In the city of Hao Zhuang in China, a man shows what's inside the walls of an apartment. With a stick he digs in the wall and removing content that looks like sand! You can see steel bars into the wall, so I guess they have made the walls in reinforced concrete, but this is only a name... It is very friable ! Can you imagine if you bought an apartment with these walls ? I hope they will pursue this dishonest contractor.