Experimental Investigation on Mechanical Properties of Hybrid Fiber-Reinforced Concrete Using Steel and Polypropylene Fibers

Concrete is inherently brittle and weak in tension, which leads to cracking and reduced durability of structures. To overcome these limitations, fiber- reinforced concrete has been widely studied. In this experimental investigation, the mechanical performance of hybrid fiber-reinforced concrete (HFRC) incorporating steel fibers and polypropylene fibers was evaluated. M30 grade concrete was designed as per IS 10262:2019. Steel fibers and polypropylene fibers were added in different combinations, and their effects on workability, compressive strength, split tensile strength, and flexural strength were studied at curing ages of 7, 14, 28, and 56 days. The results showed a slight to moderate improvement in compressive strength, significant enhancement in split tensile strength, and major improvement in flexural strength due to hybrid fiber action. Crack behaviour analysis revealed effective control of micro-cracks by polypropylene fibers and bridging of macro-cracks by steel fibers, resulting in ductile failure behaviour. The study confirms that hybrid fiber-reinforced concrete offers improved mechanical performance compared to conventional concrete.