Effect of Polymer Structure on the Sulfate-Polycarboxylate Competition

This paper describes how outstanding concrete performances are achieved nowadays using polycarboxylate-type superplasticizers. Nevertheless high performing superplasticizers are often sensitive to the cement used and in particular the cement sulfate content. Laboratory studies have shown that sulfates strongly influence the performance of superplasticizer because they inhibit polymer absorption 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 polycarboxylates. In fact, it depends very much on the detailed polymer structure. In this study, the sulfate sensitivity of polymers with systematically varied polymer structures has been measured through paste experiments and the influence of different polymer structures on the sulfate sensitivity will be discussed.