Someone asked me the other day how much antifreeze you need to prevent engine damage in freezing temperatures. Okay, that wasn't really the question, it was much more complex, but the basic idea revolved around how much you need to add.
The simple answer, that everyone already knows, is to mix antifreeze and water 50/50. Actually, as shown here, ethylene glycol in water reaches it's minimum freezing temperature when the concentration is 70% by weight.
However, the boiling point of the ethylene glycol and water solution actually continues to increase, so more is better for (but not necessary) for the prevention of overheating. In the end the 50/50 mixture should work fine.
But, if you wanted to know the minimum amount of antifreeze to add, it's not simple.
At this page of the excellent site Water Structure and Science by Martin Chaplin, the second plot has the type of information we really want, i.e., how does the pressure in a confined system (e.g. a pipe or engine) increase with freezing. The text states that pressure can increase to 25 MPa (megapascals) in a pipe of freezing water. 25 MPa = 3625 PSI and = about 246 atmospheres.
What you'd really need to know, to answer the minimum antifreeze question precisely, is (1) what is the pressure at which the container fails (breaks) and (2) what does the pressure vs. temperature plot look like for various concentrations of the antifreeze, in a contained volume. Then you can choose the concentration where the pressure at the anticipated temperature doesn't exceed the pressure in (1).
The plot is from Water Structure and Science by Marton Chaplin (link cited above).