Experimental Evaluating the Effect of Steel Fibers on the Mechanical Properties of Roller-compacted Concrete

The use of roller-compacted concrete in construction projects, such as road paving, parking lots, dam construction, and industrial pavement, is attributed to its quick implementation, relatively low cost, and sufficient strength without the need for steel bar. However, the brittle nature of roller-compacted concrete prompted an investigation into how steel fibers could improve its mechanical behavior. This research focused on the effect of steel fibers on fracture strength, compressive strength, and tensile strength of roller-compacted concrete. The study involved testing semicircular samples with edge cracks under three-point bending loading to simulate pure tension, pure shear, and their combination. Additionally, the compressive and tensile strength of roller-compacted concrete samples with steel fibers were evaluated at 7 and 28 days. The laboratory results showed that adding 0.1%, 0.3%, and 0.5% steel fibers improved the 28-day compressive strength by 12%, 15%, and 36%, respectively, and the tensile strength by 14%, 21%, and 39%, respectively. Moreover, the failure load of all samples increased in all loading modes with higher percentages of steel fibers, leading to greater resistance to crack growth. The study identified 0.3% of steel fibers as the most effective amount for improving the fracture resistance of roller-compacted concrete in different loading modes, while the optimal percentage for enhancing the compressive and tensile strength was determined to be 0.5%.