碱矿渣水泥早期反应产物微观结构演化过程  

Microstructural Evolution of Early Reaction Products in Alkali-Activated Slag Cement at Early Age

作　　者：肖建敏 李辉[1] 雷睿欣 XIAO Jianmin;LI Hui;LEI Ruixin(College of Materials Science and Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,China)

机构地区：[1]西安建筑科技大学材料科学与工程学院,陕西西安710055

出　　处：《建筑材料学报》2024年第5期381-390,共10页Journal of Building Materials

基　　金：陕西省自然科学基金资助项目(2023⁃JC⁃YB⁃096)。

摘　　要：利用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、27Al和29Si魔角旋转固体核磁共振(MAS NMR)以及1H-29Si魔角旋转交叉极化固体核磁共振(1H-29Si CPMAS NMR)研究了NaOH激发碱矿渣水泥早期反应产物的演变过程.结果表明:碱矿渣水泥在3~28 d龄期内均能观察到水化硅铝酸钙凝胶(C-A-S-H)、水滑石和单硫型水化硫铝酸钙(AFm),凝胶产物由复杂的端链硅氧四面体(Q^(1))、链状硅氧四面体(Q^(2))和Al取代的链状硅氧四面体(Q^(2)(1Al))或层状硅氧四面体(Q^(3)(1Al))构成,相对反应程度随龄期延长而增大;随着24 h内早期反应的进行,矿渣水化程度提高,铝硅比增大,铝氧四面体桥氧结构占比增大;矿渣铝氧多面体经历结构解聚、水滑石与AFm层状晶体的形成和Q^(2)(1Al)的形成过程;反应早期24 h内Q^(2)(1Al)迅速发展,水分子与硅氧四面体骨架交联,化学结合水形成,未发现聚合度更大的层状硅氧四面体(Q^(3))和Q^(3)(1Al)结构,因此0~24 h为C-A-S-H低聚态凝胶形成阶段.The microstructural evolution of early reaction products of alkali-activated slag(AAS)pastes was investigated by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),27Al and 29Si magic-angle spinning solid-state nuclear magnetic resonance(MAS NMR)and 1H-29Si cross polarization magic-angle spinning solid-state nuclear magnetic resonance(1H-29Si CPMAS NMR).The results reveal that calcium aluminium silicate hydrate gel(C-A-S-H),hydrotalcite and single sulfur hydrated calcium sulfoaluminate(AFm)are found in AAS pastes in 3-28 d.The C-A-S-H gel is a complex structure of end chain tetrahedra(Q^(1)),branching chain tetrahedra(Q^(2)),Al-replacing chain tetrahedra(Q^(2)(1Al))or Al-replacing layered tetrahedra(Q^(3)(1Al)).The degree of reaction increases with prolongation of hydration time.The hydration degree of slag,Al/Si molar ratio and proportion of bridging tetrahedra that is occupied by Al increase with the early 24 h hydration reaction of AAS cement.Aluminum oxygen polyhedral of slag undergoes the process of structural depolymerization,the formation of layered crystals of hydrotalcite and AFm,and the formation of Q^(2)(1Al).In the early 24 h of the reaction,Q^(2)(1Al)develops rapidly and water molecules are crosslinked with silicon oxygen backbone;at the same time chemical combined water is formed,the layered tetrahedra(Q^(3))and Q^(3)(1Al)structures with higher polymerization degree are not found.Consequently,the 0-24 h reaction stage is the C-A-S-H oligomer gel formation stage.

关 键 词：碱矿渣水泥 微观结构 水化早期 产物演变 

分 类 号：TQ172.79[化学工程—水泥工业]