I would suggest trying a "test Patio" before you do it. Usually anything up to 3 inches is the limit for aggreagate size, it all depends on your mixture. The stuff from the yards (professional) has 3/4 rock unless you specifiy different.
Try for a mix that is able to be built into a baseball type consistency, this tends to have less water and more portland mix. This should create a higher strenth PSI concrete. The reason is you want to be over 2500, but with a mixer this is hard to guage if you have not done this before.
These are some concrete folks around, they may chime in too, just my