Phil Stevens wrote:Round wins the compressive strength contest, no doubt. I'd be inclined to do a test casting with sonotube and/or PVC culvert pipe as forms. You'd probably want reinforcing mesh in there as well. I'd assume that commercially made ones are reinforced. Doing the operation on an old truck tyre would allow you to vibrate the form with something as simple as a hand sander, and that will allow you to use a drier mix and do less tamping.
I agree that there must be some reinforcing in the commercially-made well tiles, but I'm surprised at how little information is available on the webs. I did find teaser info on ferrocement well sections, but the full document is behind a paywall.