氧化石墨烯改性固废混凝土的制备及性能研究

Manufacture and performance study of Graphene Oxide-modified solid waste concrete

氧化石墨烯(Graphene Oxide,GO)可以改善水泥基材料力学性能的良好特性可用来改性固废(铁尾矿砂、再生粗骨料)混凝土。研究对再生粗骨料取代率、铁尾矿砂取代率和GO掺量3个因素设计了正交试验。引入考虑固废利用率的权重指标对GO改性固废混凝土的强度指标进行修正并得出加权评价指标,通过极差分析得到GO改性固废混凝土的较佳配合比,研究较佳配合比下GO改性固废混凝土的抗压强度与抗折强度、坍落度与吸水率和微观形貌。结果显示:当再生粗骨料取代率为100%、铁尾矿砂取代率为50%、GO质量分数为0.05%时,为GO改性固废混凝土的较佳配合比,对GO改性固废混凝土的评价指标影响显著性从大到小依次为再生粗骨料取代率、氧化石墨烯掺量、铁尾矿砂取代率。通过扫描电子显微镜(Scanning Electron Microscope,SEM)微观形貌分析发现,GO能优化水化产物堆叠形态,在尺度上细化水化产物,能够填充改性固废混凝土的孔隙结构,有效改善其致密度;较优配合比下的GO改性固废混凝土的力学性能优于普通混凝土的力学性能,验证了GO改性固废混凝土替代普通混凝土的可行性。

The use of GO(Graphene Oxide) can improve the mechanical properties of cement-based materials,thereby modifying the properties of iron tailings reclaimed aggregate concrete.Orthogonal tests of three factors,namely,the replacement rate of recycled coarse aggregate,the replacement rate of iron tailings,and the content of Graphene Oxide,were designed.Polycarboxylic acid superplasticizer GO-PC dispersion solution was prepared by ultrasonic dispersion technique.L_(16)(4~3) orthogonal method was used,and the mixed horizontal orthogonal table was treated by “quasi-horizontal” method.The effects of different contents of Graphene oxide on the microstructure of modified concrete were studied by Scanning Electron Microscopy(SEM).The weighted index considering the utilization rate of solid waste is introduced to modify the strength index of reclaimed aggregate concrete with modified iron tailings,and a weighted evaluation index is obtained.The optimal mix ratio of GO-modified solid waste concrete was obtained by range analysis,and the compressive strength,bending strength,slump,water absorption and micro-morphology of the better mix ratio concrete were studied.The results show that the best mix ratio of GO-modified solid waste concrete is 100% replacement rate of recycled coarse aggregate,50% replacement rate of iron tailings,and 0.05% GO content(accounting for cement mass fraction).The replacement rate of recycled coarse aggregate,the content of GO,and the replacement rate of iron tailings have a significant influence on the evaluation indexes of GO-modified solid waste concrete.Through SEM(Scanning Electron Microscope) microscopic analysis,it is found that Graphene oxide can optimize the stacking mode of hydration products,refine the size of hydration products,fill the pore structure of modified concrete,and increase the compactness.The mechanical properties of GO-modified solid waste concrete with a better mix ratio are better than those of ordinary concrete,proving the feasibility of GO-modified iron tailings recycled aggregate concrete to replace ordinary concrete.