Depends if it's a 3 bag mix, or a 6 bag mix.
Knowing DUmmies, they would leave the concrete out altogether, and just use sand and gravel.
Ya don't want to pour anything outside with less than a 5½ sack mix with a shot of air.
The air makes bubbles in the concrete so it is more waterproof. It it freezes, the bubbles protect the concrete from freezing any further than the top layer.
Just like in body work, if ya want a stress crack from going any further, ya drill a hole at the end of the crack. It will stop it every time!
Works with wood too, to a point. As long as you drill circular holes in wood, it will not effect the structural strength unless the diameter is greater than a third of the total width or thickness.