I would think that if someone was referencing concrete "characteristics" they would be referencing its "properties," I think the words are interchangeable. I think you have to address it in both of its states
Hardened State:
--Strength
--Durability
--Creep/Shrinkage
--Elasticity
--Unit weight/Density
--Insulation/Thermal Resistance
--Color
Plastic State:
--Workability
--Pumpability
--Flow
--Temperature/Hydration
I'm sure there are lots of other a lot of other terms that could be added to my list....