MECHANICAL PROPERTIES IMPROVEMENT OF FIBER REINFORCED CONCRETE

Fiber reinforced concrete mechanical properties are limited due to low adhesion between polymer fibers and cement matrix. To ensure a strong interaction between the two materials, polypropylene fibers (d = 0.305mm) were modified by an oxygen plasma treatment. The interface interaction was moreover activated using finely ground concrete recyclate, whose individual grains (1？64 μm) ensure an adhesion improvement in interfacial zones. The adhesion enhancement was verified by pull-out tests, when reference and modified fibers were pulled-out from cement matrix specimens. Such obtained results were used as a crucial parameter to numerical simulations of bending tests of specimens (550 × 150 × 150mm) with properties following fiber reinforced concrete. It was shown that samples reinforced with modified fibers and contained activating recyclate reached on higher residual bending strength then those with reference fibers