The limestone filler cement mortars with different mixing proportions were immersed into different sulfate solutions for one year,and their visual appearances, strength and mineral composition were measured at intervals.The results show that the resistance of mortar to thaumasite form of sulfate attack(TSA) increases with the reduction of water-cement ratio.The relative resistance to TSA of the cements is outlined below,from best to worst: sulphoaluminate cement,sulfate resisting Portland cement,ordinary Portland cement.The resistance to TSA of mortar is remarkably improved by the addition of silica fume or ground granulated blastfurnace slag(ggbs),and the better the resistance to TSA,the more the addition of ggbs is.Magnesium salts reinforce the thaumasite formation and the thaumasite form of sulfate attack in the cement mortars.It reveals that TSA may also occur to structures at temperatures of higher than 15℃.The influence of temperature on the whole resistance to sulfate attack of mortar is related to the material composition.
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