A Comparative Study on the Effect of Coconut Coir, Steel and Hybrid Fiber Length on the Mechanical Properties of Concrete

Although fiber reinforcement is popular for enhancing concrete's durability and cost-effectiveness, there is limited data on how natural and artificial fibers behave when used together in one mixture.This paper addresses that gap by comparing the mechanical effects of steel fibers, coconut coir and a hybrid combination of both.We prepared specimens using fiber lengths of 25 mm, 50 mm, and 75 mm, keeping a constant fiber content of 1.5% within a 1:1.5:3 concrete mix using a water-tocement ratio of 0.5.For the hybrid batches, we specifically combined 0.75% steel and 0.75% coconut coir to see if we could effectively balance structural strength with sustainability.The tests on fresh concrete showed that while adding fibers generally makes the mix harder to work with, the 50 mm length offered the best workability for the coconut and hybrid batches, avoiding the clumping issues often seen with shorter fibers.The 28 days tests confirmed that steel fibers naturally provide the biggest boost to compressive and tensile strength.That said, the hybrid samples offered a practical compromise.They were stronger than the plain coconut coir mixes and provide a more sustainable option than using steel alone.We found that the hybrid mix helps mitigate the environmental impact of steel while avoiding the severe strength loss often seen with natural fibers.When we balanced mechanical performance against workability and environmental concerns, the, 50 mm hybrid fiber stood out as the most effective choice for construction.