Mechanical properties of twisted galvanized iron fiber reinforced concrete with different contents and pitches

Utilizing galvanized iron (GI) instead of expensive steel fiber has become a new technique in concrete construction to improve the mechanical properties of concrete. Tensile strength tests confirm that twisted GI fibers could serve as a viable alternative to steel fibers. Using deformed fiber instead of straight fiber increases the strength parameters of concrete significantly. As such, twisted GI fibers were employed in this study to improve the quality of the concrete. The GI fibers were mechanically twisted with varying twisting pitches (4, 6, and 8 turns per inch) to create rope-like fibers. Thirteen different concrete mixtures were prepared using three different fiber contents (1.0%, 1.5%, and 2.0% by weight), maintaining a constant 25.4 mm fiber length. Compressive strength, split tensile strength, flexural strength, toughness indices, and residual strength of GI fiber reinforced concrete (GIFRC) were determined. Employing GI fibers increased the compressive strength to a range from 13.4% to 28.9%, the split tensile strength from 18.8% to 42.5%, and the flexural strength from 11.5% to 46.0% compared to the control specimen. Besides, twisted GI fiber increased compressive strength from 1% to 7%, split tensile strength from 2% to 11%, and flexural strength from 3% to 13% than those of plain GIFRC. Toughness indices and residual strengths were significantly higher for GIFRC beams compared to the control specimen, which indicated greater energy absorption capacity of GIFRC. Additionally, strength prediction models were established to estimate different strength parameters with varying twisting pitch of GIFRC. Experimental results resembled the proposed strength models. Therefore, using twisted GI fibers in concrete can be an excellent choice to improve the mechanical properties of concrete. •Three distinct twisting pitches (4, 6, 8 pitch per inch) are utilized in GI fibers.•Twisted GI fibers enhanced the strength parameters of GIFRC over plain concrete.•Increasing the twisting pitch of fibers increased all strength parameters of GIFRC.•Strength prediction models based on twisting pitch are established.