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Advances in Materials Science and Engineering
Volume 2017 (2017), Article ID 4247217, 11 pages
Research Article

Deterioration and Microstructural Evolution of the Fly Ash Geopolymer Concrete against MgSO4 Solution

1Sichuan Provincial Key Laboratory of Failure Mechanics and Engineering Disaster Prevention & Mitigation, College of Architecture & Environment, Sichuan University, Chengdu 610065, China
2School of Engineering, University of Liverpool, Brownlow Hill, Liverpool L69 3GQ, UK
3School of Mechanical Engineering, Chengdu University, Chengdu 610106, China

Correspondence should be addressed to Qingyuan Wang and Xiaoshuang Shi

Received 9 June 2017; Revised 3 September 2017; Accepted 12 September 2017; Published 16 October 2017

Academic Editor: Giorgio Pia

Copyright © 2017 Tao Long et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Fly ash geopolymer concrete (FAGC) and ordinary Portland cement concrete (OPCC) specimens were immersed in 5% MgSO4 solution undergoing 32 wetting-drying and heating-cooling cycles. Their compressive behavior was investigated after every 8 cycles. Several microstructure analysis techniques were applied on the samples to identify the materials formed due to magnesium sulfate attack, including XRD, FTIR, SEM, and EDS. Experimental results elucidated that the compressive strength loss ratio in the heating group of FAGC was 12.7%, while that of OPCC was 17.8%, which means that FAGC had better magnesium sulfate resistance than OPCC. The compressive strength loss of OPCC was due to the formation of gypsum under the magnesium sulfate attack exposed to wetting-drying and heating-cooling cycles. The deterioration mechanisms of FAGC against MgSO4 solution were discovered to be that sodium aluminum silicate hydrate (N-A-S-H) gels reacted with MgSO4, leading to the creation of low strength magnesium aluminum silicate hydrate (M-A-S-H) gels.