Effects of Particle Volume Fraction and Size on Polysaccharide Stabilizing Agents

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Title: Effects of Particle Volume Fraction and Size on Polysaccharide Stabilizing Agents

Author(s): Wolfram Schmidt; Sarah Peters; and Hans-Carsten Kühne

Publication: Special Publication

Volume: 302

Issue:

Appears on pages(s): 39-52

Keywords: diutan gum; starch; polysaccharides; polycarboxylate ether; volume fraction

Date: 6/1/2015

Abstract:
Polysaccharides modify the rheological properties of cement based systems. Depending upon their chemistry, molecular architecture, and adsorption tendency, they have different modes of action. Some polysaccharides like diutan gum have strong effect on the fluid phase; others like starch strongly interact with particles. This paper presents effects of diutan gum and starches in presence of polycarboxylates. Rheometric investigations with varied particle volume fractions and increasing coarse aggregate diameters were conducted. The results show that starches have stronger influence on the rheology at high particle volume fractions than diutan gum. At lower particle volume fractions this trend is inverted. Experiments with aggregates sizes up to 16 mm (0.63 in.) indicate that stabilizing agent influences on the effects of aggregates on yield stress were small; however up to 1.0 mm (0.04 in.), a significant effect on the plastic viscosity could be observed, which levelled off at larger diameters.