Title:
Synergistic and Antagonistic Effect of SO4 2– on Dispersing Power of Polycarboxylate
Author(s):
Ahmad Habbaba, Nadia Zouaoui, and Johann Plank
Publication:
Materials Journal
Volume:
110
Issue:
6
Appears on pages(s):
641-646
Keywords:
adsorption; fluidity; high-range water-reducing admixture; polycarboxylate; zeta potential
DOI:
10.14359/51686331
Date:
11/1/2013
Abstract:
The dispersing performance of polycarboxylate (PC) high-range water-reducing admixtures can be strongly enhanced or impeded by sulfate ions present in cement pore solution. Here, two PCs based on methacrylic acid–co–w–methoxy poly(ethylene glycol) methacrylate ester were tested in an inert model suspension based on CaCO3, which contained different amounts of potassium sulfate. It was found that the dispersing effectiveness of highly anionic PCs is positively affected by sulfate, stemming from concomitant adsorption of both PC and sulfate. On the other hand, sulfate negatively impacts performance of PCs possessing low anionic character as a consequence of competitive adsorption between PC and sulfate.