19 Building materials, not of metal, produced with raw materials consisting of silica sand, lime, cement, water and aluminum, namely, pre-cast concrete wall forms and concrete blocks; construction materials, namely, stones of mineral raw materials; lime and sand stones; artificial stones, in particular porous artificial stones; porous concrete; lightweight concrete; foamed concrete; concrete; mortar, dry mortar and dry concrete; assembly parts made of autoclaved aerated concrete, namely, concrete blocks, concrete bricks, concrete posts, concrete slabs and concrete panels all for use as concrete building materials; building parts, not of metal, in particular building bricks and building panels made of concrete or of autoclaved aerated concrete; prefabricated building materials, in particular prefabricated parts of concrete, cladding elements and cladding panels, floor elements, wall elements and roofing elements, namely, concrete panels, concrete cladding for construction and buildings