Abstract: A saw for cutting an extruded, prestressed concrete slab having a length, a width and a thickness includes a framework assembly movable along the length of the concrete slab. A carriage system is rotatably supported from the framework assembly about a first vertical axis perpendicular to the concrete slab and is slidably mounted on the framework assembly for movement back and forth across the width of the concrete slab. A cutting arrangement including a rotary cutter is suspended from the carriage system over the concrete slab. The cutting arrangement is movable up and down along a second vertical axis substantially parallel to the first vertical axis and is also slidable along the carriage system.