Study on Accuracy Improvement and Practical Application for Estimation of Chloride Content in Concrete Structures Using Electromagnetic Wave Method
342 , 2015-03-24 , 法政大学
Chloride induced corrosion is one of the cause of deterioration reinforced concrete structures. In generally, as one of evaluation method of deteriorated situation caused by reinforcement corrosion in the concrete, drawing cores and chemical analysis are carried out. It is possible to perceive chloride content in the neighborhood of reinforcing bars. However, it is not possible to perceive only chloride ions at the position drawn cores and difficult to perceive about any corrosion of reinforcement unless corrosion induced cracks appear on the surface. Then, if it is possible to estimate the chloride ions in concrete using electromagnetic waves as a non-destructive method, it is possible to perceive the chloride ions in concrete without giving any damages. In addition, it is possible that this method conveniently evaluate the condition of degradation in respect of the wide area. From past studies, it was confirmed that the amplitude value of the electromagnetic waves decreases with increasing chloride ions within concrete. It is possible to estimate chloride ions by utilizing this characteristic. In this report, in order to improve the accuracy of the non-destructive method to estimate the chloride content using electromagnetic waves, the construction of theory and experiments for verification were carried out. At first, the phenomenon of attenuation of electromagnetic wave due to content of chloride ions in concrete was clarified by applying the electromagnetism and physicochemical theory. Then, each optimal solution was obtained from the results of measurement using radar with specimens of concrete in which changed the depth of concrete, temperature of concrete, water content and chloride content. As the results, it is possible to estimate the attenuation characteristics of electromagnetic waves for change of the material properties of concrete and to obtain the estimation equation which contribute to improve in accuracy of estimation of chloride ions in concrete using electromagnetic wave.