The damage of calcium sulfoaluminate cement paste partially immersed in MgSO4 solution

One of controversies on the sulfate salt weathering of ordinary concrete is that MgSO4 does not show physical crystallization distress on concrete as the same as on masonry. In this paper, the Calcium sulfoaluminate (CSA) cement paste was partially immersed in 10 % MgSO4 solution to study if MgSO4 crystal can be identified in the damaged paste because the hydration products of CSA cement paste do not contain Ca (OH)(2) that playing a vital role in chemical sulfate attack on concrete. The results showed that the low parts in the solution showed more severe damage observation than the upper part in contact with air after 5 months exposure. MgSO4 could not be identified in the damaged paste of upper part. The damage of paste was still a typical chemical sulfate attack characterized by amounts of CaSO4 center dot 2H(2)O crystals formation due to the decomposition of ettringite by Mg2+, even without the effect of Ca (OH)(2). The so-called physical sulfate attack still cannot be confirmed on MgSO4 attack on CSA cement paste