纤维素纳米晶对水化硅酸钙微观结构的改性机理  

Modification of Cellulose Nanocrystals on Microstructure of Calcium Silicate Hydrate

作　　者：郑大鹏 方媛[1] 崔宏志[1] ZHENG Dapeng;FANG Yuan;CUI Hongzhi(College of Civil and Transportation Engineering,Key Laboratory for Resilient Infrastructures of Coastal Cities(MOE),Shenzhen University,Shenzhen 518060,Guangdong China)

机构地区：[1]深圳大学土木与交通工程学院,滨海城市韧性基础设施教育部重点实验室,广东深圳518060

出　　处：《硅酸盐学报》2023年第5期1146-1153,共8页Journal of The Chinese Ceramic Society

基　　金：国家重点研发计划(2019YFC1907203);深圳市基础研究重点项目(JCYJ20200109114203853)。

摘　　要：水化硅酸钙(C-S-H)作为水泥基胶凝材料的基因,其结构变化对混凝土宏观性能发展至关重要.为了明确纤维素纳米晶(CNCs)在水泥中的改性机理,采用共沉淀法制备C-S-H凝胶,探讨了CNCs的形态效应及成核效应对C-S-H凝胶结构的影响.基于X射线衍射、透射电子显微镜、纳米压痕以及核磁共振等测试,结果显示CNCs表面携带的羟基(—OH)可络合Ca^(2+),随后与溶液中的SiO_(4)^(2–)反应形成C-S-H凝胶,包裹在CNCs周围形成致密的网络结构.CNCs为C-S-H凝胶的沉淀和生长提供了额外的成核位点,促进了C-S-H凝胶聚合度的降低以及链长的缩短,并且显著提升了高密度C-S-H凝胶的含量.Calcium silicate hydrate(C-S-H)gel is a gene of cement-based cementitious materials,and its structural changes are crucial to the development of concrete macroscopic properties.To clarify the modification mechanism of cellulose nanocrystals(CNCs)in cement,C-S-H gels were prepared by a co-precipitation method,and the morphological and nucleation effects of CNCs on the microstructure of C-S-H gels were investigated by X-ray diffraction(XRD),transmission electron microscopy,nanoindentation,and nuclear magnetic resonance.The results show that the hydroxyl groups(OH)on the surface of CNCs can complex Ca^(2+) ions,and then react with SiO_(4)^(2-) ions in solution to form C-S-H gels that wraps around the CNCs.The CNCs can provide additional nucleation sites for the precipitation and growth of C-S-H gels,promote the reduction of the polymerization degree and the shortening of the chain length of the C-S-H gel,and increase the content of high-density C-S-H gel.

关 键 词：纤维素纳米晶 水化硅酸钙 晶核效应 微观结构 聚合度 

分 类 号：TU528[建筑科学—建筑技术科学]