Sulfate attack on cement mortar containing limestone powder at lower temperature

Mortar prisms, made with pure cement or cement plus 30% mass of limestone powder, were stored in 2% magnesium sulfate solution at (5±1)°C, and the strength and external appearances were tested at different storage days. The mineral components and microstructure of samples were examined. The results show that the addition of limestone powder leads to the transformation of monosulfoaluminate to monocarboaluminate with a better stability during the cement hydration period. And the limestone mortar has a higher compactness than the pure cement mortar due to the limestone powder's physical filling action. The limestone mortar shows a better erosion resistance than the pure cement mortar when exposed to sulfate solution at lower temperature for a short-term time. Sulfate attack on the pure cement mortar at lower temperature leads to formation of a mass of gypsum and ettringite. Besides gypsum and ettringite, however, a little thaumasite forms and the cement hydrate CSH gel is also eroded in the limestone mortar after 210 d of exposure to sulfate solution at lower temperature.