Effect of chemical structure on steric stabilization of polycarboxylate-based superplasticizer

Abstract

The effects of chemical structures of graft copolymer on cement-dispersing performance were investigated to elucidate the fluidizing mechanism of polycarboxylate-based superplasticizer containing graft copolymer with polyethylene oxide graft chains. A graft copolymer with longer graft chains showed better dispersing stability with a small amount of adsorption. The adsorption study indicated that the graft chains elongated as the adsorption density increased. The thickness of the graft chain in the copolymer that adsorbs on a cement particle also depends on the average distance between two graft copolymers and the graft chain spacing within the copolymers, depending on the geometric features of the copolymer. The modified steric stabilization model incorporating the extension of graft chains due to adsorption and the geometric restriction of the copolymer gives a useful explanation of the relationship between adsorption and the flow of paste containing different graft copolymers. Copyright © 2006 Japan Concrete Institute.