水泥颗粒表面原位生长石墨烯对水泥砂浆性能影响

Effect of in-situ growth of graphene on the surface of cement particles on the properties of cement mortar

  • 摘要: 将纳米材料掺入水泥基材料中可提高水泥基材料力学性能,其中石墨烯因其高比表面积和优异的物理性能而备受关注,但其高成本和易团聚的缺点限制了其在水泥基材料中的应用。为此,使用腐殖酸作为碳源降低石墨烯的制备成本,并通过在水泥颗粒上原位生长石墨烯,提升其在水泥基材料中的分散性。实验结果表明水泥颗粒表面原位生长石墨烯比直掺进相同含量石墨烯对水泥砂浆性能增强效果更好。碳源为4.75 wt%的试验组3 d抗压强度和抗折强度分别提高了58%和60%,28 d抗压强度和抗折强度分别提高24%和15%,初始吸水率和次级吸水率分别下降72.95%和77.39%。通过腐殖酸在水泥颗粒表面原位生长石墨烯可以提高石墨烯在水泥砂浆中的分散性,促进水泥砂浆水化产物生成,并优化水泥砂浆孔隙结构,在降低水泥砂浆总孔隙率的同时降低了有害孔和多害孔所占比例,进而增强水泥砂浆性能。

     

    Abstract: Adding nanomaterials to cement-based materials can significantly improve their mechanical properties, particularly graphene, which is noted for its high specific surface area and outstanding physical performance; nevertheless, its high cost and susceptibility to agglomeration restrict its use in cement-based materials. Therefore, humic acid is used as a carbon source to lower the preparation costs of graphene, and the in-situ growth of graphene on cement particles enhances its dispersion within cement-based materials. The experimental results show that graphene grown in situ on the surface of cement particles is better than that directly mixed with the same content of graphene to enhance the performance of cement mortar. The 3 d compressive strength and flexural strength of the experimental group with a carbon source of 4.75 wt% increase by 58% and 60%, respectively, the 28 d compressive strength and flexural strength increase by 24% and 15%, respectively, and the initial water absorption rate and secondary water absorption rate decrease by 72.95% and 77.39%, respectively. The in-situ growth of graphene on the surface of cement particles through humic acid can enhance the dispersibility of graphene in cement mortar, promote the generation of hydration products, and optimize the pore structure of cement mortar. By reducing the total porosity of cement mortar and decreasing the proportion of harmful and porous pores, the performance of cement mortar is thereby strengthened.

     

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