玄武岩纤维混凝土应力应变关系及孔结构分析

为了探究纤维掺量对玄武岩纤维混凝土宏、微观性能的影响规律,采用数字图像相关方法与微观气孔结构分析仪对不同纤维掺量的混凝土试件进行试验研究,通过数据回归建立了纤维掺量与平均峰值应力之间关系,给出了玄武岩纤维混凝土单轴受压应力-应变曲线上升段表达式;结合微观孔结构,建立了平均峰值应力与含气量、平均气泡弦长、气孔间距、比表面积相关公式,同时采用分形维数定量描述微观孔结构与玄武岩纤维混凝土抗压强度、弹性模量的关系.结果表明:玄武岩纤维的加入能够提高混凝土平均峰值应力和峰值应变,对试件应力-应变关系曲线上升段改变不明显;玄武岩纤维的加入能够减少混凝土内部缺陷,降低混凝土含气量、减小平均气泡弦长,使混凝土内部孔结构得到优化,孔隙分布较为均匀,抗压强度提高,割线模量有所下降.

Basalt Fiber Reinforced Concrete Stress-Strain Relationship and Pore Structure Analysis

In order to explore the effect of fiber content on the properties of basalt fiber reinforced concrete macro and micro , the digital image correlation method and the microscopic pore structure analyzer were used to test different fiber content of the concrete specimen .Based on data regression , the relationship between the fiber content and the average peak stress was established .And the expression of the ascent stage of stress-strain curve under uniaxial compression was also set up .Combine with microstructure , the formula of the average peak stress and the air content , the average bubble chord length , the hole spacing , the specific surface area was given .At the same time , the fractal dimension was used to quantitatively describe the relationship between microstructure and compressive strength and elastic modulus of basalt fiber reinforced concrete .The results show that the basalt fiber can improve the average peak stress and peak strain of concrete , but cannot change the ascent stage of stress-strain curve obviously .And the addition of basalt fiber not only reduce the internal defects of concrete , but reduce the gas content and the average chord length of concrete , also make the internal pore structure of concrete be optimized and the pore distribution is uniform , besides the compressive strength is improved and the secant modulus decreases .