Utilization of polysaccharides as viscosity modifying agent in self-compacting concrete

Abstract

Using new generation chemical admixtures makes it possible to produce self-compacting concretes (SCCs). However, to avoid the segregation of concrete, either the fine material content should be increased, or a viscosity modifying agent (VMA) should be used. In this study, the possibility of producing self-compacting concrete with a lesser amount of fine material than the conventional SCC while using a polysaccharide type VMA is investigated. For this purpose, three different polysaccharides welan gum, xanthan gum and starch ether – were used in varying dosages. Fly ash/Portland cement ratio was kept constant at 0.20 for all mixtures, while the binder content varied between 350 and 450kg/m3, except for the mixture with xanthan gum, which was tested only at the 400kg/m3 binder dosage. Slump flow and confined slump flow tests were conducted to determine self-compacting properties. Sieving, penetration and bleeding tests were performed to compare the segregation properties of fresh concretes. The strength and sorptivity properties of hardened SCCs prepared with and without VMAs were also investigated.