Elucidating how ionic adsorption controls the rheological behavior of quartz and cement-quartz paste. (22nd February 2021)

• Record Type: Journal Article
• Authors: Huang, Jizhi; Xu, Weiting; Chen, Huijun; Xu, Guoyuan
• Is Part Of: Construction & building materials. Volume 272(2021)
• Publication Date: 2021-02-22
• Subjects: Quartz -- Cement paste -- Rheology -- Zeta potential -- Electric double layer -- DLVO theory; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2020.121957
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: High pH decreases quartz viscosity by increasing the surface potential. High ionic strength increases quartz viscosity by compressing the EDL thickness. Ca 2+ adsorption leads to quartz flocculation in turn decreases cement fluidity. DLVO force dominates cement-quartz rheology rather than filling or packing effect. Abstract: This study revealed how the ionic adsorption adjusts the rheological behavior of quartz and cement-quartz paste. A series of model solutions containing different electrolytes were prepared to evaluate the influence of pH, ionic strength on zeta potential and rheological behavior of quartz. Based on the characteristics of quartz, the rheological mechanism of cement-quartz paste was interpreted. Throughout the work, it is revealed that: (1) the rheological behavior of quartz suspension is dominated by the magnitude of electric double layer (EDL) repulsion, high pH elevates the surface charge of quartz and hence decreases the viscosity of quartz suspension; (2) divalent Ca 2+ and Mg 2+ significantly reduced the zeta potential of quartz and increased the viscosity by compressing the EDL thickness; (3) the incorporation of quartz as filler decreased the flowability of cement paste due to excessive adsorption of Ca 2+ and the flocculation of quartz particles.