Thanks. actually I am trying to model a lightweight material made from concrete as a backfill material. I needed some mechanical properties of this material, I know some of them but I don't have ideal of the phi angle. I though maybe that of regular concrete should be close enough. At least for a start, I thought of using it if I know. Anybody have an idea?
may be close to "fluid" initially then set up with time. there's a few threads i recall where the phi of concrete topic was discussed (and opinions varied dramatically depending on which detail you choose to focus on).
So if I understand correctly, you are using flowable fill as backfill and need to model it.
When plastic (fluid) the material has effectively no strength and a unit weight considerably higher than water. Once it cures, it should have a strength considerably higher than soil.
In the cured state I would model it as a very hard soil with undrained and drained strengths equal to 45 degrees and cohesion based on the design strength of the mix. The cured material would exert no lateral load, only vertical.
In the plastic state i would model it as water with a unit weight equal to the weight of the plastic material.
