Considering the thickness of your collumn ( about 4" , right?) I'd stay away from steel rebar. If you get mousture in the collun and the rebar starts to rust & expand, it'll destroy your collunm from the inside out.. There was a good article in Garden Railways a few years back on this.
I'd look into glass fiber. I have used glass fiber reinforced concrete for other small projects in the past. The omnidirectional nature of the loose fiber in the concrete makes for an incredibly strong mix. Some people have had "issues" with the finished project looking "fuzzy". If you have excess glass fiber poking through the surface, just burnish the surfaces with a propane torch to burn off the excess and it's fine.
Glass fiber reinforced concrete may be worth looking into.
John, did you consider instead of concrete column, making one out of metal, PVC or aluminum, and make it like a girder type? I dont have any pics, but I am sure someone has a couple, just have a base, then build something on the base. Kind of like you see bridges over rivers, concerete base, them girder system. I hope you are getting what I am trying to describe
Thanks for comments! Yes I stated I am not going to use rebar. I have thought of the fiberglass mat theory, thanks Dave. I have a pile of various broken bags of cement I purchase when I find it for $1 bag. I think there is some "fast drying" stuff, motar and portland cement... whatever I do, it's not final and would be easy enough to change. Just like to do it "right" the 1st time. MLS has saved me from many trial and error mistakes! In which has saved tons of time and effort for sure. i was going to use standard concrete mix but do not want the rock agrigate to show on the outside, would not be to scale ya know???? A friend that does concrete for a living said to use what he calls "grout" ??? Surely not the same as tile grout eh? I would think that would be too brittle.... is Grout another professional slang word for a certain type of concrete?
Stopped at Lowe's in C'dale today to price some pavers (MENARDS ALWAYS CHEAPER) , don't know what I was thinkin.... upside-
Found out ALL plants and trees were 50% Off! Picked up my 1st dozen (beautiful) dwarf Alberta Spruces! $3.50 each....
Now I have to decide the perfect place to put them- This is the hardest part!