Equivalent Confinement in HPFRCC Columns Measured by Triaxial Test

The ductility of high-performance fiber-reinforced cementitious concrete (HPFRCC) can be developed not only in tension but also in compression. This aspect is evidenced in the present paper by comparing the behavior of HPFRCC cylindrical specimens under uniaxial compression, with the mechanical response of normal vibrated concrete (NC) and self-consolidating concrete (SCC) subjected to triaxial compression. The ductility of all the cement- based composites is computed through a nondimensional function that relates the inelastic displacement and the relative stress during softening. In the case of NC and SCC specimens, the results show that increasing the confining pressure results in an increase in fracture toughness. Conversely, the tests on HPFRCC specimens show that, even in the absence of confinement, HPFRCC can achieve practically the same ductility observed in normal and self- consolidating concretes with 1 MPa (0.15 ksi) of confining pressure. Thus, the presence of HPFRCC in compressed columns is sufficient to create an active distributed confinement.