pipe u/g crossing road backfill - flowable fill instead of soil

[AskTooMuch]

I have a pipe crossing a minor road so it went 4' u/g.
To backfill it's easier to use flowable fill because no compaction is necessary.
I want to ask if this is ok and will not affect pipe flexibility.

This is not a pipeline but a pipe mostly above ground and just went u/g for road crossing.

 

[LittleInch]

flowable fill isn't great normally because it creates a hard anchor point, but a 4" line?

shouldn't be an issue, just be careful how you compact and design the interface between flowable fill and normal fill to avoid a hard spot / edge.

Is this subject to thermal stresses or other movement?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[AskTooMuch]

The pipe isn't 4" (inches) diameter, the U/G depth is 4'(feet). The pipe is I is 12" diameter.