The expansion of water as it freezes seems to be a characteristic of the molecule itself, rather than whether or not any gases are present.

This article I looked up explains it to some extent, and those with more chemistry here than I have (if it doesn't burn in an engine, I don't know much about it) might add more.

The gimmick of ice floating on its liquid form is fortunate for life on Earth. If ice sank as it formed, it wouldn't take long for many of the waters of our world to freeze solid all the way to the bottom.

BTW, anybody remember the famous scene in "Voyage to the Bottom of the Sea" (the movie), where the submarine Seaview was buffeted by ice chunks dropping like bricks from fractured ice floes?

Of course, there's ice, and then there's ice.