Effect of fly ash microsphere on the rheology and microstructure of alkali-activated fly ash/slag pastes. (July 2018)

• Record Type: Journal Article
• Authors: Yang, Tao; Zhu, Huajun; Zhang, Zuhua; Gao, Xuan; Zhang, Changsen; Wu, Qisheng
• Is Part Of: Cement and concrete research. Volume 109(2018)
• Page Start: 198
• Page End: 207
• Publication Date: 2018-07
• Subjects: Fly ash microsphere -- Alkali-activated cement (D) -- Rheology (A) -- Microstructure (B); Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2018.04.008
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: The highly viscous property of alkali silicate-activated cements is one of the critical challenges that hinder their wide application. The present study focuses on ameliorating the rheological performance of sodium silicate-activated fly ash/slag pastes by using fly ash microsphere (FAM), which are highly spherical particles collected from fly ash with electrostatic adsorption classification technology. The FAM particles work as 'ball-bearings' in the pastes to reduce the internal friction between fly ash and slag grains, and meanwhile mitigate the agglomeration of flocs and fragmentation to release the locked water. The interrelationship between the FAM particle geometry and plastic viscosity of the paste is well described by the Krieger-Dougherty equation, which supports the proposed mechanisms of 'ball-bearings' effects. FAM can work as an inorganic dispersing agent to improve the workability of alkali-activated cement products for a variety of application aspects. Highlights: Fly ash microsphere is collected from fly ash with electrostatic adsorption classification. Fly ash microsphere acts as 'ball-bearings' in alkali-activated cements. Fly ash microsphere works as inorganic dispersing agent to improve workability. Fly ash microsphere exhibits a good compatibility in alkali-activated cements.