I am modeling lightweight concrete

[AAhhm]

I am modeling lightweight concrete flat slab, however the results are not reasonable and the run time is very short I believe there is an error and I can not figure it out.
I attached the file it is easy but I could figure it out.

 

[FEA way]

Why do you think that the results are wrong ? Did you compare them with some reference values ? Did you check forces, energies and other important outputs ? What about mesh convergence study ?

 

[AAhhm]

Yes exactly