Sharif Journal of Civil Engineering

Sharif Journal of Civil Engineering

Investigation of Parameters Affecting Bond Strength and Pull-Out Behavior of Polyethylene Terephthalate Ropes in Steel Fiber-Reinforced Cementitious Composites

Document Type : Research Note

Authors
Reza Akbarifar
Alireza Mortezaei
Ali Babaei
Department of Civil Engineering, Semnan branch, Islamic Azad University, Semnan, Iran
10.24200/j30.2025.67085.3436
Abstract
This study investigates the bond behavior of braided ropes made from recycled polyethylene terephthalate (PET) as a potential alternative to conventional steel reinforcement in fiber-reinforced cementitious composites (FRCC). Pull-out tests were conducted according to RILEM RC6 standards on FRCC specimens containing different volume fractions of steel fibers, using steel rebars and PET ropes with equal diameters (14 mm). The experimental results revealed that the maximum pull-out force was approximately 30 kN for steel bars and 7.6 kN for PET ropes, indicating a 75% reduction in bond strength for PET compared to steel. However, the displacement corresponding to the peak load was about 23.5 mm for PET ropes and only 0.6 mm for steel bars, representing a 40-fold increase in ductility for PET.
In all experiments, PET ropes failed internally without being pulled out from the matrix, while steel bars exhibited bond-slip failure.
The inclusion of steel fibers in the matrix significantly enhanced the bond performance, especially in terms of energy absorption and post-peak ductility.
For instance, in specimens containing 1% steel fibers, the maximum pull-out load of the PET ropes reached 7.6 KN at a displacement of 9.3 mm, showing a clear improvement over fiberless samples.
The experimental observations were further analyzed by comparing the bond–slip responses of PET and steel reinforcements, which demonstrated that PET exhibits a gradual softening after peak load instead of a brittle bond loss. This characteristic suggests a more stable and energy-dissipating interfacial mechanism. In addition, the use of recycled PET not only provides a sustainable and eco-friendly reinforcement option but also contributes to reducing construction waste and CO₂ emissions. Such properties make PET ropes particularly suitable for structures requiring high ductility and seismic resilience. The findings of this study can serve as a reference for future modeling of PET–concrete interface behavior and for developing design guidelines for sustainable fiber-reinforced composites.
Keywords
Recycled pet rope
fiber-reinforced cementitious composites (FRCC)
pull-out test
bond behavior
steel fiber
ductility
sustainable reinforcement
Subjects
 
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Sharif Journal of Civil Engineering
Volume 42, Issue 1 - Serial Number 1
Spring 2026
Pages 117-126