结构型纤维对开裂混凝土渗透性能的影响

为研究结构型聚丙烯纤维和结构型钢纤维对带裂缝混凝土渗透性能的影响，通过圆饼试件的反馈劈拉试验预制不同宽度等级的裂缝，借助数码显微镜（supereyes）对不同位置处的裂缝宽度进行测量，利用自行设计的常水头渗透实验装置对带裂缝圆饼试件的渗透率进行测定，利用激光扫描仪对试件开裂面形态进行测量。对比分析了结构型聚丙烯纤维和结构型钢纤维对开裂混凝土渗透性能的影响。研究表明：素混凝土试件在劈拉试验中发生脆性破坏，而掺入结构型聚丙烯纤维和结构型钢纤维的试件开裂后均表现出较好的韧性，裂缝宽度得到较好的控制；随着裂缝宽度的增大，开裂混凝土的渗透率增大；结构型聚丙烯纤维和结构型钢纤维提高了试件开裂面的曲折度和粗糙度，与同等裂缝宽度的素混凝土试件相比，掺加结构型聚丙烯纤维和结构型钢纤维试件的渗透率有不同程度的降低。修正后的泊肃叶定律（Poiseuille law）可以反映结构型聚丙烯纤维和结构型钢纤维对开裂混凝土渗透率的影响。

Effects of macro fibers on the permeability of cracked concrete

In order to study the effects of different macro fibers (including macro polypropylene fiber and macro steel fiber) on the permeability of cracked concrete, the feedback controlled splitting test was adopted to generate pie-shaped specimens with different crack widths. With the aid of digital microscope (supereyes), widths of cracks at different locations were measured. The self-designed experiment system with constant water head was used for testing the permeability of cracked specimens, and the laser scanner was utilized for the measurement of the shape of crack surface. The effects of macro polypropylene fiber and macro steel fiber on the permeability coefficients of cracked specimens were then analyzed and compared. The results show that in the splitting test, the energy absorption capacity and deformability of the specimen was improved due to addition of the macro fibers, and tortuosity and roughness of cracks were also increased. The permeability coefficients of the cracked specimens reinforced with different macro fibers were smaller than those of specimens without reinforcement. The permeability of the cracked concrete reinforced with different macro fibers can be calculated according to the modified Poiseuille law.