片状石墨烯对水泥胶砂力学性能的影响

Influence of Flake Graphene on Mechanical Properties of Cement Mortar

为研究石墨烯对水泥胶砂力学性能的影响,采用聚氧代乙烯壬基苯基醚(CO-520)、十二烷基苯磺酸钠(SDBS)、聚乙烯吡咯烷酮(PVP-K30)对石墨烯进行分散,制备了不同石墨烯掺量、不同水灰比下的石墨烯改性水泥胶砂,并借助抗压抗折试验及扫描电子显微(SEM)研究了石墨烯对水泥胶砂力学性能的增强效果及增强机理。结果表明:CO-520分散剂能有效改善石墨烯在水泥胶砂中的分散性;石墨烯的掺入显著增加了水泥胶砂7 d、28 d的抗折和抗压强度;3种水灰比均在掺量为0.07wt%取得最佳值,28 d的抗折和抗压强度分别增加了37.8%、9.4%;石墨烯掺量相同时,水泥胶砂的抗折和抗压强度均随水灰比的上升而下降。这是因为石墨烯片层以多样性形态填充在水泥基材料的孔隙中,从而细化水泥基基体的孔径尺寸,提升了水泥基体间的胶结强度,增强了水泥胶砂材料的力学性能。

In order to study the effect of graphene on mechanical properties of cement mortar,polyoxyethylene nonylphenyl ether(CO-520),sodium dodecyl benzene sulfonate(SDBS)and polyvinyl pyrrolidone(PVP-K30)are used to disperse graphene.Then,graphene modified cement mortar is prepared with different content of graphene and water cement ratio.Finally,with the help of compressive and flexural testing machine,scanning electron microscopic analysis(SEM),the mechanical properties and enhancement mechanism of graphene on cement mortar is studied.The results show that CO-520 dispersant can effectively improve the dispersity of graphene in cement mortar.The addition of graphene can significantly increase the flexural and compressive strength of cement mortar at 7 d and 28 d.The optimal values of the three water-cement ratios are obtained at the dosage of 0.07wt%,and the flexural and compressive strengths at 28 d increase by 37.8%and 9.4%,respectively.In addition,the flexural and compressive strength of cement mortar decrease with the increase of water cement ratio when the graphene content is the same.This is because the graphene sheets are filled in the pores of the cement-based material in various forms,thereby refining the pore size of the cement-based matrix,improving the bonding strength between the cement-based materials,and enhancing the mechanical properties of the cement mortar material.