Effect of ductility on load-carrying capacity of steel fibre reinforced concrete ground slabs

Abstract

Steel fibre reinforced concrete (SFRC) is increasingly being used for ground slab applications. The addition of steel fibres to concrete imparts significant post-cracking ductility (toughness). This ductility is used to determine a post-cracking strength, which when combined with the pre-cracking strength forms the so-called 'design strength' for SFRC ground slabs. Consequently, the SFRC slab thickness can be reduced in comparison with plain concrete (brittle) slabs. The aim of this paper was to assess the effect of ductility on the load-carrying capacity of SFRC slabs and subsequently compare the deformation behaviour of the SFRC slab to an equivalent plain concrete slab. Based on the post-cracking strength specified by the steel fibre manufacturer, a SFRC ground slab was designed to collapse at the same load as the failure load of a plain concrete slab. The two slabs were then cast, cured for 28 days and afterwards loaded at their centre points till failure. Although the SFRC slab was designed to be 16, 6 % thinner, the measured failure load and deflection were found to be approximately equal for the two slabs. These test results indicate that the load-carrying capacity of concrete ground slabs can be increased by inclusion of nominal steel fibre contents.