RCP (D-Loads) - Placing materials with different unit weights along profile

[CWEngineer]

Do you guys see any issue with placing different types of materials along the profile of an RCP or is this acceptable? For example placing a slurry (unit weight of concrete of 150 pcf) for certain length of the pipe, then placing soil with 139 pcf for the remaining length of the RCP?

Thanks

 

[cvg]

what are your concerns?