The damage of calcium sulfoaluminate cement paste partially immersed in NA(2)CO(3) solution

In the presented paper, the tests were designed to offer indirect evidences for the physical sulfate attack on ordinary concrete. The calcium sulfoaluminate (CSA) cement paste was partially exposed to 10% Na2CO3 solution under condition of 20oC and RH 60%. The microanalysis results showed that Na2CO3 crystallization did not occur in the CSA cement paste and the Na2SO4 crystallization, the product of chemical reaction between CSA cement paste and Na2CO3, caused the cracks formation at the edge of specimens. The Na2CO3 crystallization occurred after the chemical reactions disappeared. As comparison, it can be confirmed that the physical sulfate attack or sulfate crystallization also cannot occur in the ordinary concrete due to the chemical reactions between Portland cement paste and sulfate.

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