Effect of Curing Regime on Degree of Al^(3+) Substituting for Si^(4+) in C-S-H Gels of Hardened Portland Cement Pastes  

作　　者：胡晨光 胡曙光 DING Qingjun FENG Xiaoxin HUANG Xiulin 

机构地区：[1]School of Materials Science and Engineering, Wuhan University of Technology [2]College of Materials Science and Engineering, Hebei United University [3]School of Materials Science and Engineering, Hubei University

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2014年第3期546-552,共7页武汉理工大学学报（材料科学英文版）

基　　金：Funded by the Major State Basic Research Development Program of China(973 Program)(No.2009CB623201);National Natural Science Foundation of China(No.51302070)

摘　　要：The effect of curing regime on degree ofAl3＋ substituting for Si^4＋ （Al/Si ratio） in C-S-H gels of hardened Portland cement pastes was investigated by 29Si magic angel spinning （MAS） nuclear magnetic resonance （NMR） with deconvolution technique. The curing regimes included the constant temperature （20, 40, 60 and 80 ℃） and variable temperature （simulated internal temperature of mass concrete with 60 ℃ peak）. The results indicate that constant temperature of 20 ℃ is beneficial to substitution ofAl3＋ for Si4＋, and AI/Si ratio changes to be steady after 180 d. The increase of Al/Si ratio at 40 ℃is less than that at 20℃ for 28 d. The other three regimes of high temperature increase Al/Si ratio only before 3 d, on the contrary to that from 3 to 28 d. However, the 20 ℃ curing stage from 28 to 180 d at variable temperature regime, is beneficial to the increase of AI/Si ratio which is still lower than that at constant temperature regime of 20 ℃ for the same age. A nonlinear relation exists between the Al/Si ratio and temperature variation or mean chain length （MCL） of C-S-H gels, furthermore, the amount ofAl3＋ which can occupy the bridging tetrahedra sites in C-S-H structure is insufficient in hardened Portland cement pastes.The effect of curing regime on degree ofAl3＋ substituting for Si^4＋ （Al/Si ratio） in C-S-H gels of hardened Portland cement pastes was investigated by 29Si magic angel spinning （MAS） nuclear magnetic resonance （NMR） with deconvolution technique. The curing regimes included the constant temperature （20, 40, 60 and 80 ℃） and variable temperature （simulated internal temperature of mass concrete with 60 ℃ peak）. The results indicate that constant temperature of 20 ℃ is beneficial to substitution ofAl3＋ for Si4＋, and AI/Si ratio changes to be steady after 180 d. The increase of Al/Si ratio at 40 ℃is less than that at 20℃ for 28 d. The other three regimes of high temperature increase Al/Si ratio only before 3 d, on the contrary to that from 3 to 28 d. However, the 20 ℃ curing stage from 28 to 180 d at variable temperature regime, is beneficial to the increase of AI/Si ratio which is still lower than that at constant temperature regime of 20 ℃ for the same age. A nonlinear relation exists between the Al/Si ratio and temperature variation or mean chain length （MCL） of C-S-H gels, furthermore, the amount ofAl3＋ which can occupy the bridging tetrahedra sites in C-S-H structure is insufficient in hardened Portland cement pastes.

关 键 词：constant temperature variable temperature degree of Al3＋ substituting for Si4＋ C-S-H hardened cement pastes 

分 类 号：TQ172.1[化学工程—水泥工业]