Article
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Microstructure Evaluation of Fly Ash Geopolymers Alkali-Activated by Binary Composite Activators
Version 1
: Received: 1 June 2023 / Approved: 2 June 2023 / Online: 2 June 2023 (07:28:53 CEST)
A peer-reviewed article of this Preprint also exists.
Zhao, J.; Wang, Y. Microstructure Evaluation of Fly Ash Geopolymers Alkali-Activated by Binary Composite Activators. Minerals 2023, 13, 910. Zhao, J.; Wang, Y. Microstructure Evaluation of Fly Ash Geopolymers Alkali-Activated by Binary Composite Activators. Minerals 2023, 13, 910.
Abstract
An attempt to investigate the effect of binary composite activators on the microstructure of fly ash-based geopolymers is conducted through the comparison of 24 experiments, which consisted of Na2SiO3•9H2O, Na2CO3, K2CO3, NaOH, and KOH through a facile preparation technique. The results show that the activator of Na2SiO3•9H2O+KOH presents the highest mechanical strength, due to the synergy activation between the inherent ≡Si-O-Si≡ chains derived from Na2SiO3 and K+’s catalysis. It reveals that the K+ plays a crucial role in Na2SiO3-activated fly ash geopolymer, which is the rate-determining step of the enhanced crosslinking and propagation of N-(C)-A-S-H chains, leading to an increase in weight loss temperatures of specimens from TG/DTG results. Furthermore, the adding silica fume facilitates as-formed amorphous silicates, which also could fill into the pores of N-(C)-A-S-H amorphous gels and present a uniform and compact morphology, leading to an increase in the pore volume of the pore diameter less than 100 nm. It explores an efficient and cost-effective preparation of fly ash-based geopolymer for developing solid-waste recycling techniques.
Keywords
Alkali-activated; Microstructure; Fly ash; Binary activator; Crosslinking
Subject
Chemistry and Materials Science, Materials Science and Technology
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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