氧化石墨烯及样品形状对水泥基复合材料力学性能的影响

Effects of GO and sample shape on mechanical properties of cement-based composites

为了研究氧化石墨烯(GO)掺量、龄期和样品形状对GO水泥基复合材料的压缩强度和弹性模量的影响。分别制备7组不同GO掺量的水泥基复合材料立方体试件(边长为50 mm)和圆柱体试件(直径60 mm、高30 mm),进行3、7、28 d的静态压缩试验,给出其应力-应变曲线,提出形状效应系数及其计算式;同时用扫描电镜(SEM)观测28 d圆柱体试件断面的微观形貌,阐述GO水泥基复合材料强度随GO掺量变化的微观机理。结果表明:3、7 d立方体和圆柱体的抗压强度达到最大时,GO掺量为0.03%,28 d立方体和圆柱体的抗压强度达到最大时,GO掺量为0.04%。SEM结果发现GO可以优化水化产物的微观形貌,形成致密的微观结构。随着龄期的增加,立方体和圆柱体抗压强度呈现增加的规律。GO水泥基复合材料圆柱体试件与立方体试件测得的材料性能有差异,样品形状对力学性能的影响不可忽略,GO掺量相同时,样品形状分别对3 d时抗压强度和28 d时弹性模量影响最大。

To investigate the effects of GO content,age and sample shape on the compressive strength and elastic modulus of GO cement-based composites.Seven groups of cement-based composite cube specimens with different GO contents(side length 50 mm)and cylinder specimens(diameter 60 mm,height 30 mm)were prepared respectively.Static compression experiments were conducted on 3 d,7 d and 28 d,and the stress-strain curves were given.The shape effect coefficient and its calculation formula were proposed.At the same time,scanning electron microscope(SEM)was used to observe the micro morphology of 28 d cylinder specimen,and the micro mechanism of GO cement-based composite material strength changing with GO content was elaborated.The results show that when the compressive strength of 3 d cube,7 d cube and cylinder reaches the maximum,the GO content is 0.03%,and when the compressive strength of 28 d cube and cylinder reaches the maximum,the GO content is 0.04%.SEM found that GO could optimize the microscopic morphology of hydration products and form dense microstructure.The compressive strength of the cube and cylinder increases with the increasing of the age.The material properties measured by the cylinder specimen and the cube specimen of GO cement-based composite material are different,and the influence of the sample shape on the mechanical properties cannot be ignored.With the same GO content,the sample shape has the greatest influence on the compressive strength at 3D and the elastic modulus at 28d,respectively.