Effect of Pore Solution Composition on Zeta Potential and Superplasticizer Adsorption


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Title: Effect of Pore Solution Composition on Zeta Potential and Superplasticizer Adsorption

Author(s): Dirk Lowke and Christoph Gehlen

Publication: Special Publication

Volume: 302


Appears on pages(s): 253-264

Keywords: zeta potential; pore solution; superplasticizer adsorption

Date: 6/1/2015

The effect of pore solution composition on zeta potential and superplasticizer adsorption has been investigated experimentally. The investigations were conducted on highly concentrated suspensions, containing quartz flour, limestone flour, cement and combinations of these materials. Furthermore cement-limestone suspensions with different types of cements and a varying ratio of cement to limestone were investigated. The results show that the zeta potential is significantly determined by pore solution. In a pore solution of highly concentrated cement suspensions the zeta potential can be characterized by the ratio of calcium to sulfate concentration. Furthermore it was shown that the superplasticizer adsorption is affected the zeta potential. At higher, more positive zeta potentials the superplasticizer molecules are more likely adsorbed onto the solid surfaces. Moreover, superplasticizer adsorption in limestone-cement suspensions is predominantly controlled by the composition of pore solution rather than the ratio of cement to limestone flour. If the ion concentration of the pore solution is artificially kept constant, the polymer adsorption is almost constant independent of the cement to limestone ratio in the suspension.