Microstructure development and mechanism of hardened cement paste incorporating graphene oxide during carbonation
Microstructure development and mechanism of hardened cement paste incorporating graphene oxide during carbonation
复制标题
碳化过程中掺入氧化石墨烯的硬化水泥浆体的微观结构发展和机理
DOI：
10.1016/j.cemconcomp.2018.08.016
复制
发表时间：
2018-11-01
影响因子：
10.5
通讯作者：
Khayat, Kamal H.
中科院分区：
文献类型：
--
作者：
Long, Wu-Jian;Gu, Yu-cun;Khayat, Kamal H.
在这项工作中，研究了含有氧化石墨烯(GO)的水泥浆体在二氧化碳浓度为20%、温度为(30+/-1)℃、相对湿度为65%-70%的加速碳化条件下的电化学、动力学和微观结构特征，以探讨其碳化机理。用非破坏性电化学阻抗谱(EIS)研究了复合材料的传输性能，用热重分析(TGA)研究了复合材料的碳化动力学。EIS结果表明，GO的加入增加了离子的扩散和迁移阻力，而热重分析结果表明，由于水化程度的增加，在碳化早期，孔雀石(CH)和水化硅酸钙(C-S-H)的碳化受到显著抑制。此外，还对碳化过程中生成的杂化产物GO/水化产物进行了表征，并通过扫描电子显微镜和能谱分析观察到了包覆碳化层的水化相的形成。用压汞测孔法对碳化过程中材料的孔隙率变化进行了评估。与GO水泥基材料所观察到的效果相比，OPC在初始碳化阶段的孔隙率下降更明显。
In this work, the carbonation mechanism of cement paste containing graphene oxide (GO) was examined by evaluating its electrochemical, kinetic, and microstructural characteristics under accelerated carbonation, corresponding to a 20% concentration of CO2, a temperature of (30 +/- 1)degrees C, and a relative humidity of 65%-70%. Transport properties of the composites were studied using a non-destructive electrochemical impedance spectroscopy (EIS) technique, while their carbonation kinetics was investigated via thermogravimetric analysis (TGA). The obtained EIS results indicated that the ion diffusion and transport resistance increased after the incorporation of GO, while TGA results revealed that the carbonation of portlandite (CH) and calcium-silicate hydrate (C-S-H) was significantly inhibited during early ages of carbonation due to the increased degree of hydration. In addition, the hybrid GO/hydration products from the carbonation process were characterized, and the formation of a hydrated phase coated with a carbonated layer was observed via scanning electron microscopy and energy dispersive spectroscopy. Porosity variations of the studied materials during carbonation were also evaluated using a mercury intrusion porosimetry method. The porosity of the OPC decreased more significantly during the initial carbonation period as compared to the effect observed for the GO cement-based material.