The Efficiency of Hybrid Fibers (Steel and Carbon Fibers) in Controlling Micro Cracking of Concrete Beams

Micro Cracking (MC) is one of the major defects in concrete which significantly reduces the durability of reinforced concrete structures. Achievement of high compressive strength using high cement content is the major reason for the MC of concrete. In the present research, the efficiency of steel-fiber reinforced concrete (SFRC) and carbon-fiber-reinforced concrete (CFRC) was examined to minimize the MC in concrete. The properties of SFRC and CFRC were compared with that of plain cement concrete (PCC). Hooked steel fibers (SF) and chopped carbon fibers (CF) were used in this research. Two different combinations of fibers denoted a combination-1 (C1) and combination-2 (C2) were also prepared to check their behavior on the MC of concrete. Different tests were carried out in the laboratory such as compressive strength (CS), tensile strength (TS), modulus of rupture (MOR), and flexure strength (FS) on PCC, SFRC, CFRC, C1, and C2 specimens. The results showed that there is an increase of 28.2%, 5.6%, 7.1%, and 18.3% for SFRC, CFRC, C1, and C2, respectively, in CS of concrete as compared to that of PCC. The results also depicted that TS of SFRC, CFRC, C1, and C2 is increased by 39%, 30.1%, 8%, and 27.1%, respectively, in comparison with PCC. The maximum flexural load of SFRC beams was increased by 11.6%, while the maximum flexural load of CFRC is reduced by 10.5% as compared to the PCC beam. Therefore, it can be concluded from the results that the use of hybrid fibers is suitable for controlling the MC in concrete and enhancing the mechanical properties of concrete.