Mechanical properties of steel fiber reinforced recycled aggregate concrete

This study experimentally investigates the mechanical properties of steel fiber reinforced recycled aggregate concrete (SFRRAC). The smaller strength and ductility of recycled aggregate concrete (RAC), compared to those of natural aggregate concrete (NAC), have restricted its use to mainly non-structural applications in the construction industry. Such limitations in the mechanical behavior of RAC can be overcome by adding industrial steel fiber (SF). In this study, the split-tensile strength, the compressive strength, the toughness under compression and the elastic modulus for 25 SFRRAC mixes are experimentally investigated. These 25 mixes were prepared from combinations of five different volume fractions of SF, 0, 0.3, 0.5, 0.7 and 1.0% and five different replacement proportions of natural aggregates (NA) by recycled aggregate (RA), 0, 30, 50, 70 and 100%. From experiments, it was observed that the split-tensile strength, the compressive strength and the elastic modulus of SFRRAC mixes decreased with RA content; the split-tensile strength and the toughness under compression increased with SF content. However, there was no clear correlation observed between the SF content and the compressive strength or the elastic modulus. Regression models were established based on the RA and SF contents in the SFRRAC mixes to predict their split-tensile strength, compressive strength and elastic modulus.