High-performance fibre-reinforced heavyweight self-compacting concrete: Analysis of fresh and mechanical properties

Fibre-reinforcement of most of the concrete technologies, such as heavyweight concrete (HWC) and self-compacting concrete (SCC), would promote their practical applications through upgrading their mechanical properties, and subsequently, structural performance. This study evaluates the fresh and mechanical properties of fibre-reinforced heavyweight self-compacting concrete (FRHWSCC). Magnetite was used as heavyweight aggregate (HWA). Hooked-end steel and polypropylene (PP) fibres with length of 60 and 65 mm and diameter of 0.75 and 0.85 mm, respectively, were applied as reinforcements. Two different HWA content (75% and 100%), and four different volume fractions including 0.25%, 0.50%, 0.75%, 1.00% for steel, and 0.10%, 0.15%, 0.20%, 0.25% for PP fibres were utilized. To evaluate the fresh properties of FRHWSCC, slump flow test including slump flow diameter and T-500mm, and J-Ring test have been performed. Hardened-state density, compressive, tensile, and flexural strength were measured to assess the mechanical properties of FRHWSCC. The obtained results for the fresh properties revealed that despite the negative impact of HWA and fibres on the workability of SCC, the FRHWSCC with both steel and PP fibres were still capable to retain their self-compacting characteristics according to the EFNARC standards. The hardened densities of specimens were above the density threshold for HWC, except for the FRHWSCC containing steel fibre, which showed slight decrease by increasing the steel fibre content to 0.5%, 0.75%, and 1.00% at 75% magnetite content, revealing the void formation within the cement paste. Compressive, tensile, and flexural strength results showed enhancement in the mechanical properties of FRHWSCC by increasing the fibre content, however, for both fibre types, increasing the HWA content impacted the mechanical properties in a negative manner, especially by aging the concrete. Finally, the load-deflection curves analysis confirmed the more ductile failure mode for the FRHWSCC comparing to plain SCC. (C) 2019 Elsevier Ltd. All rights reserved.