Please refer to the following articles:
Morgan, D.R. “Freeze-Thaw Durability of Shotcrete” Concrete International, Vol. 11, No.8, August 1989, pp 86-93.
Shotcrete magazine Vol. 4, No. 5, Fall 2002, pp. 32-38
Shotcrete magazine Vol. 5, No. 2, Spring 2003, pp. 30-37, “Freeze-Thaw Durability of Shotcrete,”
Gilbride,P., Morgan, D.R. and Bremner,T.W. “Deterioration and Rehabilitation of Berth Faces in Tidal Zones at the Port of Saint John”, ACI, Concrete in Marine Environment, SP-109, 1988, pp.199-227.
Gilbride, P. Morgan, D.R. and Bremner T.W. “Performance of Shotcrete Repairs to the Berth Faces at the Port of Saint John”, Third CANMET/ACI International Symposium on Performance of Concrete in Marine Environment,1996, pp 163-174.
Morgan,D.R., Rich L. and Lobo, A, “About Face-Repair at Port of Montreal”, Concrete International, Vol. 20, No.9, September,1998, pp. 66-73.
The bottom line is that with a properly designed, air-entrained shotcrete, properly applied by qualified nozzlemen, you should be able to get a good quality product, with long-term freeze thaw durability every bit as good as a quality, air-entrained cast-in-place concrete.