Si-doped graphene in geopolymer: Its interfacial chemical bonding, structure evolution and ultrastrong reinforcing ability

• Published in: Cement & concrete composites 2020-05, Vol.109, p.103522, Article 103522
• Main Authors: Zhang, L.W., Kai, M.F., Chen, X.H.
• Format: Article
• Language: English
• Subjects: Interfacial chemical bonding; Interphase structure; Si-doped graphene/geopolymer; Ultrastrong reinforcing ability
• ISSN: 0958-9465; 1873-393X
• DOI: 10.1016/j.cemconcomp.2020.103522

Low-cost synthesis of silicon-doped graphene (Si-graphene) is attractive for the development of new graphene/geopolymer nanocomposites. In this work, a new insight into the properties of Si-graphene and the working mechanisms of Si-graphene in geopolymer is provided via molecular dynamics simulations. It is shown that Si-doping deteriorates the mechanical properties of graphene as Si-doping creates point defects, but it improves the surface hydrophilicity, which promotes its dispersion in aqueous media. By studying the polymerization process of Al(OH)4/Si(OH)4 monomers on Si-graphene, it is found that Si-graphene can be chemically bonded with geopolymer matrix by typical condensation reactions. Structural analysis reveals that the interfacial bonding has a beneficial effect on condensing the geopolymer composites, due to a denser interphase region. The tensile test reveals that the Young's modulus of 10% Si-graphene/geopolymer nanocomposites is twice larger than that of graphene/geopolymer nanocomposites. In addition, the interfacial bonding can strengthen the interfacial structure and arrest crack formation in geopolymer matrices. [Display omitted]