application of cohesive element to concrete cracks in Abaqus

Hi everybody!

I am now using Abaqus to model concrete cracks by using cohesive element and I have got two questions regarding this:

1. cohesive element, as known, is often employed to model interface especially when the integrity and strength of the interface is of interest. For my problem, there is no real interface, however, I impose a cohesive element interface artificially in the concrete and to see the crack propagation. Is this applicable theoretically?

2. Given the above assumption is correct, how to define the material properties of both concrete and the interface, as the interface is not real but dummy? I really have no sense on this point. 

Kind regards

Chris