Fracture properties and microstructure formation of hardened alkali-activated slag/fly ash pastes

Zhang, Shizhe; Li, Zhenming; Ghiassi, Bahman; Yin, Suhong; Ye, Guang

Abstract

This study presents a comprehensive experimental investigation on the fracture properties of hardened alkali-activated slag/fly ash (AASF) pastes in relation to the microstructure formation and reaction product composition. The main reaction product in AASF is C-(N-)A-S-H gel along with minor hydrotalcite phase, with the polymerization of C-(N-)A-S-H gel substantially governed by its Ca/Si ratio. Strong positive correlations are identified between the Ca/Si ratios of C-(N-)A-S-H gel and the fracture properties KIc (Jtip), whereas, the compressive strength of AASF pastes is primarily determined by its capillary porosity (>0.01 ?m). The disagreements between the Ca/Si ratios and corresponding intrinsic mechanical properties of C-(N-)A-S-H gel as proof by contradiction indicate that the fracture properties KIc (Jtip) of AASF pastes could be dominated by a cohesion/adhesion-based mechanism. These findings provide promising guidance for fine-tuning the fracture properties of AASF and also advise on the tailoring strategies for high-performance composite such as strain-hardening geopolymer composite.

Citation

Zhang, S., Li, Z., Ghiassi, B., Yin, S., & Ye, G. (2021). Fracture properties and microstructure formation of hardened alkali-activated slag/fly ash pastes. Cement and Concrete Research, 144, Article 106447. https://doi.org/10.1016/j.cemconres.2021.106447

• Journal Article Type: Article
• Acceptance Date: Mar 22, 2021
• Online Publication Date: Apr 8, 2021
• Publication Date: 2021-06
• Deposit Date: Apr 17, 2021
• Publicly Available Date: Apr 18, 2021
• Journal: Cement and Concrete Research
• Print ISSN: 0008-8846
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 144
• Article Number: 106447
• DOI: https://doi.org/10.1016/j.cemconres.2021.106447
• Keywords: General Materials Science; Building and Construction
• Public URL: https://nottingham-repository.worktribe.com/output/5474146
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S000888462100096X
• Additional Information: This article is maintained by: Elsevier; Article Title: Fracture properties and microstructure formation of hardened alkali-activated slag/fly ash pastes; Journal Title: Cement and Concrete Research; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.cemconres.2021.106447; Content Type: article; Copyright: © 2021 The Author(s). Published by Elsevier Ltd.