Title: Effect of Calcium Ions on Bio-Based Polymers for Rheology Control

Author(s): Wolfram Schmidt

Publication: Symposium Paper

Volume: 354

Issue:

Appears on pages(s): 75-86

Keywords: polysaccharides, rheology, yield stress, hydrodynamic diameter, zeta potential

DOI: 10.14359/51736063

Date: 7/1/2022

Abstract:
Due to the high carbon dioxide emissions linked to concrete production and a rapidly increasing demand for cementitious materials, particularly in the global South, it is inevitable to use cement in concrete more efficiently. This requires chemical admixtures to enhance the overall performance of the binder and to cope with the negative rheological influences of supplementary cementitious materials that are used to replace ordinary Portland cement. However, particularly in the growing economies of the Southern hemisphere, where a massive part of the future construction activities will take place, the supply chains for performance-enhancing chemical admixtures are often poor, and local production facilities are lacking today. This paper presents case studies of polysaccharide-based alternative admixtures such as acacia gum, cassava starch, and the gum of the bark of Triumfetta pendrata A. Rich, which can be used effectively as superplasticizer, robustness enhancer, and thixotropy incorporating agent, respectively. Their modes of operation are discussed based on their spread flow, zeta potentials, and hydrodynamic diameters in the presence and absence of calcium ions.