Shotcrete Construction Load?

[Ingy]

I am going to shotcrete bridge bolsters, in lieu of cast-in-place. The cross-sectional dimensions are 2' w x 3'-6" h. My question is this. What is the downward live load this will impart on the soffit form? For a standard concrete placement this would be 160 pcf (conc + rebar). However, since shotcrete is supporting a vertical face it stands to reason that that this is reduced.