Apparatus for extruding concrete

Apparatus for forming concrete articles, comprising:

• A. first means for extruding a first portion of concrete mix to form an extruded slab of concrete along a first path;
• B. means for indenting a shear key into the top surface of at least a portion of said extruded slab;
• C. means for cutting said slab and means for rotating the severed slab portions normal to said first path;
• D. second means for extruding including:
• 1. a molding station having form surfaces;
• 2. at least one auger having flights for conveying concrete mix into said molding station and for extruding concrete mix onto said severed and rotated slab portions;
• 3. at least one mandrel core former formed by walls having external surfaces in the path of extrusion from said auger flights, said auger being rotationally independent from said core former, said auger and said mandrel core former being relatively disposed so that the longitudinal axis of said auger is lateral of the longitudinal axis of said mandrel core former;
• 4. means operatively connected to introduce a second portion of concrete mix to said auger;
• and
• 5. means for rotating said auger to convey said second portion of mix to the form surfaces of said molding station with sufficient force to consolidate said second portion of mix at said molding station and extrude said consolidated second portion of mix relative to said form surfaces onto the top surface of said severed and rotated slab portions.