Adsorption of comb –type superplasticizers on calcium carbonate in alkaline medium in presence of electrolytes and rheological properties

Abstract

Adsorption behaviour of polycarboxylate type superplasticizers (PC) on CaCO₃ suspension in a basic medium has been studied in the presence of NaCl, Na₂SO₄ and CaCl2 having same ionic strength. The amount of PC adsorbed was found out by determining the amount of PC present in supernatant solution with the help of total organic analyzer. It is found that the adsorption decreased when the POE chain length decreased. The adsorption was increased in presence of CaCl₂ while NaCl and Na₂SO₄ decreased the adsorption. The adsorption is not a competitive process but depends on ionic strength. Rheological measurements of suspensions have also shown that lower the POE chain length, higher the viscosity of the CaCO₃ suspension.