Investigation of mechanical characteristics and specimen size effect of steel fibers reinforced concrete

Abstract

Steel fiber reinforced concrete (SFRC) is a new construction material with good tensile strength, fracture toughness, and ductility. Although many aspects of SFRC have been investigated extensively, the size effects on structural strength of SFRC members remain largely preoccupant. This study investigates the size effect on flexural strength of SFRC beams under three-point bending tests. For this purpose, four mixtures were made: a concrete without fibers as control concrete, and concretes reinforced with 0.5, 1, and 1.5% of steel fibers (SFs) of total concrete volume. The experimental test results indicate that the addition of fibers, even small quantities reduces concrete workability that needs more superplasticizer added. Flexural and compressive strength are improved and crack opening is limited as the fiber content increases. SFs are more efficient in flexural strength and make SFRC more sensitive to the size effect. New relationships are presented which fit the data quite well and give an accurate correlation with the experimental results according to the size effect and the quantity of fibers present in concrete mix.