First, I thought you were talking about piers 3' high. If so the wheelbarrow won't reach up that high to pour it and shoveling it is going to be back breaking.
On the upside, if you buy/rent a concrete mixer you could move it right next to the pier and dump directly into the pier. You might have to put it on a pallet or 2 to get it high enough to dump it but you could use your loader to move everything around.
You need to figure out the exact amount of concrete needed in each pier. I think you will find that it is going to take at least 4 or 5 sacks of concrete mix in each pier and each sack weighs 80 pounds. An 80 pound bag of concrete mix is only 3/4 of a cubic foot of concrete. You are talking about lifting 320 pounds or more of sacks into the mixer for each pier X how many piers.
According to the calculator at
Volume calculator a 6 inch column 6 feet tall (3' underground, 3' above ground) is 4.71 cubic feet. Divide that by .75 cu ft and that is 6.28 sacks of ready mix per pier X 80 pounds per sack is 502.64 pounds X 55 piers gets you to 11,310 pounds. Approximately 350 sacks of concrete mix. And looking back at your original post you said they were going to be 12" piers so double all the above figures.
BTW, I have never seen a residence with 12" piers. 6" is common and some 8" are used but I have never seen a 12" and I was a Licensed Texas Real Estate Inspector for a few years so I have been under a few houses. I was also a licensed Master Electrician in Dallas, Texas for 20 years and built my own 625 sq ft lake cabin virtually singlehanded so I feel I have some qualifications. (No wonder I have a bad back!)
Don't even consider trying to mix it by hand in a wheel barrow. When I had a guy I hired pour some 6" square concrete curbs for me I rented a mixer and was way ahead on both time and money. And he was an experienced concrete man.
From the size of your project it would seem that you would be better off buying than renting a mixer and selling it when the house is finished. Just make sure you buy one that is big enough to handle 6 sacks of mix (4.5 cu ft).
I have done a major remodel including building a 28 X 32 garage and an 8 X 40 front porch. I couldn't find a contractor to do the work so I hired some hands and did it myself. I got it done but it took it's toll on me, even with the hired help. Only things I subbed out were the concrete, roofing, tape and texture sheetrock, and exterior painting.
I am not trying to scare you, just trying to make you aware of what you are about to tackle.
Sounds like your wife is really supportive, you are very fortunate. My wife said she was happy to see me spend $12K on a tractor that is basically a hobby for me. Sounds like we are both very lucky husbands.
Bill Tolle
