LAUSR

Abstract Two types of blast furnace slags (HS N and HS V) with different CaO/SiO2 ratios, were activated by potassium silicate solution (Ms = 1). The results showed that most of the alkali silicate activated slag AAS mortars lost their workability within 10 min. Only an AAS mortar made from slag HS V had an outstanding fluidity even after 20 min. The microstructural evolution of the AAS pastes, as well as their selective dissolution residues after 1 h, were analyzed by an ultrasonic method, TGA, FTIR and solid state 29Si/27Al NMR. By employing a model developed for aluminosilicate glasses, Si(Qn(kAl)) species in the slags were calculated and fitted to their 29Si NMR spectra. The results indicate that slag HS V experienced incongruent dissolution during hydration and that its dispersed glass structure in terms of Si(Qn(kAl)) abundance, was significant with respect to its unusual solidification process.