MgSO_4侵蚀条件下水泥浆体相组成及Al相转变  

The Composition and Al-bearing Phases Transition of Cement Paste Subjected to MgSO_4 Attack

作　　者：丁庆军[1] 刘凯[1] 张高展[2] 张杨[1] 徐意[1] 

机构地区：[1]武汉理工大学硅酸盐工程中心国家重点实验室,武汉430070 [2]安徽建筑大学材料与化学工程学院,合肥230000

出　　处：《武汉理工大学学报》2016年第5期1-7,共7页Journal of Wuhan University of Technology

基　　金：国家重点基础研究发展计划(973计划)(2015CB655101);国家自然科学基金(51402003)

摘　　要：研究了水化7d的水泥浆体在5%浓度的MgSO_4溶液中侵蚀不同时间(7d、28d、90d、180d)以及不同浓度MgSO_4(0%、5%、10%、15%)对水化3d水泥浆体的水化产物相组成、含Al相产物迁移与转变的影响规律。XRD与27 AlNMR测试结果表明:5%浓度的MgSO_4侵蚀水泥浆体180d,浆体中CaSO4·2H2O和AFt含量显著增加,C—(A)—S—H中的Al[4]、AFm中的Al[6]以及TAH向AFt中的Al[6]转变,导致试件膨胀破坏。MgSO_4侵蚀前期形成的Mg(OH)2层可抑制C—(A)—S—H中的Al[4]、TAH和AFm向AFt转变,随着侵蚀龄期延长Mg(OH)_2层破坏,SO_4^(2-)的扩散速率增大,AFt生成量显著增加。MgSO_4侵蚀早期促进Al 3+进入C—S—H形成C—(A)—S—H,随着侵蚀龄期延长,C—(A)—S—H发生脱铝作用,Al[4]大量迁移转变为AFt中的Al[6]。MgSO_4浓度增大,其对C—(A)—S—H的脱铝作用增强,AFt的生成量显著增加。Under two conditions （7-days cement paste specimen was placed in 5% MgSO4 solution for 7 d,28 d, 90 d and 180 d, respectively; 3-days cement paste specimen was placed in different concentration MgSO4 solution）, the com- position of hydration products and the transformation mechanism of Al-bearing phases were investigated by XRD and 27 A1 nuclear magnetic resonance（NMR）. The experimental results indicate that the content of CaSO4 · 2H2O and AFt in ce- ment paste, which was placed in 5% MgSO4 solution for 180 d, significantly increases. The 4-coordinate Al of C--（A）-- S--H, the 6-coordinate Al of AFro and TAH transform into 6-coordinate Al of AFt, which cause the specimen expanded destruction. Mg（OH）2 layer formed in the initial erosion stage can suppress 4-coordinate Al of C--（A）--S--H, TAH and AFro transforming into AFt. With the increasing age of erosion, Mg（OH）2 layer was disrupted, the SO4^2- diffusion rate increased, and the content of AFt significantly increased. The initial MgSO4 erosion stage promotes A1 incorporating in C--S--H gel. With the age of erosion extending, Al3＋ was removed from C--（A）--S--H, a large number of 4-coor- dinate Al transform into 6-coordinate Al of AFt. With the concentration of MgSO4 solution increasing, the dealumination effect of C--（A）--S--H increases, the yield of AFt also increases significantly.

关 键 词：MgSO4侵蚀 水泥浆体 27Al NMR Al相 

分 类 号：TU528[建筑科学—建筑技术科学]