Inhibiting efflorescence formation on fly ash–based geopolymer via silane surface modification. (November 2018)

• Record Type: Journal Article
• Authors: Xue, Xiao; Liu, Yun-Lin; Dai, Jian-Guo; Poon, Chi-Sun; Zhang, Wei-Dong; Zhang, Peng
• Is Part Of: Cement & concrete composites. Volume 94(2018)
• Page Start: 43
• Page End: 52
• Publication Date: 2018-11
• Subjects: Geopolymer -- Alkali-activation -- Fly ash -- Effloresce -- Silane -- Surface modification; Composite-reinforced concrete -- Periodicals; Concrete -- Periodicals; Composite materials -- Periodicals; Composites de ciment -- Périodiques; Béton -- Périodiques; Composites -- Périodiques; Béton léger -- Périodiques; Cement composites; Composite materials; Composite-reinforced concrete; Concrete; Lightweight concrete; Periodicals; Electronic journals; 620.135
• DOI: 10.1016/j.cemconcomp.2018.08.013
• Languages: English
• ISSNs: 0958-9465

Abstract

Abstract: Efflorescence can be a critical issue for the application of alkali-activated fly ash–based geopolymer products, especially when the products are in a moist environment. In this study, a new method was explored to inhibit efflorescence of fly ash–based geopolymer via silane surface modifications. After the modification, the surface of the geopolymer was transformed from hydrophilic to hydrophobic, with a water contact angle of 144.1°, and the capillary absorption and diffusion of water were significantly suppressed; and as a consequence, the soluble alkali ion leaching was reduced. Analysis by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and size-exclusion chromatography demonstrated that the selected silane is attached successfully onto the surface of the fly ash–based geopolymer via chemical bonding instead of via physical absorption. A possible reaction mechanism for the silane surface modification of the fly ash–based geopolymer is proposed.