Assessment the effect of curing temperature on sulfate resistance of alkali activated slag mortar containing silica fume

This study was conducted to probable improvement of the performance of alkali activated slag mortar exposed to sodium sulfate solution. In this regard, the joint effect of silica fume replacing at levels of 0, 5 and 10% and curing at 23 ± 2, 40, 60 and 80 °C on the durability of alkali activated slag mortar against high concentration sulfate medium was tested. In order to investigate the behavior of the samples, length change and mass change tests were used and to identify the microstructure and products formed in their hardened paste, scanning electron microscopy imaging and X-ray diffraction analysis were performed. The results showed the positive effect of heat treatment and silica fume replacement on the durability of alkali activated slag mortar. Simultaneous application of 5% silica fume replacement and heat treatment with a temperature of 80℃ had the best effect on the performance of activated alkaline slag mortar in terms of sulfate resistance. Alkali activated mortar was completely superior to ordinary Portland cement in terms of resistance to sulfate medium. The results of length and mass change experiments were not enough to compare alkali activated slag mortar samples. This was made possible by adding the results of scanning electron microscopy imaging test and X-ray diffraction analysis.