Muon scattering tomography as a method for detecting rebars and cracks in concrete

There is a need for non-destructive assay of large concrete objects like bridges and buildings. Key issues are the thickness, density and reinforcement configuration as well as indications of cracks or delamination. Furthermore, changes in the condition of concrete structures like corrosion, degradation or cavitation and voids due to ageing can pose problems. Muon scattering tomography is a non-invasive method well suited to scan large concrete samples and detect low- and high-density inclusions such as iron bars or cracks/voids in concrete. The work presented here demonstrates that with muon scattering tomography it is possible to detect rebars of a volume of 894 ± 386 cm3 in a thick concrete floor. For iron volumes above 2 500 cm3, the rebar volume can be reconstructed with a resolution of 5.4 ± 0.3% and the relative uncertainty is better than 10%. It is also shown that it is possible to image rebar structures in reinforced concrete and distinguish between single and a double layer of a rebar grid. The method was developed using Monte Carlo simulations, but it is foreseen to compare simulated data to real data collected with our muon detection system in the future.