can i use cement to create or make tree trunks if so how?

Question

i went to chester zoo recently and saw excellent animal enclosures and wanted to make my own to look the same as theres they had trees and vines all made from some sort of cement and crafted to look identical to trees and vines

Answer 1

Is this going to be structural or just ornamental? For ornamental uses hypertufa works well and can be cast on the plant shape desired or carved.
Hypertufa pictures
http://www.2oldbats.com/hypertufagardenp.html
http://davesgarden.com/place/t/656018/
So for me the recipe I will use (for now) for thin wall stuff that has to be strong but also carvable is as follows.

-1 1/2 Portlands
-2 fine vermiculite, or 1 vermiculite, 1 peat moss. (Fine perlite might be OK as well.)
-1 course filter sand. I like the rough and feel and look it gives to the finish as well.
-20 to 30 % Acrylic admix in the water.
The whole mess cured 3-4 days damp and then another week really wet. With very slow drying after that.

Answer 2

It was probably concrete, cement would have no lasting strength. You can make up the concrete for your tree trunk and mix in peat, or similar to give it a more natural look, how much is dependant on you, but don't weaken the concrete by adding too much, it will need seven days to reach handleble strength and 28 days to reach effectively full strength

Answer 3

plant the cement early in the year and water every 2 days

Answer 4

I suppose you would have to have a mould first. Then pour the cement in and let it dry. If you are a dealer, this link will help:

http://www.cementmoulds.com/