Shotcrete is a placement method for concrete. Thus, structural properties are equivalent to those of concrete with specified strength. Shotcrete compressive strengths will normally range from 4000 to 7000 psi at 28 days, so your 4800 to 5000 psi (33 to 35 MPa) is very normal. Density of shotcrete placed concrete is the same as cast concrete ranging from 145 to 150 lb/ft3. Walls can generally be built at any required thickness because we will create the wall by bench shooting building the wall from the bottom to the top in vertical lifts.