Title:
Effect of Polysaccharide Gums on Fresh Concrete Properties
Author(s):
Virgilio A. Ghio, Paulo J. M. Monteiro, and Odd E. Gjorv
Publication:
Materials Journal
Volume:
91
Issue:
6
Appears on pages(s):
602-606
Keywords:
cylinders; fresh concretes; physical properties; shotcrete; tests; workability; Materials Research
DOI:
10.14359/1381
Date:
11/1/1995
Abstract:
Polysaccharide gums (PSG) are currently being used in concrete for several purposes, mostly in the form of antibleeding agents and antiwashout admixtures for underwater concreting, as well as pumping aids and sag resistance additives for shotcrete applications. To provide more information on how additions of PSG affect the fresh concrete properties, an experimental program based on a coaxial cylinder viscometer was carried out. For moderate to high rates of shear, concrete with additions of PSG typically followed the Bingham model. For very low shear rates, the flow resistance increased compared to that calculated from the Bingham model, and this increase was higher for higher concentrations of PSG. Additions of PSG distinctly increased the flow resistance but had a relatively smaller effect on the rigidity. Additions of PSG and high-range water reducers (HRWR) increased the flow resistance with time, but the rigidity was not much affected. Upon remixing, the flow resistance was recovered easily, indicating that this effect is a physical rather than a chemical effect.