Effect of magnesium salt contamination on the microstructures and properties of metakaolinite-based geopolymer: the role of MgCl2 and MgSO4

Zhang, Baifa1; Huang, Dongchao1; Li, Lijuan1; Lin, Min2; Liu, Yong3; Fang, Wei3; Lu, Junjie1,4; Liu, Feng1; Li, Yun5,6; Liu, Yi1; Xiong, Zhe1

2022-10-01

10.1016/j.jmrt.2022.09.019

Journal of Materials Research and Technology-JMR&T   Impact Factor & Quartile

2238-7854

2214-0697

Ion contamination considerably influences the properties of geopolymers. This study investigated the effects of magnesium chloride (MgCl2) and magnesium sulfate (MgSO4) concentrations on the microstructure and properties of metakaolinite-based geopolymers with Si/Al ratios of 1.3 (adding NaOH) and 1.6 (adding NaOH and Na2SiO3). The chemical structures and compositions of as-obtained geopolymers formed through the alkali acti-vation of kaolinite were characterized through X-ray diffraction, Fourier-transform infrared spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy, while the microstructure was characterised via scanning electron microscopy and mercury intrusion porosimetry. The salt-free geopolymer with a Si/Al ratio of 1.3 exhibited a loose microstructure and hence poor 28-day compressive strength (9.4 MPa). The addition of magnesium salt to the geopolymer did not considerably influence its microstructure and mechanical properties. Comparatively, the geopolymer with a Si/Al ratio of 1.6 exhibited a compact microstructure and high 28-day compressive strength (43.0 MPa). The geopolymer compressive strength gradually decreased with increasing salt concentration. MgCl2 addition induced halite formation, increased pore diameter and pore volume, and reduced Si incorporated into the geopolymer matrix. In contrast, MgSO4 addition resulted in relatively less change in the pore diameter and pore volume and based on NMR result, more Si was incorporated into the geopolymer matrix. Thus, MgCl2 was more detrimental to the mechanical properties of the kaolinite-based geopolymers than MgSO4.

Metakaolinite Geopolymer Salt ion contamination Microstructure Si/Al ratio

SCI

English

Others

National Natural Science Foundation of China["12032009","12002091"]

Materials Science ; Metallurgy & Metallurgical Engineering

Materials Science, Multidisciplinary ; Metallurgy & Metallurgical Engineering

WOS:000860988000004

ELSEVIER

Web of Science

1.Guangdong Univ Technol, Sch Civil & Transportat Engn, Guangzhou 510006, Guangdong, Peoples R China
2.Guangdong Polytech Ind & Commerce, Sch Surveying, Mapping & Remote Sensing Informat, Guangzhou 510550, Peoples R China
3.Foshan Nanhai Lijian Concrete Co Ltd, Foshan 528247, Guangdong, Peoples R China
4.Guangzhou Taihe Concrete Co Ltd, Guangzhou 510540, Guangdong, Peoples R China
5.Southern Marine Sci & Engn Guangdong Lab, Guangzhou, Peoples R China
6.Southern Univ Sci & Technol, Acad Adv Interdisciplinary Studies, Shenzhen Key Lab Nat Gas Hydrates, Shenzhen 518055, Peoples R China

Zhang, Baifa,Huang, Dongchao,Li, Lijuan,et al. Effect of magnesium salt contamination on the microstructures and properties of metakaolinite-based geopolymer: the role of MgCl2 and MgSO4[J]. Journal of Materials Research and Technology-JMR&T,2022,20.

Zhang, Baifa.,Huang, Dongchao.,Li, Lijuan.,Lin, Min.,Liu, Yong.,...&Xiong, Zhe.(2022).Effect of magnesium salt contamination on the microstructures and properties of metakaolinite-based geopolymer: the role of MgCl2 and MgSO4.Journal of Materials Research and Technology-JMR&T,20.

Zhang, Baifa,et al."Effect of magnesium salt contamination on the microstructures and properties of metakaolinite-based geopolymer: the role of MgCl2 and MgSO4".Journal of Materials Research and Technology-JMR&T 20(2022).