Qu Xiaoling, Zhao Zhiguang, Zhao Xuguang
School of Civil Engineering, Shaoguan University Shaoguan 512005 PR China
RSC Adv. 2018 Aug 7;8(49):28198-28208. doi: 10.1039/c8ra04423f. eCollection 2018 Aug 2.
The phase assembly and microstructure of the aluminum-incorporated CaO-SiO-HO system, which is technologically important in autoclaved building materials, catalysis and waste management, were investigated using XRD, SEM, FTIR and NMR depending on aluminum addition, reaction temperature and curing time. The content of each phase was obtained using the MAUD program based on the Rietveld refinement. The results revealed that the formation of the tobermorite phase was promoted at Al/(Al + Si) ≤ 0.03, and subsequently retarded by higher aluminum addition, which was corroborated by the presence of more low polymerized and cross-linked (alumino)silicate chains. The phase purity decreased with increasing aluminum addition. Aluminum changed the morphology of tobermorite from plate-like to lath-like and fibrous. About a quarter of the (alumino)silicate chains in the C-S-H structure were linked though a [triple bond, length as m-dash]Si-O-Al[triple bond, length as m-dash] configuration, and this proportion was almost independent of aluminum addition. Furthermore, only Al[4] substituted for silicon in the aluminum incorporated C-S-H, while Al[6] just exited in the hydrogarnet phase. This work is beneficial for understanding the implication on micro-properties of by-products or admixtures containing aluminum in concrete.
铝掺杂的CaO-SiO-H₂O体系的相组装和微观结构在蒸压建筑材料、催化和废物管理等技术领域具有重要意义。根据铝添加量、反应温度和养护时间，采用X射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶变换红外光谱（FTIR）和核磁共振（NMR）对其进行了研究。基于Rietveld精修，使用MAUD程序获得了各相的含量。结果表明，当Al/(Al + Si) ≤ 0.03时，雪硅钙石相的形成得到促进，而更高的铝添加量则会抑制其形成，这一点由更多低聚合和交联的（铝）硅酸盐链的存在得到证实。随着铝添加量的增加，相纯度降低。铝改变了雪硅钙石的形态，使其从板状变为板条状和纤维状。C-S-H结构中约四分之一的（铝）硅酸盐链通过[三键，长度如m破折号]Si-O-Al[三键，长度如m破折号]构型相连，且这一比例几乎与铝添加量无关。此外，在铝掺杂的C-S-H中，只有Al[4]取代了硅，而Al[6]仅存在于水石榴石相中。这项工作有助于理解混凝土中含铝副产品或外加剂对微观性能的影响。
