钢纤维连续梯度分布对水泥基材料力学性能的影响

Effect of Continuous Gradient Distribution of Steel Fiber on Mechanical Properties of Cement-based Materials

本研究制备了水灰比0.4,纤维体积率分别为0%、0.5%、1%、1.5%和2%,振捣时间30 s和过振捣2、4及6 min的钢纤维水泥砂浆试件,测试了力学性能,借助CT图像技术量化纤维的空间分布情况,研究了钢纤维含量及空间分布对材料力学性能影响。研究结果表明:振捣作用使纤维在基体内形成垂直梯度分布,并发生定向偏转,其中低掺量试件的现象较为明显;材料强度与纤维含量和振捣时间相关,纤维含量为2%的试件劈裂和弯曲强度提升率达92.36%和231.59%;过振捣6 min试件劈裂强度变化率约为10%,弯曲强度提升率也普遍在15%以上;通过振捣合理改变纤维分布,可使低掺量试件劈裂及弯曲强度达到甚至超越高掺量试件。

Steel fiber cement mortar specimens with a water-cement ratio of 0.4 and fiber volume ratios of 0%,0.5%,1%,1.5%and 2%were prepared,and then vibrated for 30 s and over-vibrated for 2 min,4 min,6 min.After testing the mechanical properties of the specimens,CT image reconstruction technology is used to quantify the spatial distribution of fibers to explore the influence of steel fiber content and spatial distribution on the mechanical properties of materials.The results show that the vibration causes the fibers in the matrix to form a vertical gradient distribution and directional deflection.Among them,the phenomenon of the low-volume specimens is more obvious.The splitting and flexural strength increase rates of the specimens with 2%fiber content reached 92.36%and 231.59%.The splitting strength change rate of the over-vibrated specimens was about 10%,and the flexural strength increase rate was generally more than 15%.Reasonably changing the fiber distribution by vibrating can make the splitting and flexural strengths of the low-volume specimens reach or exceed the high-volume specimens.