The Hydration and Carbonation of Tricalcium Aluminate (C_3A) in the Presence of Heavy Metals  

作　　者：CHEN Quanyuan C. D. Hills M. Tyrer I. Slipper 

机构地区：[1]School of Environmental Science and Engineering, Donghua University, Shanghai, 200051, P. R. China [2]Centre for Contaminated Land Remediation, University of Greenwich, Chatham Maritime, Kent ME4 4TB UK [3]Department of Materials, Imperial College of Science, Technology and Medicine, London SW7 2AZ UK

出　　处：《China's Refractories》2005年第3期27-32,共6页中国耐火材料（英文版）

摘　　要：The hydration of tricalcium aluminate （ C3A ） has a significant effect on the effectiveness of cement-based systems. In addition, the carbonation of hydration products of C3A is particularly important in respect of durability performance. The present work investigates the hydration and carbonation reactions of C 3A and the changes induced by the presence of the heavy metal ions such as Zn^2＋ , Pb^2＋ , Cu^2＋ and Cr^3＋ by X-ray diffrac- tometry （ XRD ）. During hydration of C3A, gehlenite hydrate, hydrogarnet , calcium monoaluminate （ C4AHx ） and calcium carboaluminate were detected in C3A pastes except the Zn^2＋ doped paste, where hydrogarnet did not form. The examinations revealed that heavy metals coexisted with gehlenite hydrate, calcium monoaluminate （ C4AHx ） and calcium carboaluminate, inhibiting the formation of hydrogarnet. Hydrating C3A was liable to be carbonated on exposure to air and carbon dioxide, especially in the presence of heavy metals, resulting in the formation of carboaluminate and/or calcium carbonate. The presence of heavy metals in-fluenced the polymorphism of calcium carbonate, ndicating that heavy metals could co-precipitate with calcium to form a carbonate solid solution.The hydration of tricalcium aluminate （ C3A ） has a significant effect on the effectiveness of cement-based systems. In addition, the carbonation of hydration products of C3A is particularly important in respect of durability performance. The present work investigates the hydration and carbonation reactions of C 3A and the changes induced by the presence of the heavy metal ions such as Zn^2＋ , Pb^2＋ , Cu^2＋ and Cr^3＋ by X-ray diffrac- tometry （ XRD ）. During hydration of C3A, gehlenite hydrate, hydrogarnet , calcium monoaluminate （ C4AHx ） and calcium carboaluminate were detected in C3A pastes except the Zn^2＋ doped paste, where hydrogarnet did not form. The examinations revealed that heavy metals coexisted with gehlenite hydrate, calcium monoaluminate （ C4AHx ） and calcium carboaluminate, inhibiting the formation of hydrogarnet. Hydrating C3A was liable to be carbonated on exposure to air and carbon dioxide, especially in the presence of heavy metals, resulting in the formation of carboaluminate and/or calcium carbonate. The presence of heavy metals in-fluenced the polymorphism of calcium carbonate, ndicating that heavy metals could co-precipitate with calcium to form a carbonate solid solution.

关 键 词：HYDRATION CARBONATION Tricalci-um aluminate （C3A） Heavy metal XRD 

分 类 号：TQ175.7[化学工程—硅酸盐工业]