How can I lift buckets of mortar to second floor?
If you have a pulley and no way to anchor it overhead, you could always lift from the top, with the pulley attached to the bucket. Of course, you'll need to have an anchor for the rope somewhere on the floor you're at, but it only has to be at the height you want to lift the bucket to.

The resulting load will be half of the bucket that you're lifting. If you REALLY don't have anywhere to tie off to, have a buddy hold the other end of the rope.

Obligatory MS Paint diagram: