Evaluating the effect of sample size on the flexural strength of concrete containing polyethylene terephthalate fibers with the optimal content

Aziz, Hedi Othman; Mohammed, Azad Abdulqadir

doi:10.63463/kjes1100

	Evaluating the effect of sample size on the flexural strength of concrete containing polyethylene terephthalate fibers with the optimal content
Kerbala Journal for Engineering Sciences (KJES)
Volume 3, Issue 4, December 2023, Pages 188-209 PDF (2.02 M)
Document Type: Research Article
DOI: 10.63463/kjes1100
Authors
Hedi Othman Aziz^* ; Azad Abdulqadir Mohammed
Civil Engineering Department, College of Engineering, University of Sulaimani
Abstract
This study investigates the impact of specimen size on the flexural strength of concrete reinforced with optimized polyethylene terephthalate (PET) fibers. A series of experimental tests were conducted using various PET fiber ratios (0.5 to 1.5% by the total volume of the mix) and lengths (15, 30, and 45 mm) to highlight the optimized PET fiber in concrete. Flexural strength tests were carried out on prismatic specimens of varying sizes (100x100x400 mm, 100x150x500 mm, and 100x200x700 mm) and different concrete grades (20, 35, and 45 MPa). The findings indicate a significant improvement in the splitting tensile strength of the concrete, reaching up to 18.43% with the addition of PET fibers. These fibers effectively act as bridges across cracks, reducing their width and halting their propagation. The optimal PET fiber length was identified as 30 mm, added to the concrete at a rate of 1% by the total volume of the mix. Moreover, the results revealed a noticeable effect of the specimen size on the flexural strength of PET fiber-reinforced concrete, with an inverse relationship between specimen size and measured flexural strength. As the size of the specimen increased, the flexural strength decreased. Based on the experimental data, an empirical relationship was developed to quantify the flexural strength of optimized PET fiber-reinforced concrete considering the size effect. These relationships provide practical tools for engineers to accurately account for the size effect in the design and analysis of fiber-reinforced concrete structures.
Keywords
PET fiber; compressive strength; splitting tensile strength; flexural strength; size effect; regression analysis

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