What is it about?

In this study, the influences of bidirectional carbon fiber–reinforced polymer (CFRP) confinement along with polypropylene fibers on the impact resistance of concrete samples were experimentally studied. Forty-nine concrete cylindrical samples (with compressive strengths of 20, 30, and 40 MPa) with polypropylene fibers (with content ratios of 0 %, 1 %, 1.5 %, and 2 %) were subjected to weight (46.7 and 66.8 kg) dropping at a height of 1.6 m above the cross-section of the sample. Moreover, half of the samples were tested with CFRP confinement. The number of weight releases required to destroy the samples and the weights of the samples after each release were recorded. The results indicated that the concrete without fibers and fiber-reinforced polymers (with compressive strengths of 20, 30, and 40 MPa) did not have sufficient impact resistance and were swiftly destructed. However, as the content ratios of polypropylene fibers increased, the number of cracks and weight droppings (to reach 70 % of the initial sample weight) increased. Moreover, it was observed that the concrete samples wrapped with the CFRP sheets also withstood impact loading better than fiber-reinforced concrete samples without the confinements. Besides, it was indicated that the prevailing failure mode of the samples with CFRPs was CFRP rupturing. Finally, it was observed that the more the compressive strength of concrete, the more the impact resistance.

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Why is it important?

The novelty of this study is considering the interaction between the CFRP sheets and PP fibers, and their effects on the improvement of the axial impact behavior of concrete specimens. it was also tried to compare the effects of PP fibers and CFRPs on the improvement in the impact behavior.


Writing this article was a great pleasure and honor as it has co-author s(especially Prof. Kheyroodin) with whom I have had long standing collaborations. Prof. Kheyroddin is one of the outstanding researchers has been focusing on concrete structures during recent years, and has published numerous papers regarding them.

Dr. Hamed Arshadi
Semnan University of Medical Sciences and Health Services

Read the Original

This page is a summary of: Impact Behavior of Fiber-Reinforced Concrete with Polypropylene Fibers and Carbon Fiber–Reinforced Polymers, Journal of Testing and Evaluation, April 2021, ASTM International, DOI: 10.1520/jte20200670.
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