Early reactivity of sodium silicate-activated slag pastes and its impact on rheological properties

M. Palacios (1) , S. Gismera (1) , M.M. M Alonso (1) , Jean-Baptiste D’espinose de Lacaillerie (2) , B. Lothenbach (3) , A. Favier (4) , C. Brumaud (4) , F. Puertas (1)

1 Institute of Construction Science Eduardo Torroja
2 SIMM - Sciences et Ingénierie de la Matière Molle (UMR 7615)
3 Laboratory for Concrete & Construction Chemistry
4 Computer Vision Laboratory - ETHZ [Zurich]

The fast loss of fluidity of sodium silicate-activated slag (SS-AAS) systems have been widely studied in the literature. In this study, the rheology of these cements has been correlated with the evolution of the reaction products formed over time. For this purpose, a combination of experimental characterization techniques, to study the pore solution composition and microstructure of SS-AAS pastes and thermodynamic calculations have been applied. The initial precipitation of ill-defined N-AS -H and C-N-AS -H producta leads to a fast increase of the storage modulus after 40 min of reaction. These products are formed from the reaction of the Na + ions and silicate ions of the activator with the Ca 2+ and aluminate species dissolved from the slag. However, when a shear is applied, the structure breaks down and fluidity is recovered, that infers that the attractive forces between the particles are low at the early stages of hydration.

Domaines: Matière Molle [cond-mat.soft]; Sciences de l'ingénieur [physics]; Matière Condensée [cond-mat]

M. Palacios, S. Gismera, M.M. M Alonso, Jean-Baptiste D’espinose de Lacaillerie, B. Lothenbach, et al.. Early reactivity of sodium silicate-activated slag pastes and its impact on rheological properties. Cement and Concrete Research, 2021, 140, pp.106302. ⟨10.1016/j.cemconres.2020.106302⟩. ⟨hal-03168896⟩