Carbonation Versus Efflorescence in Alkali-Activated Blast-Furnace Slag in Relation with Chemical Composition of Activator

The present work is devoted to a better insight into the identification of carbonation versus efflorescence formation in alkali-activated blast-furnace slag and investigates the relation between the chemical composition of the alkali-activator and the extent of the occurrence of these two phenomena. Obtained results showed that mixes of relatively lower alkali contents suffer not only from weak compressive strength due microstructural defects, but also from carbonation during the first few days. On the other hand, mixes containing relatively higher alkali contents strongly suffer from efflorescence formation in spite of their interestingly high compressive strengths. Carbonation during the first few days can partially neutralize the alkali content of the surface layers of the material which in turn significantly affects the activation mechanism leading to the formation of binding compounds of different molecular structure.