Towards an application of muon scattering tomography as a technique for detecting rebars in concrete

Inspection of the world's ageing population of reinforced concrete infrastructure is a multi-billion dollar problem. Historically, it has not been uncommon for structures to deviate from their designs,or for design drawings to be lost. This leaves asset managers the challenging task of making structural health assessments and maintenance decisions with incomplete knowledge. While current techniques for detecting rebars in concrete are typically limited to penetration depths of less than 50 cm, muon scattering tomography (MST) is a non-destructive, non-invasive technique which shows great promise for high-depth 3D concrete imaging. This paper uses Monte Carlo simulations to demonstrate that MST can be used to detect and locate 100 cm length rebars with a diameter of 33.7 ± 7.3 mm independently of the rebar's location within a concrete structure. This corresponds to a volume of inclusion of 894 ± 386 cm3. The volume of the inclusion can be reconstructed with a resolution of 5.4 ± 0.3% for volumes above 2 500 cm3. It is furthermore demonstrated that 30 mm diameter rebars can be distinguished as two separate objects provided their separation is more than 40–60 mm, and that single and double layers of rebars are distinguishable using the technique. It is anticipated that MST could inform practical studies which support more informed maintenance and modeling, eventually allowing digital twins to be created for a larger subset of historical steel and concrete structures.