Effect of steel fibres on the compressive and flexural strength of concrete

Concrete, which is made of cement, fine and coarse aggregates and water, is the most used building material in the world. It’s durable, strength and ease of availability have been its main advantages. Concrete is strong in compression while it is known to be weak in tensile. Over the years different methods and materials have been utilized to reinforce concrete to overcome such weakness. Fibre reinforcement has shown considerable improvement in the properties of concrete. Therefore, in this study, M20 grade concrete was reinforced with steel fibres which were added at a volume fraction of 1%, 2%, 3%, 4% and 5% and compared with a control sample with no steel fibres. The effect on the workability of concrete with the steel fibre reinforcement was determined as well as the effect on flexural and compressive strengths concrete. Based on the results, the reinforcement of steel fibres had a significant adverse impact on the workability, with the increase in fibre content, the workability decreased. On the other hand, a significant enhancement was observed in the mechanical properties of concrete with the addition of steel fibres, achieving higher strength than the control sample. The highest compressive and flexural strength was gained with the addition of 3%, a further increase in fibre content decreased the strength. Therefore, the optimum dosage of steel fibres was determined to be 3%. Although the compressive and flexural strengths are still higher at 5% reinforcement compared to controlled sample.