Measuring Force of Expansion When Water Freezes - DCM

[dcmille290]

Anyone who lives where it's cold enough to freeze water pipes can relate to the following question.

Is it possible to measure or calculate the force of the expansion when water freezes? I hope that makes sense? I have seen everything from schedule 40 PVC crack and bust open and of course Copper and iron pipes do the same.

Thanks,
DCM

 

[mgb_phys]

You can calculate the maximum pressure the ice could exert from the phase diagrams (eg http://www1.lsbu.ac.uk/water/phase.html) at a higher pressure the ice would turn back into water - this is a few 1000 atmospheres
I don't know if this is a reasonable pressure for a real pipe.

 

[Vanadium 50]

The bulk modulus of ice is 89 x 10⁸ N/m². Ice wants to expand by 8.3% when frozen, so to keep it in the same volume requires a pressure of 8.3% times the bulk modulus, or 7.3 x 10⁸ N/m². That's about 7300 atmospheres, far more than most materials can support.

Depending on the temperature, this may be enough to reliquify water, so this can be viewed as an upper bound. I suspect that, in fact, the pipes break while there is still a water-ice mixture in them, so you don't see pressures this large.