PNRC Sustainable Production of Manholes Covers with Fiber Concrete

Abstract

The use of Fiber Reinforced Concrete (FRC) as a building material is experiencing a consistent upward trend. Traditional concrete is known for its fragility, exhibiting a flexural strength that typically reaches only 10-15% of its compressive strength. The integration of fibers into the concrete mix significantly boosts several mechanical characteristics, including tensile strength, flexural strength, and ductility. One of the notable benefits of fiber-reinforced concrete is its ability to take into account the performance of cracked concrete below the neutral axis in a beam's cross-section to a certain degree. The stress-strain model suggested by Beshara is instrumental in accounting for the influence of FRC on the tension side, a factor that has been historically overlooked due to plain concrete's poor tensile properties. The current study utilizes a mix design of 1:4:2:0.8 (cement: sand: aggregate: water) to prepare plain concrete. Pine needle fibers of varying lengths—37mm, 50mm, and 62.5mm—are employed in the creation of Pine Needle Fiber Reinforced Concrete (PNFRC). Enhancements include a 2.5-fold increase in energy absorption, a fivefold rise in the toughness index, a maximum deflection of up to 12mm, and a 34% reduction in the Modulus of Rupture (MoR). Additionally, the specimens demonstrated ductile behavior in comparison to reference samples. Overall, pine needle fibers show promising potential for use in cement concrete composites for a variety of structural purposes.