Source: {"pile_set_name": "USPTO Backgrounds"}

There have been provided building elements which are principally limited to the construction of walls which when assembled together present hollow interiors intended to receive concrete or the like and the elements are provided with holes which afford internal communication between adjoining elements through which the concrete can flow. For example, German Specification DE C23003448 discloses the use of a large series of hollow square rectangular elements constructed from impregnated pressboard which are stood up side by side and then tied together by means of tie rods. The adjacent side walls of these blocks have holes therethrough so that when concrete is introduced therein it can flow therebetween to interconnect same. When such elements are used as ceilings, the holes therein are upwardly facing so that there is no provision for lateral concrete flow between adjoining elements. These hollow blocks or elements are awkward to assemble and require a great deal of handling of a large number of individual elements in their assembly into a wall formation. Moreover, their manufacture is relatively expensive requiring the assembly of the pressboard into square or rectangular form and the resulting wall does not present an impervious smooth aesthetic wall surface.
A similar brick-like building element is disclosed in German Specification DE C2324489 which also has similar disadvantages.
U.S. Pat. No. 5,216,863 discloses an elongated thin flexible walled cylinder-like shaped formwork elements with the elements being mutually interconnectable and when interconnected they provide a series of adjoining closed cylinders. These cylinders are internally connected through openings so that when concrete is poured therein it will flow therethrough to create a wall formed by a series of interconnected vertical concrete columns encompassed by the thin formwork walls which may be left in place or discarded.
The formwork walls may be formed of polyvinyl chloride (PVC) to give the columns an attractive surface coating.
Again, these individual formwork elements require a great deal of handling and, if they are formed of PVC, only virgin material can be used and the material cut out to provide the apertures becomes waste material.
These formwork elements do not have individual structural integrity but require mutual interconnection and their cylindrical form to give them any structural substance capable of withstanding the introduction therein of wet concrete.