Microwave nondestructive evaluation techniques proposed for civil structures and cement based materials offer distinct advantages in that they are non-radioactive and provide good penetration, excellent contrast between steel reinforcement material and concrete, and insensitivity to ambient temperature. This paper presents a far field frequency domain reflection coefficient measurement setup for non-invasive inspection of cement-based materials at microwave frequencies. Imaging results obtained in the X-band frequency for planar mortar and concrete samples in the presence of steel reinforcement bar are discussed.