Chemical Profiling of Sulfate Deteriorated Samples Using Milli X-Ray Fluorescence - X-Ray Spectrum Imaging

Abstract

External sulfate attack damages the structures exposed to various environmental conditions. In order to understand the damage of concrete structures with the ingress of sulfate ions, it is essential to recognize the path of sulfates into the concrete at different exposure conditions. Exposure conditions are mostly based on the real time conditions of the structures; hence partially saturated conditions, wet-dry cycles, saturated conditions are used to get a close picture of field conditions. Concrete cylinders, cast from a 0.48 w/c ratio were completely and partially exposed to 5% sodium sulfate solution for a period of two years. After two years, there was good evidence of physical degradation and this occurred due to different chemical interactions for the period of time. Milli-x-ray fluorescence technique is used to map the sulfur profile of the sulfate deteriorated samples. This gave a clear picture of the concentration levels in the concrete derived from an external source of sulfates. It also provided insight on how the sulfur ions travelled within the concrete matrix with respect to the different transport mechanisms analyzed. It was found that the presence of an evaporation plane, creating a wicking transport mechanism, did contribute to drawing a larger amount of sulfates deeper into the matrix.