simulating solid pile

Hi ,

I am trying to simulate two piles, one of them embedded totally in the soil whereas the other has free length above the soil. I did them as  volume piles. 

I set the material of the piles as a concrete and shown with a different colour from the soil borehole which is looks right so far.

       However, when I created the mesh , in the out put , the parts of pile inside the soil shown a colour similar to the soil and  Only the part of pile above the soil coloured with the right colour of concrete.

I would appreciate any help.

Regards.