Feasibility study of nondestructive diagnostic method for chlorine in concrete by compact neutron source and PGA

Abstract

As a nondestructive measurement of chloride ion distribution in concrete is important from the viewpoint of preventive maintenance against chloride attack causing deterioration of many concrete structures, a diagnostic technique of a nondestructive measurement method using a neutron-captured prompt gamma-ray analysis (PGA) is being developed. As the first step of development, the γ-ray sensitivities of mortar samples with different chloride ion concentrations were determined experimentally by PGA using the RIKEN accelerator-driven compact neutron source. The results showed that the present detection system was sensitive to a chloride ion concentration of 1 kg/m3, which is lower than the marginal chloride ion concentration of 1.2 - 2.5 kg/m3 to incur corrosion. The time of flight measurement technique with pulsed neutrons was applied concerning the depth profile of chloride ion distribution in concrete.