Effect of curing temperatures and additional activators on chloride ingress and its induced mineralogical alteration of ground granulated blast furnace slag activated by Ca(OH)2

The impact of additional activators (sodium sulfate, sodium nitrite, and calcium nitrite) and curing temperature (20 and 35 degrees C) on chloride binding and ingress resistance of ground granulated blast furnace slag activated by Ca (OH)2 was studied using X-ray diffraction, scanning electron microscopy, thermogravimetric and thermodynamic modeling. The outcomes of the study indicated that the difference in the chloride binding capacity at low chloride concentrations was primarily affected by the types of the AFm phase. The solid solution formed between Friedel's salt and various types of AFm phases resulted in a decrease in the chloride binding capacity. At a curing temperature of 35 degrees C, the chloride binding capacity reduced due to the leaching of calcium ions and carbonation induced by the coarse pore structure. It was found that the chloride ingress resistance was significantly related to the leaching of calcium and carbonation, and the denser calcite layer formed at the exposure layer had a positive impact on the chloride ingress resistance.

Automated summary

This study investigated the effects of additional activators (sodium sulfate, sodium nitrite, and calcium nitrite) and curing temperature (20 and 35 degrees C) on the chloride binding and ingress resistance of ground granulated blast furnace slag activated by Ca (OH)2 using various analytical techniques. The results showed that the types of AFm phase had a significant impact on the chloride binding capacity at low chloride concentrations. The leaching of calcium ions and carbonation, induced by the coarse pore structure, resulted in a decrease in the chloride binding capacity at a curing temperature of 35 degrees C. The formation of a denser calcite layer at the exposure layer positively influenced the chloride ingress resistance.