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

Journal Article · Tue Jun 15 04:00:00 EDT 2021 · Cement and Concrete Research

DOI:https://doi.org/10.1016/J.CEMCONRES.2021.106447· OSTI ID:23206283

Zhang, Shizhe; Li, Zhenming ^[1]; Ghiassi, Bahman ^[1]; Yin, Suhong ^[2]; Ye, Guang ^[1]

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1. Microlab, Section Materials and Environment, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN, Delft (Netherlands)
2. School of Materials Science and Engineering, South China University of Technology, Guangzhou (China)

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 K{sub Ic} (J{sub tip}), whereas, the compressive strength of AASF pastes is primarily determined by its capillary porosity (>0.01 μm). 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 K{sub Ic} (J{sub tip}) 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.

• OSTI ID: 23206283
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Vol. 144; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADHESION
CAPILLARIES
COMPRESSION STRENGTH
CORRELATIONS
FRACTURE PROPERTIES
GELS
MICROSTRUCTURE
POLYMERIZATION
POROSITY
STRAIN HARDENING