Mechanism of Thaumasite Formation in Concrete  

作　　者：宋远明 ZHOU Shaolong WANG Zhijuan WANG Bo 钱觉时 

机构地区：[1]School of Environmental and Materials Engineering, Yantai University, Yantai 264005, China [2]School of Materials Science and Engi- neering, Chongqing University, Chongqing 400045, China

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2017年第4期893-897,共5页武汉理工大学学报（材料科学英文版）

基　　金：Funded by the National Natural Science Foundation of China(Nos.51272222 and 51132010)

摘　　要：Significant efforts have been made in revealing the mechanism of thaumasite formation in concrete, which continues to be fraught with ambiguities and dissension. Chemical method was employed to synthesize pure C3S, C2S, C3A, ettringite, and thaumasite, and X-ray diffraction（XRD）, Raman spectroscopy and infrared spectroscopy（IR） were used to identify thaumasite from other hydrates. To investigate the direct route of thaumasite formation, C3S, C2S, gypsum, and calcium carbonate were used to prepare a cement paste so that the interference of ettringite formation can be avoided. The indirect route of thaumasite formation was also studied by considering the effect of C3A or ettringite content on thaumasite formation. Results show that thaumasite can be definitely generated in the absence of aluminium-bearing minerals or ettringite under appropriate conditions, while the ettringite presence promotes the thaumasite formation. No evidences support the heterogeneous nucleation route in this work. It is concluded that the method mentioned in this work can surely be used to investigate the mechanism of thaumasite formation, and thaumasite can form by both direct and woodfordite routes.Significant efforts have been made in revealing the mechanism of thaumasite formation in concrete, which continues to be fraught with ambiguities and dissension. Chemical method was employed to synthesize pure C3S, C2S, C3A, ettringite, and thaumasite, and X-ray diffraction（XRD）, Raman spectroscopy and infrared spectroscopy（IR） were used to identify thaumasite from other hydrates. To investigate the direct route of thaumasite formation, C3S, C2S, gypsum, and calcium carbonate were used to prepare a cement paste so that the interference of ettringite formation can be avoided. The indirect route of thaumasite formation was also studied by considering the effect of C3A or ettringite content on thaumasite formation. Results show that thaumasite can be definitely generated in the absence of aluminium-bearing minerals or ettringite under appropriate conditions, while the ettringite presence promotes the thaumasite formation. No evidences support the heterogeneous nucleation route in this work. It is concluded that the method mentioned in this work can surely be used to investigate the mechanism of thaumasite formation, and thaumasite can form by both direct and woodfordite routes.

关 键 词：thaumasite ettringite formation mechanism direct route woodfordite route 

分 类 号：TU528[建筑科学—建筑技术科学]