Vilela Rocha Vanessa, Ludvig Péter
Department of Civil Engineering, Federal Center for Technological Education of Minas Gerais, Belo Horizonte, Minas Gerais 30.421-169, Brazil.
Materials (Basel). 2020 Jul 15;13(14):3164. doi: 10.3390/ma13143164.
Cement composites prepared with nanoparticles have been widely studied in order to achieve superior performance structures. The incorporation of carbon nanotubes (CNTs) is an excellent alternative due to their mechanical, electrical, and thermal properties. However, effective dispersion is essential to ensure strength gains. In the present work, cement pastes were prepared incorporating CNTs in proportions up to 0.10% by weight of cement, dispersed on the surface of anhydrous cement particles in isopropanol suspension and using ultrasonic agitation. Digital image correlation was employed to obtain basic mechanical parameters of three-point bending tests. The results indicated a 34% gain in compressive strength and 12% in flexural tensile strength gains, respectively, as well as a 70% gain in fracture energy and 14% in fracture toughness in the presence of 0.05% CNTs were recorded. These results suggest that CNTs act as crack propagation controllers. Moreover, CNT presence contributes to pore volume reduction, increases the density of cement pastes, and suggests that CNTs additionally act as nucleation sites of the cement hydration products. Scanning electron microscopy images indicate effective dispersion as a result of the methodology adopted, plus strong bonding between CNTs and the cement hydration product. Therefore, CNTs can be used to obtain more resistant and durable cement-based composites.
为了获得高性能结构，对用纳米颗粒制备的水泥基复合材料进行了广泛研究。由于碳纳米管（CNT）的机械、电气和热性能，将其掺入是一种极佳的选择。然而，有效分散对于确保强度提升至关重要。在本研究中，制备了水泥浆体，其中碳纳米管的掺入量按水泥重量计高达0.10%，将其分散在无水水泥颗粒表面的异丙醇悬浮液中并使用超声搅拌。采用数字图像相关技术获取三点弯曲试验的基本力学参数。结果表明，在存在0.05%碳纳米管的情况下，抗压强度提高了34%，抗弯抗拉强度提高了12%，断裂能提高了70%，断裂韧性提高了14%。这些结果表明碳纳米管起到了裂纹扩展控制剂的作用。此外，碳纳米管的存在有助于减少孔隙体积，增加水泥浆体的密度，这表明碳纳米管还充当了水泥水化产物的成核位点。扫描电子显微镜图像表明，由于采用的方法，实现了有效分散，并且碳纳米管与水泥水化产物之间有很强的结合力。因此，碳纳米管可用于获得更具抗性和耐久性的水泥基复合材料。
