PULLOUT RESPONSES OF STEEL FIBERS IN FIBER REINFORCED MORTAR MATRICES

Abstract

In fiber reinforced concrete (FRC), a flexural toughness is enhanced by
the inclusion of fibers. The enhancement primarily depends on bond-slip
characteristics between fibers and matrices. Recently, the concept of fiber
hybridization is recognized as it synergizes the toughness performance. In
the case of the hybridization between finer and coarser fibers, the finer
fibers alter the properties of the matrices, which may affect the bond-slip
response of the coarser fibers. Such influence was studied experimentally
through a single fiber pull out test in this study. A series of tests was
conducted to test the pullout resistance of two different types of steel
fibers (i.e. hooked-end fibers and dead-drag fibers) inserted in four
different cement mortar matrices (i.e. plain mortar, cellulose fiber
reinforced mortar, 6-mm polypropylene fiber mortar, and 12-mm
polypropylene fiber reinforced mortar). Four replicates were investigated
in each combination. Results of the test show that the fibers in the
matrices improve the bond-slip responses of the dead-drag fiber but only
slightly change the bond-slip responses of the hooked-end fiber.