Handy Guide to Concreting Step 5
 

“Formwork” is what we call the walls that support concrete until it has set. It forms a mould. The best material for formwork is timber at least 25mm thick with its width equal to the concrete thickness.

Structural plywood or hardboard can be used for paths. For curved paths, hardboard or 7mm plywood is suitable but requires more supporting pegs. The forms must be strong, smooth on the top edge, and well supported with stout pegs. A good test for the strength of formwork is its ability to withstand a reasonable sort of kick.

Plywood formwork from your building supply or timber merchant is easy to cut to shape, does an excellent job and can be reused for several jobs. You can cut enough formwork out of a standard 2440mm x 1220mm sheet to make a path a metre wide and about 10 metres long.

The formwork must be deep enough to hold the thickness of concrete to be placed and to prevent slurry escaping beneath.
 
Place the forms along the borders marked out with string, and
secure them in position with stout pegs driven into the ground inside and outside the forms. The outside pegs should be placed at more frequent intervals and the forms nailed to them.

Hammer the pegs down to below the height of the forms.

Coat the formwork lightly with some thin oil or form oil from the hardware store to enable it to be removed easily.

The ground and the forms should be thoroughly soaked the night before the pour and dampened again before the Boral Concrete truck arrives. The ground should be damp but not muddy.