Abstract: The invention concerns a method for fabricating a concrete slab in a substantially horizontal slip casting process, in which method concrete mix is fed into a mold through a delimited cross section moving progressively in the casting process so as to form a concrete product of a desired shape, characterized in that onto the surface of the casting bed (1) is placed a core (3, 9, 10, 11) capable of delimiting the cross section of the concrete product (5, 5′) so as to provide an opening or a provision for an opening in the bottom surface of the slab. The invention also concerns a core for obtaining an opening or a provision for an opening characterized in that the structure and/or material of the core is/are such that the core is capable of yielding in vertical direction. A core according to the invention may also be a multipart core, the outer part of which becomes detached from the inner part of the core in conjunction with lifting off the concrete slab from the casting bed.

Abstract: A method for the production of prestressed concrete products and a plant for implementing the method. Moulds provided with pretensioned wires are moved through fixed casting machines into a hardening space. In the hardening space, the combination of mould and product is lifted sideways from the casting line before hardening, using synchronised lifting equipment. The combinations may be stacked for space economy. After hardening, the product is removed from the mould using the same lifting equipment. The moulds are returned to the beginning of the casting line, during which stage they are cleaned and refurnished. The products are transferred to cutting and finishing stations.

Abstract: The invention relates to a method and apparatus for method for fabricating a concrete product in a substantially horizontal slip-form casting process, in which method concrete mix is fed into a slip-form mold of a defined cross section moving progressively in the casting process so as to give a concrete product of a desired shape. The method is characterized by the measurement of the input power need of the concrete mix feed and compaction, whereupon the travel resistance of the casting machine is controlled based on the value of a measured process variable. The invention can eliminate quality variations in a slip-form cast product that are caused by changes in the density of the concrete mix and the travel resistance of the casting machine.

Abstract: An apparatus for forming frogs in the sides of a slipformed concrete element, especially a hollow-core slab is disclosed. In accordance with the invention, the frogs are formed in the sides of the element by removing cast material from the sides by a reciprocative scraping action. The reciprocative movement parallel to the side of the element is effected with a drive motor and a lever assembly. By the method, it is possible to obtain a desired frog shape and depth without damaging the side surfaces.

Abstract: A method and an apparatus for casting concrete elements from a concrete mix by slipforming molding which involves extruding the concrete mix onto a bed, generating pressure into the concrete mix by a first set of extruder members and by compacting the concrete by moving at least one of the movable mold walls in a direction approximately parallel to its plane. The concrete mix is tamped into a more compacted form by protrusions formed onto at least one of the movable mold walls and projecting into the mix. The method and the apparatus achieves a high degree of compaction in the concrete mix by an uncomplicated method and apparatus without generating a loud noise.