Forms

• For the concrete to take the shape you wish, you must use a form. A form can be made from many materials, or purchased already made. Heavy-duty cardboard forms are available for both round and square bollards. These are intended to be removed after you pour the concrete and allow it to cure. Forms can also be made from wood. The advantage of building your own forms with wood is that you can make odd shapes or sizes. Wood forms are also usually removed after concrete cures, but if you wish to add a decorative accent the wood can be painted and left in place
  
  

Strength

• If you want added strength, build a rebar support structure inside the form to reinforce the concrete. A rebar cage should be securely constructed either by welding it together or using wire to firmly attach each crossbar. Or you can use steel pipe for your forms, and leave it around the bollard. Steel is prone to rust and corrosion, so it should be galvanized, painted or powder coated inside and out before using it as a form. If you are placing panels between bollards, weld tabs onto the steel before coating with paint or powder.
  
  

Concrete

• No matter what material you use, keep the top of the form open to pour the concrete. If the bollard is to be used to stop a potential vehicle from entering a space, dig a hole about 18 inches deep and large enough around to fit the bollard form. The form should be placed into the hole before you pour the concrete. Calculate and mix enough concrete to fill the entire form. Use a wood or metal stick to stir the concrete to release air bubbles. Any air pockets left in the concrete can weaken the bollard. Allow sufficient time for the concrete to cure before you remove the form. Once you have removed the forms, paint the bollard, place caps on top, or leave as is.