Resistance of Sulfate Attack of Mixtures with Limestone-Portland Blended Cements

Performance of cement mixtures with portland cement and limestone-portland blended cements containing 2 different percentages of ground limestone was studied. Sound and cracked specimens of cement pastes, all at a given water/binder ratio of 0.40, were exposed to a sulfate-rich aqueous solution at 20 deg C and 5 deg C. There was no evidence of ettringite or thaumasite formation related to sulfate attack in the sound specimens independently of the temperature and cement type. Conversely, in the cracked specimens, some ettringite and/or thaumasite was found in the cracks of the specimens kept at 5 deg C, particularly when they were prepared with blended cements at 30% of ground limestone. This appears to be merely related to a higher water-cement ratio at a given water-binder ratio.