They've been used in China and have been unveiled, but not yet used, in the U.S. and Canada. Concrete panels from Essroc Italcementi are polished and let light pass through from either side, while being as strong and resistant to cracking as traditional concrete panels. "They’re made with a very clear resin cast in concrete in a kind of honeycomb lattice," said Richard McGrath, director for codes and standards with the Cement Association of Canada.