The effect of activator concentration on reaction degree and structure formation of alkali-activated ground granulated blast furnace slag

The effect of activator concentration on reaction degree and structure formation of alkali-activated ground granulated blast furnace slag, using Al and Si NMR spectroscopy, is presented. The experiment shows that the alkali activation is not a catalytic activation, but is necessary for dissolving the glassy structure of the slag. This further proves that the reaction degree is dependent on the quantity of dissolved glass and not on the amount of water. The alkaline solubility must be similar for the Al and the Si phases, since the different activation has no effect on the Si/Al ratio in the hydration products. The faster hydration observed in calorimetric investigations is due to the larger number of polymerizing units. The resulting reaction products have the same average chain length and Si/Al ratio of the end of the reaction, if all dissolved educts have been consumed. This indicates that the reaction kinetics of the condensation is unaffected by the activation.