Thermodynamic Stability of Sulfate Ions on Calcium Aluminosilicate Hydrate Microstructure  

作　　者：HU Chengguang DING Qingjun WANG Huan FENG Xiaoxin 胡晨光;DING Qingjun;WANG Huan;FENG Xiaoxin(College of Materials Science and Engineering,North China University of Science and Technology,Tangshan063210,China;Hubei Key Laboratory of Roadway Bridge and Structure Engineering(Wuhan University of Technology),Wuhan430070,China;College of Materials Science and Engineering,Wuhan University of Technology,Wuhan430070,China;Hubei Communications Investment Intelligent Detection Co.,Ltd,Wuhan430051,China)

机构地区：[1]College of Materials Science and Engineering,North China University of Science and Technology,Tangshan063210,China [2]Hubei Key Laboratory of Roadway Bridge and Structure Engineering(Wuhan University of Technology),Wuhan430070,China [3]College of Materials Science and Engineering,Wuhan University of Technology,Wuhan430070,China [4]Hubei Communications Investment Intelligent Detection Co.,Ltd,Wuhan430051,China

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2019年第3期638-647,共10页武汉理工大学学报（材料科学英文版）

基　　金：Funded by Anhui Key Laboratory of Advanced Building Materials,Anhui Jianzhu University(No.JZCL201602KF);Major State Basic Research Development Program of China(973 Program)(No.2015CB655101);State Key Laboratory of High Performance Civil Engineering Materials(No.2015CEM005);Natural Science Foundation of Hebei Province(No.E2016209283);Hubei Key Laboratory of Roadway Bridge and Structure Engineering(Wuhan University of Technology)(No.DQZDJJ201504)

摘　　要：The thermodynamic stability of sulfate ions on synthesized calcium aluminosilicate hydrate（C-A-S-H） microstructure with different Ca/Si ratios and Al/Si ratios was investigated by XRD, SEM-EDS, 29 Si and 27 Al nuclear magnetic resonance（NMR） and thermodynamic modeling. The results indicate that sulfate attack leads to both decalcification and dealumination for C-A-S-H gels, and the amount of corrosion products（gypsum and ettringite） decreased gradually with decreasing Ca/Si ratios of C-A-S-H. Sulfate ions can also promote the polymerization degree of C-A-S-H gels, improving its resistance to sulfate attack. Moreover, the 4-coordination aluminum（Al[4]） in C-A-S-H, 5-coordination aluminum（Al[5]）, 6-ccordination aluminum（Al[6]） in TAH（third aluminum hydrate） and Al[6] in monosulfate or C-A-H（calcium aluminate hydrate） can be transformed into Al[6] in ettringite by sulfate attack. Furthermore, through thermodynamic calculation, the decrease of Ca/Si ratios and increase of Al/Si ratios can improve the thermodynamic stability of C-A-S-H gels under sulfate attack, which agrees well with the experiment results.The thermodynamic stability of sulfate ions on synthesized calcium aluminosilicate hydrate (C-A-S-H) microstructure with different Ca/Si ratios and Al/Si ratios was investigated by XRD, SEM-EDS, 29Si and 27A1 nuclear magnetic resonance (NMR) and thermodynamic modeling. The results indicate that sulfate attack leads to both decalcification and dealumination for C-A-S-H gels, and the amount of corrosion products (gypsum and ettringite) decreased gradually with decreasing Ca/Si ratios of C-A-S-H. Sulfate ions can also promote the polymerization degree of C-A-S-H gels, improving its resistance to sulfate attack. Moreover, the 4-coordination aluminum (Al[4]) in C-A-S-H, 5-coordination aluminum (Al[5]), 6-ccordination aluminum (A1[6J) in TAH (third aluminum hydrate) and Al[6] in monosulfate or C-A-H (calcium aluminate hydrate) can be transformed into Al[6] in ettringite by sulfate attack. Furthermore, through thermodynamic calculation, the decrease of Ca/Si ratios and increase of Al/Si ratios can improve the thermodynamic stability of C-A-S-H gels under sulfate attack, which agrees well with the experiment results.

关 键 词：SULFATE attack CALCIUM ALUMINOSILICATE HYDRATE THERMODYNAMIC stability MICROSTRUCTURE 

分 类 号：TB[一般工业技术]