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...http://www.google.com.au/patents/US4773838?utm_source=gb-gplus-sharePatent US4773838 - Slipforming extruder for casting concrete slabs
