Analysis of Flexural Strength in Reinforced High-Sterength Concrete Beams with Macro-Polypropylene Fibers Additives

High Strength Concrete (HSC) possesses high compressive strength however relatively low resistance against tensile forces and cracking forces. The application of steel rebar in Reinforced Concrete aids in tackling tensile stresses however the brittle nature of HSC is still present. The incorporation of fiber materials such as polypropylene fibers into the concrete mix is an innovation done to improve tensile strength, flexural strength, post-cracking strength and crack resistances. This study aims to analyze the effect of addition of macro-polypropylene fibers at volume fractions 0.5%, 1.0%, and 1.5% on the compressive strength of HSC cylinders as well as flexural strength, deflection, and crack resistance of HSC reinforced beams. The methodology of this study includes the determination of HSC mix design incorporating macro-polypropylene fibers to form High Strength Macro-Polypropylene Fiber Reinforced Concrete (HSMPFRC), compressive strength testing of cylinders, design and preparation of reinforced concrete beams, flexural strength testing and comparative analysis of test results. Results showed an increase in compressive strength for fiber dosages 1.0% and 1.5% in comparison to control, with the highest increase for a dosage of 1.5%. Flexural strength test results showed increases for all fiber dosages compared to control, with a dosage of 1.0% creating the highest flexural strength. This study concludes that compressive and flexural strength improves the compressive, flexural strength and crack resistance of HSC cylinders and reinforced beams respectively. However, the effect on deflection and cracking patterns is not as conclusive.