Influence of superplasticizer on aqueous phase composition in the CaO-Al₂O₃-SO₃-H₂O system

The effect of three different superplasticizers on the formation of ettringite during the reaction of Al₂(SO₄)₃·16H₂O with Ca(OH)₂ and on the hydration of C₃A with CaSO₄·2H₂O was investigated in relation to aqueous phase compositions. The superplasticizers comprised a sulphonated melamine formaldehyde condensate (SMF) and two sulphonated naphthalene formaldehyde condensates (SNF) , with different counter-ions (Na and Ca). The addition of superplasticizer altered to varying extents the aqueous compositions, and this was dependent on the reaction system, the degree of reaction and the type of superplasticizer used. The SNF superplasticizer as the Na salt produced solution characteristics different to those produced by either the Ca salt or the SMF superplasticizer. Compositional variations occurring in the aqueous phases as a function of time, both with and without super plasticizer, have in part been explained in relation to that of the solid phase composition.