Fiber pullout behavior of HPFRCC: Effects of matrix strength and fiber type

This study investigated the effects of fiber type and matrix strength on the fiber pullout behavior of high-performance fiber-reinforced cementitious composites (HPFRCC). The correlation between single fiber pullout behavior and flexural behavior of HPFRCC was also evaluated. Two different steel fibers, i.e., straight and hooked steel fibers, and three different matrix strengths were adopted. Test results indicate that the fiber pullout performance was improved with increasing matrix strength. The hooked fibers exhibited higher bond strengths and pullout work than the straight fibers, but at large slips, they showed smaller shear stress at the interface than their counterpart. In addition, the straight fibers were more effective in improving the pullout performance with the matrix strength than the hooked fibers. For the straight fibers, the shorter fibers provided higher bond strengths and maximum shear stress at the interface than the longer fibers. The flexural performance of HPFRCC beams was improved with increasing matrix strength. The beams with medium-length straight fibers (l_f/d_f = 19.5/0.2 mm/mm) gave the best flexural performance, whereas those with hooked fibers exhibited the worst flexural performance. Due to several influential factors, the correlation between the single fiber pullout behavior and flexural behavior of HPFRCC beams was quite low.