Title: Compatibility of Polycarboxylate Superplasticizers with Cements and Cementitious Blends

Author(s): I. Schober and U. Mader

Publication: Symposium Paper

Volume: 217

Issue:

Appears on pages(s): 453-468

Keywords: adsorption; cement; cement paste; cement superplasticizer compatibility; flow test; polycarboxylate; superplasticizer

DOI: 10.14359/12931

Date: 9/1/2003

Abstract:
This paper describes a part of a current European research programme (started March 2001) addressing superplasticizers of improved properties. The number of different cement types and blended cements is increasing. Incompatibilities of the cementitious compounds with admixtures can therefore not be excluded, especially at low water/cement ratios. Polycarboxylate superplasticizers with variations of side chain length, content of anionic groups and degree of polymerisation of the backbone were synthesised. The interaction of these polymers with different cements and cement blends was investigated by measuring adsorption, flow of cement pastes and mortar tests. Interesting performance differences can be seen between the different superplasticizer-cement combinations, especially at low water to cement ratios. The results of the paste flow can be explained with the polymer structure and the cement chemistry and can be used to predict polymer performance in mortar. The low alkali cement shows lower sensitivity to differences in structure of polycarboxylate superplasticizers than cements with higher alkali content. The adsorption of polycarboxylate polymers on cement is driven by the structural features of the polymer and can be directly related with the flow of the cement paste.