Flowable Fill Mix Proportions

[WBell]

I am having a contractor backfill an over-excavated spread footing with flowable fill. The volume required is less than a yard (27 cubic feet) so I am providing the contractor with a mix proportion by volume for the material. Several articles give the mix design based on weight, but the mix will be prepared onsite and weight measurement is not an option. The volume conversion is for a mix design given by weight by the American Concrete Pipe Association which is for 1 yard of mix = 100 lbs cement + 3000 lbs sand (saturated surface dry) + 600 lbs water. When calculating equivalent volumes, there is a question of what density of portland cement should used in the weight-volume conversion. There are two values discussed in mix design: 94 pcf and 197 pcf, the latter value calculated using the specific gravity of portland cement = 3.15. Intuitively, I think the 94 pcf is more reasonable.

Any comments or suggestions are welcome.

 

[bridgebuster]

94 sounds right. I haven't bought a bag of cement for a while but I recall that's what a bag weighs.

 

[coloeng]

A Google search puts cement at 94 lbs/cu ft.