19 NON-METALLIC CONSTRUCTION MATERIALS, NAMELY, CEMENT, CONCRETE, MORTAR, STONE, LIME, GYPSUM, GRAVEL, SMALL STONE SLABS, PARTITIONS, BRICK, ROOFING TILES, FLOOR TILES, NON-METALLIC RIGID PIPES FOR CONSTRUCTION; ASPHALT, TAR AND BITUMEN; PORTABLE NON-METALLIC CONSTRUCTION ELEMENTS, NAMELY, MODULES, PANELS, PRECAST COLUMNS AND NON-METALLIC MONUMENTS