Zhou Ao, Yu Zechuan, Wei Huinan, Tam Lik-Ho, Liu Tiejun, Zou Dujian
School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen, Shenzhen 518055, China.
School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China.
ACS Appl Mater Interfaces. 2020 Sep 30;12(39):44163-44171. doi: 10.1021/acsami.0c12477. Epub 2020 Sep 22.
Interfacial bonding between a fiber and a matrix plays an essential role in composites, especially in fiber-reinforced cementitious composites that are superior forms for bearing flexural and tension load in construction applications. Yet, despite the importance, effective and economic approaches to improve the interfacial bonding between a steel fiber and a cementitious matrix remain unfeasible. Herein, we report a pathway adopting a silane coupling agent (SCA) to modify an interfacial transition zone (ITZ) and enhance interfacial bonding. This approach involves coating a SCA layer onto a steel fiber, where tight physical and chemical bondings (via cross-linking of silicate chains) with a cementitious matrix are formed, leading to an 83.5% increase in pullout energy. Combining nanoindentation and an atomistic force microscope with molecular simulation, we find that SCA increases the surface roughness of the steel fiber, accelerates the hydration reaction of cement clinker, and promotes the volume fraction of the C-S-H phase, inducing a denser and more uniform ITZ with an adequate stress-transfer capability that shifts the mode of failure from interfacial debonding to cement cracking. This work presents an effective and economical approach to improve interfacial bonding, and it enables us to design more durable fiber-reinforced cementitious composites, which can be massively used to build innovative infrastructures.
纤维与基体之间的界面结合在复合材料中起着至关重要的作用，特别是在纤维增强水泥基复合材料中，这种复合材料是建筑应用中承受弯曲和拉伸载荷的优异形式。然而，尽管其重要性，提高钢纤维与水泥基体之间界面结合的有效且经济的方法仍然不可行。在此，我们报告了一种采用硅烷偶联剂（SCA）来改性界面过渡区（ITZ）并增强界面结合的途径。这种方法包括在钢纤维上涂覆一层SCA，在那里与水泥基体形成紧密的物理和化学键合（通过硅酸盐链的交联），导致拔出能量增加83.5%。结合纳米压痕、原子力显微镜和分子模拟，我们发现SCA增加了钢纤维的表面粗糙度，加速了水泥熟料的水化反应，并促进了C-S-H相的体积分数，形成了一个更致密、更均匀的ITZ，具有足够的应力传递能力，使破坏模式从界面脱粘转变为水泥开裂。这项工作提出了一种有效且经济的改善界面结合的方法，使我们能够设计出更耐用的纤维增强水泥基复合材料，可大量用于建造创新基础设施。
