Combined effect of iron ore waste and basalt fiber with high-volume supplementary cementitious materials on the workability, strength, and microstructure of sustainable concrete

Meeting the requirements of the construction market and addressing the scarcity of virgin materials pose significant challenges in increasing the required concrete amounts for construction projects. This study explores the workability, density, and strength properties of sustainable concrete containing partial replacement of natural sand with iron ore waste (IOW) as a fine aggregate. In the first group, four concrete mixtures were prepared using different percentages of IOW (0 %, 15 %, 30 %, and 60 %) to replace natural sand. Basalt fiber was added into the second group of four concrete mixtures to enhance fiber-reinforced concrete (FRC) in the volume of 2 % of the cement weight. High volume of supplementary cementitious materials (SCMs) including fly ash (FA) and silica fume (SF) were used to replace cement in proportions of 35 % and 15 %, respectively to achieve sustainable concrete with low cement content. The results obtained show that an increase in replacement levels of IOW led to a decrease in the slump value of the concretes, from 120 mm to 80 mm, with a reduction rate of 33 %. The addition of 30 % IOW as fine aggregate led to an increase in the compressive strength of concretes by 47.34 %. Scanning electron microscopy (SEM) images revealed that the high porosity of IOW contributed to these changes in concrete properties. It is recommended to optimize concrete mixes based on the specific needs of civil engineering applications. This includes selecting different mix designs tailored for the desired structural performance, durability, and environmental conditions. Using IOW as fine aggregate in the concrete mix will help conserve resources for the next generations and enhance waste management, leading to greater sustainability in the construction industry.