Carport using unusual construction method

I have a similar issue with parking and shop access. Curious if you ran rebar down through the posts, and if so, what did the multiple pieces look like wired together? I see the concrete mixer in the picture. What type of mixture did you use for this structural column work? Where you able to fill each column in one pour? and finally, are you going to pour a concrete floor for the cars to sit on?
5:1 gravel to cement, with fortifier/bonding agent.

The fortifier/bonder is a little expensive, but it really makes the concrete a lot stronger.

I usually mix a couple of small batches to fill one column because it is easier than trying to do one large batch.

For the time being I am going to bring in some decomposed granite for the floor because it isn't really any more expensive than gravel and I like it better.

I would like to add exterior walls at a later date.