Improving the ductility properties of lightweight concrete by steel fiber addition

In this study, the mechanical and fracture properties of the cold bonded fly ash lightweight aggregate concretes (LWACs) with and without steel fiber were experimentally investigated. The LWAC with a constant water-to-cement ratio of 0.40 and 400 kg/m3 cement content were produced with two different volume fraction of artificial fly ash lightweight aggregates. Three types of hooked-end steel fibers with the aspect ratios of 55, 65, and 80 were utilized with four different volume fractions of 0.35, 0.70, 1.00, and 1.50% of concrete volume. The effectiveness of aspect ratio, steel fiber volume fraction, and lightweight aggregate volume fraction on the compressive, splitting tensile, flexural and bond strengths, modulus of elasticity, fracture energy and characteristic length of concrete were investigated at the end of 28-days of water curing. The results have revealed that utilization of steel fiber enhanced splitting tensile, flexural, bond strengths of LWACs. The compressive strength, however, were not affected significantly by the steel fiber addition. The utilization of steel fiber considerably increased the fracture energy and characteristic length. Moreover, the compressive, splitting tensile, flexural and bond strengths, fracture energy, and characteristic length were significantly influenced by the artificial fly ash lightweight aggregate content.Keywords: Concrete; Fracture properties; Lightweight cold-bonded fly ash aggregate; Mechanical properties; Steel fiber.