Understanding the rheological properties of alkali-activated slag pastes from the cohesion and friction interactions. (12th July 2021)

• Record Type: Journal Article
• Authors: Tian, Yi; Yang, Changhui; Yuan, Shijun; Yuan, Hongxiao; Yang, Kai; Yu, Linwen; Zhang, Mingtao; Zhu, Xiaohong
• Is Part Of: Construction & building materials. Volume 291(2021)
• Publication Date: 2021-07-12
• Subjects: Alkali-activated slag pastes -- Rheology -- Cohesion and friction interactions -- Extend DLVO theory; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.123311
• Languages: English
• ISSNs: 0950-0618

Abstract

Graphical abstract: Highlights: The cohesion interactions mainly determine plastic viscosity of AAS pastes. The greater attractions between particles is the reason for its higher viscosity. The friction interactions mainly determine the yield stress of AAS pastes. Abstract: The workability and pumping performance of alkali-activated slag (AAS) concrete are affected by its rheological properties, which are related to the interactions between slag particles in the pastes. The rheological properties of AAS paste with different equivalent sodium oxide (Na2 Oeq ) dosage activated by sodium hydroxide (NaOH) and sodium silicate (waterglass) with different SiO2 /Na2 O molar ratios were investigated in this study. The rheological mechanism was studied from the cohesion and friction interactions by calculations from parameters such as the Zeta potential of particles in the pastes, surface energy, hydrogen bond, and friction coefficient of the alkaline activators. The results indicated that the yield stress of AAS pastes was lower than that of the paste made with slag and water, whereas the plastic viscosity was higher. The yield stress of AAS pastes was mainly determined by the friction interactions between particles. The plastic viscosity was mainly affected by attractive interactions, including van de Waals interactions and Lewis acid-base interactions. The electrostatic repulsion interactions were felt at a very short distance because the AAS pastes were systems with the high ionic strength, which means that the electric double layer were severely compressed, therefore, the attractive interactions were predominant. Taken together, these results suggest that the improvement of plastic viscosity of AAS pastes should be achieved by changing the attractive interactions.