Effect of cristobalite on the mechanical behaviour of metakaolin-based geopolymer in artificial seawater

ABSTRACT

Few studies have focused on the effect of mineral composition on the mechanical behaviour and evolution of a geopolymer binder in artificial seawater environment. In this study, a geothermal clay-based geopolymer rich in micron-size cristobalite and metakaolin was compared with a metakaolin-based geopolymer in artificial seawater. The effects of the cristobalite on the mechanical behaviour and microstructure of geopolymers were characterised through compressive strength measurements, x-ray diffraction (XRD), scanning electron microscope (SEM) and nuclear magnetic resonance (NMR). The micro-size cristobalite enhanced the compressive strength of the geothermal clay-based geopolymer. Without cristobalite, zeolite formed in metakaolin-based geopolymer and led to compressive strength decrease obviously first then increase slightly. The formation of the geothermal clay-based geopolymer gel was delayed in seawater. The cristobalite in the geothermal clay-based geopolymer hindered the formation of Q⁴(4Al), Q⁴(3Al) and Q⁴(2Al).

KEYWORDS:

• Cristobalite
• zeolite
• geopolymer
• properties
• artificial seawater

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Shaoxian Song http://orcid.org/0000-0003-3570-6401

Qinyong Ma http://orcid.org/0000-0001-7278-7875

Additional information

Funding

This study was financially supported by the Consejo Nacional de Ciencia y Tecnologia (CONACyT) of Mexico under the grant number 270186, the Natural Science Foundation of Hubei Province of China under the grant number 2016CFA013 and the Wuhan Science and Technology Bureau of China under the project no. 2016070204020156, for which the authors are grateful. X. Li would like to thank the CONACyT for offering her the scholarship number 831134 during her PhD studies.