Shotcrete is a placement method for concrete. If the berm is composed of granular materials, one wouldn’t expect the shotcrete to actually bond to the soil. Rather, placing a thin shotcrete layer would create a uniform, relatively impermeable layer of concrete to prevent water from penetrating through and washing out the soil underneath. The emulsion may help to stabilize the soil to help withstand the pressure of shotcreting directly against the berm, but many similar soil stabilization projects will shotcrete directly onto the natural soils. Also, when considering using the emulsion, be aware that some oils may contain ingredients (like sulfur) that can attack the concrete over time. You should consult with an engineer or concrete materials specialist to ascertain whether the specific oil you want to use will have a long-term effect on the shotcreted layer.