Inhibiting efflorescence formation on fly ash–based geopolymer via silane surface modification

By Xiaolan Xue, Yun-Lin Liu, Jian-Guo Dai, Chi-Sun Poon, Weidong Zhang, Peng Zhang. Cement & Concrete Composites, 2018

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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.

Subfields: Building and Construction, Civil and Structural Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/e9ee2b2ba83492e7ff959bfc513c9383f1191b0d