短切碳纤维对混凝土孔结构及特征的影响

为探究短切碳纤维(CFs)对混凝土内部孔结构微观特征的影响规律,制备体积掺量分别为0%、0.1%、0.2%、0.3%和0.5%的短切碳纤维增强混凝土(CFC)试件,采用压汞法(MIP)分析各组试件内部孔结构特性,并引入分形理论对孔径分形规律展开进一步探讨。结果表明:掺入适量的CFs可有效降低混凝土总孔隙量和平均孔径,且掺量为0.1%时改善效果最佳;混凝土内部孔径具有显著的分形特性,各组试件ln(W_n/r²_n)、ln Q_n曲线拟合相关系数R²均在0.996以上,斜率可作为孔表面积分形维数(D_p);随着CFs掺量的增加,D_p先减小后增大,且D_p越大,平均孔径越大,进一步验证了CFs对混凝土内部结构的改善规律。

Effects of Chopped Carbon Fibers on Pore Structure and Characteristics of Concrete

For the purpose of explore the effects of chopped carbon fibers (CFs) on the microscopic characteristics of the internal pore structure of concrete, chopped carbon fibers reinforced concrete (CFC) specimens with volume content of 0%, 0.1%, 0.2%, 0.3% and 0.5% of CFs were prepared. The internal pore structure characteristics of each group of specimens were analyzed by means of mercury intrusion porosimetry (MIP), and the fractal law of pore size was further discussed by introducing fractal theory. The results show that adding an appropriate amount of CFs can effectively reduce the total porosity and average pore size of concrete, and the improvement effect reaches the best when the content of CFs is 0.1%. The inner pore size shows remarkable fractal characteristics, and the fitting correlation coefficient R² of ln(W_n/r²_n) and ln Q_n of each group specimens of concrete is more than 0.996, which means the slopes can be used as pore surface fractal dimension (D_p). The D_p decreases firstly and then increases with the increase of CFs content, and the larger the D_p is, the larger the average pore size is, which further verifies the improvement law of CFs on the internal structure of concrete.