Direct shear strength of steel fiber reinforced concrete

Abstract

Conventional concrete presents in its mechanical behavior low tensile and shear strengths when compared to the compressive strength. In order to improve these mechanical properties, several researches have evaluated the combination of concrete matrix with steel fibers, resulting the steel fiber reinforced concrete composite (SFRC), a heterogeneous mixture that aims to adequately unite the characteristics of its components and obtain improvements in the mechanical behavior of the material, especially when applied to structures. This work evaluates the mechanical behavior of SFRC specimens compared to conventional concrete. A reference concrete mixture with axial compressive strength around 40 MPa was produced, in which hooked end steel fibers of 60 mm in length, diameter of 0.75 mm and shape factor of 80 were added, in the volumetric fractions of 0.5 and 1.0%, percentages in relation to the total volume of concrete. Eighteen prismatic specimens (150mmx150mmx500mm) were cast and submitted to the direct shear test until rupture, and the ultimate stress and vertical displacement of the shear plane were evaluated. The results showed a reduction in the axial compressive strength due to the addition of fibers, however, it obtained gains in tensile and shear strength and increased concrete toughness, avoiding its sudden rupture.