Mechanical strength and the degradation mechanism of metakaolin based geopolymer mixed with ordinary Portland cement and cured at high temperature and high relative humidity  

作　　者：Xia Miao Xiaofan Pang Shiyu Li Haoguang Wei Jianhao Yin Xiangming Kong 

机构地区：[1]State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 100101,China [2]Sinopec Research Institute of Petroleum Engineering Co.,Ltd,Beijing 100101,China [3]Department of Civil Engineering,Tsinghua University,Beijing 100084,China

出　　处：《Chinese Journal of Chemical Engineering》2023年第8期118-130,共13页中国化学工程学报（英文版）

基　　金：supported by the State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development (20YYGZ-KF-GC-04)。

摘　　要：Geopolymer is a new type of eco-friendly cementitious material, and its superior drying and high temperature resistance has been widely recognized. The service performance of geopolymer under 150 ℃ high-temperature hydrothermal conditions is still less discussed. In this paper, the mechanical strength of pure metakaolin system with low calcium content and metakaolin-cement system with high calcium content under hydrothermal and non-hydrothermal conditions were studied. The results show that under 150 ℃ hydrothermal conditions, the strength of pure metakaolin geopolymer sharply decreases by reduction rate of 81.8% compared to the sample under 150 ℃ drying conditions, while the strength of metakaolin-cement geopolymers is well retained with only a slight decrease of 14.4%. This is mainly because the predominantly hydration product sodium aluminosilicate(N-A-S-H) gel of pure metakaolin system undergoes the process of “dissociation–repolymerization–crystallization” under 150 ℃ hydrothermal conditions, resulting in the loss of cementation ability and obvious deterioration of mechanical strength. In the metakaolin-cement system, the high-calcium calcium silicate gel(C-A-S-H)gel maintains a stable structure, thereby maintaining the macroscopic strength of the material under the hydrothermal conditions.

关 键 词：GEOPOLYMER Hydrothermal conditions Strength Degradation CRYSTALLIZATION GELS 

分 类 号：TQ177[化学工程—硅酸盐工业]