Examining Duct Leakage on Prestressed Concrete Bridges via a Multiple Neutron Sources Method

Tendon corrosion and the leakage of water through the grouting voids are important contributors to the degradation of prestressed concrete (PC) bridges. Therefore, leakage inspections are beneficial in determining whether a tendon is corroding. This work addresses the inspection of duct leakages on PC bridges using a special multiple neutron source method. This approach is based on the principle of elastic collision between fast neutrons and hydrogen atoms during the emergence of thermalization. Multiple neutron sources should be combined with multiple detectors and an appropriately extended detection time. The probability of capturing thermal neutrons can thus be increased to inspect PC duct leakage. An equation was derived from a combination of theoretical studies and experimental outcomes as a reference for properly selecting the numbers of neutron sources and detectors as well as the detection time. The experimental results show that this approach increases the detection depth of leakage within concrete.