Building and construction materials and elements, not of metal, namely, concrete slabs with voids and cavities; non-metallic structural elements for use in building, namely, concrete foundations with voids and cavities; construction elements of plastic, namely, plastic void formers in the nature of molds for forming cavities in concrete during construction; building materials of plastics material, namely, concrete shapers being void formers in the nature of molds for forming cavities in concrete during construction; non-metallic building materials, namely, concrete shapers being void formers in the nature of molds for forming cavities in concrete during construction; structural components, not of metal, for buildings, namely, concrete walls with voids and cavities; non-metal concrete slabs; concrete parts, namely, concrete slabs with voids and cavities, concrete foundations with voids and cavities, and concrete walls with voids and cavities; concrete floors; concrete panels; concrete beams; concrete formwork elements, not of metal, for concrete, namely, plastic void formers in the nature of molds for forming cavities in concrete during construction; slab panels, not of metal for building non-metallic prefabricated building components, namely, concrete slabs with voids and cavities and concrete walls with voids and cavities; non-metallic molds for forming concrete for building; non-metallic woven fabrics for concrete for use in civil engineering; non-metallic interlocking panels for building; non-metallic materials, for construction works, namely, concrete shapers being void formers in the nature of molds for forming cavities in concrete during construction; non-metal floor panels; slabs, not of metal, for building; plastic void-formers for construction being non-metal forming systems for concrete and other curable construction materials comprised of non-metal modular casting forms