颗粒负载氧化石墨烯复合水泥基材料的微观结构及自修复性能

Microstructure and self-repairing performance of granular loaded graphene oxide composite cement-based materials

以纳米SiO_(2)、CaCO_(3)粉体为氧化石墨烯(GO)载体得到SiO_(2)-GO(SG)、SiO_(2)-CaCO_(3)-GO(SCG),并将其掺入水泥基材料中,实现GO在水泥基材料中的分散,并研究其掺入对水泥基材料力学和自修复性能、水化产物和微观结构等方面的影响。研究表明:SG和SCG掺入进一步提高了水泥基材料的力学性能,SCG掺入水泥28天抗折和抗压强度较空白试样分别提高了7.3%和18.7%,高于掺入SiO_(2)和SG试样。SCG掺入使水泥石具有良好的自修复性能,其中抗压强度修复率达到110.6%,28天抗渗性能修复率达到100%,裂缝面积测试表明SCG对于水泥基材料裂缝具有更明显的修复效果。XRD分析显示SiO_(2)、SG和SCG掺入均有助于促进水泥早期水化。TG分析表明,随着水化龄期的延长,SCG复合水泥试样中Ca(OH)_(2)和SiO_(2)之间的反应程度较高,与早期水化3天相比,SCG复合水泥基材料28天Ca(OH)_(2)含量降低至14.90%。微观结构分析表明SCG与水泥石界面具有更好的相容性,能够促进水泥水化后期生成较多水化硅酸钙(C-S-H)凝胶,有效填充水泥石微观裂缝,SCG复合水泥基材料具有优良的自修复性能。

To improve the dispersion performance of graphene oxide(GO)in the cement materials,nano SiO_(2) and CaCO_(3) powder were used as support of the GO and the SiO_(2)-GO(SG)and SiO_(2)-CaCO_(3)-GO(SCG)were prepared.The effects of the SG and SCG on the mechanical strength,self-repairing performance,hydration products and microstructure of the cement materials were studied.The results show that the mechanical strength of the cement material is improved as the addition of SG and SCG,the flexural strength and compressive strength of the cement-based materials with SCG at 28 days are improved by 7.3%and 18.7%,respectively.The self-repairing performance of SCG composite cement is also improved which shows a higher compressive strength repairing rate of about 110.6%and a higher water permeability repairing rate of 100%.The crack area testing shows that SCG has a more significant repair effect on cracks in the cement materials.XRD analysis shows that the early stage cement hydration is accelerated as the addition of SG and SCG,especially for the SCG,the hydration degree at 3 days is obviously improved.TG analysis shows that with the extension of hydration age,a higher reaction degree of Ca(OH)_(2) and SiO_(2) is achieved in the SCG composite cement,compared with the early 3 days hydration stage,the Ca(OH)_(2) content of SCG composite cement at 28 days reduces to 14.90%.Microstructure analysis shows that the SCG has better compatibility with the cement,more hydrate calcium silicate(C-S-H)gels in the late hydration stage is generated and the microcracks of cement could be filled,which makes the excellent self-repairing performance of the SCG composite cement.