Crystallization Characteristic of Periclase in Clinker and Effect of Mg2+ on Hydrate of Cement Pastes  

作　　者：SONG Qiang HU Yaru CHEN Yanxin 宋强;HU Yaru;陈延信(College of Materials Science and Engineering, Xi’an University of Architecture and Technology)

机构地区：[1]College of Materials Science and Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2019年第6期1384-1395,共12页武汉理工大学学报（材料科学英文版）

基　　金：Funded by the National Key R&D Program of China(2016YFB0303400,2017YFB0309903-03);the Natural Science Foundation of Shaaxi Province of China(2017JM5097)

摘　　要：Crystallization characteristic of periclase in clinker and effect of Mg^2+ on hydrate of cement pastes were investigated. Morphologies and relative content of periclase were characterized with scanning electron microscopy and X-ray diffraction. Derivative thermogravimetry analysis and backscattered electron imaging were used to characterize the effect of Mg^2+ on hydrate of cement pastes. The experimental results show that in ample space, periclase forms octahedron structure, and subhedral or anhedral crystal is formed in limited space. Due to the accelerated burning temperature and prolonged holding time, coarse pericalase crystals are formed. Mg(OH)2 particle thickness increases due to faster crystal growth rate along c axis at later age. Mg^2+can substitute Ca^2+ in C-S-H or C-A-H to form magnesium silicate hydrate(M-S-H) or magnesium aluminate hydrate(M-A-H), and the substitution extent for C-A-H is higher than that for C-S-H. Cured in 80 ℃ water, the decalcification rate of C-A-H in pastes is higher than that cured in 50 ℃ water. M-A-H with an atomic Mg/Al ratio of 2 is formed through substitution of Ca by Mg in C-A-H.Crystallization characteristic of periclase in clinker and effect of Mg2+ on hydrate of cement pastes were investigated. Morphologies and relative content of periclase were characterized with scanning electron microscopy and X-ray diffraction. Derivative thermogravimetry analysis and backscattered electron imaging were used to characterize the effect of Mg2+ on hydrate of cement pastes. The experimental results show that in ample space, periclase forms octahedron structure, and subhedral or anhedral crystal is formed in limited space. Due to the accelerated burning temperature and prolonged holding time, coarse pericalase crystals are formed. Mg（OH）2 particle thickness increases due to faster crystal growth rate along c axis at later age. Mg2+can substitute Ca2+ in C-S-H or C-A-H to form magnesium silicate hydrate（M-S-H） or magnesium aluminate hydrate（M-A-H）, and the substitution extent for C-A-H is higher than that for C-S-H. Cured in 80 ℃ water, the decalcification rate of C-A-H in pastes is higher than that cured in 50 ℃ water. M-A-H with an atomic Mg/Al ratio of 2 is formed through substitution of Ca by Mg in C-A-H.

关 键 词：high magnesium clinker PERICLASE magnesium silicate hydrate magnesium aluminate hydrate 

分 类 号：TQ172.1[化学工程—水泥工业]