Backfilling pipe in subfloor

[Mr.Mincer]

I've to run a 110mm pipe approx 8m under my concrete subfloor.
Getting the fall etc correct is no problem but I'm wonder what the best way to backfill the channel is ?
I'm thinking DPC, then a bed of sharp sand then pea gravel.
Finished with a skim of cement (probably self leveling over the whole room ).

Any thoughts?
Thanks

 

[denso13]

Just sharp sand then 50mm of sharp sand/cement to finish.

 

[noseall]

I've to run a 110mm pipe approx 8m under my concrete subfloor.
Getting the fall etc correct is no problem but I'm wonder what the best way to backfill the channel is ?
I'm thinking DPC, then a bed of sharp sand then pea gravel.
Finished with a skim of cement (probably self leveling over the whole room ).

Any thoughts?
Thanks

Lay pipe with falls.

Carefully pack pea gravel around and under the pipe.

Top up and surround with pea gravel. Deeper areas fill up to conctrete layer with MOT stone.

Sand blind. Lay DPM.

Lay concrete.