玄武岩纤维对3D打印混凝土力学性能的影响

Effect of basalt fibers on mechanical properties of 3D printed concrete

为探究玄武岩纤维对3D打印混凝土力学性能的影响,设计0%、0.25%、0.50%、0.75%和1.00%共5种不同玄武岩纤维掺量,通过单轴压缩、三点弯曲和层间双剪试验分析玄武岩纤维掺量对3D打印混凝土力学性能的影响,并利用双目倒置金相显微镜和扫描电子显微镜从微观形貌层面分析玄武岩纤维增强混凝土力学性能的作用机制。研究结果表明:掺加玄武岩纤维可显著提升3D打印混凝土结构的力学性能。随着纤维掺量的增加,抗压和层间抗剪强度呈现出先增加后减小的趋势,掺量为0.50%时共同达到最优,相较于未掺入玄武岩纤维的混凝土分别提高了28%和61%;抗折强度则随着纤维掺量增加一直增加,掺量为1.00%时效果最佳,相较于未掺入玄武岩纤维的混凝土提高了21%。打印材料力学性能存在各向异性,沿Z方向加载时抗压和抗折强度最高,Y方向最低;随着纤维掺量增加,力学性能各向异性逐渐增大。结合试验结果和电镜扫描结果可知,玄武岩纤维优异的抗拉性能够抑制裂缝的产生与扩展,从而提升3D打印混凝土结构的整体力学性能。

In order to explore the effect of basalt fibers on the mechanical properties of 3D printed concrete,five different basalt fiber contents of 0%,0.25%,0.50%,0.75%and 1.00%were designed.The effects of basalt fiber content on the mechanical properties of 3D printed concrete were analyzed by uniaxial compression,three-point bending and interlayer double shear tests.The mechanism of basalt fiber reinforced concrete mechanical properties was analyzed by binocular inverted metallurgical microscope and scanning electron microscope.The results showed that the addition of basalt fiber can significantly improve the mechanical properties of 3D printed concrete structures.With the increase of fiber content,the compressive strength and interlayer shear strength show a trend of increasing first and then decreasing.When the content is 0.50%,the optimum is achieved,which is 28%and 61%higher than that of concrete without basalt fiber,respectively.The flexural strength increases with the increase of fiber content,and the effect is the best when the content is 1.00%,which is 21%higher than that of concrete without basalt fiber.The mechanical properties of the printing material are anisotropic.The compressive and flexural strength are the highest in the Z direction and the lowest in the Y direction.With the increase of fiber content,the anisotropy of mechanical properties increases gradually.Combined with the test results and electron microscope scanning results,it can be seen that the excellent tensile resistance of basalt fiber can inhibit the generation and expansion of cracks,thus improving the overall mechanical properties of 3D printed concrete structures.