Effects of Steel Fibers on the Mechanical Properties of Concrete

Abstract

Steel Fiber reinforced concrete is constructed by adding short fibers of small cross-sectional size to the fresh concrete. Fibers reinforce the concrete in all directions, as they are randomly oriented. The mechanical properties of concrete, that are improved, include ductility, impact resistance, compressive, tensile and flexural strength and abrasion resistance. These unique properties of the fiber reinforcement can be exploited to a great advantage in concrete structural members containing both conventional bar reinforcement and steel fibers. The improvements in mechanical properties of cementitious materials resulting from steel fiber reinforcement depend on the type, geometry, volume fraction and material properties of fibers, the matrix mix proportions and the fiber matrix interfacial bond characteristics. Effects of steel fibers on the mechanical properties of concrete are investigated through a comprehensive testing programme by varying the fiber volume fraction and the aspect ratio (L/d) of fibers. Significant improvements are observed in compressive, tensile, flexural and impact resistance of concrete accompanied by marked improvement in ductility. Optimum fiber volume fraction and aspect ratio of steel fibers is identified. Test results are analyzed in details and relevant conclusions drawn. The research is finally concluded with future research needs.

ABBREVIATIONS & NOTATIONS

ACI American concrete institute PCC Plain cement concrete SFRC Steel fiber reinforced concrete FRC Fiber reinforced concrete SFRS Steel fiber reinforced shot Crete Psi Pounds per square inch Ksi Kips per square inch ASTM American standard of testing materials BS British standards Lb Pounds Yd Yards in (") Inch / Inches Mm Millimeter Fol Following /Follows min Minutes MS Mild steel fc´ Compressive strength of concrete Fig Figure Kgs Kilograms % Percent / Percentage Dia Diameter Mix Mixture