Flowable Fill Backfilling Cast Iron Pipe

[CalvinD82]

I have a specification for flowable fill that prevents metal pipes from being backfilled with flowable fill unless coated with some sort of manufacturer coating material or plastic casing. The question has arose from a contractor as to why this is the case becuase the contractor wants to use plain cast iron with no coating or covering. Does anyone know if this will harm the flowable fill (cementious, flyash material), I'm not necessarilly concerned about the pipe corroding? Thank You.

 

[Ron]

CalvinD82....no reason that you can't use flowable fill in this application. As long as it doesn't contain a calcium chloride admixture, go for it.

 

[cvg]

we usually recommend 8 mil poly wrapping on iron pipe before backfill or pouring encasement or thrust blocks. The poly provides a bond break which makes excavation / removing the concrete a bit easier in the future. It also provides additional corrosion protection. The poly is relatively cheap and easy, might be reasonable to have it done.