Experimental investigation of effects of fly ash in mechanical properties of Hybrid fiber reinforced cementitious composite

Document Type : Research Article


1 assistant professor, faculty of engineering, lorestan university,khorramabad, iran

2 Graduated MS of Structural Engineering, Department of Engineering, Science and Research Branch, Islamic Azad university, Tehran, Iran


Enhancement of the tensile strength of conventional concrete by using fibers is expanding. The use of fiber cementitious composite and the benefits of microfiber and PVA fibers can be considered to improve the mechanical property of self-compacting concretes. This study deals with the mechanical properties of high-performance Hybrid fiber reinforced cementitious composite samples reinforced with micro steel fibers and PVA as well as a combination of them. In order to achieve the study goals, 10 mix designs were considered. All mix designs of composite underwent compressive, tensile, flexural strength and ultrasonic pulse velocity tests. The compressive strength, tensile and flexural strength tests were performed on cube (100mm), cylindrical (100x200mm) and prismatic beams (320x80x60mm), respectively. Also, ultrasonic pulse velocity testing was carried out on cubic (100mm) specimens. Results of these tests exhibit high variability and vary considerably with the different types of mixtures, fiber contents so that the micro-steel fibers have a great effect on the mechanical strength of the specimens than PVA fibers. The specimens with a high percentage of micro-steel fibers compared to those with a high percentage of PVA showed higher resistance to the first flexural crack, failure, and final energy absorption. In addition, by adding a pozzolanic material like fly ash, the 28-day resistance of all the mechanical property of the specimens were reduced.


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