An experimental study on the post-cracking behavior of Polypropylene Fiber Reinforced Concrete core samples drilled from precast tunnel segments

In the scientific community and among designers there is a growing interest on macro-synthetic fibers for use in underground structures, especially for precast tunnel segmental linings. Moreover, in the last decade, important research efforts have been devoted to the development of new types of structural macro-synthetic fibers, which are now able to impart significant toughness and ductility to concrete. The enhanced post-cracking strengths of concrete, which are provided by the presence of polypropylene fibers, can be included in analytical and numerical approaches for designing precast tunnel segments in Polypropylene Fiber Reinforced Concrete (PFRC). However, it is still a matter of discussion the actual post-cracking performances exhibited by PFRC in precast tunnel segments. Within this framework, an experimental study on core samples drilled from precast tunnel segments in PFRC (considering different positions and directions) was carried out in order to shed some new lights on fiber distribution and orientation. The actual PFRC post-cracking performances evaluated by uniaxial tensile tests on drilled core samples from segments, were compared against the results of typical flexural standard tests on notched beams.