Making a concrete column is a straightforward process for a do-it-yourself-er with some experience in handling concrete.
Place the footer for your column. One method is to bury part of the column in the soil, as you would a fence post. Another method is to use a precast concrete footer that will circle the column and spread its weight over a wider area for greater stability.
Place the form firmly on the footer. Reinforce it with rebar if the column will be taller than three feet.
Mix the concrete according to package directions, but use a little less water than the directions require. This makes the wet concrete stiffer, which will result in stronger dry concrete.
If your column is very wide or tall, have a local company deliver premixed wet concrete. It’s difficult to mix large amounts of concrete in a short period of time.
Pour the wet concrete into the mould, working quickly but smoothly. Tap the mould from time to time to remove any air pockets that would weaken the finished column.
As the concrete sets, you may find that the top sinks down a bit in the centre. That’s normal, but since you don’t want a well in the centre of your column, fill it up with more wet concrete.
Let the concrete dry, or “cure,” in the mould for at least 48 hours. If your column is wider than eight inches, or if the weather is humid, let it dry for a longer time -- as much as four or five days.
Peel the form off the cured concrete column.
Seal the concrete (optional).
If you seal your concrete, do not use silicone sealers. Choose a breathable sealant or water repellent.
Always wear gloves when working with concrete. Wet concrete can “burn” your skin. Be sure your footers are strong enough to hold the height and weight of your column securely.