There is a THERM library called "Material-Arch.lib" which does have a few Concrete materials defined.
To load that file, go to the Library menu, Material Library option.
In the Material Definitions dialog box that appears, click the Load Library button.
This will open another dialog box which will show the Material-Arch.lib file, which you can select, and click the Open button to load into THERM
You will see a few different materials from the default "material.lib" library, which is more oriented to modeling fenestration products.
And you can always add new materials to that library if you can find the appropriate properties of the material you are trying to model