19 Building Materials-Namely, Suspended Roofs and Linings Made of Refractory Bricks and/or Mineral-Based Construction Materials for Constructing Suspended Roofs and Linings of Combustion Chambers as Well as Such Roofs and Linings, and Prefabricated Structural Parts Made of Concrete, Steel and/or Plastic for Erecting Chimneys and Cooling Towers