Question

What unusual property of water is responsible for frost wedging?

Answer 1

1. The fact that water requires more volume when it solidifies (freezes). Most liquids will turn into a solid when they freeze and in the process of freezing, take a smaller volume. But water is unusual in that when it freezes, it increases its volume. And during that expansion, it can exert a LOT of force. If water is in an enclosed space, it can exert about 1000 times atmospheric pressure against its surroundings.

Answer 2

The property of water that it expands and becomes less dense as it freezes. The property is unusual because it is not the case in other liquids.
Ice wedging is a form of mechanical weathering or physical weathering in which cracks in rock or other surfaces fill with water, freeze and expand, causing the cracks to enlarge and eventually break.