Influence of new organic alkali activators on microstructure and strength of fly ash geopolymer. Issue 9 (1st May 2022)

• Record Type: Journal Article
• Authors: Lu, Chunyang; Wang, Qingping; Liu, Yuxin; Xue, Tingting; Yu, Qingbo; Chen, Shuai
• Is Part Of: Ceramics international. Volume 48:Issue 9(2022)
• Page Start: 12442
• Page End: 12449
• Publication Date: 2022-05-01
• Subjects: Sodium tert-butanol -- Sodium silicate -- Geopolymer -- Microscopic mechanism; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.01.109
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: The fly ash geopolymer with improved mechanical properties was prepared by a new mixture alkali activator. In this paper, sodium tert-butanol, an organic strong alkali was used as an activator for preparing fly ash geopolymer to improve their mechanical properties. The effect of activator content and type on the macroscopic level of fly ash geopolymer was investigated experimentally by three types of activators: sodium tert-butanol, sodium silicate, and sodium tert-butoxide/sodium silicate mix activator. The microstructure of the fly ash geopolymer was characterized by ATR-FTIR, SEM-EDS, XRD, and Brunauer-Emmett-Teller (BET) physical adsorption method. The results showed that the new mixture alkali activator prepared by 5% sodium tert-butoxide and 10% sodium silicate improved the denseness and integrity of the microstructure of the fly ash geopolymer. Consequently, the mechanical properties of fly ash geopolymer are improved. The microscopic results demonstrated that the C–OH in tert-butanol after the hydrolysis of sodium tert-butoxide and Si–OH in the geopolymer can form C–O–Si bonds, forming a more complex three-dimensional network structure. This paper reveals the enhancement mechanism of organic alkali as activators for preparing fly ash geopolymer, and provides support for the subsequent development of organic strong alkali activators. Highlights: Sodium tert-butoxide can improve the compressive properties of fly ash geopolymer. Sodium tert-butoxide reacts with fly ash to form C–O–Si bonds. Formation of three-dimensional structure in submicroscopic.