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Impact of interatomic structural characteristics of aluminosilicate hydrate on the mechanical properties of metakaolin-based geopolymer
https://orcid.org/0000-0001-8683-1312
https://orcid.org/0000-0002-0164-7741
https://orcid.org/0000-0001-8875-8307
https://orcid.org/0000-0002-7820-480X
https://orcid.org/0000-0002-8511-6939
Abstract This study explores the influence of the interatomic structure of sodium aluminosilicate hydrate (N-A-S-H) with varying silica contents on the mechanical properties of metakaolin-based geopolymer. Geopolymer pastes comprising Si/Al ratios between 2.0 and 3.0 were synthesized. A larger number of Si-O-Si linkages compared to Si-O-Al linkages and a higher atomic number density were found in the geopolymers with higher silica contents, which enhanced the compressive strength of the geopolymer pastes up to the optimal Si/Al ratio of 2.5. The paste with a Si/Al = 2.5 exhibited a greater portion of Q4(1Al and 2Al) and denser morphology compared to the other geopolymer pastes. Furthermore, in-situ high-energy synchrotron X-ray scattering experiments were conducted to assess the elastic modulus of the aluminosilicate structure at a local atomic scale. The modulus value in real space decreases with increasing silica contents up to Si/Al = 2.5 and increases with the presence of excessive unreacted silica fume. The modulus value in reciprocal space for the axial and lateral directions both presented a positive value at the geopolymer comprising a Si/Al ratio higher than 2.5, indicating that the load-bearing property of N-A-S-H changed at higher Si/Al ratios. Moreover, the smallest difference between the strains along the axial and lateral directions was detected for the geopolymer with Si/Al = 2.5 in both the real and reciprocal space, owing to the most interconnected and flexible nanostructure, which led to the highest mechanical strength.
Graphical Abstract Display Omitted
Highlights Metakaolin-based geopolymer comprising Si/Al between 2.0 and 3.0 is investigated. Geopolymer with SiAl = 2.5 exhibits the densest nanostructure and highest mechanical strength. Atomic number density increased with silica contents due to shorter Si-O compared to Al-O. Load-bearing properties of nanostructure of N-A-S-H changed when Si/Al reached 2.5. Excessive silica fume contents deteriorate the mechanical properties of geopolymer.
Impact of interatomic structural characteristics of aluminosilicate hydrate on the mechanical properties of metakaolin-based geopolymer
https://orcid.org/0000-0001-8683-1312
https://orcid.org/0000-0002-0164-7741
https://orcid.org/0000-0001-8875-8307
https://orcid.org/0000-0002-7820-480X
https://orcid.org/0000-0002-8511-6939
Abstract This study explores the influence of the interatomic structure of sodium aluminosilicate hydrate (N-A-S-H) with varying silica contents on the mechanical properties of metakaolin-based geopolymer. Geopolymer pastes comprising Si/Al ratios between 2.0 and 3.0 were synthesized. A larger number of Si-O-Si linkages compared to Si-O-Al linkages and a higher atomic number density were found in the geopolymers with higher silica contents, which enhanced the compressive strength of the geopolymer pastes up to the optimal Si/Al ratio of 2.5. The paste with a Si/Al = 2.5 exhibited a greater portion of Q4(1Al and 2Al) and denser morphology compared to the other geopolymer pastes. Furthermore, in-situ high-energy synchrotron X-ray scattering experiments were conducted to assess the elastic modulus of the aluminosilicate structure at a local atomic scale. The modulus value in real space decreases with increasing silica contents up to Si/Al = 2.5 and increases with the presence of excessive unreacted silica fume. The modulus value in reciprocal space for the axial and lateral directions both presented a positive value at the geopolymer comprising a Si/Al ratio higher than 2.5, indicating that the load-bearing property of N-A-S-H changed at higher Si/Al ratios. Moreover, the smallest difference between the strains along the axial and lateral directions was detected for the geopolymer with Si/Al = 2.5 in both the real and reciprocal space, owing to the most interconnected and flexible nanostructure, which led to the highest mechanical strength.
Graphical Abstract Display Omitted
Highlights Metakaolin-based geopolymer comprising Si/Al between 2.0 and 3.0 is investigated. Geopolymer with SiAl = 2.5 exhibits the densest nanostructure and highest mechanical strength. Atomic number density increased with silica contents due to shorter Si-O compared to Al-O. Load-bearing properties of nanostructure of N-A-S-H changed when Si/Al reached 2.5. Excessive silica fume contents deteriorate the mechanical properties of geopolymer.
Impact of interatomic structural characteristics of aluminosilicate hydrate on the mechanical properties of metakaolin-based geopolymer
https://orcid.org/0000-0001-8683-1312
https://orcid.org/0000-0002-0164-7741
https://orcid.org/0000-0001-8875-8307
https://orcid.org/0000-0002-7820-480X
https://orcid.org/0000-0002-8511-6939
Abstract This study explores the influence of the interatomic structure of sodium aluminosilicate hydrate (N-A-S-H) with varying silica contents on the mechanical properties of metakaolin-based geopolymer. Geopolymer pastes comprising Si/Al ratios between 2.0 and 3.0 were synthesized. A larger number of Si-O-Si linkages compared to Si-O-Al linkages and a higher atomic number density were found in the geopolymers with higher silica contents, which enhanced the compressive strength of the geopolymer pastes up to the optimal Si/Al ratio of 2.5. The paste with a Si/Al = 2.5 exhibited a greater portion of Q4(1Al and 2Al) and denser morphology compared to the other geopolymer pastes. Furthermore, in-situ high-energy synchrotron X-ray scattering experiments were conducted to assess the elastic modulus of the aluminosilicate structure at a local atomic scale. The modulus value in real space decreases with increasing silica contents up to Si/Al = 2.5 and increases with the presence of excessive unreacted silica fume. The modulus value in reciprocal space for the axial and lateral directions both presented a positive value at the geopolymer comprising a Si/Al ratio higher than 2.5, indicating that the load-bearing property of N-A-S-H changed at higher Si/Al ratios. Moreover, the smallest difference between the strains along the axial and lateral directions was detected for the geopolymer with Si/Al = 2.5 in both the real and reciprocal space, owing to the most interconnected and flexible nanostructure, which led to the highest mechanical strength.
Graphical Abstract Display Omitted
Highlights Metakaolin-based geopolymer comprising Si/Al between 2.0 and 3.0 is investigated. Geopolymer with SiAl = 2.5 exhibits the densest nanostructure and highest mechanical strength. Atomic number density increased with silica contents due to shorter Si-O compared to Al-O. Load-bearing properties of nanostructure of N-A-S-H changed when Si/Al reached 2.5. Excessive silica fume contents deteriorate the mechanical properties of geopolymer.
Impact of interatomic structural characteristics of aluminosilicate hydrate on the mechanical properties of metakaolin-based geopolymer
Kim, Gyeongryul (author) / Cho, Seongmin (author) / Im, Sumin (author) / Suh, Heongwon (author) / Morooka, Satoshi (author) / Shobu, Takahisa (author) / Kanematsu, Manabu (author) / Machida, Akihiko (author) / Bae, Sungchul (author)
2023-12-07
Article (Journal)
Electronic Resource
English
PC , Portland cement , SCMs , supplementary cementitious materials , LC<sup>3</sup> , limestone calcined clay cement , N-A-S-H , sodium aluminosilicate hydrate , MK , metakaolin , SF , silica fume , PDF , pair distribution function , XRD , X-ray diffraction , FT-IR , Fourier-transform infrared , NMR , nuclear magnetic resonance , SEM , scanning electron microscopy , TEM , transmission electron microscopy , TGA , thermogravimetric analysis , EDS , energy-dispersive spectrometry , T , silica or alumina , Geopolymer , Silica content , Sodium aluminosilicate hydrate , Interatomic structure , Elastic modulus , Local atomic scale , Load-bearing property
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