In this study, carbon fibers (CFs) were used as toughening materials to improve the mechanical properties of cement stone. The surfaces of the CFs were treated with concentrated nitric acid and sodium hypochlorite to increase the interfacial adhesion between the CFs and the cement. The CFs subjected to surface treatment were evaluated by scanning electron microscopy and infrared analysis to find a significant increase in the number of oxygen-containing groups on the surface. The CFs subjected to surface treatment were added to the cement matrix. The effect of the modified CFs on the mechanical properties of the cement matrix was evaluated by testing the means of mechanical properties. The maximum tensile strength, maximum compressive strength, and ultimate strain of the enhanced cement stone of the CFs treated with sodium hypochlorite increased by 68.2%, 12.0%, and 4.4%, respectively. The maximum tensile strength, maximum compressive strength, and ultimate strain of the enhanced cement stone of the CFs treated with concentrated nitric acid increased by 72.7%, 14.7%, and 4.5%, respectively. The addition of CFs to the cement stone exerted no effect on the type of cement hydration products, as determined by infrared analysis and X-ray diffraction. The toughening mechanism of the modified CFs added to the cement stone was ultimately explored, and the bridging effect, deflection effect, and pull-out effect of cracks were evaluated.

中文翻译：

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浓硝酸和次氯酸钠处理的碳纤维表面增强油井水泥石的力学性能及增强机理

在这项研究中，碳纤维（CFs）被用作增韧材料以改善水泥石的机械性能。CFs的表面用浓硝酸和次氯酸钠处理，以增加CFs与水泥之间的界面粘合力。通过扫描电子显微镜和红外分析评估进行了表面处理的CF，发现表面上含氧基团的数量显着增加。将经过表面处理的CF添加到水泥基体中。通过测试机械性能的方法，评估了改性CFs对水泥基体机械性能的影响。最大抗拉强度，最大抗压强度，次氯酸钠处理的CFs的增强水泥石的极限应变和极限应变分别增加了68.2％，12.0％和4.4％。浓硝酸处理的CFs的增强水泥石的最大抗拉强度，最大抗压强度和极限应变分别增加了72.7％，14.7％和4.5％。通过红外分析和X射线衍射确定，向水泥石中添加CFs对水泥水合产物的类型没有影响。最终探讨了改性CFs添加到水泥石中的增韧机理，并评估了裂缝的桥接效应，挠曲效应和拔出效应。浓硝酸处理的CFs的增强水泥石的极限应变和极限应变分别增加了72.7％，14.7％和4.5％。通过红外分析和X射线衍射确定，向水泥石中添加CFs对水泥水合产物的类型没有影响。最终探讨了改性CFs添加到水泥石中的增韧机理，并评估了裂缝的桥接效应，挠曲效应和拔出效应。浓硝酸处理的CFs的增强水泥石的极限应变和极限应变分别增加了72.7％，14.7％和4.5％。通过红外分析和X射线衍射确定，向水泥石中添加CFs对水泥水合产物的类型没有影响。最终探讨了改性CFs添加到水泥石中的增韧机理，并评估了裂缝的桥接效应，挠曲效应和拔出效应。