Abstract: The effect of active MgO on the chloride ion binding ability of cement-based materials with high SCMs addition, and the test was taken by the measure of reactive MgO and CaO mixing. The total and free chloride contents of pastes were tested by automatic potentiometric titrator, and the phase composition of pastes were analyzed by means of XRD, DTG. The experimental results shows that in the case of reactive MgO and CaO mixed content 10%, the early compressive strength of the paste decreased with the increase of reactive MgO content, while the later growth rate of compressive strength increased. With the addition of 5% reactive MgO, the binding of chloride ion content reached the maximum. XRD, DTG and other analysis showed there are C-S-H gel, hydrotalcite and Friede salt in the paste.

Key words: reactive MgO;high addition;chloride ion binding;hydrotalcite;friede salt