Backfill of trenches under existing footings

[gsullivan]

We just got involved with a project where a concrete retaining wall is partially complete, with the footing completed but not the stem. Due to poor coordination, a 54 inch pipe has been installed under and perpendicular to the footing, with the top of pipe about 2 ft below the bottom of footing. They are in the process of backfilling with stone. Obviously that won't provide sufficient contact with the footing. I am thinking a flowable fill (CLSM) backfill, but I am concerned that will shrink during curing. Can dry pack grout be placed over cured flowable fill to restore support of the footing? Any other ideas?

 

[csd72]

You could use cement stabilisised sand - has 5% cement plus water mixed in so it is basically self compacting.

 

[cvg]

drypack could be used, but sounds like that would be difficult to completely fill this small void. You might be better off pressure grouting this void, if you really think it needs to be done. I thought that higher cement content equalled higher shrinkage - so that CLSM would not have that much shrinkage?