Experimental investigation on the effect of sulfate attack on chloride diffusivity of cracked concrete subjected to composite solution

The presence of crack and sulfate ion will significantly affect the chloride diffusivity of concrete resulting in the performance degradation of concrete material and structure. This paper experimentally investigated the chloride diffusivity of cracked concrete subjected to the chloride solution and the composite attack of sulfate and chloride ions. The concentration distributions of both the total and free chloride ions in the cracked concrete are tested to evaluate the influences of sulfate and crack on the chloride diffusivity of concrete material. The experimental observation indicated that the presence of crack resulted in a 2-D chloride diffusion in concrete and the crack width has a notable impact on the chloride diffusion rate. It is found that the presence of sulfate ion decelerated the chloride diffusion in cracked concrete with a lower concentration of both free and total chloride ions. This influence of sulfate ion on the chloride diffusion was enhanced with the elapsed immersion time. Moreover, the chloride binding capacity of concrete material was found decreased by the action of sulfate ion in solution. Finally, the evaluation of corrosion products by X-ray diffraction (XRD) during the erosion process provide a sound mechanism validation for the experimental observations. This study laid an experimental foundation for the upcoming numerical modeling of the diffusivity of cracked concrete material. (C) 2019 Elsevier Ltd. All rights reserved.