Title:
The Role of Adsorption Energy in the
Sulfate-Polycarboxylate Competition
Author(s):
R.J. Flatt, J. Zimmermann, C. Hampel, C. Kurz, I. Schober, L. Frunz, C. Plassard, and E. Lesniewska
Publication:
Symposium Paper
Volume:
262
Issue:
Appears on pages(s):
153-164
Keywords:
adsorption energy; atomic force microscopy; sulfate; superplasticizers.
DOI:
10.14359/51663229
Date:
10/1/2009
Abstract:
The interaction between sulfates and polycarboxylate polymers has become a subject of much discussion and occasional concern over the past years.
Laboratory studies have shown that sulfates may prevent some polycarboxylate polymers from adsorbing, which causes a reduction in flow properties of cementitious materials. This seems to have led to the belief that this phenomenon is generally true for all polycarboxylates. In fact, it depends very much on the detailed polymer structure. Examples of this will be shown both with flow examples on paste, and experiments by atomic forces microscopy that illustrate in a very convincing way that this competition does not always turn to the advantage of sulfate ions. Furthermore, it is discussed how the outcome of this competition is governed by variations in the adsorption energy of the polymers.