Expounding structures of roller compacted concrete dam specimens by means of hard conventional X-ray inspection

A simple solution to improve the contrast between the different concrete composites in X-ray imaging (radiography and tomography) of a highly compressed composite sample of real size roller compacted concrete (RCC) specimens is presented. This is made by applying a 9.5 mm thick Copper (Cu) filter at the output window of the X ray tube in a conventional X-ray inspection equipment. Our results show that with the employed filtration, at 140 kV and 200 kV, we were able to distinguish the gravel from the other concrete composites even in a highly compacted specimen. Cement and sand grains as well as porosity were not detected mainly due to the low spatial resolution of our detector system. This suggests a further improvement by using the now available high voltage microfocus X-ray tube (>= 200 kV), a bow-tie (or through) Cu filters and a high resolution flat panel detector for phase contrast imaging on real size compacted concrete specimens.