中文摘要：

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。

英文摘要：

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.