Muthanna Journal of Engineering and Technology
Volume (12), Issue (1), Year (30 June 2024), Pages (13-21)
DOI:10.52113/3/eng/mjet/2024-12-01/13-21
Research Article By:
Iman H. Majeed, Mazin A. Ahmed and Haleem K. Hussain
Corresponding author E-mail: pgs2350@uobasrah.edu.iq
ABSTRACT
The use of fibers has become widely adopted to enhance the properties of concrete within structural applications, enabling them to withstand various loads. In this research, an experimental study was carried out to examine the impact of incorporating polyolefin fibers (PF) in different ratios on the structural response of reinforced concrete beams to a purely torsional load. The study examined four polyolefin fiber ratios (PFR) (0.0%, 0.5%, 1.0%, 1.5%) for both normal and high strength concrete. A total of 8 reinforced concrete beam specimens were fabricated; four specimens were made of normal concrete and the remaining four were made of high strength concrete. In addition to assessing the torsional behavior of the specimens, the mechanical characteristics of the concrete were investigated. The results demonstrated that the PF had a negligible influence on the concrete compressive strength of both levels. However, the tensile and flexural concrete strengths showed an improvement as the fiber content increased. Specifically, the tensile strength increased by approximately 78% and 41% for normal and high strength concrete, respectively when using a 1.5% PFR (polyolefin fiber ratio). Likewise, the flexural strength increased by approximately 88% and 65% for normal and high strength concrete, respectively, with 1.5% PFR. The experimental torsional test results indicated that torsional performance improved with increasing PFR. The ultimate torsional load demonstrated a 74% and 45% increase for a 1.5% PFR compared to specimens without fibers for normal and high strength concrete, respectively. Additionally, the twist angle of the specimens increased with increasing PFR, reflecting an improvement in their ductility. It is worth noting that the rate of improvement decreased after reaching a PFR of 1.0%.
Keywords: Torsional Strength, Polyolefin Fiber, High Strength, Normal Strength, Pure Torsion.