Fill a gap around a drain

[Paul not got a clue]

hi I had a drain with hollow sounding concrete. I chipped away at it to reveal the sink pipe going into a round trap only thing is what do I use to fill the gaps around the drain? I’m going to use plumbers mate around the waste pipe to seal it.
And then re concrete it after as before it was running into the drain next to it.

 

[JohnD]

You have a broken drain. Probably at a trap, gulley or bend. It is very common. You need go dig it out and replace with new

You can't mend it

Post some photos please.

 

[Paul not got a clue]

I had some damp and wanted to see if the drain was broken. But I can see around the drain that it’s fine. But when I took the concrete off around the drain there was bits of Broken brick to cover up the gaps and the concrete on top of that. All I want to know is the gap around the the actual drain, to I fill it with concrete or stone clippings and then concrete around the drain the old concrete covered the round drain and it was shaped the run in the square drain for the rain water run off I guess?

 

[Harry Bloomfield]

I would find and cut some thick rigid plastic (6mm) to shape to act as a support, then add cement over the top of that. The plastic used for gutter facias is ideal.

First make sure there is nothing dropped in the bottom of that gulley, you mention bricks. Wet around the area suggests a possible obstruction - try poking the end of a wet and dry vacuum down there, to clear any debris in the bottom.