What could I use to fill this?

[budest]

I had to dig up a bit around this radiator pipe to move it and now I want to cover it up again.

There was a top layer of screed which I am not concerned about here as it’ll be tiling but the concrete was relatively easy to get out. I’d like to fill it with something similar in case I have an issues and need to get at it.

Any advice on mixture?

 

[^woody^]

5:1 any sand. Wrap some rag around the pipe, if none there already.

Or expanding foam and cut it flush after.

 

[budest]

5:1 any sand. Wrap some rag around the pipe, if none there already.

Or expanding foam and cut it flush after.

The pipe is sheathed and was then just concreted over. All I did was chipped away at the concrete to move the pipe 45mm leftwards to fit a new towel rail. I have now just filled it with Bostik ready mix cement.