碳纳米管增强水泥净浆的动态力学特性

Dynamic Mechanical Properties of Carbon Nanotubes Enhanced Cement Paste

利用分离式Hopkinson压杆(SHPB)装置对不同掺量(占水泥的质量分数)碳纳米管(CNTs)的水泥净浆试样在冲击荷载下的动力学特性展开研究,并利用扫描电子显微镜揭示了含CNTs水泥净浆的微观形貌特征。结果表明:在恒定冲击荷载下,试样的动态抗压强度、弹性模量和峰值韧度均随CNTs掺量的增加呈现出先增加后减小的趋势;CNTs掺量为0.1%时,三者达到最大值,与空白对照试样相比,其增幅分别为34.1%、70.0%和15.4%;试样的破坏程度表现出相反的变化规律,0.1%CNTs掺量的试样破碎程度最低,分形维数较空白试样减小了22.3%;适量的CNTs可改善水泥基体的孔径分布,对孔洞、裂缝进行填充与桥接,使其更加致密,但当其掺量过高极易发生团聚,降低基体的力学性能。

The dynamic characteristics of cement paste samples with different contents(mass ratio to cement) of carbon nanotubes(CNTs) under impact loads were investigated by a split Hopkinson pressure bar(SHPB) apparatus, and the microscopic characteristics of cement paste with CNTs were revealed by scanning electron microscopy. The results show that the dynamic compressive strength, elastic modulus and peak toughness of the samples all firstly increase and then decrease with the increase of CNTs content. When the CNTs content is 0.10%, the three samples reach the maximum values, and the increments are 34.1%, 70.0%,and 15.4%, respectively. However, the damage degree of the sample shows an opposite change law. The sample with 0.10% CNTs content has the lowest degree of crushing, and the fractal dimension is reduced by 22.3%, compared to the blank sample. Adding an appropriate amount of CNTs can improve the pore size distribution of cement matrix, and fill and bridge pores and cracks to make it denser, but the excessive amount of CNTs addition can cause aggregation and deteriorate the mechanical properties of cement-based composites.