Mechanism of preventing the alkali–aggregate reaction in alkali activated cement concretes

Processes of structure formation taking place in the interfacial transition zone “cement paste – aggregate” have been studied on a variety of cement model systems. The results of this study suggest that, depending upon the contents of components capable of actively interacting with alkalis in the presence of reactive SiO2 in the cement and aggregate, the processes taking place during an alkali-aggregate reaction could be constructive or destructive in character. So-called “constructive processes” are attributed to binding the corrosion reaction products with the formation of the alkaline aluminosilicate hydrates. The results of this study have been taken as a base in developing a mechanism of preventing the alkali–aggregate reaction in the alkali activated cement concretes through the introduction of additional quantities of Al2O3-containing substances.