Open AccessInfluence of Ca on the mechanical properties and microstructures of slag-fly ash geopolymers
Author(s) -
Jing Li,
Lu Yang,
Feng Rao,
Wenbiao Liu,
Hang Ma,
Xiaopeng Chi,
Shuiping Zhong
Publication year - 2022
Publication title -
minerals and mineral materials
Language(s) - English
Resource type - Journals
ISSN - 2832-269X
DOI - 10.20517/mmm.2021.02
Subject(s) - geopolymer , materials science , fly ash , aluminosilicate , ground granulated blast furnace slag , carbonization , calcium aluminosilicate , sodium silicate , compressive strength , calcium silicate hydrate , slag (welding) , chemical engineering , portland cement , microstructure , scanning electron microscope , fourier transform infrared spectroscopy , composite material , cement , chemistry , biochemistry , engineering , catalysis
A deep understanding of the role of Ca in geopolymers exposed to various environments is essential for geopolymerization. This work evaluates the role of Ca by observing the behavior of hierarchically calciferous geopolymers under different environments including air, carbonization and freezing-thawing cycles. The structural and morphological differences between the geopolymers and the related mechanisms in various environmental conditions are assessed based on compressive strength, brunauer emmett teller, X-ray diffraction, fourier transform infrared spectoscopy, nuclear magnetic resonance spectroscopy and scanning electron microscopy measurements. It is found that two kinds of geopolymer gels, calcium silicate hydrate and sodium aluminosilicate hydrate, are formed in the geopolymerization of blast furnace slag and fly ash. Regardless of the specific air, carbonization or freezing-thawing cycle environment, the former gel dominates the properties in low Ca geopolymers, while the latter gel determines the properties in medium and high Ca geopolymers. Moreover, the carbonization environment enables calciferous geopolymers with higher surface areas and smaller pore sizes. Such adequate pore structures can significantly improve the performance of the geopolymers. This study presents novel insights into the influence of Ca on geopolymerization and in strengthening geopolymer properties.