基于混凝土切割面统计方法的纤维取向分布研究

Study on the Distribution and Orientation of Fibres Based on Statistics Method of Concrete Cutting Section

纤维分布和取向是影响纤维增强混凝土力学性能的重要因素。本文采用混凝土切割面统计方法研究不同水胶比和振捣时间对钢纤维混凝土中纤维分布及取向的影响。结果表明:随着水胶比和振捣时间的增加,边壁效应对纤维分布影响减弱;高水胶比条件下纤维在垂直于振捣方向上出现了偏析现象(垂直方向上的不均匀分布),随振捣时间增加,偏析更显著;对于高性能混凝土,增加振捣时间有利于纤维的均匀分布,而普通混凝土应缩短振捣时间。此外,统计结果表明,钢纤维取向角分布呈现高斯分布规律,峰值处于40°~50°。当水胶比为0.45,振捣时间为20 s,纤维取向角在45°附近,纤维数量占比最大,纤维取向系数达到0.73。

The distribution and orientation of fibres exert important effect on the properties of fibre-reinforced concrete(FRC).In this study,the effect of water/binder ratio and vibration time on the distribution and orientation of fibres in concrete were investigated by statistical method.The results showed that with increase in water/binder ratio and vibration time,the effect of boundary on the distribution of fibres decreased and an obvious segregation of fibres(uneven gradient distribution)appeared in the vertical direction of vibration.Furthermore,as the vibration time increased,the fibres was evenly distributed,the impact was more pronounced for the low water/binder ratio.In order to improve the dispersibility of fibers,it is better to increase vibration time for high performance concrete and reduce the time for ordinary concrete.In addition,the statistical analysis indicated that the orientation of fibers on cutting section took on a Gauss distribution,the peak point of the curve was at about 40°~50°.When the vibration time was 20 s,the water/binder ratio was 0.45,the fiber dispersion coefficient reached the maximum of 0.73.