The effect of chlorides on the thaumasite form of sulfate attack of limestone cement concrete containing mineral admixtures at low temperature

摘要

Two factors which affect concrete's durability were investigated, including the effect of the mineral admixtures used, as well as the effect of chlorides on concrete's deterioration due to the thaumasite form of sulfate attack. Concrete specimens were prepared with Portland limestone cement as well as by replacing a certain amount of limestone cement with natural pozzolana, fly ash, blastfurnace slag or metakao-lin. The specimens were immersed in two corrosive solutions (chloride-sulfate; sulfate), and stored at 5 ± 1 °C. Visual inspection of the specimens, mass measurements and compressive strength tests took place for 24 months. The partial replacement of limestone cement with mineral admixtures retards and inhibits concrete's deterioration. In the case of limestone cement concrete without mineral admixtures, chlorides mitigate the corrosive effect of sulfates. Regarding concrete containing mineral admixtures, the concomitant presence of chlorides amplifies the detrimental effect of sulfates and leads to a worse level of damage.