| Nano-scale study on molecular structure, thermal stability, and mechanical properties of geopolymer |
| Wei Li1, Yunkai Wang2, Chunxiu Yu2, Zijuan He1, Chuan Zuo1, Yang Yu3 |
1Sino-Platinum Metals Co., LTD , Kunming 650106 , China
2State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals , Kunming Institute Of Precious Metals , Kunming 650106 , China
3Centre for Infrastructure Engineering , Western Sydney University , Penrith , NSW 2751 , Australia |
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Received: July 14, 2022; Revised: October 19, 2022 Accepted: October 27, 2022. Published online: December 12, 2022. |
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| ABSTRACT |
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The well thermal stability and mechanical properties of geopolymer can be attributed to its predominant adhesive constituent, sodium alumino-silicate hydrate (N-A-S-H). However, the intrinsic relation between molecular structure, stoichiometry, and performance of N-A-S-H is far from being understood. Herein, the structure, thermal stability, and tensile behavior of N-A-S-H at different Si/Al ratio are investigated by means of ReaxFF molecular dynamics. The results show that, after extreme low/high temperature treatment, the atomic configuration can also recover to a large extent. The hydrolysis during high temperature treatment slightly inhibits the structure recovery. Its expansion strain at elevated temperature is much smaller than that of calcium silicate hydrate, the primary component of Portland cement. Aluminum addition diminishes alumino-silicate skeleton’s connectivity and promotes the formation of energetically unstable Al–O–Al bonds, resulting in the drop of thermal stability and mechanical properties. The consistence between simulations and experiments demonstrates the considerable function of molecular structure of N-A-S-H for the macro-performance of geopolymer. |
| Key words:
N-A-S-H · Geopolymer · Thermal stability · Mechanical properties · ReaxFF molecular dynamics |
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