Feasibility study of a neutron-based method for field measurement of chloride in concrete

Abstract

Abstract Sub-percent levels of chloride in concrete is known to promote corrosion of the interior metal reinforcement which leads to structural degradation. The current industrial practice of chloride analysis through destructive chemical processes can be augmented by on-site non-destructive techniques such as prompt gamma activation analysis (PGAA), which can measure Cl along with Si and Ca in bulk concrete. PGAA commonly performed in a nuclear reactor is not suitable for field work. We tested a portable neutron generator based PGAA system for measuring Cl in a set of 90 cm �� 90 cm �� 12.7 cm concrete slabs in a laboratory setting. The measured results were compared to Monte Carlo radiation transport simulated gamma-ray spectral response as a function of Cl mass fraction. This work serves as feasibility study for a field-deployable chloride sensor for concrete structures, providing useful information for future effort in improving the detection limit and in designing robust detection and quantification methods.