Evaluation of sulfate and salt resistance of ferrochrome slag and blast furnace slag-based geopolymer concretes

In this study, mechanical, visual, and microstructure changes of geopolymer concrete exposed to sulfate and salt effects were investigated. Elazig ferrochrome slag (EFS) and blast furnace slag (BFS)-based geopolymer concretes which completed curing time were immersed in 5% sodium sulfate (Na2SO4), magnesium sulfate (MgSO4), sodium chloride (NaCl), and magnesium chloride (MgCl2) solutions for 12 weeks. The compressive strength values, ultrasonic pulse velocities, visual inspections, weight, and length changes of the samples were determined in this investigation. In addition, scanning electron microscopy was performed for the microstructure analysis of the samples removed from the solutions. Sulfate solutions had a more negative effect on the samples than salt solutions. As the EFS ratio in the mixture increases, the loss rate in the strength of the samples exposed to sulfate and salt solutions decreased. While samples exposed to sodium chloride, sodium sulfate, and magnesium sulfate solutions occurred weight gain, samples exposed to magnesium chloride occurred weight loss. The samples in salt solutions shrank, while the samples in sulfate solutions expanded. No deterioration occurred on the surfaces of the samples exposed to the solutions for 12 weeks.