Ice-rock (silt/sand/gravel) composites are a thing, so a pycrete composite might be made to sink. But that's still lighter than rock, so gravity dam overturnin

Ice-rock (silt/sand/gravel) composites are a thing, so a pycrete composite might be made to sink. But that's still lighter than rock, so gravity dam overturning moment means the dam would need to be bigger.