What kind of cement do you use to make sculpted garden art

https://www.hometalk.com/diy/outdoor/garden/cement-rhubarb-leaf-tutorial-18428815

my husband is a sculptor and we have been discussing this very topic recently. He has a sculpture we can not afford to cast in bronze (lifesized) and we were talking about materials suitable for outside here in Maine. Do you definitely have to have cement?

We have another copy of this sculpture in our yard. The yard one is made of Portland cement and silica sand and water. It has been there oh, maybe 30 years, anyway a long time. It is fine. This is Quannah Parker the famous Commanci chief, but this bust is not made of cement. Both pieces were cast after being sculpted in clay.

I answered this question last night. I get confused because it seems that many question posts get posted twice so hard to tell which one is answered.