A formwork assembly is adapted to receive concrete to produce structures
such as wall structures. The formwork includes PVC tubular form elements
having recessed female engagement portions. The female engagement
portions are adapted to receive respective male engagement portions. An
octagonal form element has a female engagement portion positioned at each
vertex between adjacent sides. A recessed female engagement portion is
closed to the interior of the form element but open to the exterior of
the form element. Thus, the form element includes a plurality of vertices
open to the exterior. The form elements also include male engagement
portions at an open side. Wall panels, corner panels, and joint
connectors can also include male engagement portions. The male engagement
portions and female engagement portions are adapted to mate to form a
formwork arrangement having a substantially flat exterior wall. A
formwork assembly can additionally include concrete flow apertures and
insulation