it can be either aggregate or cement, depending on how finely it is ground.