Is the process of water getting into the cracks of rock or pavement and freezing and breaking it considered erosion, weathering or deposition?
Let's take a look at the meanings of erosion, weathering and deposition, and then we'll be able to see what kind of process we have here.
Erosion is the effect of surface processes (such as the wind or water flow) that remove part of the material (like from the soil, or from a rock) from one location and then transport it away to another location. In our case, no material is being removed and then transported, so we don't have erosion here.
Deposition is the final process of an erosion, which is the part where the particles of a material (which probably suffered erosion at first) get deposited in a certain location by the transporting medium. The material then settles down on a new surface. Again, this is not our case: although water could have been transported to this pavement or rock by a certain medium, the water is not settling down to become part of this surface, it is freezing and breaking it.
Finally, weathering is the breaking down of rocks, soil, minerals and artificial materials by the action of elements of a planet's atmosphere, water or biota (the collection of organisms at a certain location). Thus, water getting into the cracks and freezing and breaking the rock or the pavement is considered weathering, because the water is acting on this surface/rock by breaking it.
I hope I succeeded in showing you the differences between these processes!