Study on the reaction process of alkali‐activated carbonatite by means of polarizing microscope and digital holographic microscope technology

The reaction process of alkali‐activated carbonatite and the dissolution rate of carbonatite with different content of MgO in water glass solution were studied in this paper by means of in‐situ technologies, that is, polarizing microscope (PM) and digital holographic microscope (DHM). The volume change of carbonatite particles as a function of dissolution time was also quantified by using DHM. The results show that the dissolution rate of carbonatites decreases as the increase of Mg content (from 0 to 21.6 wt. %) in carbonatites. The average dissolution rate of carbonatite with a MgO content of 11.37 wt. % in water glass (M = 1.6, c = 35%) is 75.33 μm 3 /h within the first 12 hr of dissolution. Both dedolomitization and alkali‐silica reaction are present in the alkali‐activated carbonatite system. The Mg‐carbonatite tends to dedolomitize first before it reacts with silicate ions. It explains why the Mg‐rich carbonatite has a lower dissolution rate in water glass.