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.