Experimental study of properties of concrete with dosage of recycled steel fibers

Currently, is observing a huge increase in waste tires in the world. Over 1 billion waste tires increase yearly, bringing environmental and health issues. Material recovery of particular waste allows for obtaining recycled steel fibers (RSF). RSFs incorporated in concrete significantly improve recycled steel fiber reinforced concrete's tensile strength and energy absorption (RSFRC). The goal of the experimental research presented in this paper is to investigate the compressive strength of RSFRC, tensile splitting strength and to determine particular fracture mechanical parameters of RSFRC with different doses of RSF. RSFRC compressive strength tests were carried out on three samples for each batch of RSF according to STN EN 12 390-3. Determination of tensile splitting was executed according standard STN EN 12390-6 in case three specimens, cilinders in shape. Selected fracture mechanical properties were determined on three RSFRC beams with a notch for each batch of RSF according to JCI-S-001-2003 and JCI-S-002-2003. Experimental research has shown that with a dose RSF higher than 1.9% by volume an increase in RSFRC compressive strength was observed. Further was invented, that with increase dosage of RSF increase tensile splitting strength of concrete. The bending test result is an increasing trend of fracture energy with an increasing dose of RSF. From this experimental research, it emerged that it is necessary to choose a dose of RSF of at least 1.9% by volume.