Effect of Multiple Corrosive Ions Coupling Interaction on C-S-H Microstructure in Portland Cement Pa

• 作 者: HU Shuguang HU Chenguang DING Qingjun
• 机 构: School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
• 出 处: The 14th International Congress on the Chemistry of Cement (
• 发表日期: 2015年8期
• 关键词: Corrosive ions cement fly ash C-S-H microstructure Al[4]/Si

　　On the basis of the severe damages of concrete structure by multiple corrosive ions coupling interaction in our Ocean and Western regions, 29Si and 27A1 Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) combined with deconvolution technique were used to study the effect of 5wt% corrosion ions (viz.SO42-, Mg2+,C1-and CO32-) on C-S-H microstructure in Portland Cement-30% fly ash pastes.The results indicate that under coordination corrosion of Mg2+ and SO42-ions, Mg2+ corrosion enhances the decalcification of C-S-H by SO42-attack, leading to the increase of silicate tetrahedra polymer, thereby the mean chain length (MCL) of C-S-H higher than that under SO42-single corrosion, however, the degree of A13+ substituting for Si4+ (Al[4]/Si) in this pastes doesnt change evidently.Compared with SO42-single corrosion, the action of sulfate attack on C-S-H is not significantly influenced by Cl-ions when specimens are under SO42-and Cl coordination corrosion,therefore the MCL of C-S-H and Al[4]/Si in fly ash-cement pastes show little change.When specimens are under coordination corrosion of SO42-, Cl-and CO32-ions, the decalcification of C-S-H by sulfate and carbonate attack, as well as the activation of fly ash by SO42-results in the increase of the MCL and Al[4]/Si, which are both higher than that under SO42-single corrosion, Mg2+ + SO42-or SO42-+ Cl-coordination corrosion.