An investigation in the city of Shenzhen found that at least 15 buildings under construction were using low-quality, unstable concrete. The faulty, low-cost concrete, made with unprocessed sea sand instead of river sand, includes salt and chloride that is corrosive to steel and can potentially cause a building to collapse. Of the buildings discovered to be using the disapproved material is the Ping'an International Finance Center, which at 660 meters is the tallest in the nation and the second tallest in the world. The building was designed by architecture firm, Kohn Pedersen Fox, and has been in construction since 2009.

[via Dezeen]