Title:
Selecting the Optimum HRWR for SCC
Author(s):
I. Schober and U. Mader
Publication:
Symposium Paper
Volume:
235
Issue:
Appears on pages(s):
283-290
Keywords:
adsorption; polycarboxylate; self-compacting concrete; superplasticizer
DOI:
10.14359/15917
Date:
3/22/2006
Abstract:
Polycarboxylate type Superplasticizers have become the most widely used in SCC since they show outstanding performance regarding water reduction and flow retention. In some cases, depending on polymer structure and binder used, incompatibility problems like rapid slump loss may be observed. In order to overcome such problems, the mode of action of different polycarboxylates was studied by measuring the adsorption of the polymer on cement, the flow in cement paste, the flow and strength development in mortar as well as in standard concrete and self compacting concrete. The structure of the polycarboxylate (molecular weight, length of side chains, grafting degree) strongly influences its adsorption on cement and thus the performance as Superplasticizer. The increase of flow of the cement paste and polymer adsorption follows a quasi linear relationship. However the polycarboxylate with the highest adsorption is not necessarily the best performing in SCC applications. The outstanding performance of polycarboxylates in SCC and the importance of using a knowledge based approach for reaching the optimal properties of this materials is demonstrated in case studies.