Evaluation of chloride ion content in concrete structures using near-infrared spectroscopic technique
ABSTRACT: For predicting the life time of concrete structures damaged by chloride attack, it is necessary to measure chloride ion content in concrete structures. In such cases, the potentiometric titration method is usually applied for chemical analysis but this method requires much effort and time. Then, authors propose a near-infrared (NIR) spectroscopic method to evaluate chloride ion content in hardened concrete as a new method. This method is very simple and can be applied on site in short time. In this study, mortar and concrete specimens containing premixed chloride were prepared and near-infrared spectroscopic measuring was carried out. As the result, it could be confirmed that the absorbance spectrum of particular wavelength changed with chloride mixing. Moreover, there was a correlation between the estimated value and the chloride ion content in mortar or concrete. The proposed method could be applied not only to specimens but also to actual structures.