A computerized tomography system suitable for the examination of concrete has been developed. The system has been used on various test specimens of concrete. The tomograms (cross-sectional density maps) of 6 in. (150 mm) diameter piers of various cement-to-aggregated mixes show aggregate and voids down to 1 mm in diameter, and fractures less than 1 mm wide. The location and density of reinforcement bars, the density of the background mortar, and the density of the aggregate are accurately reconstructed. A Cesium-137 isotopic source was used to provide a 662 kev photon beam, with plastic scintillator strips used to detect and count each transmitted photon. It is predicted that the technique will find extensive application in quality control in the casting and fabricating of reinforced concrete and steel structural elements. The technique provides periodic inspection for deteriorating elelments subjected to wear and repeated stressing such as pipes and valves, and provides wear and failure analysis for pipes, concrete piers, and beams. -- CAL