Three-dimensional quantification of pore structure in coal ash-based geopolymer using conventional electron tomography

•We report the pore structure of geopolymers at the nanoscale for the first time.•The porosity is determined to be 7.15% for the volume of interest, 0.00748μm3.•Most of the pores are not connected and have irregular geometry.•The research results will contribute to understand the durability of geopo...

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Bibliographic Details
Published in:Construction & building materials 2014-02, Vol.52, p.221-226
Main Authors: Lee, Sujeong, Jou, Hyeong-Tae, van Riessen, Arie, Rickard, William D.A., Chon, Chul-Min, Kang, Nam-Hee
Format: Article
Language:English
Subjects:
Aluminum silicates
Analysis
Chemical properties
Coal
Construction materials
Durability
Electron tomography
Geopolymer
Mechanical properties
Nanostructure
Pore connectivity
Porosity
Portland cement
Properties
Three dimensional
Tomography
X-rays
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Summary:•We report the pore structure of geopolymers at the nanoscale for the first time.•The porosity is determined to be 7.15% for the volume of interest, 0.00748μm3.•Most of the pores are not connected and have irregular geometry.•The research results will contribute to understand the durability of geopolymers. X-ray tomography, mercury intrusion porosimetry, and gas adsorption are used to characterize the nano-scale pore structure of geopolymers with little success. This is because X-ray tomography still lacks high resolution for nanometer-sized pores and the other techniques use the incorrect assumptions of regular pore geometry and interconnected pore systems. To reveal the three-dimensional structure of nanometer-sized pores in coal ash-based geopolymer, conventional bright field electron tomography is used in this study for the first time. Because artifacts resulting from diffraction effects of newly-formed zeolite-like phases are introduced only in the matrix surrounding the pores, the pore size distribution has been investigated successfully. Most of the pores had irregular geometry and were found to range from 20 to 60nm in equivalent perimeter diameter. The porosity was determined to be 7.15% for the volume of interest, 0.00748μm3. The first successful outcome of the reported experiment indicates that electron tomography will play an important role in the future for measuring the porosity and pore connectivity of geopolymers enabling predictions of durability and optimization of material properties.
ISSN:0950-0618
DOI:10.1016/j.conbuildmat.2013.10.072