Ceramics-Silikáty 43 (1) 18-22 (1999)

ELECTROKINETIC POTENTIAL MEASUREMENTS IN A SYSTEM OF SiO₂ - CaCl₂ - H₂O

N. Jíchová, J. Havlica 

The aim of the presented work was to study the dependence of the SiO₂ sol zeta potential on the contents of calcium chloride. The sol contained 2.27 wt. % of SiO₂ and the content of anhydrous CaCl₂ varied between 0.126 and 13.0 wt.%. The experiments demonstrated an influence of calcium and chloride ions on the electrokinetic potential. Formation of gels based on calcium-silicate hydrates can be expected with an increasing content of calcium ions in the solution. On the other hand, increasing content of chloride ions brings about a lowering of the pH of the solution, thus slowing down the transport of the silicate components into the solution. These chloride effects are more apparent at higher CaCl₂ concentrations. The described phenomenon explains the behaviour of calcium chloride as an additive accelerating the hydration of the silicate components of clinker minerals.

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