An Experimental Study on the Effects of Adding Steel and Polypropylene Fibers to Concrete on Its Resistance after Different Temperatures

Abstract

The use of fibers in concrete improves strength, ductility, and durability of concrete. Concrete has fireproofing properties, but rebars are the most important concern of reinforced concrete structures in the event of a fire outbreak. Therefore, one of the recommendations to reduce these risks is the use of alternative materials like fibers. In this article, the effects of different temperatures on the mechanical properties of concretes with different cement contents containing steel and polypropylene fibers were studied. The specimens were placed under temperatures of 25°C, 100°C, 250°C, 500°C, and 700°C, and the results revealed that the effects of fire on concrete containing steel fibers are more damaging. Also, the compressive strength and modulus of rupture at 25°C and tensile strength at 250°C have the maximum values. Compressive and tensile strengths of concrete containing steel fibers were 40 % and 50 %, respectively, more than the concrete containing polypropylene fibers. However, their flexural strength was almost equal. By comparing the flexural strength of specimens with grade 400 and grade 700, it can be concluded that the specimens with grade 400 have more resistance by about 10 to 40 %.

Use of polypropylene fibers extracted from recycled surgical face masks in cement mortar

“…When the fiber content surpassed the volume fraction of 0.36 %, the concrete’s strength declined because of interference from high-volume fibers due to concrete–matrix cohesion, making concrete compacting more difficult (reducing its workability) [17] . PP fibers have also been used to potentially enhance the fire resistance of concrete in high-temperature conditions [18] , [19] , [20] , [21] . According to Pachideh et al [18] , [19] , [20] and Gholhaki et al [21] the primary reason for adding PP fibers, steel fibers, and recycled metal springs to concrete is to prevent the formation of large cracks in high temperatures.…”

An experimental study to evaluate the postfire mechanical properties of concrete specimens

“…Six target temperatures ( T u ) of 25, 100, 250,500,700, and 900°C were selected. The target temperatures were selected according to the behavior of concrete in different conditions which have been investigated in previous studies 23,24 . After reaching the target temperature, temperature will be constant for 60 min until the sample reaches thermal stability stage and uniform distribution of heat is achieved.…”

“…The study of concrete delamination and its mechanical properties are the most important focuses of this research. Pachideh et al 23,24 investigated the performance of concrete containing recycled springs, steel, and polypropylene fibers at different temperatures.…”

بررسی تأثیر الیاف هیبریدی در مقاومت الکتریکی و مقاومت دینامیکی بتن در برابر انفجار بتن

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