Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Silica Fume Enhances the Mechanical Strength of Alkali-Activated Slag/Fly Ash Pastes Subjected to Elevated Temperatures

Version 1 : Received: 30 May 2023 / Approved: 31 May 2023 / Online: 31 May 2023 (12:10:38 CEST)

A peer-reviewed article of this Preprint also exists.

Dai, W.; Wang, Y. Silica Fume Enhances the Mechanical Strength of Alkali-Activated Slag/Fly Ash Pastes Subjected to Elevated Temperatures. Fire 2023, 6, 252. Dai, W.; Wang, Y. Silica Fume Enhances the Mechanical Strength of Alkali-Activated Slag/Fly Ash Pastes Subjected to Elevated Temperatures. Fire 2023, 6, 252.

Abstract

The fireproof design of geopolymer has intriguing increasing attention by adjusting multi-component metallurgical solid wastes, due to its low-carbon emission, cost-effectiveness, and environmental conservation. Herein, the effects of silica fume (SF) on the microstructure and mechanical properties of alkali-activated slag/FA (fly ash) pastes subjected to elevated temperatures (150, 500, 850, and 1200℃) are investigated, to clarify the fact that whether or not the SF generates positive roles in mechanical strength of slag/FA (slag: FA=30:70, wt.%) geopolymers during building fires. The results show that the replacement of FA with 10 wt% SF (silica fume) promotes the increasing pore volume with a diameter of 0.2~3 μm, leading to an increase in the compressive or flexural strength below 850℃, “right shifts” of the endothermic peak, appearing uniform and compact fracture surfaces. Meanwhile, the gehlenite and labradorite generate after exposure above 850℃. While the bloating effect of the SF-containing sample occurs at 1200℃, leading to a greater deformation, due to the further restructuring of the amorphous geopolymer chain N-A-S-H or N-(Ca)-A-S-H composed from the [SiO4]4− and [AlO4]5−. It explores an effective approach for improving geopolymer’s fireproof performance by adjusting the solid-waste formulation.

Keywords

alkali-activated; silica fume; elevated temperatures; slag; fly ash

Subject

Chemistry and Materials Science, Physical Chemistry

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