氧化石墨烯水泥基复合材料的性能及研究进展

Properties and Research Progress of Graphene Oxide Cement-based Composites

水泥基材料在建筑领域应用广泛,但其存在抗弯强度低、抗裂性和韧性差等缺点,因此改善水泥基材料性能一直是建筑材料领域研究的热点之一。氧化石墨烯(GO)是在石墨烯基面和边缘修饰了含氧官能团的一种二维衍生石墨烯材料,具有蜂窝状的结构形貌,亲水性、分散性和反应活性好。将GO加入水泥基材料中,可促进花状形貌晶体的形成,并加速水化进程的成核速度,使其形成致密的交联结构,进而细化水泥浆体的空隙,有效降低孔隙率,从而增强水泥基材料的力学性能,但流动性等有所降低。因此研究人员主要从微观作用机理、静态力学性能及耐久性等方面开展了深入研究,并取得了丰硕的成果。GO自身较大比表面积的结构性质致使水泥基复合材料流变性差,利用硅灰(SF)和氧化石墨烯包覆硅灰(GOSF)等外加剂对GO进行改性,从而提高GO水泥浆体的流动性。基于微观结构作用机理,对比不同GO掺量、试件尺寸、水灰比下的抗压强度和抗弯强度的增长率,分析GO水泥基复合材料的力学性能的增强机理。GO对水泥基材料抗压、抗拉、抗弯强度增长率存在较大差异,其中抗弯强度提高幅度最大。GO对硅酸盐水泥力学性能的提高程度较磷酸镁钾水泥更为显著。对于动态力学性能,不同应变率下裂纹扩展路径存在差异,在高应变率下GO的增强效应更为显著。水泥基材料工作环境中各类离子化合物及酸碱度对其基体有消极的影响,GO对其耐久性有明显的提高作用。本文对近年来GO水泥基复合材料的研究状况进行梳理,分析其微观结构作用机理、流动性、力学性能及耐久性等,阐述了目前国内外的研究状况及存在的问题,并展望了GO水泥基复合材料未来的发展趋势。

Cement based materials are widely used in the construction field,while they have the disadvantages of low flexural strength,poor crack resistance and toughness.Therefore improving the properties of cement based materials has always been one of the research hotspots in the field of building materials.Graphene oxide(GO)is a two-dimensional derived graphene material modified with oxygen-containing functional groups on the base and edge of graphene.It has honeycomb-like structural morphology,good hydrophilicity,dispersion and reactivity.The GO to cement-based materials can facilitate the formation of flower-like morphology crystals,accelerate the nucleation rate of hydration process,and make it form a dense cross-linked structure,and subsequently refine the voids of cement paste.Thus,the mechanical properties of cement-based materials are enhanced,while the fluidity is reduced.Therefore,the previous researchers mainly investigated the microscopic mechanism of action,quasi-static mechanical properties and durability and other aspects,and achieved fruitful results.The structural properties of GO with large specific surface area lead to poor rheological properties of cement-based composites.The GO is mo-dified by admixture such as silica fume(SF)and graphene oxide encapsulated silica fume(GOSF).Thus,the fluidity of GO cement paste is improved.Based on the mechanism of microscopic structure,the strength enhancement mechanism of GO cement composites and the effects of GO content,specimen size and water-cement ratio on the compressive and flexural strengths are analyzed.The increase rate of compressive strength,tensile strength and flexural strength of cement-based materials is different with the addition of GO,and the enhancement of flexural strength is the largest.It has been found that GO improves the mechanical properties of Portland cement more significantly than that of the magnesium potassium phosphate cement paste.For the dynamic mechanical properties,the crack growth path is different at different strain rates,and the enhancement effect GO at high strain rates is more significant.In the working environment of cement-based materials,various ionic compounds and pH have a negative effect on the matrix.GO can significantly improve the durability of its cement composites.The research status of GO cement-based composites in recent years is reviewed in this paper.Microstructure mechanism,fluidity,mechanical properties and durability of GO cement matrix composites are summarized.The current domestic and overseas research progress and existing problems are expounded.Moreover,the future development of GO cement-based composites is prospected.