19 Concrete building materials, namely, blocks, bricks, posts, slabs, panels; roofing tiles, not of metal; tiles, not of metal, for building; roofing, not of metal, incorporating solar cells; framework, not of metal, for building; roofing, not of metal, incorporating photovoltaic cells; roof coverings, not of metal; palings, not of metal; ducts, not of metal, for ventilating and air-conditioning installations; buildings, transportable, not of metal