I've been retro-fitting linear drain around my 1920s house which has block paving but no drainage. While excavating I've also been repointing / filling between any bricks where mud has replaced the mortar. I'm doing this a section at a time to be safe. I also have a couple of bricks I am going to replace.
The footings are about 3 courses of bricks under the block paving. The footings are concrete on clay.
https://photos.app.goo.gl/nnDCdbzsYmLxKyWJ7
Originally it looks to be the footings are covered in about a course height of clay with some stones. Then there is some sub-base (very mixed in size not graded). Then sand for the block paving. It's foot traffic area and hasn't sunk (its been like this for over 10yrs before I moved in)
My question is, should I fill it back in the same way I found it? I want to protect the footings from and brickwork from water /frost. Is clay against the brick a good idea?
https://photos.app.goo.gl/ytvW5FT1sA3fKbZD9