Sonotubes are tubular, concrete forms made of very heavy paper. Concrete forms are a way to "cast" fluid concrete into shapes in the same way that foundries cast fluid metal into shapes using molds. Sontotubes are used to cast columns. The tubes come in standard 12 and 20 foot lengths. They can be filled all the way to the top without bursting. Some paper forms must be filled at a specified rate but Sonotubes do not. The product is usually placed over a reinforcing bar lattice. The tubes are not reusable.
Coat the interior of the Sonotube with a form release agent.
Place and brace the tube where you want to pour the column. Brace 12-foot-long Sonotubes at the top and bottom of the form with light lumber. All concrete forms should be braced with a wooden or metal framework to keep the form from moving.
Brace 20-foot-long forms with light lumber at the top, bottom and middle of the form.
Pour concrete into the form at any rate. Submerge a submersible concrete vibrator into the form at the start of the pour. Never vibrate the concrete in these forms from the outside of the Sonotube.
Position the vibrator at the bottom of the pour for about 20 seconds and then pull the vibrator up through the pour at a rate of about 12 feet per minute. Do not touch the interior of the tube with the concrete vibrator. Concrete vibrators remove air pockets from poured concrete.
Remove the form no sooner than 24 hours and no later than five days after the pour. Strip the forms from the columns by slicing the top foot of the form with a utility knife and then peel the form from the concrete column in a spiral.