Study of cracking in concrete by neutron radiography

The digital neutron radiography (NR) technique was employed to visualize cracks in concrete. The radiographs were obtained by the direct method with a gadolinium converter screen and the facility is installed at the radial beam tube 08 of the IEA-R1 Nuclear Research Reactor, which provides a neutron flux of around 3 × 106n s−1 cm−2 at the sample irradiation position. The samples were 5 mm thick polished slices sawn from two cylindrical concrete specimens, one of them submitted to a compressive strength test. In order to enhance crack visualization, these samples were impregnated with a high neutron absorbing substance (contrast agent). The digital radiographs presented, interms of crack visualization, better results when caompred with the digital X-ray radiographys and with the analog ones obtained by the NR technique of the same samples.